Ok I have been reading alot about the 3.4 ohv swap. I think I am going to go with the Oreif formula on building the engine. My question is what is a 62mm J body throttle body? I am thinking of the quad 4 throttle body which I thought was only 56mm. Please someone point me in the right direction like which engine and year I need to look for.
Thanks,
Zack

It is a custom made throttle body made by Z-spec (originally RSM).
They make it for "J" bodies and Grand Am's to use on the 3100/3400 engines.
It is the 11th item down on the list:
http://www.z-spec.com/grandamperformance.htm

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Happiness isn't around the corner...
Happiness IS the corner.
ZZ4 Powered !!

Someone please correct me if I'm wrong, but I was under the impression that the restriction wasn't so much from the throttle body, but the intake plenum.

I'm going with a 3.4 swap to replace my 3.2 also (just to have a better over-all driving Fiero, and I didn't do the 3.2 rebuild properly).

If you want the most power from the 3.4, the only way to get it is to get a Truleo intake, or have your stock Fiero intake configuration sent to an extrude-hone dealer. Basically, they will send a pudding like substance at a high rate of speed through the entire intake passage. This "pudding" contains abrasive material in it. What this will do is actually grind away the intake passages effectively making them larger.

It IS expensive. And dollar for dollar, most people would say that you're totally wasting your money. But, if you're like me... and you want to keep your Fiero looking totally stock, but have more horsepower... this is the only way to do it. I think it costs around $700 bucks to have the intake plenum, the runners, and the lower intake manifold extrude-honed together. (they bolt it all together and then send the stuff for it). You're basically getting a complete port-matching, and a complete port & polish.

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Todd,
2006 Pontiac Solstice
2004 Volkswagen Beetle Convertible (Wife's Car)
2002 Ford Crown Victoria LX
1987 Pontiac Fiero SE / V6 (3.2) 5-Speed
1984 Pontiac Fiero 2m4 SE
1984 Porsche 944 5-Speed
1981 Pontiac TransAm (Olds 455BB)
1973 Volkswagen Type-2 Transporter

Your correct Todd, it is the intakes, haven`t heard of the type you mention, would be interesting to see or read about, it`s kind of hard to top out the trueleo system , I found a side by side of the t.b`s before and after for you--their at the bottom of the post--I think you`ll like the bored t.b. I`m also interested in what you did or didn`t do to the 3.2 --as I`m building one now...Hope this helps some..
https://www.fiero.nl/forum/Forum2/HTML/077969.html

extrude honing will NOT fix the main restriction of the stock intake: the neck.

$400 for a custom TB? Ouch. How much air does that 62mm TB flow?

I am also looking for a compatable TB for a custom plenum to go with my future turbo upgrade. Is there an OEM TB that one could find in the junk yard that uses the IAC and TPS of the V6 Fiero?

most early efi cars from gm use the same sensors. so you can look at things like vettes, camaros, 90* v6s, and a few others. just take a trip to the junk yard and look around. i think the tps can be used from another gm...i think the all have a signal of .05 to 5.4 volts, just may have to modify the wiring from stock. and for the iac, look for the screw in types, not the ones held in by screws. this is all realitive to the iac and tps tho, so dont try to use a lt1 vettes twin 48mm...it wont bolt up (lol and i dont thing a 2.8-3.4 would ever need that much air) , but it has the same sensors.... ytour going to have to modify the stock tb opening to get anything to fit.

quote Originally posted by Hudini: $400 for a custom TB? Ouch. How much air does that 62mm TB flow? I am also looking for a compatable TB for a custom plenum to go with my future turbo upgrade. Is there an OEM TB that one could find in the junk yard that uses the IAC and TPS of the V6 Fiero?

Actually it is $345 as the prices listed are Canadian dollars not U.S. dollars.
It can flow 435cfm as opposed to the Fiero TB bored is only 334cfm.

Adding a 62mm TB to the Fiero intake will do nothing for you. The intake is the restrictive area. But the 62mm on the Trueleo intake will be more than the engine could possible use N/A and provide excellent flow if you decide to go forced induction.

You can have the TB mounting on the Trueleo set up for a specific TB so if you want to use the LT1 twin 48mm TB, they can make the mount.

You could possibly find a bored out GN TB on ebay for about half the price of a Z-spec. It uses the same sensors.

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85 GT 3.4
14.9 @ 90 1.9 60' Old TH125/3.06
Unknown New 4T60/3.42

Wow thanks guys. I am going with the trueleo intake so I want the flow from a better TB. I guess I should also look into exhaust. Does anyone have experience with the set that the trueleo guys make?

Do a search in the technical section for "improving the stock plenum". You will be able to see where the restrictions ( and ther are several) are. My result is a stockish looking intake on a 3.4 making 172rwhp and 211 pounds of torque.
The 3.4 with a stock Fiero intake in famous for running out of air at 4800rpm. By modifing the stock plenum, and using a 56mm throttle body along with a Darrell Morse ported intake I was able to flow air and make power to 6100rpm. I was still making 150rwhp at 5900 rpm.

Chuck

quote Originally posted by fierochild: Do a search in the technical section for "improving the stock plenum". You will be able to see where the restrictions ( and ther are several) are. My result is a stockish looking intake on a 3.4 making 172rwhp and 211 pounds of torque. The 3.4 with a stock Fiero intake in famous for running out of air at 4800rpm. By modifing the stock plenum, and using a 56mm throttle body along with a Darrell Morse ported intake I was able to flow air and make power to 6100rpm. I was still making 150rwhp at 5900 rpm. Chuck

yes, I will be doing this myself this winter.

https://www.fiero.nl/forum/Forum2/HTML/077346.html

Let it breathe.

[This message has been edited by goatnipples2002 (edited 12-15-2006).]