Whipple Tensioner vs Standard Idler/Tensioner

So I'm having belt slip issues. Apparently 3.73 gears and 10.6:1 compression with a 2.8 upper on VMP is gaining RPM too fast for my belt to grab well. (or so my tuner is saying). Thinking of going 3.1 or 3.0 upper and a 4# lower but thinking of swapping out my standard upper idler to the Whipple tensioner. I can see the Whipple make have the advantage putting the wrap on the leading side of the pulley but curious of other's opinions before I just more on replacing one after market with another.

Long story short dropping voltage and boost on the top end they're saying its the belt. Honestly I'm not entirely convinced it's not just alternator issues. I feel my setup SHOULD be losing boost in the upper RPMs thanks to big cams. Also I don't trust my J2 alternator right now.

This is probably going to be something resolved by a team of parts. Personally I'm a fan of a bigger pulley set up to get the same boost.

The perk of the Whipple set up is being able to adjust for different belt lengths. But its not going to make up for a failing tensioner or really small blower pulley. How old is the tensioner?

Are you on a factory lower? If so I would try the whipple tensioner before swapping to 4lb lower. Change one thing at a time before changing the whole line up.


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01yellercobra said:

This is probably going to be something resolved by a team of parts. Personally I'm a fan of a bigger pulley set up to get the same boost.

The perk of the Whipple set up is being able to adjust for different belt lengths. But its not going to make up for a failing tensioner or really small blower pulley. How old is the tensioner?

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About a 500 mile old American Racing Solutions billet tensioner. Pretty sure it's not that. Really Im noodling the advantage of the whipple tensioner that goes under the blower and wraps the left side. Compared to the traditional extra idler that goes to the upper right and wraps the opposite side.

Intuitively I would think I rather wrap the left "upstream" (before the load) but then the lower is pushing not pulling compared to the blower right? Unless I have the direction of the belt backward in my head. Dont have to car here to look. Have to dig in to the how wrapping different sides effect belt tension in individual belt segments when you consider the drive pulley vs the load.

Whipple says their idler works on the "right" side of the blower. If it's true or just marketing I couldn't tell you. There are a lot of people out there with the non adjustable idler that haven't had any issues.

I will say having the adjustment is nice. It's saved me a few bucks on belts.

01yellercobra said:

Whipple says their idler works on the "right" side of the blower. If it's true or just marketing I couldn't tell you. There are a lot of people out there with the non adjustable idler that haven't had any issues.

I will say having the adjustment is nice. It's saved me a few bucks on belts.

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Which "right" before this becomes Abbetto and Costello skit? I tend to agree with Whipple. Dunnon it's worth the cost.

I have the same feeling though. Only thing I can guess is breather filter blow by mist and high compression ramp up for their argument.

Personally I'm thinking electrical side. I really don't totally grasp blower slip making lower voltage. I get if the crank slip that makes sense, lower belt speed. But slipping at the snout shouldnt make the next pulley (alt) slip in my head.

Black02GT said:

Which "right" before this becomes Abbetto and Costello skit? I tend to agree with Whipple. Dunnon it's worth the cost.

I have the same feeling though. Only thing I can guess is breather filter blow by mist and high compression ramp up for their argument.

Personally I'm thinking electrical side. I really don't totally grasp blower slip making lower voltage. I get if the crank slip that makes sense, lower belt speed. But slipping at the snout shouldnt make the next pulley (alt) slip in my head.

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Pretty much. It comes down to whether or not it's worth the cost to you. I picked one up because I thought I would be swapping pullies between pump gas and E85. At this point I don't see myself doing that. So if I had to do it over I probably would have stuck with the standard idler I had. I would've also been able to route my return line the way I wanted.

It could be slipping at the blower and crank. But it would take a lot of slip to lose voltage I think.

roy_1031 said:

Are you on a factory lower? If so I would try the whipple tensioner before swapping to 4lb lower. Change one thing at a time before changing the whole line up.


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Well the 4# lower I already have. Ending up going with a 3.1 upper (since no one has 3.0 in stock including VMP) and a 4# lower. From there I'll decide on the Whipple tensioner or ditching the J2 for a Nations if I still have problems.

roy_1031 said:

Are you on a factory lower? If so I would try the whipple tensioner before swapping to 4lb lower. Change one thing at a time before changing the whole line up.

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Click to expand...

I agree with this completely. It would be far more valuable to only make one change like the tensioner before throwing a bunch of new parts into the mix that may, or may not fix the problem. Small incremental changes are the best way to solve these types of issues. I’ve made mistakes several times getting over zealous and doing several things all at once “since I was in there”, only to sometimes create other issues, or at the very least not known which thing was the problem. I’d say idler first, then move to alternator. Once you fix the issue, then do your pulley swap if so inclined.

I don't care what anyone says, but the whipple adjustable idler does more than just being able to run different belt sizes.

There is no way I could get away with a traditional style 100mm auxiliary idler on the right side of the blower with a little 2.6 upper pulley.

It only makes sense to put the tensioner on the correct side of the blower. That's what whipple's unit does.

I would definitely start with that. And if you don't like it, I wouldn't mind buying a spare one...

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