Supercharger Efficiency and Weak Numbers

[don_w]

OK, guys, here's what I don't understand. Several of you have commented on loss of boost due to restrictions, either from stock exhaust or intake manifold. This doesn't make sense to me since boost is basically a measurement of restriction. The less the engine flows the more boost you should have, all things being equal. You would probably make less power with a restrictive intake or exhaust, but you would have more boost. What am I missing?

What he said...

 

[smoken1986]

OK, guys, here's what I don't understand. Several of you have commented on loss of boost due to restrictions, either from stock exhaust or intake manifold. This doesn't make sense to me since boost is basically a measurement of restriction. The less the engine flows the more boost you should have, all things being equal. You would probably make less power with a restrictive intake or exhaust, but you would have more boost. What am I missing?

The boost loss is because it can spike to 15psi but if the motor can only release 8psi worth of air the motor is not going to keep pulling the same amount of air from the outside because there is still air in the blower

 

[smoken1986]

In short the airpump on top of the motor is not strong enough to push that volume of air through the top of the motor and out

 

[joedls]

The boost loss is because it can spike to 15psi but if the motor can only release 8psi worth of air the motor is not going to keep pulling the same amount of air from the outside because there is still air in the blower

That doesn't make sense to me. The engine is not pulling air. The blower is forcing air into the engine. The less it flows, the more pressure is going to build up, thus more boost. I can guarantee you that a drop from 15 psi of boost to 8 psi is not caused by a restrictive exhaust or intake.

 

[don_w]

The boost loss is because it can spike to 15psi but if the motor can only release 8psi worth of air the motor is not going to keep pulling the same amount of air from the outside because there is still air in the blower

But it will still register as 15psi, so there is no loss.

 

[joedls]

In short the airpump on top of the motor is not strong enough to push that volume of air through the top of the motor and out

That would cause it to build pressure, thus more boost.

 

[smoken1986]

Yes in theory that would be correct but the blower is at a major effeciency loss and cant mantain the pressure. Just because the blower is made to build pressure does not mean it can maintain it if the air is not being removed fast enough. You will lose air flow velocity and lower pressure or cause belt slip from backed up air.. Belt slip being the direct cause of psi loss..

 

[joedls]

Belt slip being the direct cause of psi loss..

Now that I can buy.

 

[NastyStang113]

Here is the dyno sheet. I am using factory manifolds, my other mods are listed in my signature, other than that I'm pretty much stock. I am not saying I am disappointed that I only made the HP that I did, I am disappointed that, if true, the Edelbrock supercharger I just dropped $6k on won't provide enough air. I thought the new Eaton Gen 6 TVS rotors would handle a lot more. It's not like I'm using an aftermarket pulley, this pulley is provided by Edelbrock for this supercharger, and it's too much for it? Just doesn't seem right.

Who's your tuner? I don't know if you ever said and I just missed it. I'm running the Roush TVS which uses the same rotors as the Edelbrock. I'm making 530 rwhp & 501 rwtq SAE corrected at ~11 lbs on a Dynojet 224xLC with a safe amount of timing for my car on 93 octane on the stock block. Granted, the OEM motor has a higher compression you should still be able to make decent power just fine. Also, the only other performance mods that would effect my numbers are a Magnaflow catback and a O/R X Pipe, factory exhaust manifolds too.

 

[smoken1986]

Now that I can buy.

After I read what I typed it looked like I was saying things different. Looking at his dyno sheet even with the 3.75 pulley he has a 15-25 hp loss at high rpm which looks like it could be belt slip, and if its slipping with that pulley its sure going to slip with the smaller one. I was meaning with better flowing exhaust and heads there would be less chance for belt slip because the supercharger would be more effecient and would hold boost better.

Sometimes its hard to type exactly what you are thinking and make sense lol

 

[RED09GT]

Belt slip.
It's not that the compressor doesn't move enough air, it's that the engine can't flow enough air. To remedy it you either need to get a better grip on the pulley to force the air in or improve the engine to move more air.
The only limit of the blower you've reached is the capacity of a small 6 rib pulley.

 

[don_w]

Sometimes its hard to type exactly what you are thinking and make cents [sense] lol

Oy....

 

[smoken1986]

Oy....

Man you cant get anything by you guys lol Was just going to fix it

 

[GerRod]

Who's your tuner? I don't know if you ever said and I just missed it. I'm running the Roush TVS which uses the same rotors as the Edelbrock. I'm making 530 rwhp & 501 rwtq SAE corrected at ~11 lbs on a Dynojet 224xLC with a safe amount of timing for my car on 93 octane on the stock block. Granted, the OEM motor has a higher compression you should still be able to make decent power just fine. Also, the only other performance mods that would effect my numbers are a Magnaflow catback and a O/R X Pipe, factory exhaust manifolds too.

The E-force has the same Eaton TVS supercharger as the Roush TVS kit that you're making 530 hp with. I'm wondering about MAF on the E-force kit. Is it much smaller than the Roush MAF and is that limiting its power?

 

[projeremy]

The E-force has the same Eaton TVS supercharger as the Roush TVS kit that you're making 530 hp with. I'm wondering about MAF on the E-force kit. Is it much smaller than the Roush MAF and is that limiting its power?

I am running the edelbrock competition air intake with the 95mm MAF sensor.

 

[2kanchoo]

Belt slip.
It's not that the compressor doesn't move enough air, it's that the engine can't flow enough air. To remedy it you either need to get a better grip on the pulley to force the air in or improve the engine to move more air.
The only limit of the blower you've reached is the capacity of a small 6 rib pulley.

This is what I'm thinking.

 

[NastyStang113]

The E-force has the same Eaton TVS supercharger as the Roush TVS kit that you're making 530 hp with. I'm wondering about MAF on the E-force kit. Is it much smaller than the Roush MAF and is that limiting its power?

Like I said, it uses the same rotors. The MAF isn't limiting the power on that car. Still want to know who's tuning the car.

 

[Tommygun]

its the low compression. plain and simple.

we build all of our motors at 9.5 minimum

I would get a 10% lower and let it eat some boost

 

[NastyStang113]

The Roush P51 cars use roughly the same compression ratio and there are cars running around with 16 lbs of boost and 600 rwhp.

 

[smoken1986]

its the low compression. plain and simple.

we build all of our motors at 9.5 minimum

I would get a 10% lower and let it eat some boost

The problem is it wont take the boost. The topend of his motor does not flow enough to move the air and causing belt slip so he needs either a better tensioner or better flowing topend or both.

I think everyone is in agreement that he is getting belt slip if you look at the dyno sheet it looks like he is getting it even with the 3.75 pulley.

BTW- It looks like it was dynoed by A R T so they probably are tuning it also