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Latest Wisdom on Mild Cam & Rockers for 3.4pr by thesameguy
Started on: 02-20-2021 11:21 PM
Replies: 46 (511 views)
Last post by: thesameguy on 03-01-2021 11:15 PM
thesameguy
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Report this Post02-20-2021 11:21 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm gonna be dropping the drivetrain out and thinking maybe putting some effort into the motor. It's a 3.4pr, running the stock ECM. I don't have the ability to change that. What's my best option for a mild cam - maybe a Comp 260? Maybe 1.5 rockers are the same time? Is that likely to push the computer too far out of its comfort zone?
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Report this Post02-21-2021 12:23 PM 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
If you want to save money and get a performance boost, you can get 1.6 roller fulcrum rockers from the Gen2 3.1 and not need extra hardware. I think there is still something about the nut but I wouldn't know as I've never used them. If you do a search, I believe there is a forum post dedicated to their re-use.

You can run narrow body FULL roller rockers (1.6) if you use these crane stud adapters:
https://www.summitracing.com/parts/crn-99148-2

These are the rockers from Scorpion and Crane:
https://www.summitracing.co...-body-style%3Anarrow

You'll also need my 1/8" valve cover spacers as the nut hits the stock valve covers ($130 shipped in the US). I've sold several sets already so you can ask around about them.

So that setup is pricey and that's what I do when I get an engine rebuilt - I buy all new parts... However, I've had zero failures and nice performance. Both me and La Fiera run this setup in our engines. He made his own spacers...others used custom valve covers. With the spacer's you'll need the F-body 2.8 valve cover gasket as the lower gasket...the stock Fiero one still gets inset into the valve cover.

This will get you from .410" lift to .436" on the exhaust and .390" to .416" on the intake if you are using the stock Fiero/3.4 cam.
My 3.4 made 160 rwhp with the stock 3100 roller cam and these rockers when it had a bad old-style distributor. Only other mods was the 57mm throttle body, dawg-modded ported upper intake, ported middle and lower intake and ported heads using Fiero Store SSI valves...and finally Fiero Store short headers and cross-over. I had a 3100 block bored to OEM 3.4 and used F-body 3.4 pistons and kept it's stock roller cam setup. It's probably making 170 now since replacing the distributor and opening up the channel across the ports of the bottom side of the middle intake.

[This message has been edited by lou_dias (edited 02-21-2021).]

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Report this Post02-22-2021 12:33 PM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thesameguy, aren't you concerned that the cam/rocker upgrade will fail smog check?
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thesameguy
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Report this Post02-22-2021 02:49 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I am, yes. But the engine is tight, cat is good, and it runs very clean right now. I think I've got some headroom and I'd be interested to see what that looks like. TBH, almost my biggest concern is showing up with a Comp 260 and them failing it because the idle sounds off.... although I've read varying accounts that once it's warmed up it's pretty smooth.

I'm also not sure what's in it right now... it came to me with a 3.4pr, but I don't know whether it's a donor motor, a crate 3.4ht, or whether they did something like keep the stock Fiero cam (which I believe is a bit more lift?)

I'd like to shift the power band a bit higher up the revs, I don't think the Fiero's stock gearing needs all the torque that motor makes. Although tbh I'm not sure how functional that is with the stock intake manifold. I can legally ditch that, but I don't think there are any *easy* options there.

@Lou - Your post recently is actually what made me start thinking about this - that approach is high on my list of candidates!

[This message has been edited by thesameguy (edited 02-22-2021).]

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Patrick
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Report this Post02-22-2021 04:27 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thesameguy:

What's my best option for a mild cam - maybe a Comp 260? Maybe 1.5 rockers are the same time?


What else are you planning to do to improve the engine's breathing? Simply adding more cam lift and/or duration to an otherwise stock engine will not accomplish much if anything... especially if your engine is still running the highly restrictive factory 2.8 Fiero intake unmodified.
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Report this Post02-22-2021 06:02 PM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
I can come up with a cam design to compensate for that restrictive intake system. Since my cams have very short seat timing I can get away with a bit more duration and it wll shift the power higher in the rpm range.
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Report this Post02-22-2021 06:43 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I like that idea. The old Crane 2030/3.4ht cam seemed like a good option for me, but it's NLA. The Comp 260 seems just a smidge much.

If there's an easy button for the intake manifold, I'm happy to press that button. The only legal requirements are that it maintain the function of the stock manifold, so as long as it has all the relevant vacuum ports and EGR port, I have free reign. It seems like there is no amount of porting - even something like extrude hone - which is gonna do anything useful, and I don't think there are any factory manifolds which are helpful, nor any aftermarket options at all.

