Cobra down 50 RWHP - Ideas?

[Tom]

I had the car on a dyno just to see where I was @ before the Whipple. To my surprise the car dyno'ed @ 412 RWHP.

When the car put down 463/463 I had the following done:

AFCO H/E
Intake
2.76 upper
Stock Mid Pipe
SLP LMII Exhaust
Tuned

Now, @ 412 the only differences:
1) Changed Mid Pipe from stock to Pro Chamber.
2) SLP LMII Exhaust to Bassani.
3) Just changed the intake filter to a clean/new one just before the dyno test. The other one was pretty dirty.
4) Suspension (e.g. Sub Frames etc.) work done - shouldn't matter.
5) Rears from 275/40 to 315/35.
6) Running a *little* rich.

Car was fine boost wise... No vacuum leaks to be found...

On my way there, 30 min. drive, I never had it into boost.

Jim suggested a compression test, but, wondering if anyone else has any ideas -or- just chalk it up to warm engine and need a new tune?..?

Click to read more...

 

[rdsnake]

Those tires will make a nice drag on the dyno plus your running rich so...between those two that's where the power went

 

[Tom]

Those tires will make a nice drag on the dyno plus your running rich so...between those two that's where the power went

K, that was what I was told (running a bit rich / tire size) were the main diffs. I just didn't think it made that much of difference. Shows you what I know.

Tune was spot on with the orignal setup and haven't had it tuned since.

Thx for the input Kevin.

 

[Wiked03]

I assume this was on the same dyno as the first numbers?

Yeah I am sure the bigger/heaver tires ate up some power... you would also lose some without a good cooldown and even more if it was running a bit rich. 50 hp is a lot though.

 

[Tom]

I assume this was on the same dyno as the first numbers?

Yeah I am sure the bigger/heaver tires ate up some power... you would also lose some without a good cooldown and even more if it was running a bit rich. 50 hp is a lot though.

Agree... 50 seems a tad high.

Same dyno - yes.

I'll just chalk it up to tires, need a new tune from Mr. K and cool down.

Everything else seemed to be fine.

Thx Carl.

 

[SVT SPEED 04]

first pull was around 30 rwhp after maybe a 15 minute cool down from the drive in

2nd pull was 412 , but even more heat soaked ( 5 minute cool down ) so that's expected

tune was approx 1/2 point richer then previous dyno / tune

heat soaked

wheels / tires

muffler with the Bassani over none with the SLP LM can show a small HP loss

Mac Pro-chamber over stock mid-pipe could show some TQ loss

rainy day and humidity up doesn't help either

loss bigger then I would expect..sure

lots of thing to contribute to lower #'s....don't see anything to really worry about as mentioned Sat.

 

[Nicky Pass]

Its amazing how much stupid little things can mess with cars!

 

[Skrat]

Its amazing how much stupid little things can mess with cars!

Like woman drivers?

 

[Tom]

first pull was around 30 rwhp after maybe a 15 minute cool down from the drive in

2nd pull was 412 , but even more heat soaked ( 5 minute cool down ) so that's expected

tune was approx 1/2 point richer then previous dyno / tune

heat soaked

wheels / tires

muffler with the Bassani over none with the SLP LM can show a small HP loss

Mac Pro-chamber over stock mid-pipe could show some TQ loss

rainy day and humidity up doesn't help either

loss bigger then I would expect..sure

lots of thing to contribute to lower #'s....don't see anything to really worry about as mentioned Sat.

Thanks Larry

Its amazing how much stupid little things can mess with cars!

No kidding... That and the fact I'm just not as well versed as most that freq. the site.

Like woman drivers?

Don't tell Wiked L that.

 

[Stangfreak91]

On a dyno jet, just changing from a factory 275 to the Nitto 315 the car lost 8hp...

 

[Tom]

On a dyno jet, just changing from a factory 275 to the Nitto 315 the car lost 8hp...

Yeah... 275 to 315's among the other things that were said. I was just surprised. No big, if I want a couple extra HP maybe I'll just swap out the mid-pipe and cb again

Oh well... Goes in for the New Gen. Whipple this month :headbang:

Speed Inc. & Kurgan FTW!

 

[ITLLOWNU]

ive seen a 10degree diff. in air temp rob 30hp so if it was warmer and more humid than your last pull ,then thats where your power went. tires wouldnt make that big a diff. if they are the same diameter just wider. if they are taller then you will loose some power.

 

[Racerx66]

How's your clutch? It can help you loose hp.

 

[SVT SPEED 04]

We found the HP issue and it was the IC pump was bad.

IAT's had to have been high and pulling timing

We did not see any issues on the dyno tonight with new IC pump and the Whipple

 

[VenomInside]

nice larry!

 

[Tom]

It was an excellent find.

Very happy w/ the end result!