take a look at my dyno results. belt slipping

[GrayGhost03]

had the car tuned after the stg 5 port and n20 kit. my tuner said voltage was dropping off at high rpms causing it to lean out and the belt was slipping. im having the alternator rebuilt to correct the lean. the car has idler pulleys, idler stop ground off and the belt feels pretty tight. my question is if i get the next smallest belt will it stop the slip or is this something im going to have to live with? i installed the belt myself with a little work but ive read where some of you had to have a helper. im running a 2.93 upper and 6# lower. for the crappy pic and thanks

503/515 street
582/600 n20

 

[twhitey]

How big of a shot is that?

 

[latemodelracer2]

those numbers are low and fall of like its getting alot of belt slip

 

[GrayGhost03]

100 shot. im going to get a size or 2 smaller and have someone help me get it on. my tuner said to fix the voltage/slippage and bring it back.

 

[Satyr]

Wow...100 shot is only getting you 85hp? Something's wrong...

Usually whatever shot people run yields 2 times the shot in torque. For example, a 75 shot would give 150 tq, roughly speaking.

 

[GrayGhost03]

Wow...100 shot is only getting you 85hp? Something's wrong...

Usually whatever shot people run yields 2 times the shot in torque. For example, a 75 shot would give 150 tq, roughly speaking.

wrong as in severe belt slippage or something else?

 

[Satyr]

Well, the way your HP/TQ fall off it definitely looks like belt slip but usually your graph will have more zig-zags from that point forward, and your's does not. What was your timing at and did it drop at all throughout the pull?
Did you check your duty cycle and fuel trims? Where is your shot hooked up at and is it wet or dry?

What's your list of mods (including fuel mods)?

 

[GrayGhost03]

mods:
eaton stg 5 port and matching plenum
acccufab tb
60# injectors
bap
mafia
2.93 upper
6# lower
kook headers
bassani catback no cats

i dont know the timing but ill find out. duty cycle im sure was not right cuz my tuner said the voltage was dropping off at high rpms which was causing the injectors to fall off making a lean condition. a/f stayed at 12 most of the pull but it did shoot to 13 towards the end.

 

[baby2000]

What kind of bottle pressure did you have? I put dowmn almost the same exact number with a stage 4 and 2.76 upper and 4lb lower and 100 shot. My bottle presure was only 650 and someone on here told me that my bottle pressure should be at 950 and that is why i only got 80 horse out of 100 shot.

 

[Brutal Metal]

650 is NOT enough pressure, your gonna get the biggest numbers on the first blast of a fresh bottle!

 

[GrayGhost03]

just went out and checked the bottle pressure and it shows 1100psi.

 

[Satyr]

i would wait until you get your voltage straightened up and get it back on the dyno to see what it does then

 

[latemodelracer2]

what was the voltage dropping to?

 

[GrayGhost03]

at idle it was 13.5 and if i remember right he said it would drop to 9. it was low enough that the battery light was coming on. forgot to say im running a wet kit with a ported plate.

 

[dsfelton]

Sounds like a bad battery or alternator to me. Your charging system should hold a constant 14v at idle and through the RPM range.

 

[Satyr]

Yeah, I would say that the voltage drop is causing much, if not all of this.
I would get a belt locally (so it can be returned) and give it a shot on the dyno once the alternator is fixed. After that, see if you're getting any belt slip and go from there.

 

[GrayGhost03]

thanks for the help. ill post back in about a week with the results