More BOOST!

[white_lightning]

After 23,000kms of running the 3.625" pulley and seeing about 8.5 lbs of boost I had the service department throw on the 3.5" pulley on.

Didn't feel any gains on the butt dyno, but I am taking it to the track Friday to confirm any gains. Does anyone think there could be belt slip from the initial pulley being bigger? Whipple says both pulleys use the same belt size so I just reused my existing belt.

 

[JeremyH]

Did you get the tune looked or the a/f checked? Belt is fine.

 

[white_lightning]

Haven't checked anything yet, just a quick drive post install.

When I spoke to my tuner he said I would not need a retune based on the pulley change, the PCM would add fuel as needed. It was tuned on his dyno initially by this tuner.

 

[JeremyH]

As long as the fuel system etc can support it, it should adjust for the added airflow depending on how your tune is setup. I personaly would at least check to ensure everything is still good when adding 2-3psi like that. Just some advice.

 

[AbdullaGT500]

Theoretically, you shouldn't need any tune adjustment; however, it is definitely wise to have the air/fuel ratio checked over. Better to be safe than sorry. I went from 8 lbs of boost to 16 lbs and the car actually ran more rich on the same tune.

 

[white_lightning]

Fuel system consists of GT500 dual fuel pumps and GT500 47lb/HR injectors. Should be okay in the fuel department from my research.

I agree I want to have it back on the dyno for a check. Better to spend $200 instead of $5000 on a forged setup. I thought 1 size smaller pulley would be 1.5 pounds if boost increase, not 2 or 3. I'm also at 3600 feet altitude if that makes any difference...

 

[JeremyH]

You should be fine then, every setup is different as far as boost you will see. Belt is good, tensioner will pick up the slack from the slightly smaller pulley.

 

[white_lightning]

^ thanks for all the help. 1/4 mile ET and MPH results to follow after Friday night drags.

 

[ChiDiddy]

i would run a 3.25 whipple pulley. I ran a 3.375 when i had mine and it ran perfect with a JDM tune. I could have changed it from 3.25-3.625 without any adjustments to the tune.

i made 434 rwhp 1/4 was 11.8@116 and i believe 1.8 60ft

 

[88_50]

I had mine tuned at Murillo Motorsports when I switched fro a 3.5 to 3.25 pulley. Better to be safe than sorry, and the tuner can always get a little more extra ponies out of it for ya.

 

[ChiDiddy]

in all honesty, i know others will scream blasphemy, but when it comes saleen, whipple, or roush superchargers on a 3v, i will take an email tune from brenspeed or JDM over a custom dyno tune. They have done thousands of these cars and as long as you mention every aftermarket part on your car, your tune would likely be perfect. Seen this happen with many people and my own car. By no means did i cheap out on a tune, just the cheaper option was the better option.

regarding the 3.5 to 3.25 pulley change, what exactly did they do to your tune? Reason i ask is because the computer would automatically adjust for more fuel at that small increment. Whipple and JDM allow for the same tune for the range i stated above. Whipple tunes have been known to be SPOT ON from the factory.

 

[white_lightning]

3.625 -> 3.5 pulley. Previous best was 12.98 , new best 12.699 @ 113 with 60' of 2.05. Room for more improvement for sure, but I was happy with the gains nonetheless.

 

[AbdullaGT500]

Get that 60' down!

 

[white_lightning]

I know that 60 blows...my 2nd best pass was a 1.92 60' foot - 12.76 @ 111.13MPH.

I have 305/35/20 555R's so not ideal. But at least now I know I can cut a low 1.9.

Had I had a 1.9 on the 12.69 pass I feel like a 12.50 could be possible.