The exhaust is a good size aftermarket with a Flowmaster, and the manifolds are WCF "stock replacements." I think the exhaust side is fine. If there's a decent cam & intake setup that won't break the bank, now is the time.
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Report this Post02-22-2021 07:11 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thesameguy:

The exhaust is a good size aftermarket with a Flowmaster, and the manifolds are WCF "stock replacements." I think the exhaust side is fine.


I take it that the WCF "stock replacements" don't have those ridiculous restrictions in the ports that the factory exhaust manifolds left in place?

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Report this Post02-22-2021 08:52 PM 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
 
quote
Originally posted by Patrick:

I take it that the WCF "stock replacements" don't have those ridiculous restrictions in the ports that the factory exhaust manifolds left in place?


The Fiero Store cross-over doesn't have the D-crimp restrictions...and for pre-88 they offer a larger (2.25") diameter down-pipe section.
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Report this Post02-22-2021 08:59 PM 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 thesameguy:
The exhaust is a good size aftermarket with a Flowmaster, and the manifolds are WCF "stock replacements." I think the exhaust side is fine. If there's a decent cam & intake setup that won't break the bank, now is the time.


That's when a good custom cam comes into play. I'd do a reverse split pattern cam to compensate for the intake restriction, that's the same cam profile approach I do for the 2 barrell V8 engines.
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Report this Post02-22-2021 10:52 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by lou_dias:

The Fiero Store cross-over doesn't have the D-crimp restrictions...


That's good to know... but what about the WCF exhaust manifolds? Any restrictions like the factory manifolds have?

 
quote
Originally posted by Patrick:

This photo taken from an old porting thread shows the factory restrictions which we were targeting for removal.


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Report this Post02-23-2021 12:03 AM Click Here to See the Profile for NotorioSend a Private Message to NotorioEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by La fiera:

I can come up with a cam design to compensate for that restrictive intake system. Since my cams have very short seat timing I can get away with a bit more duration and it will shift the power higher in the rpm range.


A custom-ground cam sounds like that could be an expen$ive option ... do they start with some sort of universal GM v6 cam and grind away what they don't want? Is there a hardening process?
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Report this Post02-23-2021 12:55 AM Click Here to See the Profile for cvxjetClick Here to Email cvxjetSend a Private Message to cvxjetEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hey guys- I had a custom cam made by Comp cams for my 460 Ford Jet boat engine and it cost no more than one of their catalog cams. You could just take the specs from that N/A Crane cam and have Comp make it for you.
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Report this Post02-23-2021 08:18 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 Notorio:


A custom-ground cam sounds like that could be an expen$ive option ... do they start with some sort of universal GM v6 cam and grind away what they don't want? Is there a hardening process?


Starts with a brand new core, its not a regrind of an old cam. After the cam timing is decided for your specifics needs taking in consideration things like bore, rod ratio, piston speed, valve sizes, compression, intented use, ect. The cam is then grind and parkerized. I don't use generic grinds out of a catolog intented for a V8 for the 60 degree V6.

https://youtu.be/xNMBcoScZis
Since all my cams are racing cams I decided to start doing street cams.This is one prototype. Performance testing and feedback by the customer will be available in the summer.
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Report this Post02-23-2021 11:46 AM Click Here to See the Profile for BillSClick Here to Email BillSSend a Private Message to BillSEdit/Delete MessageReply w/QuoteDirect Link to This Post
The path to releasing more power from the 3.4 is breathing - relieving the restrictions GM built into the design.

If you do want a bit better cam, I'd advise you to leave the rocker ratio stock (high ratio results in increased guide wear and unless you buy springs from the same source you can get into issues with coil bind).

The 260 cam isn't enough to get you much - go for the 272 cam (I used a Crane - you'd have to see who offers one today). Helps breathing higher up without adding any lope.

Don't forget the restriction in the Fiero intermediate pipe (that bolts to the manifolds).
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Report this Post02-23-2021 12:09 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Bill - your commend about lope is interesting. About the 260, Comp says:

"Lope at idle with extremely good top end power."

but I have read in numerous places that while lopey when cold it smooths out pretty quick with some heat. I'd be interested to hear any other stories.

