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Airflow testing V6 stock versus stock modified intake parts by Brucepts
Started on: 08-28-2011 10:20 AM
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Last post by: Patrick on 12-01-2014 07:55 PM
Brucepts
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Report this Post08-28-2011 10:20 AM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Since there are numbers posted all over the forum of various tested parts, I'm going to post my flowbench numbers in one post so I can keep all my testing together for easy reference. Some followup to my initial testing of the stock 2.8L intake parts (which is on someone else's post here on PFF). I was sent by a forum member (this member can reveal himself if so desired) a modified stock upper intake and a bored throttle body (TB) for comparison testing to a stock setup. The modified intake had the neck area cut out and piece welded in place as can be seen in the photo below. The bored TB was from throttlebodys.com

Airflow was blown through the parts so it would be going in the same direction as when installed on the engine. This also allows me to add on intake system parts so I can end up with a complete intake tract mock-up for flow testing. For reference my flowbench is calibrated with precision orifice plates in intake and exhaust mode.

I started with testing the stock TB on my flowbench comparing it to the bored TB:

stock - 374cfm @28"

bored - 445cfm @28"




I then took the stock and bored TB and added the stock upper intake:

stock - 310cfm @28"

bored - 325cfm @28"

(sorry, no picture of the stock parts being tested)

After this I tested the stock and bored TB with the modified upper intake:

stock - 363cfm @28"

bored - 384cfm @28"



I want to note that I used a stock TB gasket on the bored TB so you might see a few more cfm out of this combination. I only had one gasket and wanted to get these parts tested so I failed to take the time to make a larger gasket. Had the numbers been closer I would have taken the time to make a larger gasket.

This pretty much confirms prior discussion on the forum about the neck of the upper intake being a restriction for overall flow. One thing to note while testing, the runners for 2,4,6 cylinders or the left side of the intake (right side in pic) there was a drastic reduction in flow coming out. Runners 4,6 were actually flowing back in to the plenum.

My next testing will be on each individual runner to compare those numbers to each other for flow distribution. I’ll add those results when I get the numbers.

I’m posting my results for those who would like to follow along, learn and add to the discussion using stock modified parts. For myself, learning is what I am after, if you want the ultimate power than feel free to do the bolt on mods and engine swaps. I want to play with stock parts

I'll add my water separator numbers to this post so all my testing is in the same location.

Feel free to add your thoughts . . .

At some point I’ll be moving on to the rest of the intake parts middle, lower intake and heads and post my results. My end goal is to use these on a 3.4L build I am going to do for myself.

I’d still like to find someone with a V6 filter assembly that would be willing to donate for testing?


------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

[This message has been edited by Brucepts (edited 08-28-2011).]

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Report this Post08-28-2011 10:32 AM Click Here to See the Profile for Tony KaniaSend a Private Message to Tony KaniaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I too like the stock appearing intake. A plus to you sir, and please post more often. 183 posts in 10 years just doesn't cut it. You are too valuable to waste it. Please keep posting up these test numbers. There are many of us grunts that desire the truth.

Tony
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Report this Post08-28-2011 11:31 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
+ for the great work so far!

I am hoping you take the time to add the middle/lower intake and heads to the intake setup. Then you could baseline the complete stock setup and start swapping in the modified parts 1 by 1 to see what gains they are bringing to the table and then see how a modified stock looking setup (bored throttle body, neck mod, ported runners/transistions) compares to the truleo or even a dual throttle body intake setup
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Report this Post08-28-2011 11:44 AM Click Here to See the Profile for CarrollesClick Here to Email CarrollesSend a Private Message to CarrollesEdit/Delete MessageReply w/QuoteDirect Link to This Post
It would be interesting to see what simply gasket match porting of the upper, middle, and lower intake does with a stock throttle body. I did the along with exhaust manifold porting when I installed a Grooms 2.8L Longblock in my 85SE back in 99. The new combo was much peppier and had better high rev power but I mostly attributed it to a fresh engine.
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Report this Post08-28-2011 11:49 AM Click Here to See the Profile for Tony KaniaSend a Private Message to Tony KaniaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Carrolles:

It would be interesting to see what simply gasket match porting of the upper, middle, and lower intake does with a stock throttle body.


