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Had some strange thing happen tonight when getting on the gas hard. I don't know if it is wheel spin or SC belt slippage...I'm leaning towards the latter. Haven't had this happen before.

It is an 08 GT 500 with an Evolution Stage II kit / 93 Octane tune. Numbers after the kit / tune was installed (while the engine was still hot) were 509 rwhp and 520 rwt.

Have had the kit on since mid-July and have not had anything like this happen before. However, tonight was a quite a bit cooler than normal here...15-20 degrees cooler.

I normally don't have problems breaking trackion (stock tires) 1st and 2nd gear, but breaking traction in 3rd, 4th, 5th or 6th is like not happening...I have broke traction in 3rd before, but it is rare.

Anyway, I'm getting onto a highway and in 3rd gear I punch it. The whine of the SC kicks in as normal then about 3000-3500 (I think) the RPMs surge and I get a little shake and then the squeek of a sneaker on a basket ball court. Same kinda sound you get sometimes when the tires spin and then grab.

This did the same thing later in 2nd, 3rd and 4th. I thought something was broke, so a group of us (I was cruising w/3 other stangs) pulled into a parking lot and we talked about the problem. So I had another guy ride with me and we went down the highway again, and same thing. SC kicks in normal sound and then hit higher RPMs (I'm thinking 3000-3500, but not sure), I get that little shake and the RPMs race up...just like wheel spin, and then a little squeak. We get back to the parking lot and he thinks it is wheel spin. I somewhat think it could be too, but am not ruling out SC belt slippage or something else.

On the way home, I was doing about 40 mph and I put it in 6th gear and floored it. The SC sound comes in, but it is boggy sounding because I'm at such a low rpm. Then when it hits the higher RPM same thing...RPMs just rev right up there, a little shake and then the sneaker squeek. This time I watched the boost guage and it is maxing out at 15. Stock it would get up to about 9. After I put the kit it would get up to about 12 or 13...but now it is maxing out. So I get home, open the hood and have my son gun it a little and I watch the SC belt. I don't see the belt jumping or anything (maybe it happens to fast for the eye, I don't know). But the belt is tight. I do have the 2.6 upper pulley and the idler is installed. The belt is not cracked or shredding...looks good and is tight.

Thoughts?

Could this be a just a lot more power because of the 15-20 degree cooler weather?

SC belt slippage?

Something else?
 

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It's most likely due to drop in temps, and loose belt. If you got the idler from EVO then you can adjust it to tighten the SC belt.
 
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