I'm not looking for any sort of major improvement - the Fiero generally does well for me, but it does fall flat on its face around 4500rpm, and that's what I'm hoping to solve. I still have to pass smog, which means I've got to be careful. I'd rather go conservative and maybe leave some on the table rather than push my luck and end up having to take it apart again ... I've got so much car work scheduled for 2021 I can't get hung up on the Fiero for too long. I gotta get in, replace the clutch & oil pan gasket and get out as quickly as possible.

I've got maybe 3 weeks of work buttoning up my XR4Ti and then it's the Fiero's turn... so I'd need to be able to get my hands on parts early April.
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Report this Post02-23-2021 01:53 PM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
Well i did this build last year. 260H cam, 1.6 roller tip rockers, ported heads, sprint headers, fixed cross over pipe, ported and gasket matched all intake, bored out the bottom of the middle intake and custom work to the plenum to match the PPG style intake and tb bored to 58mm. pulls super nice all the way to 5400rpm. i stasrted with the stock plenum at first and only had the neck bored to match the TB and gasket matched the ports. needless to say it fell on its face once it hit 4200 rpm. swapped the plenum, had a chip burnt by sinister and bam, in business.





[This message has been edited by jjd2296 (edited 02-23-2021).]

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thesameguy
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Report this Post02-23-2021 04:07 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
That feels like a great solution, although way beyond my ability and probably beyond the time I've got to offer this project. It is a little disheartening to hear that even with all the work on a stock plenum was still such a major issue. Maybe I'm best off leaving well enough alone for the time being, and circling back around to this when I've got more time. And maybe more skill. Of course, I suppose I could always throw the cam in when it's easily accessible and follow up with the other bits later. Something is probably better than nothing.
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Report this Post02-23-2021 04:37 PM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
I could possibly get you one of these plenums made and ship it to you. would cost approx 450 plus shipping
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thesameguy
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Report this Post02-23-2021 06:35 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is an attractive proposition. What would timing on your end be like? The alternative, I suppose, is WCF's option but my experience with them isn't great, and I wouldn't wanna hang any expectations of timing on them at this point. Plus, the more stock it looks the easier it is for me, even if there isn't a legal requirement about it looking stock. I could probably bolt ITBs on as long as they connected to the EGR tube!

Can you tell me a little about your experience with Sinister as far as setting up the tune for this?
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Report this Post02-23-2021 06:47 PM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
I can find out turn around time for the plenum. I can’t imagine it will be more than a few weeks. As for the chip I can do one better. If you do this plenum and the other mods I listed I can sell you my chip as I’m almost done installing my supercharger and have a new chip for that. And if you don’t have 17lb injectors I can sell you those as well. You will need the adjustable fuel pressure regulator for optimal performance as I have it set at 47 psi which is in the range for the original set up in the camaro.

[This message has been edited by jjd2296 (edited 02-23-2021).]

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Report this Post02-23-2021 09:14 PM 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 jjd2296:

Well i did this build last year. 260H cam, 1.6 roller tip rockers, ported heads, sprint headers, fixed cross over pipe, ported and gasket matched all intake, bored out the bottom of the middle intake and custom work to the plenum to match the PPG style intake and tb bored to 58mm. pulls super nice all the way to 5400rpm. i stasrted with the stock plenum at first and only had the neck bored to match the TB and gasket matched the ports. needless to say it fell on its face once it hit 4200 rpm. swapped the plenum, had a chip burnt by sinister and bam, in business.









That is awesome work!! How much power did your 3.4L swap made with all that work at the wheels. Below is my 2.8 with ported heads, custom intake, 24lbs injectors, custom cam by me, 1.6 rockers, stock computer, custom chip and exhaust like yours. I transfered all this to a 3.4L along with oversized valves and it made a HUGE difference. But for Cali, its not good. Here in my town I get rid of all the mosquitoes when I drive my car, that's my way of helping with the decises spread by mosquitoes.




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Report this Post02-23-2021 11:50 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by La fiera:
But for Cali, its not good. Here in my town I get rid of all the mosquitoes when I drive my car, that's my way of helping with the decises spread by mosquitoes.


Would specifying a camshaft that can pass an emissions test be a new/interesting challenge for you?

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Report this Post02-24-2021 11:26 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jjd2296:

I can find out turn around time for the plenum. I can’t imagine it will be more than a few weeks. As for the chip I can do one better. If you do this plenum and the other mods I listed I can sell you my chip as I’m almost done installing my supercharger and have a new chip for that. And if you don’t have 17lb injectors I can sell you those as well. You will need the adjustable fuel pressure regulator for optimal performance as I have it set at 47 psi which is in the range for the original set up in the camaro.