I had done my exaust with my new 3.1 stroker upon install. I had a lower intake gasket seperate, and required taking the top half of my engine down. I gasket matched during this process. My GT now pulls strong up until 5,400 rpms, and the 600 to 800 rpm gain makes the sweetest sounds. No dyno other than "seat of the pants", but the power is quite noticeable. If not that, the increased pull in the middle to upper range is quite welcome.

Tony

[This message has been edited by Tony Kania (edited 08-28-2011).]

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Report this Post08-28-2011 12:25 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
The modified parts are only in my care for a little while and need to go back to the owner of the parts. I will though be testing all my stock parts I have as I get a chance to get a good baseline before any grinding takes place.

From this little bit of testing I will be modifying a stock intake (need to pickup another one) in a similar manor and boring a stock TB.

This testing will be an ongoing project . . . I'm not selling Fiero parts nor looking to do anyone's porting work, I'm simply sharing my findings.

Also keep in mind what the end goal of your engine build is, some are going to want results for a +7,000 screamer and others are looking for something a tad better than stock so testing needs to be tapered to those results. I see most here are looking for max HP numbers and there is nothing wrong with that. But max HP doesn't mean it's going to be the best combination for your driving style. Bigger is not always better

I myself am not looking for a +7,000 screamer but would like something better than stock with a nice torque curve for my weekend fun driving.

If someone has modified parts I would be willing to test them on my flowbench and add this data to this thread but, it might not be an overnight thing as I have to find the time to setup and do the testing. My flowbench biz work comes first though until my second flowbench comes online sometime soon, then I can leave Fiero setups up for my personal testing.

As for my lack of posts over my 10 years well I had nothing to add I had taken a break from my first Fiero (DD 84SE) some years back and in 2009 picked up an 85GT to play with and this is where I am at now . . .

[This message has been edited by Brucepts (edited 08-28-2011).]

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Report this Post08-28-2011 11:28 PM Click Here to See the Profile for Kevin87FieroGTSend a Private Message to Kevin87FieroGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
A + for you sir.

I appreciate the good work. Like you I plan to keep our car stock, however, should I have to remove the intake I would certainly cleanup the metal work. Same goes for the exhaust manifolds and Y pipe. Why not, a little extra never hurt. Thanks for you validations!!

[This message has been edited by Kevin87FieroGT (edited 08-28-2011).]

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Report this Post08-29-2011 12:49 AM Click Here to See the Profile for 86FieroSEv6Click Here to Email 86FieroSEv6Send a Private Message to 86FieroSEv6Edit/Delete MessageReply w/QuoteDirect Link to This Post
I hate to add to your work load, but once you get to adding the heads to the mix, would it be possible to measure the port velocity changes as well? I am interested because of the articles I have read showing that greatest airflow is not always correlated with largest static volume of the intake/exhaust components.
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Report this Post08-29-2011 01:37 AM Click Here to See the Profile for TiredGXPSend a Private Message to TiredGXPEdit/Delete MessageReply w/QuoteDirect Link to This Post
That small intake modification is an amazing mod. You measured 17-18% more flow with both TBs.

It'll be interesting to see how restrictive the mid-intake is.
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Report this Post08-29-2011 01:11 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
If one were to bore a TB, then what, do you need to calibrate the car with a chip or something to compensate?
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Report this Post08-29-2011 03:51 PM Click Here to See the Profile for Rick 88Send a Private Message to Rick 88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for posting you findings!

It would be nice to see how much more a "Dawg" modified intake flows. He cuts open the bottom of the intake neck and welds a fitted piece of aluminum tubing to the bottom to eliminate the restriction. It eliminates the EGR and is hardly noticeble from above.

