>>Good point. Also some of the manufacturers and distributors (other than Randy of course) tend to inflate the numbers as well. I wonder how important Randy thinks the throttle body is...

Check the throttle body how-to. In it Randy give a god description of what it does and why it is f any benefit. In brief I think he says something to the effect that a larger opening allows it to do its job faster. I'm interested because it looks like something that I can actually do myself.

Untimately I think that the intake, pulley, throttle body all try to do the same basic thing -> stuff more air into the combustion chamber. Whereas the header and exhaust try to remove the back pressure from the combustion chamber. Albeit this is a pretty unsophisticated analysis but in my mind it kind of explains why the hp gained from mods are not strictly addative. My theory is that if you were to do only 2 mods and you'd get the most addative results by doing one for intake and one for exhaust.

Cheers,

Chuck

 

Seeing the ~5 whp I gained with the Magnaflow, I couldn't imagine that making any reproduceable change in my 0-60 time.

Also, the air intake and throttle body are trying to reduce pressure drop before the air gets to the supercharger. The pulley is trying to make the supercharger take more gulps of air per engine revolution.

 

>>Also, the air intake and throttle body are trying to reduce pressure drop before the air gets to the supercharger. The pulley is trying to make the supercharger take more gulps of air per engine revolution.

Right. By reducing the pressure you effectivly increase the mass of air allowed in a given volume --> increased density. In my simple model, the volume in question is the combustion chamber. More accurately the supercharger volume/fan speed/ air displacement etc. has to be taken into account but the end result is still more air in the chamber is it not?

 

Andy,

Have you considered the differences between your car and others with a pulley and exhaust? It seems like you've run up against a bottlenecek (intake?) that others who've put the MF exhaust on haven't experienced.

For instance, Randy was reaching (IIRC) 185 and has basically just focused on improving breathing from end to end, and installing the pulley.

Hope you get it sorted, and thanks for the Winter reading for those of us with upgrade lust.

Jeff

 

I plan to test a couple intakes and will try to mix and match to test all the combinations of components so far.

 

greatgro,

The throttle body is one of those mods that is still an unknown on a stock car - I'll be testing it soon by itself. I don't know if you'll see 5 and I know it won't be 10hp. It will depend on how restrictive stock is for the fuel economy equation.

The labor is about 20 minutes - it's really simple to change. Check out the how-to.

The exhaust system on the stock car is pretty bad, so the key for those of you who don't want the excess noise will be to find a system liekt he Quicksilver or (hopefully) the UUC. The good thing about this mod is that it does not void the warranty.

A motor is essentially an air pump, so the more help you can give it to pump air faster, the better. That means giving it as much air as it can use, and exhausting that air as quickly as possible. That's why we make the modifications to the intake and exhaust sides.

To get the additive gains (which are not cumulative), I've done as much as possible - the header and exhaust, the intake and throttle body, and finally the pulley. To tie it all together, you then need to tell the ECU to play nice with all the other stuff you've done, which is where I'm at now.

The head is the next step in the efficiency quest. I swear, I'll try to do it this week!

Hope that helps!

Randy

 

Comparing my car (stock airbox) with JLM's car (Rogue intake), there is only about 0.5 psi difference at redline. There is only about 1.5 psi theoretical improvement with a lossless intake and throttle body (which just ain't gonna happen). The throttle body and intake may be worth a few ponies, but I think it is unreasonable to expect significant gains.

 

Randy, In regard to the throttle body mod it seems to me that the dia increase is awful small. When doing my 5.0 mustang I went from a 58mm (same as MINI) to a 70mm and this is on a na motor. Some guys are going much larger. Didn't you say the new TB is something like 62mm? With the forced induction it seems to me that we could use a larger dia. Thanks for your thoughts. Anything on the Hotchkis stuff yet? I don't know how you can keep up with all of our questions and still get the stuff tested but we do appreciate it.
Rich