I always thought that the fiero had major traction problems with the huge motor build ups. It seems however that if you put bigger tires and slicks that you just kill the tranny. So why is it then that people want to build up these huge displacement motors that are all bottom end torque? Just curious as to why noone has done like a 68 DZ 302 or such. Those motors had like no torque until like 4500rpm and could be made to spin at like 9k redline. Wouldn't it seem something like this would be popular and useful, while being easier on the tranny.
Or then again is it that the tranny can't handle those kind of RPMs? Perhaps I guess thats why the northstar is so popular, another higher hp, lower torque (til higher rpm) motor. Just curious as the the attraction huge low end torque when theres a problem actually being able to use it all.
Just for the side note, I'm guilty of this myself for I have a 4.9 mated to a 4 speed (economy from 84).
Hope this doesn't turn into a flame war, just looking for insight from those who know better.
------------------ 18 Year Old Fierophile. --1986 GT Daily Driver, NX 50 Shot, Borla exhaust, ported manifolds, and a few other goodies --1984 SE 4.9, IMSA spoiler, Duel exhuast, GT rear bumper, Konis, drop spindles, Rear adjustable perch, Poly total kit, Poly cradle bushings, Big front bar, Added rear bar, 11.25" brakes on all corners w/SS hoses, Fancy wheels wrapped w/soft rubber, and much much more.
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09:14 PM
PFF
System Bot
perkidelic Member
Posts: 772 From: Masury Ohio USA Registered: Aug 2002
Good topic, I have been going back and forth for a couple weeks now over that very thing. I am deciding between a 383 torque motor and a 355 rpm motor. My reason for considering the rpm motor (9000) is a little different though. I am concerned with keeping my front end on the ground when I race (drag) the car. The bottom end torque from the 383 would make that more of an issue. My other reason for considering the 355 is the mere thought of having a 5-or-6spd car that can wind to 9K!!! That would be fun, fun, fun!!!
You make a good point, but there is still the issue of getting the car acelerating quickly. In order to do that with the old 302, you have to rev it up and launch hard, which still results in the same high torque loading. It's a very similar situation, just happens at different rpm levels. The old 302's were never very quick until they were past 60mph.
A better solution is to go with a size/compound tire that allows a little slip, and stay away from super sticky tires.
Well, tires are fuses. If the fuse won't blow something else will. After a couple of Fiero swaps, I've gone away from all out horsepower and back to some refinement.
I think the 3.4L DOHC is the best combo of power and revs. Yep, tons of 3800's and V8's are faster but there's something about driving a high rever in the Fiero.
Speaking of fuses and origami, back in my VW Bug days the SPG Roller Bearing crank was the hot thing. But unless you pinned the crank journal you could twist it (and sometimes in half) with big sticky tires. Damn, that was a beautiful crank.
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09:57 PM
skitime Member
Posts: 5765 From: Akron, PA, USA Registered: Aug 2000
The transmission is not the weak link. It is the differential. We have a local guy with a 500 HP Chevy V8 with 200 HP shot of nitrous. He has 700 HP going through the 4 speed trans without problems. He was blowing transmissions until he had a limited slip unit built for it. He has not blown a trans yet. What seem to happen with high horsepower Fieros is one wheel will spin and as soon as the second wheel gets traction the resulting torque inside the trans causes too much stress. If you keep both wheels spinning the trans hold up fine.
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Red 88 GT T-Top 3800 Supercharged White 88 GT Stock Please give me a rating if you appreciate my contribution.
Actually this thread will prove to be a very good one. I believe that in order to solve this problem you must analyze what you want out of your Fiero. I wanted a lot of Low end torque and a nice sound so I chose the 4.9. It gives me a great smooth ride and can be driven like a 2.5 if needed. However, I’d love a nice high revving Fiero and I believe that the 302 / 3.8 / 3.4 would be the best solution for that. It has been said that the Fiero should have came stock with a 3.4 because it just feels right in a Fiero. I believe that every swap has its on PLUS side. To deal with the torque and tranny problems I’d also agree with Ski, if some sort of traction system could be made it would make that problem extinct very quickly, that is why strong Auto tranny might be best for torque engine swaps…so it could keep the lead footed people out of trouble.