I really like the look of the Fiero intake but I know it really affects the performance of a 3.4. I have a Darrell Morse bored throttle body, and bore matched intake opening on my 3.4. I have considered the "Dawg" modification but have never seen any flow tests.
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Report this Post08-29-2011 05:06 PM Click Here to See the Profile for timgrayClick Here to visit timgray's HomePageClick Here to Email timgraySend a Private Message to timgrayEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:

If one were to bore a TB, then what, do you need to calibrate the car with a chip or something to compensate?


If that is the only change, no tuning changes are needed, what it will do is raise the RPM where the engine runs out of air.

changes to the intake will do nothing at all to <4000 rpm. except push torque up further. this will make automatics feel more sluggish off the line from a idle.

Fix the intake plenum and exhaust at the same time. you can flow 600cfm in your heads and intake but if your exhaust does not flow more than you will get minimal gains.

If you get a bored out TB, to get the most out of it, have the stock logs ported. that is a very nice combo for a stock 2.8.

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Get your copy of the Fiero 25th Anniv book at http://www.blurb.com/bookstore/detail/349809

My Motorcycle Camping Hints and tips. http://motorcyclecamper.blogspot.com/

[This message has been edited by timgray (edited 08-29-2011).]

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Report this Post09-01-2011 07:53 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Got some time to do a little more testing. Couple more numbers for review:

Stock TB + Stock Upper & Middle Intake 310cfm @28"

Bored TB + Stock Upper & Middle Intake 325cfm @28"

Note adding in the middle intake made no change to the CFM, kinda goes against the common theory most have that the sharp turn takes away flow?

I did not get a chance to look at the modified upper, but would assume the numbers to be the same after seeing these findings.

My next testing will be individual runners and comparing flow . . .

------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

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Report this Post09-01-2011 08:53 PM Click Here to See the Profile for Rick 88Send a Private Message to Rick 88Edit/Delete MessageReply w/QuoteDirect Link to This Post
http://www.fiero.nl/forum/Forum4/HTML/051596.html

Here is the link to the "Dawg" modified intakes. Perhaps he would be willing to send you one to test.

[This message has been edited by Rick 88 (edited 09-01-2011).]

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Report this Post09-02-2011 09:57 PM Click Here to See the Profile for timgrayClick Here to visit timgray's HomePageClick Here to Email timgraySend a Private Message to timgrayEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Brucepts:

Note adding in the middle intake made no change to the CFM, kinda goes against the common theory most have that the sharp turn takes away flow?



Yup I confirm that as well, I made 1.5" spacers for between the top and middle and they made no difference except for moving the torque curve down in RPM's slightly. Although the restriction at the neck may be affecting this. get rid of that neck restriction and you may start to see the bend causing a change in flow.

[This message has been edited by timgray (edited 09-02-2011).]

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Brucepts
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Report this Post09-04-2011 06:47 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Some interesting numbers from today's testing:

Stock TB + Modified Upper & Stock Middle Intake 366cfm @28"

Bored TB + Modified Upper & Stock Middle Intake 387cfm @28"

Note adding in the middle intake made a +3 cfm change on both TB's, kinda goes against the common theory most have that the sharp turn takes away flow?

Makes you go hummm . . . .

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"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
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Report this Post09-04-2011 09:29 PM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
What is the direction of flow of those test? Never mind, Just read the 1st post. Nice work!

[This message has been edited by La fiera (edited 09-04-2011).]

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Report this Post09-04-2011 09:39 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Second paragraph first post in this thread explains the method of testing

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"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

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Report this Post09-05-2011 01:04 AM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniEdit/Delete MessageReply w/QuoteDirect Link to This Post
How about adding the lower intake to the stack? I'm convinced the bumps for the injectors partially block the runners.
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Report this Post09-05-2011 07:16 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Hudini: How about adding the lower intake to the stack? I'm convinced the bumps for the injectors partially block the runners.

Plus, the bottom ends of the runners (where they mate up with the heads) are filled in about 25% or so. The drastic transition from partially filled lower intake port to full-size head port can't be good for airflow.

