It appears as if you could lower the CR quite easily using quad4 pistons. They have the same bore, pin diameter, and compression height, but they are dished. I haven't done the math to see what the result would be, but I imagine there are a lot more piston options available for the Quad4. It also looks like you could enlarge the combustion chambers on the heads quite a bit.

[This message has been edited by rockcrawl (edited 11-02-2002).]

Turbo LS1's run over 6 psi with over 10:1 compression and aluminum heads. I don't see why 6-8 psi would be a problem on a 9.5:1 engine with iron heads

yeah will but those engine probably have performance forged pistons wheras the 4.9 has stock cast ones

Has anyone tried simply having the heads shaved to raise compression height for more power? Like 10 or 10.5:1 ?

A set of headers for the 4.9 would make a substantial gain in power and make the engine look alot cooler

Rockcrawl, you gonna CNC and sell custom 4.9 parts? Some polished valve covers with engraved 4.9 V-8 or Fiero V-8 or something would be cool. Dunno if you can cnc custome intakes or not, be sweet to have a tunnel ram

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--Adam--
1987 Blue GT 5-speed
IM AOL: GTFiero
Remember, always brush your milk, drink your teeth, dont do sleep and get eight hours of drugs

remember, Drive it like you stole it...nice and slow so you dont get your @$$ caught by the cops

The 4.9 has cast pistons, but the LS1 has hypereutectic, NOT forged.

Ohh boy how many times have I BUGGED PBJ asking this question.Although you didn't ask me i'll tell you what i used to do my swap.

I used
~Oil cooler
~Carb (2bbl)
~High performance Starter (had to cut bell housing a little to make room)
~Stock Fuel Pump (PFI takes more)
~Flywheel (1994 CAV Z24)
~Cav Z24 Clutch (Holds up GREAT to a 4.9)
~Standalone tachometer

Oddly enough if you get a cavalier Z24 Flywheel and Clutch from 1990-1994 model it will do just fine

Obviousley i'd recomend a custom made Flywheel, however, If properley machiened and refaced the Flywheel works great. The clutch also handles the power of the 4.9 very well.

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Steven Rossi
2M4 Cadero Converted GT

Hi Steven,
How is that clutch-pressure plate differant than the stock 2.8? I'm researching for my 4.9 swap.
Thanks
Captain Midnight

I had no idea that we had such smart people here on the forum... Seriously!! You ALL have been rated with a *+* ...

You guy's are the reason that people here are able to upgrade their Fiero's to a 4.XL V/8. Ya'll are GREAT. Great information, great help, great picture's, great link's, technical support, etc...

Thank You!!
Smooth!!

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SmoothFieroGT@Yahoo.com
Have you RATED me today??

originally posted by 1fst2m6

quote I have two coins that equal 30 cents and one of them is not a nickle. What are the two coins that I have?

A quarter and a nickle. You said "one of them is not a nickle"....thats correct, one of them is not a nickle, but the other one is.
Ok, with that out of the way, Ive got a quick question. I know the 4.9 bolts directly to a stock Fiero manual tranny. Will the 4 speed work ok? Or do you need that 5th gear? Im thinking really in terms of road trips (as well as everyday daily driving). Thanx.

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The Force will be with you, always.

The 5th gear would be a great benifit to the 4.9. I am taking the auto 125 out (which worked great other than high rev's on the hwy) tomarrow and replacing it with an overdrive trans. Just too thirsty for fuel on high way.

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quote Originally posted by Captain Midnight: Oddly enough if you get a cavalier Z24 Flywheel and Clutch from 1990-1994 model it will do just fine Obviousley i'd recomend a custom made Flywheel, however, If properley machiened and refaced the Flywheel works great. The clutch also handles the power of the 4.9 very well.

Do you mean that a 90-94 Z24 flywheel bolts right to the 4.9, or that a 90-94 Z24 flywheel can be plugged and redrilled to the 4.9 pattern?

