Supercharger Efficiency and Weak Numbers

[LASO]

Just found out I was doing 15lbs of boost and it dropped to 7-8 when I exceeded the efficiency range. I know the total boost has to do with how the motor is set up, but how did he get to 20 lbs? I know that I did not build a more free flowing engine than JDM Engineering, especially with POS factory manifolds, stock heads, and stock cams on it!!

18% crank pulley and 2.6 blower pulley I believe.

And although those (cams/exhaust) would help you make more power they would also more then likely drop boost pressure (in a good way).

 

[ZmanM3]

What is the displacement of your engine? Also what type of heads are you using? These are factors that will lower the boost, but the SC is still pushing the same amount of air, it is just filling a larger volume of space.

 

[smoken1986]

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.

What rpm is your motor at when it hit 130mph? You are getting belt slip or something you should not be dropping power like that at high rpm. I dont think the problem is that the supercharger wont put out more, it looks more like the air cant leave fast enough to keep it building power..

 

[ZmanM3]

What rpm is your motor at when it hit 130mph? You are getting belt slip or something you should not be dropping power like that at high rpm. I dont think the problem is that the supercharger wont put out more, it looks more like the air cant leave fast enough to keep it building power..

Hmm, stock exaust manifolds? What type of header are you using if any?

 

[smoken1986]

Hmm, stock exaust manifolds? What type of header are you using if any?

Me? Pypes lt's.. What I am saying is you can stuff all the air you want into the intake but it doesnt mean it can flow through the heads and out the motor efficiently to make power without boost loss

 

[ZmanM3]

Me? Pypes lt's.. What I am saying is you can stuff all the air you want into the intake but it doesnt mean it can flow through the heads and out the motor efficiently to make power without boost loss

I was agreeing with you over 2 posts, I asked about the exaust and the heads and displacement of the engine.

 

[LASO]

OP- Make sure your not getting belt slippage. Check the tune over again. Then see where your at. If you still want more power after that you need to look into longtubes/cams/heads/overdrive pulley. My 2 cents.

 

[smoken1986]

I was agreeing with you over 2 posts, I asked about the exaust and the heads and displacement of the engine.

Sorry wasnt sure..lol He is running stock headers w/magnaflow xpipe with high flow cats. and stock heads..

 

[projeremy]

What is the displacement of your engine? Also what type of heads are you using? These are factors that will lower the boost, but the SC is still pushing the same amount of air, it is just filling a larger volume of space.

The engine is a Ford Racing Aluminator. I'm pretty sure it is listed as a 281. The heads are stock, non ported.

What rpm is your motor at when it hit 130mph? You are getting belt slip or something you should not be dropping power like that at high rpm. I dont think the problem is that the supercharger wont put out more, it looks more like the air cant leave fast enough to keep it building power..

Not sure what RPM, I know it was towards the top of the range though. That makes sense, the blower will only charge the motor to a certain pressure before it starts to "free wheel" and no longer grab the air.

 

[projeremy]

I appreaciate all of the advice and feedback. How did people do this stuff before forum's were invented?! I think my next step is going to be long tubes, stage 2 heads, and cams so the engine can dispell the air quicker.

 

[ZmanM3]

I'd just go with the stage III heads if your going the livernois route.

 

[projeremy]

I'd just go with the stage III heads if your going the livernois route.

Will the stage 3 heads pass an emissions inspection?

 

[ZmanM3]

Visually yes, and as long as your car is tuned correctly yes.

 

[DynamiteBlues]

OP- Make sure your not getting belt slippage. Check the tune over again. Then see where your at. If you still want more power after that you need to look into longtubes/cams/heads/underdrive pulley. My 2 cents.

just an FYI, underdrive pullies on blowers take boost and power away. Overdrive pullies are what you would look into to increase the boost and power output. I think a nice longtube is crucial with a built bottom end a a smaller pulley, will really help out the top end (as well as the entire powerband with that setup). I think a longtube on that setup will make more power than you're expecting. I'm guessing at least 30+ hp as well as retaining boost up top. If you're still looking for more top end a mild port on those stock heads and a blower cam couldn't hurt either! That compression is definitely capable of some satisfying numbers

 

[projeremy]

just an FYI, underdrive pullies on blowers take boost and power away. Overdrive pullies are what you would look into to increase the boost and power output. I think a nice longtube is crucial with a built bottom end a a smaller pulley, will really help out the top end (as well as the entire powerband with that setup). I think a longtube on that setup will make more power than you're expecting. I'm guessing at least 30+ hp as well as retaining boost up top. If you're still looking for more top end a mild port on those stock heads and a blower cam couldn't hurt either! That compression is definitely capable of some satisfying numbers

I guess I'll be ordering some long tubes then!! If you listen closely... you can hear my wife screaming at me already!!

 

[ZmanM3]

just don't tell her.

 

[LASO]

just an FYI, underdrive pullies on blowers take boost and power away. Overdrive pullies are what you would look into to increase the boost and power output. I think a nice longtube is crucial with a built bottom end a a smaller pulley, will really help out the top end (as well as the entire powerband with that setup). I think a longtube on that setup will make more power than you're expecting. I'm guessing at least 30+ hp as well as retaining boost up top. If you're still looking for more top end a mild port on those stock heads and a blower cam couldn't hurt either! That compression is definitely capable of some satisfying numbers

Meant overdrive captain obvious

 

[DynamiteBlues]

Those stock manifolds are very restrictive and could potentially cause the boost loss. Its interesting because TVS blowers tend have a boost spike characteristic and increase in the upper rpms. If long tubes don't help bring the boost back then i would focus on fixing that boost loss up top before worrying about HP numbers

 

[joedls]

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?

 

[GlassVapor]

Finally got everything up and going and got the tune done today. Pretty disappointed..... With the 3.75" pulley at 8psi I managed 430rwhp\431rwtq. They installed the 2.75" pulley and got 496rwhp/ 497rwtq, but found that the Universal Load had dropped off. I was told that this meant we were maxing out the supercharger and it was leaving it's efficiency range. I was also told that the reason I was seeing such low numbers was because my new block was only 8.7:1 compression. Basically that the supercharger was not big enough for the new motor? Any thoughts, I'm an idot when it comes to this, so I welcome any input. We ended up putting the 3.75" pulley back on. I'm not doubting what the guy is telling me, just don't really know where to go from here. I thought this kit was capable of 600+rwhp?

Its not the blower, your car can't handle the 2.75" pulley your tuner is nuts for even trying it (suprised he didn't have to give you a ride home) 3.50" pulley without head mods and LTs is the best size. It just can't ingest that much air thats why you saw only 66rwhp difference the boost must have been at the danger Will Robinson level. My car stock with the E-Force pulled 426rwhp 410rwt using stock 3.8 pulley boost was 8psi @6100rpm. Your not that far off