How to gain 22 rwhp from the Fiero intake @ 6000 rpm... (Page 2/3)
lou_dias JUL 17, 10:28 AM

quote
Originally posted by BillS:

Very nice results, Lou.
Great to see some dyno evidence instead of the more common "I swear it had 100 bhp more...' we see so often. What is the intake you started with - 3.1 F body?



It's a ported Firebird 2.8 upper intake. I had the neck bored to 59mm and all the ports were gasket matched on 3 sides and the inner wall was bored about ~3/16" on the 6 ports to increase flow to the middle manifold. The middle manifold's upper inner wall on the ports were similarly opened up as well. Again I feel I went a bit overboard with how much material was removed at the base of the middle manifold... Perhaps some angled cross-drilled holes would have achieved close to the same results without giving up so much mid-range...

BUT it does show that the main problem with making power > 4500 rpm is the middle and upper manifolds...
BillS JUL 17, 04:06 PM

quote
Originally posted by lou_dias:

BUT it does show that the main problem with making power > 4500 rpm is the middle and upper manifolds...



Very useful information.

I used a late Camaro intake on the 3.4 I use and did a bunch of port work and manifold modification including boring and fitting a 62 mm throttle body.Worked very well. The engine runs cleanly through 6,000 plus with no falling off (Crane 272 cam).

It is sad that the GM engineers couldn't be bothered to eliminate bottlenecks that cost horsepower but could have been improved for a small amount of money. Relieving the stock Fiero exhaust manifolds is the worst example.

The more modern example is the Solstice. They had a tune that they made an option. It was approved for warranty, yet they didn't offer it as anything but an add on option. It added 30 bhp and 50 Tq and actually resulted in slightly better fuel consumption. If they had standardized it before submitting the cars to the magazines for the road tests, the car would have been better than the other candidates in terms of performance which would have sold a lot of cars.
Wonder which bean counter botched that one....

[This message has been edited by BillS (edited 07-17-2019).]

lordfiero JUL 17, 05:03 PM
Nice Im not suprised you gained HP, Its in line with my flow measurements of these intakes.
It is intresting that no major loss of TQ in the mid RPM range occurs, you kind of moved the plenum down all the way to the LIM..
lou_dias JUL 17, 06:54 PM

quote
Originally posted by BillS:
Very useful information.


It's about building the type of engine you want without breaking the bank. It amazes me how a little grinding here and there can make such changes to a motor. Ideally if somehow intake ports could expand and contract in a controlled manner, you could make an engine very efficient for it's entire RPM range.

My next engine will have much higher compression since E85 can handle it quite nicely. ;-)
jdv DEC 21, 10:11 PM
Lou nice set up . What type of brakes are you running on that thing in race trim?
lou_dias DEC 22, 03:23 PM

quote
Originally posted by jdv:
Lou nice set up . What type of brakes are you running on that thing in race trim?


I'm using the original HELD/Rayne 12" kit.

http://www.fiero.nl/forum/A...070315-2-072050.html

But I've since switched to scallop'd versions of the rotors to save some weight in rotating mass.

https://www.wilwood.com/rot...%20Scalloped%20Rotor

[This message has been edited by lou_dias (edited 12-22-2019).]

lou_dias FEB 18, 11:09 AM
So I just did this mod on my daily 3.4 Formula this week as well. Using stock 3100 roller cam and Sprint F1 Headers...and Camaro stock 9.0:1 3.4L pistons. (Yes I bored a 3100 to 3.4L...)

This time I grinded out less material. No dyno yet, however it feels like I didn't lose any torque but now the engine revs faster (as in more HP). Idle has gone up.
This is on 87 octane fuel. I am probably running lean until the computer adjusts however the power gain is quite noticable.

Does anyone have an 88 V6 5 speed BIN file with the EGR disabled programming in place? I'd like to tune it using that as a base.

[This message has been edited by lou_dias (edited 02-18-2020).]

lou_dias FEB 21, 10:12 AM
Update:

Seems my high idle is a vacuum leak as I realized my cruise control no longer works...
jjd2296 MAY 02, 10:26 AM
So I did this mod to my 3.4 last year and there was a noticeable difference in the upper rpm. Yes have now installed a vortech supercharger V1 S trim with a 2.8 pulley. My boost is only around 5-6 at 4500 rpm. I can’t push it as it needs another tune being lean and all. with the factory crank pulley and the small sc pulley I should be higher in the boost then showing on the gage right now. Im no engineer but im wondering if the boost is registering lower than it should due to the runners in the middle intake being eliminated?
jjd2296 MAY 02, 11:33 AM
So I did this mod to my 3.4 last year and there was a noticeable difference in the upper rpm. Yes have now installed a vortech supercharger V1 S trim with a 2.8 pulley. My boost is only around 5-6 at 4500 rpm. I can’t push it as it needs another tune being lean and all. with the factory crank pulley and the small sc pulley I should be higher in the boost then showing on the gage right now. Im no engineer but im wondering if the boost is registering lower than it should due to the runners in the middle intake being eliminated?