Hi,

I am planning to build a lysholm supercharger on my 944 for 84'
The question is: how much boost can a normal 944 engine take?


etienne

 

if your engine has the euro pistons which i assume it does you will be somewhat limited in your boost because the CR is so high. however you may have access to higher octane than we do here which opens up some possibilities. with the right management and intercooling you should be good with maybe 6 psi, maybe more.

 

I have a UK 84 n/a and I am also considering supercharging it. I think its about 10.5:1 compression ratio.

Im not sure what you will get the boost up too but 5psi or so should be easily possible and enough to take you to around 200hp. Perhaps combined with new cams and some head work and a decent engine management system you wouldnt need much more boost to get around 250?

Edit:

Ive seen methods to change the boost on a supercharger like changing the gearing etc. Is there anything you can get that will let you dial in what boost you want like with a wastegate on a turbo?

 

with an SC boost is determined by pulley ratio..

 

Early 944s don't quite have the necessary internals to run more than 5 or 6 lbs of boost safely because the rods and pistons aren't forged and as a rule the stock engine management system (DME) only permits 5lbs of boost. To get any real performance out of a S/C 944, you have to redo the internals, put in a stand alone mgmt system, set up an intercooler, put in turbo injectors... You get what I mean. The cost is high.

 

http://www.speedforceracing.net/prod...erchargers.php

the speed Force Racing stage II kit run 8 PSI

I bet someone (not me) was smart enough you could do the math and compare the internal pressure of a 951 at high boost vs a 944 and that difference would be how much boost you could run. the connecting rods, crank and rings are the same. the trubo is 8 to 1 while the 944 is 9.5 to 1.

if i were a betting man i be you could run 12-15 lbs of boost. you would want an intercooler, larger injectors and the works

 

Pistons are different in a turbo - forged not cast IIRC.

 

A member here had a 83 Callaway he rebuilt and has a page that will give you and idea of what had been done to make that era 944 put out 284 hp. 83 Callaway 944 Turbo

 

thanks for all the info!! I like the callaway turbo

I live in holland sow I have Euro CR, on the callaway website you can see that US pistons have a bit of bubble hole in the top.

etienne

 

callaway cars had their compression dropped to 8:1, the same level the factory later used for 951.

early cars had forged connecting rods, not sure about the pistons.

there is no restriction on the dme related to boost pressure...no such thing exists within the Motronic in the NA. in the 951 yes but that is entirely different.

 

[QUOTE=McLovin69;6662076]http://www.speedforceracing.net/prod...erchargers.php

I bet someone (not me) was smart enough you could do the math and compare the internal pressure of a 951 at high boost vs a 944 and that difference would be how much boost you could run. the connecting rods, crank and rings are the same. the trubo is 8 to 1 while the 944 is 9.5 to 1.


Meaning no disrespect, only the crank is the same. The con rods and the pistons are not. Turbos have all forged internals, NAs do not.