Supercharger Efficiency and Weak Numbers

[projeremy]

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?

 

[Hatchman]

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?

How many pounds of boost where you showing with the 2.75" pulley?

 

[dsmx17]

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?

the kit IS capable of over 600whp WITH the proper boost and timing, it doesnt mean the supercharger will make the power in a given efficiency range, if you overlay the supercharger map vs your boost to power curve you should see what I mean.

what was the recorded boost level for the smaller pulley? if it was 14psi or under on that compression with safe timing curve those numbers seem accurate.

 

[Steedman07]

What dyno?

 

[projeremy]

What dyno?

it was a dynojet, not sure what the psi was. i dont know if he looked at it or not. if he did he didnt tell me

 

[projeremy]

the kit IS capable of over 600whp WITH the proper boost and timing, it doesnt mean the supercharger will make the power in a given efficiency range, if you overlay the supercharger map vs your boost to power curve you should see what I mean.

what was the recorded boost level for the smaller pulley? if it was 14psi or under on that compression with safe timing curve those numbers seem accurate.

maybe i was using too small of a pulley?

 

[dsmx17]

maybe i was using too small of a pulley?

Smaller is going to net more power.

 

[2kanchoo]

Only gained 60rwhp going from a 3.75 to 2.75 pulley?

 

[dsmx17]

Only gained 60rwhp going from a 3.75 to 2.75 pulley?

Could be belt slip, thats why i asked the boost.

 

[2kanchoo]

Could be belt slip, thats why i asked the boost.

Ahh I didn't even think about that. Good point.

 

[timfoster405]

I think your issue is a combination of low compression ratio and not knowing anything else...meaning.... what was the a/f ratios?...amount of boost...boost curve... to see if you are having belt slip... how much ignition timing was the tune providing...

I think the optimum a/f's are 11.7 and timing around 18-20 degrees on 93 pump...

Also, what type of gas were you running...

goodluck

 

[smoken1986]

May be belt slip for sure, also ck your cats they could be clogged. Also what heads/cams are you running?

 

[smoken1986]

Really need to see the dyno sheet

 

[ZmanM3]

I think that a 1" smaller pulley should have netted more then 60HP. What type of MAF and housing do you have? What type of fuel system and what size injectors are you running? Also that is a very low compression engine, very boost friendly but the down side is you need more boost to make power.

 

[Jeffs FRC]

Like others are saying you need some more info to see whats really going on with the car. Did your tuner give you any suggestions other than the blower being too small?

Timfoster, 14.7:1 is what youd like to see in part throttle situations. A blown car at wot is gonna be around 11.8:1 give or take depending on the tuner.

 

[jason0156]

What intake setup?

 

[dsmx17]

Timfoster, 14.7:1 is what youd like to see in part throttle situations. A blown car at wot is gonna be around 11.8:1 give or take depending on the tuner.

Took the words out of my mouth. even 11.8:1 doesnt leave much room for error in timing tuning.

 

[projeremy]

I think your issue is a combination of low compression ratio and not knowing anything else...meaning.... what was the a/f ratios?...amount of boost...boost curve... to see if you are having belt slip... how much ignition timing was the tune providing...

I think the optimum a/f's are 14.7 and timing around 18-20 degrees on 93 pump...

Also, what type of gas were you running...

goodluck

93 octane, not sure where he set the numbers on the tune

May be belt slip for sure, also ck your cats they could be clogged. Also what heads/cams are you running?

The cats are brand new magnaflow high-flow cats. heads and cams are stock.

I think that a 1" smaller pulley should have netted more then 60HP. What type of MAF and housing do you have? What type of fuel system and what size injectors are you running? Also that is a very low compression engine, very boost friendly but the down side is you need more boost to make power.

the intake is the upgraded intake system from edelbrock. GT 500 dual pumps, MMR billet fuel rails, 60lb injectors.

I understand about the more boost, but I just can't believe the edelbrock system can't produce enough even with the smallest pulley. Unless, as mentioned above, I was getting pretty bad belt slip. I'll upload the dyno sheet tomorrow.

 

[Jeffs FRC]

93 octane, not sure where he set the numbers on the tune

Dyno sheets don't have psi or a/f charts?

 

[jason0156]

Found the problem! You have something from MMR on your car. Take it off and it will run like a champ.