How do you figure the boost (supercharger) to compression (engine) ratio. What I mean is how much boost is safe at what compression. Right now I have 5.5lbs of boost at stock compression. I would like to increase the boost... however I'm concerned the stock compression is too high. So new internals... right? I would like to get more power (torque and some of those horsies). Right now I have 220Whp and 150Wtq. Someone once told me that 2 pounds of boost is equal to 1 increase in compression??? I did look with the ctrl + F thing and didn't see any reference to superchargers... maybe I missed it. Right now I have a daily driver... I would like that daily driver to be more powerful. Thanks.

 

umm.....superchargers are not as safe on high boost as turbos witha nicely set up intercooler systyem. but id say about 250whp is a safe level for your motor. and this is with the proper tuning, not the shitty managment that the jrsc comes with

 

What are you engine goals?

When is it 'fast enough?'



The ITR 10.6:1 compression motor does not give you a large margin for tuning error once you start to get the boost numbers up there.

Get yourself a good engine management system (Hondata comes to mind) and a dyno tuner with his head on straight, then go from there.



I do know that there is a formula floating around out there that shows the lbs.:comp ratio but I can't remember where it is. I think I saw it on T-I.net.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dsav4shawn &raquo;</TD></TR><TR><TD CLASS="quote">How do you figure the boost (supercharger) to compression (engine) ratio. </TD></TR></TABLE>

The most basic equation for figuring out your CR under boost is [(boost/14.7) +1] x CR. So in your case it would be [ (5.5/14.7) +1 ] x 10.6 = 14.57. If you wish to factor in altitude, then use: <FONT SIZE="+1.5">[</FONT> [ (5.5/14.7) +1 ] x 10.6 <FONT SIZE="+1.5">]</FONT> - [ (altitude/1000) x 0.2 ]

If you modify the motor's internals, then the whole equation changes and becomes much more complex.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dsav4shawn &raquo;</TD></TR><TR><TD CLASS="quote">How do you figure the boost (supercharger) to compression (engine) ratio. What I mean is how much boost is safe at what compression. Right now I have 5.5lbs of boost at stock compression. I would like to increase the boost... however I'm concerned the stock compression is too high. So new internals... right? I would like to get more power (torque and some of those horsies). Right now I have 220Whp and 150Wtq. Someone once told me that 2 pounds of boost is equal to 1 increase in compression??? I did look with the ctrl + F thing and didn't see any reference to superchargers... maybe I missed it. Right now I have a daily driver... I would like that daily driver to be more powerful. Thanks.</TD></TR></TABLE>

What are you using for engine management ?
Tuning is one of the most important factors to consider when it comes to high compression + forced induction.

An inexpensive modification to lower your compression would be a cometic MLS headgasket + arp head studs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dsav4shawn &raquo;</TD></TR><TR><TD CLASS="quote">How do you figure the boost (supercharger) to compression (engine) ratio. </TD></TR></TABLE>

I find this question both puzzling and frustrating.

Part of the reason for this it the question of, are there any absolute limits or requirements (other than general thermodymics) that relate to your particular question, which is itself vague.

What type of supercharger are you speaking of?

Is this going to be a Roots type system mounted on/as the intake manifold, or a centrifugal type system with which there may be provisions for cooling of the compressed intake charge?

Another thing to consider is that with turbo systems (which are easily provided with a method for cooling the intake charge), there is also the issue of not only what PSI (gauge, i.e., boost) one may be running, but also what the airflow (CFM) is at a particular boost setting.

So, in short, as Mythias said ... it's a complex issue.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Supercharger question -how much is too much???</TD></TR></TABLE>

... it depends ...
Did this answer your question?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dsav4shawn &raquo;</TD></TR><TR><TD CLASS="quote">How do you figure the boost (supercharger) to compression (engine) ratio. What I mean is how much boost is safe at what compression. Right now I have 5.5lbs of boost at stock compression. I would like to increase the boost... however I'm concerned the stock compression is too high. So new internals... right? I would like to get more power (torque and some of those horsies). Right now I have 220Whp and 150Wtq. Someone once told me that 2 pounds of boost is equal to 1 increase in compression??? I did look with the ctrl + F thing and didn't see any reference to superchargers... maybe I missed it. Right now I have a daily driver... I would like that daily driver to be more powerful. Thanks.</TD></TR></TABLE>

if you want it to last.. keep it where it is now