I have been told that the ATI Procharger is the way to go with the inner or aftercooler, don't remember. I have a 355 with iron heads, 9.89;1 compression ratio, LT-4 hot cam, and many other mods. Would this supercharger work, or is the CR too high? I am running Federal Mogual hyperuetectic flat top pistons. I am looking at either NOS or a blower, what do you suggest? I do not want to change anything on my engine as it is about 4 months old. Thanks...
More engine info can be found at this site.
http://sc3gfb.org/members/jason.html


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1991 Camaro TPI, 355ci. Sportsman 11 heads, LT-4 Hot cam,Pete Jackson gear drive, on,and on, and on... 13.6 @ 102.5 with a 2:73 open rear, no traction, no tuning, no practice.

1985 California Edition IROC red, polished TPI and polished wheels, otherwise completely stock 305ci. & automatic trans.

1991 fullsize Blazer 4-wheel drive, 350,700r4, Pro Comp lift, K&N, TBI spacer, 3" Catco cat, 3" cat back Flowmaster, etc....

 

i think that with that high of compression to be safe and only run on pump gas i would limit boost to about 7psi with an intercooler. You could also just get a thicker head gasket and lower the compression that way. if you could lower the compression about .5 point you could run the 9psi kit without a problem and maybe the 12psi, but i run the 12psi kit and just get away with it with 2 stage colder plugs, lower intial timing, and 9.3

 

i think that you would be fine as the fuel injection helps with more precise delivery allowing higher comp ratios.i'm running 10-1 but use afr heads that allow for more heat transfer and less of a detonation chance.
pete

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1990 Trans Am,350 TPI(L98),WS6suspension ,bridgestone RE71's /245/45/zr16
paxton supercharger, alston sfc's,msd 6AL-BTM,
8.5 superconductor wires SLP 1-3/4 headers,duel cats,3"slp exaust, lakewood LCA's,T.B.Bypass
160 degree stat,alum driveshaft,fiberglass wing, secret mods

"if you cant win fair CHEAT"

 

I'm sure that you are aware that those pistons will not tolerate any detonation. I don't know what your engine tuning skills are like but if you have any doubts about tuning the engine with a supercharger & avoiding detonation, then you might be better off with nitrous, it isn't as compression dependant as a blower. As I'm sure you know, near 10:1 compression with iron heads won't allow lots of boost (even with an intercooler). There are just to many variables in an engine buildup that allow you to put an excact number on boost and compression compatibility. You should be able to use at least 6PSI boost, maybe more. The only true way to know what you and your particular setup can use is to start low and sneak up on it.
Just a few of the many things that will/can decrease the amount of boost you can run are:

• sharp edges in the combustion chamber
• sharp edges on the pistons
• poor combustion chamber shape
• iron instead of aluminum head material
• poor flame travel
• large (loose) quench area
• high crevise volume
• camshaft design
• incorrect timing curve
• tight torque converter
• heavy car
• high gearing

The largest limiting factor of all is your tuning prowess.
Your combustion chamber shape should be good. I don't know how much prep work if any went into smoothing the surface of the chambers & pistons. Sharp edges retain heat. If your piston to deck clearence is tight that will help improve the quench area. Only you or your engine builder knows that. A looser converter & lower gears will help too by reducing the load on the engine. Of course the quality of gasoline you have available will make a huge difference.
If you still want a blower, start with a smaller boost kit with an intercooler. As you get it dialed in step up the boost. A good puchase at the same time would be a boost oriented timing control &/or water injection kit. On the street you can set the timing retard & turn on water injection to protect the engine. At the track you can fuel up with some race gas & turn off the retard & water.

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Tracy /AKA IROCKZ4me

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo

 

Thanks for the help. I will need to talk with my builder on the specs mentioned. I know most of what went into this motor, but the assembly area is not where I am knowledgable. As for tuning, I have a DFI that I am figuring out at the moment, so I should be able to get things squared away. I will contact some of the mentioned shops for help... Thanks again.

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1991 Camaro TPI, 355ci. Sportsman 11 heads, LT-4 Hot cam,Pete Jackson gear drive, on,and on, and on... 13.6 @ 102.5 with a 2:73 open rear, no traction, no tuning, no practice.

1985 California Edition IROC red, polished TPI and polished wheels, otherwise completely stock 305ci. 700r4

1991 fullsize Blazer 4-wheel drive, 350,700r4, Pro Comp lift, K&N, TBI spacer, 3" Catco cat, 3" cat back Flowmaster, etc....