I’d say that if it was up to me I’d go for the 3800SC as best swap (please don’t get mad at me…I’ve got a V8 in my car!)
It’s: Light High revving Lots of low end and high end power And it goes well with both auto and standard Fiero trannies
But then again…nothing can match up with a SBC or 8 cylinder in general.
Originally posted by skitime: The transmission is not the weak link. It is the differential. We have a local guy with a 500 HP Chevy V8 with 200 HP shot of nitrous. He has 700 HP going through the 4 speed trans without problems...
Now that's right up my alley! Any et/mph on this car, and what's he running for tires? That makes a lot of sense on street tires, but when there is enough traction (sticky rubber and/or surface) it sounds like the tranny would bust anyhow.
California Kid said:
quote
You make a good point, but there is still the issue of getting the car accelerating quickly. In order to do that with the old 302, you have to rev it up and launch hard, which still results in the same high torque loading. It's a very similar situation, just happens at different rpm levels. The old 302's were never very quick until they were past 60mph. A better solution is to go with a size/compound tire that allows a little slip, and stay away from super sticky tires.
I agree with you Cali. I thought about that, just wanted to consider the other option. Another problem is stratosphere rpm launches are hard on parts. Having instantaneous throttle response from lots of torque is my main reason for wanting the 383. Another is I plan to dump tons of NOS in my motor and the big intake side needed for a high winder is not the best for NOS.
Guess you guys just helped me find my answer - hehehe - thanks!
i've been planning a 302 build up utilizing a 327 block i have and a 289 (forget the actual displacement) crank... that gives you a rev happy short stroke, large bore SBC that hopefully wouldn't have too many traction problems and could pull like snot!
only concern i have is taking a pushrod motor up that high in revs, and the longevety it would have.
with regards to the hard launching... i belive it would not be necessary... due to the fact that the 302 would never have less torque at any point in the rev range than the stock 2.8v6...
THEREFORE, even with relatively low torque levels for a v8, 60 foot times would be quite similar or faster than a stock v6...
and we all know that its hard to beat even a stock v6 off the line....
just in the 302 case the power would kick in right where the v6 would start to disappoint.... WOOSH! ------------------
[This message has been edited by The Aura (edited 10-07-2002).]
[This message has been edited by The Aura (edited 10-07-2002).]
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11:47 PM
Oct 7th, 2002
Fierobsessed Member
Posts: 4782 From: Las Vegas, NV Registered: Dec 2001
IMHO, If you have a high reving engine, go stick so you can spend more time winding out. If you have a low reving stump puller go automatic, the gears are alot longer, and shift programming is easier. That way you are pretty well matched, also, automatics tend to sap more power the higher the RPM's get. As for the differential issue. Seen way too many differentials loose there pins, then shatter the whole tranny. It usually comes from burnouts where one tire is spinning much faster then the other, at that point the spider gears on the differentials pin are rotating pretty fast then start to eat the pin they rotate on (the pin actually forces them to spin) to the point where the pin finally breaks, and takes the whole transmission with it. Solution, posi, or lay off the burnouts.
------------------ Matt D 1984 Indy Fiero 4sp. 1985 2m4 now equipt with a 1996 3.4 DOHC.
