compression ratio

[vega]

Well i am going to be building up a 3400 from a 00 grand am not a gt- i am going to blow it with a m90 from a 92 bird and intercooled. here is my question that thing pushes out 12psi. and the compression is 9:5.1 already. so is this going to be too high? ans is there such a thing as a boost controller for a supercharger? i know there is for turbos- i have lots of experience that way no supercharged. will the pistons hold to that kind of boost for long at all even as a very quick daily driver?

(not getting many good answers as far the compression ratio goes from the z24 guys- just them trying to explain boost to me as if i did not know how it works)

http://www.v6z24.com/jbodyforum/viewtopic,p,1037336.html#1037336

[SappySE107]

The pulley is the boost controller.

Your compression ratio should be no problem for an M90 at 12 psi with enough injector and tuning done.

[Mars]

The pulley is the boost controller.

Your compression ratio should be no problem for an M90 at 12 psi with enough injector and tuning done.

You will probably need a smaller pulley on that blower to get 12 psi. But yes, it will work.

As said above, it will work perfect. I have a stock 3400 running 14 psi @ redline on a cerntifugal blower. (intercooled) 30# fuel injectors with TGP chip. Runs awsome.

You will NEED to upgrade your valve springs. ( I recommend LS-6) The boost just pushes the stockers open @ high RPM.

[bjornmk1]

hey MARS,

how come he would need a smaller sized pulley ?

those m90 already do 12 psi with the stock pulley.


bjorn

[Mars]

My mistake, Seing as the T-bird SC was so underpowered, I figured it was only running 5-6 psi... haha.

[vega]

no no that's cuz itz uh ford

[CNCguy]

SC pulley size really depends on the crank pulley size. Changing the size of the crank pulley has the opposite effect of changing the SC pulley. Bigger crank pulley = more boost.

[bjornmk1]

correct,it's al about the relation of crank and sc pulley sizes.

how can one calculate the pulley size if you know engine displacement
and capacaty of the sc.

don't know the VE of the 3400 engine though????

B

[vega]

VE? i could find out- but i remember reading that somewhere but i can't remember what the acrinim means.

[vega]

check out what i just found! http://kb-silvolite.com/article.php?action=read&A_id=57

um that means the compression ratio for the 3400 at 12psi would be 17.3 that thing WOULD blow up if that were true. your recommendations?

here is another interesting article for personal use.

http://dtcc.cz28.com/gminfo.htm

[bjornmk1]

VE means : volumetric efficiency

I need to know the specific VE on the 3400 engine.

B

[Guest]

check out what i just found! http://kb-silvolite.com/article.php?action=read&A_id=57

um that means the compression ratio for the 3400 at 12psi would be 17.3 that thing WOULD blow up if that were true. your recommendations?

here is another interesting article for personal use.

http://dtcc.cz28.com/gminfo.htm

Funny how people run 12 PSI+ on teh 3400 and they don't blow up.

[ForcedFirebird]

Funny how people run 12 PSI+ on teh 3400 and they don't blow up.

What about 11.78:1 boosted?

[Mars]

I went for a cruise in my car last night. 17 psi.

Haha, yup, that's seventeen @ 6500 RPM.

Doesn't even sputter. I think my heads were milled a TAD to get them straight as well, so I have a tad more compression than stock.

Amazing what a half decent tune and a BIG intercooler can do. I should get a vid, but the torque steer and all that, it's hard to film.

So, as I said before, RUN 12 PSI, just make sure you have a good tune. It will be 100%.

[vega]

sweet so either i read that site wrong or that site was wrong.

forcedfirebird how did you get 11.78:1? for math that is? whats the equation? if you will.