experienced tuner / workshop wanted

[Montanamotor]

Hi, folks.

I am from Germany and I am new to this thread.

Only recently, I stumbled upon an article about the Pontiac Fiero, which reminded me that I was quite fascinated when I met a Fiero on a gas station over here in Germany in the late 1980ies and was quite stunned that a US-carmaker could pull off a sportscar like that at all.

I understand that the Fiero has it's flaws. But a 1988 Fuero might be a good start for building a car according to my own preferences.

I am aiming at 300 HP from a 3.4 L-engine.

Therefore, please allow me to ask you several questions, to which some of you might have an answer or two.

Equipping the stock Fiero long block overhauled by http://www.engine-parts.com/GMV6/gm34da.html with two four-valve DOHC cylinderheads from a fifth gen. 1995-1999 Chevrolet Monte Carlo - Wikipedia, the free encyclopedia
might be a quite straightforward solution.

Breathing freely, the Monte-Carlo Four-valve DOHC is said to develop 275 HP in standard-trim already. With even a humble 5 PSI supercharging (No intercoolers required!), this engine should develop in excess of 350 HP at 7000 rpm with ease.

Pistons: Forged JE's http://www.jepistons.com/ProductReleases.aspx or
H-beam forged steel conrods AND slipper-pistons from Carillo: http://www.cp-carrillo.com/Tech/Pist...0/Default.aspx
damper: Fluidampr http://www.fluidampr.com/

I might as well transplant a complete, overhauled Monte Carlo-Engine http://www.wikipedia.org/wiki/File:G...tion_II_LQ.jpg into the Fiero of my dreams http://s111.photobucket.com/user/mon...Dream.jpg.html .

AFAIK, there are Monte Carlos in abundance to have on US-scrapyards, which virtually BEG for a second life as a sportscar-engine. Is that right?

Regarding the rpm-limit: A 300 HP 3.4 -Fiero should reach a Vmax close to 165 mph, versus the stock 124 mph at 4500 rpm with the nimble 139 HP 2.8 L-engine.

To achieve 165 mph with identical gearing, either the engine has to rev up to 6000 rpm, OR I will need a diff with a 25 % lower gearing, to achieve 165 mph at 4500 rpm.

Speaking of gearing: Is there an LSD availlable for the Fiero somewhere?

I am hoping to hear from you soon.

Also: Are there any serious tuners / workshops specialized in Monte Carlo DOHC-four valve 60 degree V6 GM-engines around?

Regards, Montanamotor

[walterdude]

As far as your first idea about swapping DOHC heads onto a pushrod engine,,, NO GO.... The heads can't be interchanged.. There is a thread on this site with pictures and explanations of why they won't interchange.. Swapping in a complete DOHC engine IS do-able and seems to be a very good option... There are a number of sites with guides on what needs to be done... It's also a pretty high raving engine, even stock...
Whoever said the DOHC had 275HP is on DRUGS!!! There is a short thread on that subject on this site... 350HP seems fairly unlikely without some major work and a lot of boost... there are people on this site that have made bigger numbers, 410 comes to mind, but it takes work... The DOHCs LOVE boost though and they rev higher than pushrod engines.. It sounds like swapping in a complete DOHC is a good start for your goals...
Good Luck and keep us posted,,,
Tom....

http://60degreev6.com/forum/showthread.php/28369-Anyone-hear-of-the-3-4dohc-having-275hp-originally

http://60degreev6.com/content.php/198-3-4-DOHC-Heads-on-a-3x00-Block

[caffeine]

There is an LSD for the Getrag F23 transmission, which is commonly swapped into Fieros. The stock 4 and 5-speeds used to have some available as well. I'm not sure where you could find one these days.

[timg]

Custom forged pistons and rods have been made for the DOHC engine, but there are only a handful of them currently running. You don't need to rebuild the engine for less than 10 psi of boost. The compression ratio is relatively low and the stock parts are fairly strong. You do want an intercooler for anything over 7 psig.

To hit 350 whp, you would need ~ 10 psi of boost. An easy equation that assumes the engine's efficiency remains the same:
Boosted power = stock power * boost pressure (in bar)
Example:
Boosted power = 210 * 1.69 = 355 hp
where 1.69 bar = 24.5 psia and 24.5 psia = 10 psig

While I love the 3.4 DOHC, parts are becoming more scarce even in the US. Depending on the year, tuning could also be a challenge. Since you're doing an engine swap into an older car, running a standalone engine management like Haltech could make a lot of sense. You could also consider using the twin turbo V6 from the Saab 9-3 (06-09). That is something you could tune with HPTuners.

Tim