After porting a set of stock 2.8 V6 intake manifold pieces from the throttle body down to the heads, I'm convinced that the plenum neck and the lower manifold are the worst restrictions. The middle manifold has hardly any restriction at all... just some casting flash, and a little extra material near the mating surfaces.

[This message has been edited by Blacktree (edited 09-05-2011).]

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Report this Post09-05-2011 09:26 AM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Hudini:

How about adding the lower intake to the stack? I'm convinced the bumps for the injectors partially block the runners.


I'm getting to it . . .

Hummm . . . working with airflow don't convince yourself of anything It doesn't always flow like one "thinks" it should flow! If you are willy-nilly just grinding away at something you really have no clue what you are going to get in the end!

The results above show that, most were convinced the sharp turn had to be choking airflow simply because "it looked like it would"

On another note; I see alot of talk about gasket matching intakes but nobody has shown any flow numbers of before and after? All one has to do is look at a stream or river and compare it's flow to that of an intake tract, in the wide areas of a stream the flow slows down and in the narrow areas it speeds up? Is the gasket area the correct cross sectional area? If you change the cross sectional area of a piece you are going to get the same thing, areas of slow velocity and fast velocity.

It could be quite possible the air speeds up as it's going through the injector boss area with no reduction in cfm? This could be a good thing if your head port is so designed to take this velocity increase and use it to get the airflow past the valve and into the chamber? Remember you are now adding fuel into the airflow which will make the column of air more dense.

All this data I have posted so far was raw data, my "plan" is to sit down over the Winter and do some exhaustive testing with a velocity probe and trying to understand more about what is happening or not happening. With my goal being an education for myself and sharing my results with the members here so the ones who want to know also gain a better understanding and healthy discussion might take place.

Will you end up with a 2.8-3.4 mega HP monster? Nope, lots of prior posts already state this is not going to happen. Will you end up with a better understanding/education of what's going on within your engine and nice little boost in power? Probably so

If you stick around long enough . . . we might even get into a little wet-flow testing as I develop an adapter for my DIY flowbench market. I have a friend who has a complete wet-flowbench in his shop and we have been talking about a DIY setup.

I also welcome anyone local from the PFF community to stop by my place if they would like to actually get some hands-on time with this testing or talk Fieros.
------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

[This message has been edited by Brucepts (edited 09-05-2011).]

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Report this Post09-05-2011 10:05 AM Click Here to See the Profile for murrreyClick Here to Email murrreySend a Private Message to murrreyEdit/Delete MessageReply w/QuoteDirect Link to This Post
has anybody flow tested the 3.4pr intake?
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Report this Post09-05-2011 10:21 AM Click Here to See the Profile for Joe 1320Click Here to visit Joe 1320's HomePageClick Here to Email Joe 1320Send a Private Message to Joe 1320Edit/Delete MessageReply w/QuoteDirect Link to This Post
It all boils down to whether the engine actually needs more airflow or not. Gone are the day when simply swapping an intake manifold and carb shows a 40 HP increase. Sometimes intakes are made smaller to aid in drivability and resonse on the road, not on the track. I can remember times in the old days that a builder put together an engine with an appropriate intake and a 750 Holley carb. The owner takes delivery and immedialy puts on a 850cfm carb and is mystified as to why the HP didn't pick up. Same thing here. Just because a part flows more doesn't mean the engine can take more.

[This message has been edited by Joe 1320 (edited 09-05-2011).]

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Report this Post09-05-2011 12:10 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Today's testing adding in the Stock Lower Intake:

Stock TB + Stock Upper & Stock Middle Intake & Stock Lower Intake = 308cfm @28"

Bored TB + Stock Upper & Stock Middle Intake & Stock Lower Intake = 323cfm @28"

-----------------------------------------------------

Stock TB + Modified Upper & Stock Middle Intake & Stock Lower Intake = 358cfm @28"

Bored TB + Modified Upper & Stock Middle Intake & Stock Lower Intake = 376cfm @28"

------------------------------------------------------

As you can see there is a reduction in flow due to the addition of the Lower Intake. I'm done with this round of testing right now. I need to get my "borrowed modified parts" back to the original owner. I'll make up my own set of modified TB and Upper Intake Manifold for my future testing.

