low compression for blown motors

[silver03cobra]

all the same........ they both need to last. AND I didnt just build funny cars....

[WildBill]

all the same........ they both need to last. and AND i didnt just buil funny cars....

Listen
I'm not here for a pissing contest. I want the young man to be happy with his car IF he builds his engine. And I don't really care where he gets the work done. I want him to have valid and accurate info to make a decision on what direction to take his car and be happy with the hard earned money he will have spent.
It's very simple engineering basics.
The car will run better on the street with higher compression when not in boost. The blower will last longer when operating at lower boost pressures. He will still have room left in his combo if he want to up the HP at a later date without having to go into the engine and spend more money.
Given the same effective cylinder pressures in both systems as stated by Jeff, there's just no way that the system that has higher inlet air temps and higher parasitic losses will make more HP.

If you think so, please explain and be as detailed as possible, in how your skills will overcome those losses, be a better street combo, all while maintaining the same effective cylinder pressures.

[silver03cobra]

low CR + (big boost pulley) with a blow off valve set to the desired PSI will be the best of both worlds AS long as the blow off valve is before the mass air... Blower will last no matter how much boost... EX.

281ci 9.0:1CR + D1SC pulleys set to 25psi (guess, must tune for right combo) blow off valve set to 10-15psi
BEST SET UP!

or
281ci 10.0:1CR + D1SC boost set to 5psi (or 8psi) wont even come close to the first set up.... DO YOU THINK I AM WRONG???a???? WHY DO PISTON COMPANIES SELL FORCED AIR PISTONS AS A LOWER COMPRESSION THAN STOCK??? i bet they know something..... I bet they Have A LOT OF MONEY IN THE "engineering basics".......

[BurnTire]

Ok Bill here is the deal.

1 Point of CR = 2% to 3% Gain in Horsepower
1 Pound of Boost = 15-20 HP

So my car makes 625 RWHP 20 PSI 8.5:1.
If I upped the CR to 9.5:1 I would put down 644. 625 x .03= 18.75+625 = 643.75

So now with 9.5:1 I lower the boost to 16 PSI so I have the same effective CR as 8.5:1 with 20 PSI. I will be super conservative and use only 15HP per pound of boost.
15 x 4 = 60HP 644-60 = 584

8.5:1 with 20 PSI and an Effective CR of 19.8 = 625HP
9.5:1 with 16 PSI and an Effective CR of 19.8 = 584 RWHP

Boost is your friend when used correctly.

[silver03cobra]

Ok Bill here is the deal.

1 Point of CR = 2% to 3% Gain in Horsepower
1 Pound of Boost = 15-20 HP

So my car makes 625 RWHP 20 PSI 8.5:1.
If I upped the CR to 9.5:1 I would put down 644. 625 x .03= 18.75+625 = 643.75

So now with 9.5:1 I lower the boost to 16 PSI so I have the same effective CR as 8.5:1 with 20 PSI. I will be super conservative and use only 15HP per pound of boost.
15 x 4 = 60HP 644-60 = 584

8.5:1 with 20 PSI and an Effective CR of 19.8 = 625HP
9.5:1 with 16 PSI and an Effective CR of 19.8 = 584 RWHP

Boost is your friend when used correctly.

been drinking too much 100proof southern comfort to do math but that looks right..

[WildBill]

Neither one of you guys are addressing the young man's problem.
He has a PS1C. It won't make or carry the boost numbers you two are wanting to use in your scenario. And you are not using the same effective cylinder pressures in each combo.

Say what you want. Shout as loud as you like. Cast as many dispersions as you wish. It still won't change the facts.
Pretty ridiculous that either of you guys want to conduct yourself in such a fashion to TRY and prove a point.

[BurnTire]

Neither one of you guys are addressing the young man's problem.
He has a PS1C. It won't make or carry the boost numbers you two are wanting to use in your scenario. And you are not using the same effective cylinder pressures in each combo.

Say what you want. Shout as loud as you like. Cast as many dispersions as you wish. It still won't change the facts.
Pretty ridiculous that either of you guys want to conduct yourself in such a fashion to TRY and prove a point.

Reading Comprehension Bill
I used the same effective CR in the math problem two post above.

What next c16 isn't a supercharged fuel?
A steel cage is only good to 11.0?

Oh wait you already made those claims.

It is amazing the lengths one will go to cover the fact that they don't know what they are talking about.

[About2Bite]

[BurnTire]

[Stanger00]

HAHA...this has turned into should I dare say..."Will a plane take off from a treadmill" discussion.

LMAO.

This discussion seriously made me laugh.


One question though, how do you get 19.8 for effective cylinder pressure? Or are you just using your car and your cars compression ratio as a base line to prove a point?

The point being that a car with 8.5: 1 compression with 19.8 effective cylinder pressure at 20 psi will make more power over a car with 9.5:1 compression with the same 19.8 cylinder pressure.

BUT like you mentioned above if said motors run the SAME boost at a HIGHER compression ratio then of course more power will be made...but then we have other issues like cylinder heat, IAT's fuel delivery BLAH BLAH...stuff I the consumer doesnt really need to think about.

but really all of this info should be typical R&D for engine builders and a simple phone call will have you on your way.