I am also interested in the flywheel issue. Do you mean to say that the Z24 Cavalier flywheel and clutch will work in a 4.9 swap without any mods? If so that would be great!

And you can definitely run 6-8 lbs of boost on cast pistons with 9.5:1 compression. Proof of this has been generated by a friend of mine in the CTFBA (RCR, you know this guy ), Andris who has a twin turbo Z28 with that kind of boost on a stock 305 bottom end.

Also just for clarification, is the cam hydraulic roller? Is there any other cam that will fit this car?

It has been said the cavalier clutch works but the flywheel requires modification.http://members.fortunecity.com/bubbajoexx/id17.htm

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"Oddly enough if you get a cavalier Z24 Flywheel and Clutch from 1990-1994 model it will do just fine. The clutch also handles the power of the 4.9 very well."

How is that clutch-pressure plate differant than the stock 2.8?
Thanks
Captain Midnight

quote Originally posted by Captain Midnight: "Oddly enough if you get a cavalier Z24 Flywheel and Clutch from 1990-1994 model it will do just fine. The clutch also handles the power of the 4.9 very well." How is that clutch-pressure plate differant than the stock 2.8? Thanks Captain Midnight

I don't know the exact make-up of this clutch and why it's better then a 2.8, however i'll tell you what i do know. The flyhweel was taken fron a 1995 Cav Standard...the entire center part was cout out and machined to be exactly like the 4.9 flywheel (automatic plate i guess would be best to call it since standard and auto flyhweel are SOO much different) I took it to a very well known machiene shop said "i want this to be EXACTLY like this" and they did it perfact...and they garunteed me that it will NEVER break or else they'd pay for the damages...i believe them. The 1994 Cav Z24 clutch is made for a high perf Cavalier...although it's not 275Ft/Lbs it's comprised of very tough material and will handel the power at any rate or load...I'm sorry i can't tell you why it works without being SMOKED but all Mech's that i've spoken to say that it's a very tough Clutch and Pressure plate...i've used it and to be honest i burnt one...but that was because I was in soo much of a rush to finish I forgot to re-fact the Flywheel...after i dropped the cradel again and took out that flywheel to have it professionally refaced (my mistake...everyone should have the flywheel refaced before re-using it) i've since driven the car quite a bit, before the winter season, without any slippage and grinding...and if there is any it's becasue of the flimsy clutch pedal that is begining to bend a lot...the cluch will and HAS help up for a few people even when "beating the crap out of the car" so i'm pretty sure that it can hold up to the 4.9 just fine

Any questions...ask me or e-mail Bubba Joe

*sorry if there are many spelling mistakes...i'm in a rush*

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Steven Rossi
2M4 Cadero Converted to Aero Notch Back
Visit my website at http://members.rogers.com/jrossi
E-mail me with any questions at steven.rossi@rogers.com
Please rate me if you appreciate my contribution to the Forum

A bump and some thoughts. There are Comp Cams energizer roller lifters for the Ford 5.0 that raise the ratio to 1.7. Kinda like a more aggressive cam. The stock ratio and compression IS high, yet the intake/exhaust ports are smaller than the (similar) square bore Ford motor. Why not borrow from the Ford guys...Manley makes race-flo valves that are necked down around the valve area for better flow for the 302 I just don'r know what other machining or modifying to make them fit. (I'm totally bench engineering here)You may have to mix parts from other Caddy 4.X motors to change compressions and all if you insist on turbo'ing. The Allante intake even looks like the Mustang runners! Yeah, I know the Allante intakes are all but unavailable. Keith Black makes stock hypereutic replacement pistons for the Cadillac. I'm still against adding weight back to the car with a turbo, though and I'd see more sense in maintaining the smooth torque curve of the factory V8 in the Fiero. But then we're getting back to spending as much as you would for the smallblock chevy V8 and to me the value of the Cadillac conversion is the $ to HP ratio!

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John DuRette
Black 85 SE, undergoing work as we speak!