Whipple winter mode - largest pulley?

I live in Colorado and drive my car year round. It's almost time to swap on winter tires and make the car boring again. Since I can't get any traction with the winter tires, I was thinking about swapping to a larger pulley to hopefully gain some highway gas mileage since my commute is 80% highway.

What's the largest pulley we can fit? I see Whipple makes a 4.25" pulley, but the clearance to the closest smooth idler pulley looks pretty tight.

Also, will the tune adapt ok to the big change in pulley size?

What about flight control if you are using the Whipple tune? and dial down 1-2-3 down a bit?

My thought is that flight control won't buy me any gas mileage. At highway cruise speeds, I'm still spinning the blower at the same speed. If I could get 2 more mpg, the pulley would pay for itself over the winter.

I've also found that I can spin 4th and chirp 5th with the 245 wide snow tires...

Whipple doesn't really use any hp at cruising speeds. Just adjust your right foot. Or, the better answer, buy a 1k dollar beater..

I also drive my car year round and found that putting the car in wet/snow mode provides great results driving in the snow, whether or not you use flight control to reduce power. I use the General G-max AS05 tires and they work extremely well. I feel they hook better than the OEM Pzeros even in the summer.

Earlier this year I experimented with flight control reducing power by 25% across all gears to see what effect it would have on gas mileage. Back to back fill ups with Sunoco 93 octane showed no difference in mileage from no flight control to 25% reduced flight control.

Oddly, with 25% taken out, you get far less crackles and pops in the exhaust upon deceleration while in gear, than you would when flight control isn't set.

On a side note, the stock Whipple tune still makes 480 rwhp and 390 ft-lbs of torque on a Dynojet at 25% reduction.

F1scamp said:

Whipple doesn't really use any hp at cruising speeds. Just adjust your right foot. Or, the better answer, buy a 1k dollar beater..

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I disagree, you are always using power to turn the supercharger. My average gas mileage went from 22mpg down to 16.5mpg after the supercharger install. Most of that is just power wasted turning the blower cruising down the highway.

I'm not really worried about traction, just want to gain some gas mileage. Anyone try running a pulley larger than the 3.75"?

Ruiner46 said:

I disagree, you are always using power to turn the supercharger. My average gas mileage went from 22mpg down to 16.5mpg after the supercharger install. Most of that is just power wasted turning the blower cruising down the highway.

I'm not really worried about traction, just want to gain some gas mileage. Anyone try running a pulley larger than the 3.75"?

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well which kit did you do? you probably did larger injectors. it really shouldn't take much power to spin at highway speed.

I have a stage 2, but the larger injectors shouldn't matter at highway speeds. The ECU is just commanding enough fuel to maintain 14.1 AFR at cruise. If it was injecting extra fuel, the AFR would be rich. The ECU is trying to maintain a stoich AFR at cruise.

Turning a blower takes power and fuel to do at any speed, cruise included. You can't spin a blower for free. The only thing I can think of to raise gas mileage is to spin the blower slower. The only way to do that at the same engine speed is to change the pulley.

You would be able to run up to the 4" Pulley if you wanted to make the change. Whipple confirmed fitment, and stated the factory file would be OK.

Great, thanks Matt.

I ran the 3.75 last year with some blizzaks with flight control turned up in 1-3 and ran fine but Pa snow isn’t comparable to Colorado:lol:

Foxracing19931 said:

I ran the 3.75 last year with some blizzaks with flight control turned up in 1-3 and ran fine but Pa snow isn’t comparable to Colorado:lol:

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How was riding the mustang all winter? I'm right down the road from you in Greensburg and I almost went with Blizzaks for winter but found a good deal on a beater Corolla and ran with that. It sucked not driving my car for 4 months though.

cdq85 said:

How was riding the mustang all winter? I'm right down the road from you in Greensburg and I almost went with Blizzaks for winter but found a good deal on a beater Corolla and ran with that. It sucked not driving my car for 4 months though.

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Wasn’t bad at all..i just babied the throttle and kept the mind set of not getting into boost I’m debating on getting a beater just for the ease of mind

I cant imagine trying to drive one of these in the snow let alone with the whipple installed. Lucky Im not in that situation to have to.

I'll stick to my S4 for winter, keep a blower, no salt on my 5.0 and AWD. Good luck on your quest.