I'm going to get all the numbers into a spreadsheet format for easier viewing, I'll get a link up later on . . .

------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

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Report this Post09-06-2011 06:46 AM Click Here to See the Profile for timgrayClick Here to visit timgray's HomePageClick Here to Email timgraySend a Private Message to timgrayEdit/Delete MessageReply w/QuoteDirect Link to This Post
I want to thank you for running this testing and posting here. This information is incredibly valuable and giving us all REAL readings instead of the "I think it would be" or "I am sure it does" based on guess and experience with unrelated cars. I actually learned 2 things already that proved a couple of my preconceptions wrong.

I just wonder if a extrude hone to a modified set would also increase air flow or just make it smoother.

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Report this Post09-06-2011 07:15 AM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by timgray:
I just wonder if a extrude hone to a modified set would also increase air flow or just make it smoother.


Extrude Hone is uncontrollable in it's flow path! Extrude Hone would flow the same path as the air in my test and remove more from one area than another. Nobody who does serious porting work even thinks of doing it!

From what I have seen so far in this testing, a large percentage of the flow is coming out of only a few runners. I want to next move on to measuring each runner separate and compare to the others to see if there is a balanced flow. From this data I can then start porting the intakes to try and balance out the runners.

Just remember bigger is not always better . . .

------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

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Report this Post09-06-2011 10:03 AM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Brucepts: All one has to do is look at a stream or river and compare it's flow to that of an intake tract, in the wide areas of a stream the flow slows down and in the narrow areas it speeds up? .

Yes, very true. I second that. But the wider area will flow more volume. That is why we want wider passages for a high RPM engine, it will not flow much at a lower speed compared to a narrower passage but increase that speed and everything changes. On the narrower passage the increase in air speed will create more friction on the walls slowing down the airflow and creating turbulance, and only a minimal amount of air volume will freely flow at higher speed. The same applies for the wider passage but a larger amount of air will freely flow and at the same speed of the narrower passage, the larger one will not suffer as much from turbunlance and thermal loses due to friction .
That is why bruce is right when he said "bigger is not always better" . Yes, in a stock engine. Increase the pumping efficiency of the same engine and the "Bigger" will be better.
Very good thread Bruce, I'll be contacting you for some test for my intakes.

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Fiero Thomas
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Report this Post09-06-2011 10:51 AM Click Here to See the Profile for Fiero ThomasClick Here to visit Fiero Thomas's HomePageClick Here to Email Fiero ThomasSend a Private Message to Fiero ThomasEdit/Delete MessageReply w/QuoteDirect Link to This Post
+ for you sir keep up the good info. This will help some folks that are looking for better air flow in there cars like me with the drag one I am trying to work out.
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Report this Post09-06-2011 11:53 AM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
I didn't have have a Dawg mod but I did bore and polish the beginning of the S and I had the upper and middle cut down to eliminate the length where they meet allowing better (deeper) polishing in those areas

http://www.fiero.nl/forum/Forum2/HTML/075502.html

187 rwhp 3.4 can't be wrong... would be nice to try the DAWG mod as well but now I'm running a Trueleo intake...
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Rick 88
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Report this Post09-06-2011 04:35 PM Click Here to See the Profile for Rick 88Send a Private Message to Rick 88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Was the upper intake just matched to the bored T/B, or were there other mods done to it? It made a good differnce in flow compared to the stock upper intake.
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Arns85GT
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Report this Post09-06-2011 04:40 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I run a vacuum guage on my 2.8. It has long tube headers, ported heads with 1.6 rockers, and a 390 cfm intake.

I get, under full decelleration, about 28" of vacuum. Cruising I get about 15" and idling fully warm I get 17".

