Estimated horse power and torque goals

ScSteven

Registered User
Hey guys, just wondering what some of the more knowledgeable sc guys thought about my car and how much hp and tq ill be expecting. Right now my 89 5 speed sc is getting head gaskets and I've been slowly putting it back together. These are all the parts I've aquired and are either on the car and are going on the car.. it has 2.5 inch true duals, 255lph fuel pump, #42 injectors, slightly ported late model blower, 17% od, stock tb, stock inlet plenum, fmic, cai with k&n cone filter and mp air divider, and it has a tune. I'll also be running a wet nitrous system with a 50 shot. So what do you guys think?
 
I have no idea about hp, but i would back off the od witb the roots blower. I would think 10% would be plenty. I think it may just make heat with that much od.
 
Thanks for the heads up guys I appreciate everyone's input. You guys think 17% od is too much for a late model? It's has very minor porting done to it. I've heard people running 15-20 od with a fmic and they were ok when it came to the heat being generated but maybe that was all hear say?
 
Thanks for the heads up guys I appreciate everyone's input. You guys think 17% od is too much for a late model? It's has very minor porting done to it. I've heard people running 15-20 od with a fmic and they were ok when it came to the heat being generated but maybe that was all hear say?


I wouldnt do that... again lol...
Its not that the blower wont take the abuse , however there is way more than just the blower to make that amount of Overdrive useful
kevin L ran around 30% on his s port

However in ur situation
1 15% OD on a latemodel generates
19psi-20psi
2 20psi is about danger zone on pump gas especially if not tuned correctly and even worse if u are running nitrous things can go wrong fast
3. If u have a stock top end and cam you are only wasting more HP by turning the blower that fast
u need heads a cam

Keep in mind parasitic losses can never be re gained with cooling
theres a big difference

How i am telling u this is because i did it without the nitrous and it was no bueno sure it made decent pulls and felt strong had about every bolt on there is
but it was not good for the engine
another thing is you better use ARP studs or u will be re doing a headgasket job soon
and the 42lb injectors may run out of steam sooner or later if u want much more power



For your application
how about you try
a 10% JS
put on ur fmic
ur exhaust , port ur manifolds as well and start there
also make sure u have a good tune contact Xr7dave for some tuning if u havent already


If that is running well
then try out the 50 shot

And when all that is dialed in correctly then you can move up and enlarge the intake , thing is the stock inlet and tb are too small and starve the blower from air especially if u want to spin it much faster than stock
 
Out of curiosity, how restrictive is the intake manifold, and what do you (Miguel, or anyone else) feel that it would do in terms of lowering the internal engine psi in terms of making more effective power and power, in general?
 
Out of curiosity, how restrictive is the intake manifold, and what do you (Miguel, or anyone else) feel that it would do in terms of lowering the internal engine psi in terms of making more effective power and power, in general?

I think the design is quite poor im not sure how big of a restriction it is , but the cylinder air distribution is very poor
 
10 years ago I would have said the intake manifold is a major obstacle to making HP with this motor, but after seeing for myself how much power can be made with only some porting to match the heads and minor changes to the return plenum.... I've changed my mind. What really convinced me that the intake manifold wasn't that much of a problem, was seeing my boost drop from about 21 psi to 17.5 psi when switching from a 3.8 motor with heavily modded/oversized intake ports and matching intake manifold, to a 4.2 motor with a ported stock intake. Used the same 1.7 AR and same size pulleys on both motors.

Biggest obstacles to making power with an SC motor are the supercharger, heads and cam. I'm making right around 500 rwhp through a non locking AOD and the intake manifold isn't holding me back from making more, it's actually the intercooler that is limiting power. With a manual transmission the same motor would be making at least another 5% at the wheels.

David
 
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