Unfortunately I can't go that far.... I got emissions rules to follow, and things like major exhaust mods and AFPRs fall outside of the rules. Technically, a cam does as well, but if they can't tell and it still passes the sniffer, nobody actually cares.
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Report this Post02-24-2021 11:42 AM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
well then to be honest, becuase your in Cali, i would only replace the lifters with 1.6 roller tip and port the manifolds and crossover and call it a day. the fabrication work on my plenum and middle intake will cause the factory ECM tune to try and dump more fuel to compensate for the extra air and will just foul the spark plugs.
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Report this Post02-24-2021 12:06 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
An adjustable fuel pressure regulator is a pretty useless mod.

Instead, roughly adjust fueling by selection of injector flow.

Then, fine-tune using adjustments in the ECM tuning (which is stealth). If you need different fuel injectors, they can be painted black to improve the stealth factor.

I find that the stock 2.8 regulator works fine and doesn't need changing.

[This message has been edited by pmbrunelle (edited 02-24-2021).]

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Report this Post02-24-2021 12:57 PM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
the ajustable fuel pressure regulator allowed me to turn up the psi enough without burning another chip, knowing that i would just be pulling the injectors when i installed my supercharger. worked well for me and avoided uping my injector size as the 17s were fairly maxed out by the time my mods were all done. I was way too lean on the top end, once i ajusted the PSI a bit i was golden!

[This message has been edited by jjd2296 (edited 02-24-2021).]

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Report this Post02-24-2021 01:10 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
The manifolds and crossover are WCF and good.... or as good as they're gonna get. The cam invisible, so as long as the idle isn't bananas and I have good enough vacuum to get a useful MAP signal it should be okay. I can effectively do whatever I want with injectors so long as they are connected to the stock harness - it's not like a smog tech is gonna check part numbers or knows the colors of obscure '80s injectors. I replaced the injectors recently, but I don't remember what with... I know I was agonizing about that, but I don't recall where I ended up.

I think as long the cam/intake can be usefully matched to an ECM/injector package I should be okay. I guess the question becomes how do I get that done? I'm used to plugging a laptop in, reading SRAM, making some tweaks, and writing back out to flash. I'm older than these cars, but "chip tuning" is above my comprehension level.

I'm not looking to make crazy power or anything like that... I'm really looking to solve my 2500rpm useful rev range problem, which sucks. I don't want perfection to become the enemy of good enough... I'm ok with incremental improvement.
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Report this Post02-24-2021 06:29 PM Click Here to See the Profile for pmbrunelleClick Here to Email pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thesameguy:
I'm used to plugging a laptop in, reading SRAM, making some tweaks, and writing back out to flash.


Sounds like you're computer-literate enough.

 
quote
Originally posted by thesameguy:
I'm older than these cars, but "chip tuning" is above my comprehension level.


Sounds like chip tuning is an area you lack knowledge in, but that doesn't mean it's above your level... with sufficient study the subject can be learned.

My knowledge on this is VERY limited, but Fiero computer reads a PROM chip containing the calibration data.

So, to change the tune, you will use a chip burner connected to your computer to write to a chip containing some changes you want to try. Then, you will physically place the chip into the Fiero ECM. You will drive and observe the results. Then, change some parameter(s)... wash, rinse, repeat.

There also exists emulator boxes. They plug into the Fiero ECM and emulate an actual PROM, but internally it has RAM and can be updated via your laptop computer (with the appropriate software).

Once you've converged on a good tune with the emulator box, you can set your tune in stone by burning a chip, and by running the car from a real chip.

Refer to Moates.
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Report this Post02-24-2021 06:54 PM 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 pmbrunelle:


Would specifying a camshaft that can pass an emissions test be a new/interesting challenge for you?


Unfurtunately I don't have a stock Fiero as a test car. But I recently did a street cam for a local customer but the engine hasn't been started yet.

[This message has been edited by La fiera (edited 02-24-2021).]

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Report this Post02-24-2021 07:25 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pmbrunelle:
Refer to Moates.


Oh, man, I have. Moates is the go-to for Ford EEC as well. I think I have a Quarterhorse at home somewhere.

There's just a lot of technical mumbo jumbo that I seem to really have a problem coming up to speed on..... I played around a bit with TunerPro but I got way out of my comfort zone quickly. It's probably a lack of context ... I get bogged down trying to follow engine swap threads around here!