Just curious as to why you are testing at 28". The engine really doesn't draw that hard under normal load. In fact, it draws down around 4" on WOT. Please explain.

Arn
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Brucepts
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Report this Post09-06-2011 04:53 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Rick 88:

Was the upper intake just matched to the bored T/B, or were there other mods done to it? It made a good differnce in flow compared to the stock upper intake.


No matching of parts was done, simply bolted it all together and these are the results for this round of testing. The bored TB was even tested using a TB stock gasket.
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Brucepts
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Report this Post09-06-2011 05:04 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Arns85GT:

Just curious as to why you are testing at 28". The engine really doesn't draw that hard under normal load. In fact, it draws down around 4" on WOT. Please explain.

Arn


Is your gauge in Hg or H20? 4" of Hg = 54.38" water

28" of water is pretty much the industry standard for flowbench testing, the move now is to go higher than that but it takes ALOT of power to get higher depressions. I know some who are testing heads at +60". I can run my current bench up to 38" but do all my testing at 28". More emphasis is placed on FPS numbers than CFM numbers in most pro porting shops. CFM sells parts though because everyone thinks they need big numbers

I'll post a reply from my flowbench forum from a member who does heads for living and holds more than a few records:

 
quote
From a post off Meaux Racing Heads forum with permission from Larry to post here
MaxRace Software
ET_Analyst ( DragStrip Simulation Software )
PipeMax ( Engine Simulation Software )
http://www.maxracesoftware.com

Quote:
Why is 28" any more valid then 10" if it still isnt anywhere near real world depressions for accurate data


if every Port shape were a perfectly straight round tube that magically did not need a Valve and Stem inside, 10" WC would be about all you needed to get good accurate Data.

10"WC will still give you decent Data in most Port shapes
28"WC will give you more accurate Data in a greater majority of Port shapes
36"WC is still even more accurate, very seldom will the FlowBench fool you at 36"WC +
and from what i've seen, 45"WC to 48"WC should be more the Flow WC Standard than 28"

10" Water Column Height (WC) = 209.343 fps or 142.73 mph potential molecular speed in the centerline of a perfectly straight round tube

28" WC = 350.297 fps or 238.839 MPH

48" WC = 458.647 fps or 312.714 MPH

105" WC = 678.348 fps or 462.51 MPH


Analogy->
Suppose you are designing and testing a Formula One RaceCar , and you do all your Suspension/Tire setups and testing at 10" WC or 142.7 MPH well you will get good Data but probably not good enough to Win the Race .

at 142.7 MPH is probably going to be slow enough speed that just about any good Formula One Car can handle a normal shaped Curve without spinning out and blocking out most other Cars in that Turn.

Now suppose you Test and design for more realistic MPH Speeds of Formula One and you Test at 28" WC = 350.297 fps or 238.839 MPH and now those same Curve "Shapes" that you easily went around at 142.7 MPH, now at 238.8 MPH you spin out or barely make it thru.

i know the above is not the Worlds best Analogy to give you , but i think its the easiest to understand ?

Now suppose again you have the ability to change the Road Course into a straight line, which is analogy to straight round tube, then it becomes a DragRace and all the Cars ( molecules) don't have much a problem going straight at 142.7 MPH to 238+ MPH , so its who gets to finish line first , Wins

getting back to Curved Shapes, lets make the Formula One Cars tow a Trailer with heavier Fuel on it ( Wet Flow ) and see how fast and how many Formula One Cars that can make it around a Curved Shape ??

FlowBench = Dry AirFlow testing , no heavier Fuel suspended in AirFlow stream trying to make a turn in your Tests.

there are some Port Shapes that definetly need to be tested on a FlowBench at 45" WC upwards to get accurate enough Data,
and more Port Shapes that when tested at 28" to 36" WC give very accurate correlation to Real World

Another major problem with a given FlowBench Test Pressure is that Test Pressure is the theoretical average pressure thru the Port CenterLine or the theoretical average Speed thru the Port Shape, but because a Port has a Valve/Stem and Curves in its Shape, and changes in CSA area, the actual local FPS speeds will be drastically different than the theoretical speed.

