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To Pull or Not To Pull?
Thread Starter
Melting Slicks
Joined: Jun 2009
Posts: 3,142
Likes: 1
From: SE Coast FL
To Pull or Not To Pull?
Pulleys, are they worth the investment? Whats the Hp gain?
If worth it, I would prob get them done when I do the MAF/Ported TB/Headers and Tune.
I havent seen any forum discussion on pulleys and remember they used to be a hot item back in the day.
If worth it, I would prob get them done when I do the MAF/Ported TB/Headers and Tune.
I havent seen any forum discussion on pulleys and remember they used to be a hot item back in the day.
Thread Starter
Melting Slicks
Joined: Jun 2009
Posts: 3,142
Likes: 1
From: SE Coast FL
Former Vendor
Joined: Jun 2006
Posts: 300
Likes: 0
From: Lubbock Texas
I think they are worth it. We typically see a gain of 8 RWHP as well. However, in a vette, I wouldn't do it until you put a cam in the car. What you will pay in labor to swap it will probably be similar to a cam swap since you have to drop the rack. The labor on a cam swap would overlap so it would basically be the labor on the pulley for free!
Jon
Jon
Burning Brakes
Joined: Aug 2004
Posts: 1,207
Likes: 147
From: St. Louis MO
Roughly speaking, if you are putting out let's say 370hp at the rear wheels, then the claimed "average gain" horsepower saved from a pulley is less than 3%.
3% must be is less than the reliable resolution of most dyno systems.
Small differences in horsepower between dyno runs can be attributed to so many environmental and operator factors that the results are questionable. Certifiable testing is beyond the expertise of most shops.
Also, the physics of the horsepower recovery claimed by under-driving the accessories dictate that you do not see anywhere near the full amount of horsepower savings until you are near WOT.
So think about the fact that you are paying 3 figures for a mod that only helps at the top of the power band. Those games are for drag racers that are trying to get every last ounce of power for the 1/4 mile.
You're not asking for a muscle car are you? Because the vette is not a drag car!
There has been debate for a long time whether the Granatelli MAF is better than the stock MAF. One thing for sure, the stock MAF is not a restriction till you are making BIG power
3% must be is less than the reliable resolution of most dyno systems.
Small differences in horsepower between dyno runs can be attributed to so many environmental and operator factors that the results are questionable. Certifiable testing is beyond the expertise of most shops.
Also, the physics of the horsepower recovery claimed by under-driving the accessories dictate that you do not see anywhere near the full amount of horsepower savings until you are near WOT.
So think about the fact that you are paying 3 figures for a mod that only helps at the top of the power band. Those games are for drag racers that are trying to get every last ounce of power for the 1/4 mile.
You're not asking for a muscle car are you? Because the vette is not a drag car!
There has been debate for a long time whether the Granatelli MAF is better than the stock MAF. One thing for sure, the stock MAF is not a restriction till you are making BIG power
Melting Slicks
Joined: Dec 2007
Posts: 2,031
Likes: 4
From: Ottawa
The ATI pulley for the LS7 underdrives a max of 10% and it's only underdriving the Alt, WP and PSP, the A/C is run off another belt which isn't underdriven. Other LS pulleys from ATI will go 25% under for the main three and 10% under for the A/C.
So the LS7 pulley is unlikely to get even half the HP advantage that previous LS engines got from a pulley swap. Given a 35-40 hp loss for ALL accessories I can't see how a pulley swap on the LS7 would be worth more than 3 hp. Is simple math causing me to miss something?
Cheers, Paul.
So the LS7 pulley is unlikely to get even half the HP advantage that previous LS engines got from a pulley swap. Given a 35-40 hp loss for ALL accessories I can't see how a pulley swap on the LS7 would be worth more than 3 hp. Is simple math causing me to miss something?
Cheers, Paul.
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