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Report this Post02-24-2021 07:29 PM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by thesameguy:


Unfortunately I can't go that far.... I got emissions rules to follow, and things like major exhaust mods and AFPRs fall outside of the rules. Technically, a cam does as well, but if they can't tell and it still passes the sniffer, nobody actually cares.


Do you have E85 in Cali?
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lou_dias
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Report this Post02-24-2021 07:32 PM 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
 
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Originally posted by jjd2296:

Well i did this build last year. 260H cam, 1.6 roller tip rockers, ported heads, sprint headers, fixed cross over pipe, ported and gasket matched all intake, bored out the bottom of the middle intake and custom work to the plenum to match the PPG style intake and tb bored to 58mm. pulls super nice all the way to 5400rpm. i stasrted with the stock plenum at first and only had the neck bored to match the TB and gasket matched the ports. needless to say it fell on its face once it hit 4200 rpm. swapped the plenum, had a chip burnt by sinister and bam, in business.





ah I see you opened the channel there....I gained 22rwhp at 6000 rpm from doing that...

[This message has been edited by lou_dias (edited 02-24-2021).]

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La fiera
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Report this Post02-24-2021 07:48 PM Click Here to See the Profile for La fieraSend a Private Message to La fieraEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by lou_dias:


ah I see you opened the channel there....I gained 22rwhp at 6000 rpm from doing that...



The reason you gained 22whp at that high rpm was because by doing that mod you shortened the pathway of the intake airflow to the cylinders. In other words, the long narrow runners were chocking at high rpm, then a gate was provided to slow down the chockin incoming airflow by sharing it with the adjacent cylinder which gave it a boost at high rpms. The downside is a loss of midrange torque. Then again, that lost torque can be re filled with a custom cam profile to bring everything back together and also take advantege of the shorter runners.

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rlndhill
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Report this Post02-24-2021 08:44 PM Click Here to See the Profile for rlndhillClick Here to Email rlndhillSend a Private Message to rlndhillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by jjd2296:

I could possibly get you one of these plenums made and ship it to you. would cost approx 450 plus shipping


Sir,
If you could get me one, I'll take it? I did everything that you have done to your engine expect for the plenum and I always thought that would be a good addition.

Please advise?

Thanks!
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lou_dias
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Report this Post02-24-2021 08:44 PM 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
 
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Originally posted by La fiera:


The reason you gained 22whp at that high rpm was because by doing that mod you shortened the pathway of the intake airflow to the cylinders. In other words, the long narrow runners were chocking at high rpm, then a gate was provided to slow down the chockin incoming airflow by sharing it with the adjacent cylinder which gave it a boost at high rpms. The downside is a loss of midrange torque. Then again, that lost torque can be re filled with a custom cam profile to bring everything back together and also take advantege of the shorter runners.

Yeah, I lost 8 ft*lbs of peak torque but it was all gains from 4500 rpm and up including a gain of 6 peak rwhp at 4900 rpm. A trade-off I was willing to make. The torque loss was only between 3000 and 4500. Still daily drives like normal.
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thesameguy
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Report this Post02-24-2021 11:03 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is what I would expect as well, and I'm totally willing to make that "sacrifice" and more... the 3.4 has grunt to spare, and I'd trade it in a heartbeat to have a wider rev range. What's wrong with the Fiero is what's wrong with my XR4TI, and I've worked really hard over 15 years to get a useful rev range on a big 8v 4-cylinder.... and every time I drive that car I'm happy I did it!

[This message has been edited by thesameguy (edited 02-24-2021).]

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jjd2296
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Report this Post02-25-2021 07:59 AM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by lou_dias:


ah I see you opened the channel there....I gained 22rwhp at 6000 rpm from doing that...



yes i followed your thread and did the same mod, big difference and the loss of torque wasnt noticable but the upper end gain was huge!

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jjd2296
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Report this Post02-25-2021 08:01 AM Click Here to See the Profile for jjd2296Send a Private Message to jjd2296Edit/Delete MessageReply w/QuoteDirect Link to This Post

jjd2296

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quote
Originally posted by rlndhill:


Sir,
If you could get me one, I'll take it? I did everything that you have done to your engine expect for the plenum and I always thought that would be a good addition.

Please advise?

Thanks!


working on it, stay tuned. If there is anyone else that wants one then speak up now or forever hold your peace!

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thesameguy
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Report this Post02-25-2021 12:04 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by La fiera:


Do you have E85 in Cali?


Yep.... there is a fuel distributor called Propel that sells E85 and biodiesel out of most Shell stations. I use the latter frequently!
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