hey all ....

I have been searching this forum for opinions on S/C reduction pulleys.

From what I have read so far the 15% (Alta) pulley will be better for someone who does enjoy a day at the track since it will not generate as much heat (since at the track we are normally at WOT) but will not increase torque as much as the 17% pulley

Now the 17% (Cravenspeed) increases torque a lot more but also generates a significant amount more heat

I know M7 does a 16% pulley. Would that be the best of both worlds ???

Thx

 

Been running mine for 50k miles also their 2% crank pulley trouble free. Not much difference between the 3. Yes the 17 will produce more heat, but not increase the torque a lot more? Alittle, but not much more.

 

Hind sight being 20/20 I wish I went with the 16%. I have a 15%.

 

Just go ahead and get a 17% pulley, otherwise you'll always be wondering what if. Plus the 17% is cheaper and won't hurt your car any more than the 16%. I personally think 16% is a marketing size.

 

If I plan on tracking the car a couple of times wouldn't the 17% pulley cause a lot more heat therefore decreasing overall performance ?

 

Your not really going to see much difference in heat from a 16% to 17%. And like you said your planning on tracking it a couple times. Build the car for what you use it for 90% of the time, not 10% of the time. That way you'll be happier 90% of the time.

Also FYI I have a 17% pulley on one of my track cars. If we were talking about a 19% I would say no go on that. And that's not really about the heat that is more about turning the water pump too fast. The 17% is a good compromise in the middle. In all reality I recommend the 15% more than anything else. But I base my 17% recommendation to you because your considering a 16% and 17%. And from experience I find that customers that go with the lesser pulley always seem to wonder and it will bother you long term having you wonder "should I have done the 17%?" So going with the 17% will just put those thoughts to rest.

 

I am debating on 15% vs 16% vs 17%

Why would you recommend 15% if it has less low end torque

Also, if I were to choose a 17%, wouldn't I be hitting the the harmonic frequencies near redline ???

 

The torque numbers are going to be the same regardless of size, what will be different is when does the HP and torque begin showing up. The smaller the pulley the faster they will come up. It simply moves the curve towards the lower end.

 

I love my 16% got it used on here for 90 bucks.

 

i think what you mean to say is that the peak HP and torque doesn't really change but there is more beef under the curve at lower RPM's?

 

the power would come earlier in the RPM range and the peak HP is lower with the lesser reduction pulleys. Like Way said, 17% on a track is fine, that's also what Jan from RMW ran while he was using the stock supercharger and said he had no problems either. Get the bigger reduction and dont wonder down the line, 17% is more power earlier... anyone who says theyre all the same is just wrong, rev limits how fast a 15-16-17 or 19 will spin the SC. go with the 17.

 

lets now debate fuel economy.

If the supercharger kicks in earlier with the higher reduction (17%), wouldnt that hurt gas mileage as compared to the lesser 15% reduction ???

 

I average 30mpg with my 17

 

Driving style will affect gas mileage far more than pulley size. When I switched from stock to 15% my average actually improved by about 1 mpg.

 

SC's don't "kick in" as they are always providing boost when you step in the gas, it isn't like a turbo that has to spin up to get the boost. As for fuel, you will lower your MPG with a reduced pulley but it really isn't all that much and there is little difference between 15 and 17. Way is spot on... I was one of those people that regretted not going 17 right away.

 

Just wanted to make a correction... I referred to Way as Doug (been a little sick) and I meant that Way is correct. Sorry Way!

 

No I meant exactly what I posted....the curve doesn't really get any bigger, too much heat at the higher rpm's.

 

So what you are basically saying is that the curves will translate to the left (lower RPM) but will drop near top RPM due to overdue heat ?

 

It won't drop, It will just begin to level off.

That being said, a better IC (GP) and Water/meth system can combat this.

And I think what Mgrant meant by "Kick in" was as the boost goes up from higher revs, the ECU must dump more fuel into the cylinders to keep AFR correct. He is correct, however, the difference is tiny.

 

How is the possible?? I have never got more than 20-28 mpg (28mpg is on long trips )on either of my cars. I average 22mpg and only have CAI and 16% pulley....

 

Sounds like you may have a less than optimal factory tune on the car. I get easily the high 30's and have the reg mods.....15%, CAI, one-ball, and custom tune.

 

I thought retuning the ECU wasn't necessary with just a pulley ?

 

It isn't, but there has been shown a HUGE difference between cars, the stock tune they have, and the performance. I have seen a difference of as much as 25hp on the same year car with similar mods before tuning. It just shows how big of a difference some cars have from the factory. And they can all benefit from a custom tune.

My car with 15%, CAI, one-ball, NGK JCW plugs pulled 192hp on the pre-tune dyno run. The car just before me with the same mods pulled 165. We were both able to get over 210hp after the tune. Bigger change for him cause his car didn't like the stock tune as well as mine did.

 

I'm guessing a custom tune would be the best but are the pre-programmer piggy back systems any good ?

 

No