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03:51 AM
fieroX Member
Posts: 5234 From: wichita, Ks Registered: Oct 2001
Ski is right. There are other weak links that occur after the diff is fixed, but that is always the first to splode. What exactly happens is when you do a one wheel burnout the spider gears get spinning real fast on the pinion shaft. The immense friction and heat occuring causes the shaft to expand, (it only takes .0005" of expansion to bind) and the spider gear binds on the shaft. At this point the spider gear trys to spin the pinion shaft and it shears off the roll pin. Now the pinion shaft is lose and its only a matter of seconds before the whole assembly comes flying apart. Usually the spider gears will fly out at mach 7 and destroy the extension housing. Im getting an LSD soon, as right now it hooks well, but I can feel a wheel slip on the launch, and when it rehooks I know it cant be good on it. I should have that by the time my turbo project is finished.
same as aura, i have the basic 302 bottom end pieces. if i can pull off a small block v8 this is what i want. i'm also hoping an advantage will be that a fiero is a little lighter than the camaro 302's originaly came in (don't know about the actual racers), so the lower torque won't be as much of a disadvantage. i'm not a racer anyway, more someone who wants to build a backyard exotic for fun so hopefully the drivetrain can take whatever abuse i might give it.
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09:50 AM
PFF
System Bot
perkidelic Member
Posts: 772 From: Masury Ohio USA Registered: Aug 2002
So, who makes limited slip diffs for the Fiero? Do they fit either of the strongest two trannies (Getrag & Muncie) or does each have a different final drive design? On the drag racing thread Orief posted info about beefing up the Muncie's internals. EIP offers "cryo" coating for the gears and maybe the diff that help 'em handle more abuse; as well as a sweet 6spd tranny.
Mutt, you spin a 302 at 9k RPM very much and I'll guarantee it ain't goin' last long. Of course you'll need to use solid lifters, super heavy duty valve springs, and light weight valves to do that. I had a 327 with the off-road Z-28 mechanical cam and lifters once (back in my youth). I wound it up to 8 grand plenty of time. It was fun and fast, but didn't last long. When I took it apart, the piston wrist pins, rods, crank, and entire valve train were toast. High RPM for street use and longevity are not compatible with pushrod engines.
Aura, to build a 302 out of a 327, you need the early small journal 327 (the later 327 engines used a large journal crank like the 350's). Then you use a steel forged 283 crank (not a Ford 289 like what you posted) and 302 pistons. Not all the 283 cranks were steel forged, but they are fairly common.
This thread has lots of good info. Sounds like some of us gear heads are finally getting smart... hehehe. To recap some of the important info: High HP motors work best with stick shift cars. High torque engines are great with autos. Torque rules on the street and short road race tracks. High HP rules at high speed and long oval racing tracks (like NASCAR). High torque motors give you quicker 1/4 mile ET times while high HP motors will give you faster top end MPH. Burnouts are bad. Spinning the tires means you are not getting traction and are probably going to eventually tear stuff up.
Since I don't like replacing trannies, I do "soft" launches with no tire spin. Once it is all hooked up, then I punch open the 4 barrels. With my auto and the torque of the 350, this works quite well. The Fiero is light enough where a lot of low end torque really sets you back into the seat and puts a smile on your face.
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12:34 PM
The Aura Member
Posts: 2290 From: Winnipeg, Manitoba, Canada Registered: Nov 2001
Originally posted by batboy: Aura, to build a 302 out of a 327, you need the early small journal 327 (the later 327 engines used a large journal crank like the 350's). Then you use a steel forged 283 crank (not a Ford 289 like what you posted) and 302 pistons. Not all the 283 cranks were steel forged, but they are fairly common.
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yeah sorry, was really tired when i posted that... 283 that's it (not 289, but i didn't use the "F" word)! the 327 block is out of a 67 stingray and i'm planning aluminum heads and a mpfi system to boot! but it'll need an archie kit none the less.
[This message has been edited by The Aura (edited 10-07-2002).]
I didn't mean to imply you HAD to only use a steel forged crank, but those are more desirable because they're tougher. Here is a link for part numbers and years of application. It also describes how to indentify steel forged vs. cast cranks. Looks like a 1967 327 should have a small journal crank, so you should be in business.
Originally posted by batboy: I didn't mean to imply you HAD to only use a steel forged crank, but those are more desirable because they're tougher. Here is a link for part numbers and years of application. It also describes how to indentify steel forged vs. cast cranks. Looks like a 1967 327 should have a small journal crank, so you should be in business.
