finally got dyno'd and something is up

[VanWilder]

Well I finally got my car to the dyno (dynojet). Mods are JBA LTs, O/R H-pipe, JLT CAI, Delete Plates, Mutha Thumpr Cams w/ phaser limiters, Tillman Speed 93 All-out tune, and 4.10s...my car didnt quite get to where I was expecting...uncorrected I only put down 329hp/309tq and SAE corrected at 321hp/302tq...as you can see at the 3800 mark my hp/tq curve droped significantly which I'm sure cost me a good chunk of power...it looks to me like its pulling timing or something. I have Chris Rose at Tillman checking it out to see if its something he can fix or if its mechanical which I hope its not...I'm thinking based on other peoples recent dynos with the same mods that I'm about 20-30hp/tq off from where I should be...what do you guys think?!

-Lance

 

[jroc07gt]

its gotta be in the tune, either the timing or vct.

 

[VanWilder]

its gotta be in the tune, either the timing or vct.

yeah I agree...hoping Chris will get it figured out

 

[mac10chap]

true...with JBA L/T's O/R H pipe, Steeda CAI, delete plates, and U/D pulleys I was putting down 325HP/340TQ. Add the cams and it should be about 15-20 more HP. I'd say it is all in the tune

 

[VanWilder]

true...with JBA L/T's O/R H pipe, Steeda CAI, delete plates, and U/D pulleys I was putting down 325HP/340TQ. Add the cams and it should be about 15-20 more HP. I'd say it is all in the tune

yeah I just hope he can get it figured out...it sucks because I was going to datalog the dyno pulls for him but once I got to the dyno only about 10 min. from my house my computer battery had died and I didnt think of bringing the cable to plug it in...

 

[Greg Hazlett]

I know you said you are a 5 spd but is that auto/manual?

 

[VanWilder]

I know you said you are a 5 spd but is that auto/manual?

manual

 

[jtscuba02]

Did you run those times in your sig with those same mods, minus the dyno tune?

 

[tillman speed]

its gotta be in the tune, either the timing or vct.

Timing is roughly 27-30 at WOT. Knock sensors are limited so there's no way the dip in his graph could be related to minimal timing being pulled with knock sensors.

VCT, it's set up for limiters, and VCT rolls up to 17 at WOT nice and smooth. I think it's something mechanical with VCT, or a clutch slip issue. I am acquiring the DRF Dynojet Run File to look at gear ratio to see if I can see something slipping drivetrain wise.

Air/Fuel was spot on, and timing was spot on for our mail order tune. It was .8% lean... less than a percent off from target 12.85.

 

[ChevyKiller]

Timing is roughly 27-30 at WOT. Knock sensors are limited so there's no way the dip in his graph could be related to minimal timing being pulled with knock sensors.

VCT, it's set up for limiters, and VCT rolls up to 17 at WOT nice and smooth. I think it's something mechanical with VCT, or a clutch slip issue. I am acquiring the DRF Dynojet Run File to look at gear ratio to see if I can see something slipping drivetrain wise.

Air/Fuel was spot on, and timing was spot on for our mail order tune. It was .8% lean... less than a percent off from target 12.85.

I agree with the mechanical possibility. Seeing the a/f not duplicate the spike with the tq and HP leans away from a tune parameter IMO.

Is he on the stock differential? Did you check it? How is his pinion angle on his DS? Is it the stock DS? I'd be looking mechanically at the VCT and the stock rollers/lifters as well after the limiters install.

 

[Riptide]

If the clutch is slipping shouldn't he just try the old 40mph in 5th gear and stab the throttle test?

 

[smoken1986]

I agree with Chevykiller, with no change in A/F seem mechanical. Are you running stock clutch?

 

[VanWilder]

Did you run those times in your sig with those same mods, minus the dyno tune?

Yeah and I had a 20mph headwind coming at me

 

[VanWilder]

I agree with the mechanical possibility. Seeing the a/f not duplicate the spike with the tq and HP leans away from a tune parameter IMO.

Is he on the stock differential? Did you check it? How is his pinion angle on his DS? Is it the stock DS? I'd be looking mechanically at the VCT and the stock rollers/lifters as well after the limiters install.

Yes I am on the stock differential with 4.10s...as far as pinion angle it's never been adjusted and I am lowered approximately 2"...I am still using the stock driveshaft...as far as checking the VCT/stock rollers/lifters etc what do I need to look for??

If the clutch is slipping shouldn't he just try the old 40mph in 5th gear and stab the throttle test?

the owner of the dyno did have me do a 5th gear run 2500-6500 about 180mph and it didnt feel like it was slipping or anything

I agree with Chevykiller, with no change in A/F seem mechanical. Are you running stock clutch?

and yes I am running the stock clutch with 64000 miles on it

 

[VanWilder]

Timing is roughly 27-30 at WOT. Knock sensors are limited so there's no way the dip in his graph could be related to minimal timing being pulled with knock sensors.

VCT, it's set up for limiters, and VCT rolls up to 17 at WOT nice and smooth. I think it's something mechanical with VCT, or a clutch slip issue. I am acquiring the DRF Dynojet Run File to look at gear ratio to see if I can see something slipping drivetrain wise.

Air/Fuel was spot on, and timing was spot on for our mail order tune. It was .8% lean... less than a percent off from target 12.85.

Thanks a lot Chris for helping me out...hopefully we can get it figured out...I will get you the 4th gear 2500-6500 datalogs as soon as I can once the roads here clear up

 

[ChevyKiller]

Sure sounds like it's time for a new flywheel/clutch combo...

 

[VanWilder]

Sure sounds like it's time for a new flywheel/clutch combo...

you sir could definately be right

 

[bullitt boy]

If the clutch is slipping shouldn't he just try the old 40mph in 5th gear and stab the throttle test?

What should be the outcome? I have always tested clutch by rev up and dumping it it first through 2nd tach will tell and tires should smoke right through.

 

[antonio1988]

It's in the tune man, you should be at about 340rwhp

 

[irishpwr46]

definitely sounds like its time for a clutch. that dip in the torque could be where the clutch is really starting to lose its hold. especially since you have 60+k miles on it. put in an exedy mach 500 (basically a roush p51) and you should see a drastic change in your numbers. also make sure your pinion angle is correct especially since youre dropped so low. every degree that your off is equal to a loss of about 10 hp. have you done anything to the suspension besides lower it? control arms especially? if not you will want to look at the adjustable upper at least.