Pulley sizes, RWHP, and Octane.

[Crossfiaah]

I'm considering a FFSC, and am curious what kind of horsepower the different pulley sizes generate. Is there a chart somewhere?

This applies to a 2002 with 93 octane available in a 4 seasons climate (KY). Which pulley size would provide the highest HP safetly?

Thanks

[socal pat]

There are too many variables to quote RWHP numbers. The exact answers to your question are burried somewhere in previous posts, but I seem to remember the boost numbers are something like...
105mm = 8-9lbs boost
110mm = 10-11lbs.
115mm = 12-13lbs.
As for 93 octane...well, once again there are variables at play. As a matter of fact I just sent Tom a check for a new pulley and asked him to ship me whatever he thought best. He has seen my car on the Dyno so he knows how my AFR looks. I expect though that 110 is the SAFE bet.

[Crossfiaah]

Thanks for the info. As a suggestion I think guests to the site would appreciate a chart with the pulley sizes and dynos on stock cars, if that is doable.

I can get 110 octane and higher gas, but it isn't cheap and isn't something I'd like to do. :P

[Tom @ Fast Forward]

Pat has the numbers correct. Model year has an effect on boost and WHP vs. pulley size as well. At the moment it looks like 110mm is the biggest for the 01-05 netting ~205WHP. For the 99-00 I think the new PC-Pro might let us run up to 120mm and 220WHP. For the 94-97, I think we could go even larger but have no data to confirm that. We try to run them safely on 91 octane in Arizona heat so people in cooler climates with better gas can make the higher WHP numbers. A lot depends on the condition of your cat/exhaust. A poor exhaust will raise boost, lower WHP and cause ping.

The typical kit, shipped with the base 105mm pulley, on a car with typical exhaust restrictions will make ~195WHP. Add about 7WHP for each 5mm increase in crank pulley. Add another ~5-10 WHP for a high flow exhaust.

Hope that helps. Those are all loose numbers and will vary from car to car but historically they are close.

BTW, crank pulleys are only $60 and take about 15 minutes to change so it is cheap and easy to have a street gas setup and a track setup for good fuel.

[Banshee]

I'm probally wrong, but I believe that the 01+ will see a little more boost for the same pulley as compare to the 99-00.

I've used a 95mm,100mm, and now 105mm pulley. Keep in mind that I don't have the E-cool setup, but rather use alky/water injection.

With the 100 pulley, I'm seeing 8.25# at redline, with the 105mm pulley, I'm seeing 9.75-10# at redline.

Also boost is highly dependent on the concentration of alcohol. So far I've only tried 0% and 33%. 33% lowers boost about 1-1.5 psi.

When I went from 95 to 100mm. I gained 20whp. After going from 100 to 105mm, I feel its more than 7whp. I'll know for sure when I redyno it.

[Tom @ Fast Forward]

There are soooooo many factors that generate boost that I talk boost as little as possible. I still think "More flow, less boost" is a great slogan. If you put 87 octane, for example, in your boosted enging, your boost will go up and WHP down and probably have ping. If you put 120 octane fuel in the engine and stuff the cat, your WHP will go down, boost will go up and you might have ping. If you have perfect combistion, maximum advance and a free flow exhaust, your boost will go down, WHP will go up and you will have a happy engine. That is why I talk with 2 PSI variations like 8-10PSI for a given system. Throw into that mix compression ratio and VVT and all bets are off as to what boost you might see on a given day at a given air pressure with a given amount of moisture in the air and a given temperature.

Isn't the world of defining WHP fun? :)