Okay, here is my question...

How come with the same engine, the lsj... the sc will hit about 250hp at 17psi or something of that matter, no direct numbers...

A turbo will hit like 300 something, same psi or maybe a little more or less..

I understand the s/c takes power to make power, but a whole 75 or more hp?

What are the logistics behind it..

a TVS produces more hp... how, and where can you buy these suckers?

Thanks!
Andy

 

intake manifold has something to do with it

 

supercharger isnt nearly as efficient or advanced at a turbo and since the supercharger is belt driven it robs power where a turbo doesnt. but since a turbo doesnt spool up right away a supercharged car will usually pull away from a stop untill the turbos spools up on top end.

 

hmm... sweeet thanks for the input!

anyone else?

 

my guess is that although the pressure of both the turbo and the supercharger are the same, the actual volume of air going into the motor will be different. I am assuming that the turbo setup will flow more air and therefore produce more power (more O2 in the combustion chamber).

The pressure that the system runs at is not always a clear indication of the power being created.

 

here's the problem, which you un-knowingly posted about. people associate power with psi. a cobalt running 15 psi can make more poewr than a cobalt running 17psi. a different car can make more power pushing 8 psi. another car can make less power pushing 19psi.

you can't just look at the amount of boost and compare like that.

 

Especially since the intake manifold on the super charged cobalts is the bottle neck of the whole system

 

I agree... in addition a 15psi cobalt could put down more power than another 15psi cobalt provided the flow is more in the first Cobalt

I understand that our intakes are somewhat of a complex piece but it would be nice to see if there was a solution to this problem. I am sure there has been something posted about this though.

 

That is currently being worked on by rebel and some others

 

Thanks for the info... that would be nice to see that come to market!

 

no prob search posts by rebelautoworx it'l l be something like intake manifold or something and read up, it'll also give you insight on your question

 

psi doesn't make power

air flow/temp..ect is what determines power.

 

i make 300whp at 21psi with the stock manifold and tvs

 

Andy, Andy, Andy, tisk tisk

How many times have I have to tell you boost means doodley squat as an indicator of power

Every car is different in how it takes boost.
Many factors include,

The type of boost - Supercharged or Turbocharged
Both use forced air (forced induction) but do it differently which is why outcome of power from one or the other is different at equal psi. A Turbo is exhaust gas driven. The downside is it takes x amount of exhaust velocity to make the turbine spin. Thus why we have whats called turbo lag.
Now with Superchargers you get instant boost as they are belt driven but this hurts as it takes power from the engine to spin the belt so if an S/C makes 15psi and a Turbo makes 15psi the turbo will make more horsepower....generally there are exceptions. This lose of power is called parasitic loss.

Now every Supercharger and Turbocharger is different as different Turbo's spin due to the size of the turbine.

Superchargers are different due to various rotor sizes and designs.
Thus why the TVS makes more power under lower boost.

Every thing is subject able what works for one person doesn't another.
Thats the thing, to find what works and what doesn't.

 

Typical parasitic supercharger can be 20-30%. Say original 2.0 engine=150hp (hypothetical); that's 45 there. It's possible the losses with the lsj are more, who knows?!?.

 

Supercharger = More Heat
More Heat = Less Timing
Less Timing = Less Power

Therefore

Supercharger = Less Power

Hope that makes sense.

 

Hmm.. i honestly didnt think parasitic loss was that high... i was thinkin ony like 10 percent, IF!... haha..

Haha james, it kinda rolled off the tongue that way, but ive finally figured out that boost=NOTpower...

I guess the question was more of why two different systems work at the SAME psi with different yields...

Our engine bays do get REALLY hot... I guess that would have alot to do with it... Do turbos generate that much heat at all? If you go turbo is there a "IAT2" like reading you need to pay attention to?

 

efficiency.

think of it like this. your engine is nothing more than a big air pump. the more air that goes in, the more fuel it can put, which means more power. different turbos and different supers put different amounts of air. that's where the varying power comes from.

as far as the parasitic loss from a super, like people said the super is run off of a belt that s spun by the engine. that spinning of the belt takes power. so, the harder it is to spin, the more power it uses up just to spin the super and the less power you actually make. turbos, which run off of exhaust gas, are much more efficient. they don't "steal" the engine's power to run. the downside is that if your turbo is too big, there will be a big lag because it takes time for the turbo to spool. but, if you have a properly sized setup with a turbo that is right for your engine/power levels, spool time should not really be an issue.

and as far as the engine bays, most of the temps are from the exhaust temps. the air coming out of the engine is VERY hot, well over 1,000 degrees. if you put your hand on your exhaust manifold, even 30 seconds after starting your car, you're going to burn yourself. at the same time, you should be able to put your hand on the supercharger, and it won't be very hot.

 

No ****? Thats crazy hot.. haha...

Thanks for the explainations!

I guess basicallly the over all word to use is efficiency... Whether it be due to power using, heat, or just plain air flow...