Lets say your Flow Test Pressure = 28" and use Pitot Probe your Port Shape in many areas inside, and you can see Pitot speeds/pressures 10+" inches higher than your Test Pressure.


------------------
"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

[This message has been edited by Brucepts (edited 09-06-2011).]

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Arns85GT
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Report this Post09-06-2011 07:45 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the explanation. I understand that a measurement of flow is relative.

To ascribe to an intake 325 cfm usually refers to the maximum cfm at the maximum available rpm, which on the Fiero is normally about 5400. My Edelbrock intake with a 390 cfm carb allows the engine to freely rev to 6200 rpm. I frankly don't have the gonads to push it to where it wants to go. I expect it peaks closer to 6800-7000 if allowed to do so.

So far as I know, the figure of about 360 cfm is what the engine can potentially use if it is allowed to breath.

I'd hate to think a guy would base his performance expectations on figures from your bench, not that they are inaccurate by any means. It's just that many years of performance testing on the bored throttle body and ported intake have shown a definite ceiling on the available cfm and it doesn't ever seem to get to that 360 cfm number the engine can use.

Is there any way to use the data you've established, against a horsepower or torque measurement? In other words, can the ported throttle body and intake be put on a dyno to see if they actually deliver what the cfm flow bench seems to indicate?

Not trying to flame here, but I do not understand how the flow testing relates to hp and torque output.

Please educate me.

Arn
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Francis T
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Report this Post09-06-2011 08:33 PM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Hudini:

How about adding the lower intake to the stack? I'm convinced the bumps for the injectors partially block the runners.


I agree, you should add the lower intake and a cylinder head; an example of which follows from our site at trueleo.com:

Flow-bench numbers for Stock intake and SR14 & LR17 below. NOTE: I can't seem to get the collums to line up when I paste them here, they look fine when editing and then, daaa? Anyway you can read them easier at trueleo.com
Valve lift .100" .200" .300" .400" .500"
stock intake CFM 55.945 106.88 124.415 131.93 139.445
Discontinued: Trueleo Long runner CFM 59.786 111.055 130.26 144.455 146.125
Trueleo Short runner CFM 62.625 114.395 133.6 146.96 146.96
no intake-head CFM 64.295 116.9 133.6 146.96 146.96

On the flow-bench we tested the cylinder head with no intake on it all to get a baseline. We tested the bare cylinder head and intakes at 5 different valve lifts in the above listed amounts. We then tested the stock intake manifold with the results above. The long runner intake and short runner intake were also tested. As you can see with the results, both intakes are improved over stock and the short runner intake will flow as much CFM as no intake on there from .300" lift and above. Please note these test were done using our first prototypes which did not flow quite as good as our currant units whereas I dont believe we had the velocity stacks at that and the new units have a better TB neck design.

Great thread you have going here BTW



------------------

trueleo.com
RSpiderII@aol.com

[This message has been edited by Francis T (edited 09-06-2011).]

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Brucepts
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Report this Post09-06-2011 09:32 PM Click Here to See the Profile for BruceptsClick Here to visit Brucepts's HomePageClick Here to Email BruceptsSend a Private Message to BruceptsEdit/Delete MessageReply w/QuoteDirect Link to This Post
The only way to actually correlate the numbers is to run all the parts on a dyno and compare.

You can use these numbers in a desktop dyno and get a good idea of what you might see. Personally, I'm working with Larry Meaux's Pipemax and will be using my velocity and cfm numbers to help me improve my stock parts. His program numbers are based off dyno data and is widely respected in the head porting community.

My intent on my testing was to show the differences for the guys interested in working with stock looking parts. I will be moving on to more extensive testing in the future which will include the heads. As stated in prior posts, for me it's just playing around with my flowbench and sharing what I find.

If someone is looking for all out HP there are other venues to spend your money and time on.

