Supercharged HP question

[netapp]

I have an 06 which I mistakenly had hennessey do the supercharger upgrade to. It was finished at the beginning of the year with their reported HP of 661 (did receive a dyno sheet). It seemed to have good power and would easily spin the tires through 3rd gear. Well, I had some small issues with other things so the car had to go back to them. Once I got it back, it would not spin very easy as it did before. I finally got time to take it to another shop and the dyno results are attached. Not sure why the large range but it is definately lower than what the original 661 was.

The shop it is at now (dallas performance) said it has the stock/standard pully which comes with the paxton and they do not think that it would produce 660 HP with the standard pulley. They said it needed to have 10-11 lbs of boost to get up to 660-700 rwhp which would require a different pulley. It does have the long tube headers and high flow cat, everything else is stock.

I don't know anything about tuning or reading the dyno indept.

I am thinking due to some arguments I had with hennessey, they done something to the car when it was sent back to their shop the second time.

Any one have any thoughts on the HP range / variance? (Yes, I know, I should not have sent it to hennessey, so I don't need that as a reply)

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[TowDawg]

There are quite a few guys running around with 650+ rwhp on the stock pulley. If you've got the headers and good exhaust, a good tune should get you there without changing the pulley. I don't think you can even dream of putting 11lbs to stock Gen III bottom end.

 

[plumcrazy]

i still cant believe anyone would take thier car and hard earned cash to hennessey...... i dont really mean it but you almost deserve it. (not really)

dallas perf is a good shop from what i can recall. call around to woodhouse, DLM, DC, A&C and see what they say for expected power from your car. all of those guys are top notch and always willing to help.

 

[shooter_t1]

There are quite a few guys running around with 650+ rwhp on the stock pulley. If you've got the headers and good exhaust, a good tune should get you there without changing the pulley. I don't think you can even dream of putting 11lbs to stock Gen III bottom end.

I 2nd this. My 06 w/Paxton had the stock pulley and a Corsa cat back. Put 651 rwhp down here in the Tx heat. Was installed by DC Performance and had a nice safe tune. And as Plum said, I wouldn't let JH "wash my car", much less work on it.

 

[ViperGeorge]

Big difference in power figures based on the make of the dyno. Dynojets tend to be the most generous in my experience. Different readings at different shops really don't mean a hill of beans especially if car is run on different Dynos. Heck even the operator can make a difference with the calibration and smoothing curves that they apply. My SC 06 with stock pulley puts down around 650 on a Dynojet. Had it dyno'd by another shop with a different dyno (Dynomax???) and it put down like 550. Dynos are only good for determining the benefit of any mods as long as the car is run on the same dyno under similar conditions. By the way, my 06 gained exactly 200HP on the Dynojet after SC install. Same operator, same conditions.

 

[Black Moon]

661 best number with stock pulley. I was warned not to go smaller with stock bottom end but I still want to. LOL keep the stock pulley and buy my complete 355 differential. It will fell like 750. I'm going to a gen4 307 dif.

 

[Bobpantax]

The stock kit properly installed with a D.C Performance blower tune is bullet proof. Your highest run on the above chart was at 8 pounds of boost. That's about it for a car with a stock bottom end. As a poster said above, results can vary quite a bit. For instance, what was the temperature on the day of the 661 run? What was the temperature on the day of the above runs? Same question for humidity and barometric pressure. If the temperature was higher when the above runs were done, that could be the reason for the lower result.

 

[ssjcreeper]

I agree. Different dynos, conditions, etc will yield varying results. Have you checked your boost pressure to see if it's dropped? Also, a reputable tuner once told me my vette would lose boost with headers over the stock exhaust. Not sure how applicable this is to the Viper stock exhaust manifolds vs headers, but they did recommended switching out to a smaller pulley to compensate.

One more thing - stating the obvious, but temperature plays a big part too. Not sure of your experience with S/C cars, but in lower temps it felt like I had 1000 rwhp. It was noticably different when heat-soaked and on hot/humid days.

 

[Ghoust]

im at 660rwhp at stock pulley 8.4psi of boost.

 

[TR930]

661 best number with stock pulley. I was warned not to go smaller with stock bottom end but I still want to. LOL keep the stock pulley and buy my complete 355 differential. It will fell like 750. I'm going to a gen4 307 dif.

Black Moon, I found this on the site or on the web. Looks like 3.33 would be pretty good setup...

http://xse.com/leres/bin/gearratio?...rence=85.26&revs=743&section=&profile=&wheel=