I think what has been seen so far should open a few eyes though with what can be done with stock parts and a few changes. I personally didn't think a bored TB would make that kind of change.


Just for reference carbs are rated at 20.1" of water not the head "standard" of 28"


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Francis T
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Report this Post09-07-2011 06:54 AM Click Here to See the Profile for Francis TClick Here to visit Francis T's HomePageClick Here to Email Francis TSend a Private Message to Francis TEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Brucepts:


I personally didn't think a bored TB would make that kind of change.




Quite true, you have to get the CFM a lot higher before the TB size becomes a limiting factor.
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Blacktree
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Report this Post09-07-2011 08:06 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Brucepts:

On another note; I see alot of talk about gasket matching intakes but nobody has shown any flow numbers of before and after? All one has to do is look at a stream or river and compare it's flow to that of an intake tract, in the wide areas of a stream the flow slows down and in the narrow areas it speeds up? Is the gasket area the correct cross sectional area? If you change the cross sectional area of a piece you are going to get the same thing, areas of slow velocity and fast velocity.

It could be quite possible the air speeds up as it's going through the injector boss area with no reduction in cfm? This could be a good thing if your head port is so designed to take this velocity increase and use it to get the airflow past the valve and into the chamber? Remember you are now adding fuel into the airflow which will make the column of air more dense.

There is always a tradeoff between flow and velocity. If you increase one, you will decrease the other. There is no free lunch.

Also, restrictions in a pipe (port) will increase friction. That added friction absorbs power from the engine (i.e. parasitic power loss). That is why people will tell you to make sure the port is uniform in shape and size, through the entire port. This is why IMO port matching is more important than gasket matching.

Although, with an engine like the 2.8 V6 in the Fiero (which has long, thin intake ports), port AND gasket matching would be a good idea, assuming you want better upper-end performance. But if you just want good low / mid range torque, and don't care too much about 5000 RPM+, then port matching should suffice.
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Rick 88
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Report this Post09-07-2011 12:55 PM Click Here to See the Profile for Rick 88Send a Private Message to Rick 88Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Blacktree:

There is always a tradeoff between flow and velocity. If you increase one, you will decrease the other. There is no free lunch.

Also, restrictions in a pipe (port) will increase friction. That added friction absorbs power from the engine (i.e. parasitic power loss). That is why people will tell you to make sure the port is uniform in shape and size, through the entire port. This is why IMO port matching is more important than gasket matching.

Although, with an engine like the 2.8 V6 in the Fiero (which has long, thin intake ports), port AND gasket matching would be a good idea, assuming you want better upper-end performance. But if you just want good low / mid range torque, and don't care too much about 5000 RPM+, then port matching should suffice.


Based on this information, would the "Dawg" intake neck modification, significantly reduce low speed torque, just to gain a few hundred rpm, and a little more top end power.

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Arns85GT
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Report this Post09-07-2011 02:08 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Blacktree:

There is always a tradeoff between flow and velocity. If you increase one, you will decrease the other. There is no free lunch.

Also, restrictions in a pipe (port) will increase friction. That added friction absorbs power from the engine (i.e. parasitic power loss). That is why people will tell you to make sure the port is uniform in shape and size, through the entire port. This is why IMO port matching is more important than gasket matching.

Although, with an engine like the 2.8 V6 in the Fiero (which has long, thin intake ports), port AND gasket matching would be a good idea, assuming you want better upper-end performance. But if you just want good low / mid range torque, and don't care too much about 5000 RPM+, then port matching should suffice.


The theory about restrictions in a pipe is good in theory, but in practice it just is not true for the Fiero iron head.

Port matching is somewhat critical for the Fiero. You have the fin in the port to channel air around the valve stem. It increases the net flow. You have the venturi effect in the contour of the intake runner. If you hog it out too much, you get poor low rpm response and good high end power. It has to be a balance to use the venturi effect to good advantage, and the air channeling built in to the head. It just is not simple to port like a Honda.

Arn
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