? for FI gurus
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
? for FI gurus
I have a 99 with a Kenne Bell Supercharger,I have the stock heads on it from the factory,other than the springs have been upgraded for the cam I had installed.The last time I had a different cam installed and had it dyno'ed in Las Vegas it came out at about 540 rwhp.Would it be worth getting a set of 317 heads and lowering my compression.If so what else should I have done to the heads before I install them.Do you think I would gain anymore hp by doing it.Seems like it MIGHT be a fairly cheap way to get more HP.I do have 1 3/4 headers on it and will be changing to 1 7/8 at the same time.What do all you smart guys think.worth it or not?Thanks for any info.
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
ttt
I would think about 15 to 25 max. Get a set of trick flow 215 heads maybe around 45 over the stock if you have a good cam with the car.also get a set of harden push rods and a set of roller rocker arms.
Race Director
Joined: Apr 2005
Posts: 10,179
Likes: 2,306
From: Wesley Chapel, FL Las Vegas, NV
The head change and a tune will cost you a couple Gs. Then you'll have to pulley up for more boost and will possibly end up right where you are right now.
Don't believe the 1/8th" larger tube will yield much either.
What boost are you running now? Gotta be at least 8-9. If you over spin for higher boost you may get higher IATs which will be counter productive.
The real answer is more cubes but that's a whole new deal.
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
The head change and a tune will cost you a couple Gs. Then you'll have to pulley up for more boost and will possibly end up right where you are right now.
Don't believe the 1/8th" larger tube will yield much either.
What boost are you running now? Gotta be at least 8-9. If you over spin for higher boost you may get higher IATs which will be counter productive.
The real answer is more cubes but that's a whole new deal.
If all your bottom end is stock, Like was said above you may be trading a good running car now and may get a problem in something for tring to get just a few hp more out of the car.
Drifting
Joined: Jul 2007
Posts: 1,350
Likes: 19
From: In a house
Shops I called when pondering this same head swap idea sd with fi it's not worth the small gains unless your current compression is just way too high. I know a fella here on the board that runs a built 403 and Ysi setup that got some high dollar heads and did not yield a significant increase but did change the power curve a bit.....I personally couldn't justify the small increase.
Like the one guy said....it gets real expensive. Go for a forged stroker.
Like the one guy said....it gets real expensive. Go for a forged stroker.
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Race Director
Joined: Sep 2005
Posts: 11,060
Likes: 291
From: Pasco WA
I installed my A&A system on a stock LS6 block, with TF heads milled to give 10.9 SCR. I'm using the stock 3.8" pulley, and getting 7.5 lbs. of boost peak. I won't bother lowering my compression until the time comes my stock shortblock breaks something. I don't beat on the car, so it may last a long time. GL to you and me. We're pushing our motors beyond what they were designed for, and have to be willing to pay to fix everything, if the worst happens. Right now I'm really enjoying the power level, and drivability. I did re-cam mine for a lower DCR, to a blower specific cam. I don't want to use meth if I don't have to.
Burning Brakes
Joined: Jul 2006
Posts: 764
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From: felton de
Set up
Heads in your case are not going to be worth it. You should save your money for a forged set up because believe me it is coming your way sooner or later. Are you running the 8 rib set up ? If not put your money there. How about a Dewitt radiator ? How about an oil cooler ? These are the things that make the KB set up better IMHO.
Unless you are an avid racer your HP level is more than needed for the street. If it is for the track you will be breaking the 11.50 number so save for a roll bar.
Unless you are an avid racer your HP level is more than needed for the street. If it is for the track you will be breaking the 11.50 number so save for a roll bar.
Burning Brakes
Joined: Feb 2004
Posts: 1,130
Likes: 0
From: Camarillo/Oxnard CA
Don't waste the money and time on heads or dropping compression.
Put all that money into your drivetrain and suspension. Make it able to dead hook all that TQ your KB should be making and then see where it's at.
Or if you really have the power bug, sell the KB and put on any supporting vendors centri setup with a Flip Drive and make the car faster.
Just my .02
Put all that money into your drivetrain and suspension. Make it able to dead hook all that TQ your KB should be making and then see where it's at.
Or if you really have the power bug, sell the KB and put on any supporting vendors centri setup with a Flip Drive and make the car faster.
Just my .02
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Thanks for all the info everyone,thats why I asked on here,lots of good guys with great advice.I even tried to put this up earlier thinking my post made it all day with out getting 1 KB hater,almost though,should have done it quicker.I'll wait and start saving to go forged.thanks again
Last edited by Crabr1; Nov 4, 2010 at 07:32 AM. Reason: spelling
Pro
Joined: Mar 2008
Posts: 664
Likes: 6
From: Kearney Nebraska
Well by switching to a better flowing head you will likely drop your boost level to put less stress on your setup. Even tho your boost will drop down this does not mean you will loose horsepower. Boost is just a measure of how effiecent your engine is, NOT a MEASURE OF HORSEPOWER. If your looking for a budget head to free up some boost id look into a set of Patriot ported LS6's with the 2.02 1.60 valves. If your looking to spend a little more coin Look into a set of PRC 227 heads!! Steve @ SNLperformance can hook you up with a set (abt $2k i believe). For a FI setup i would try to find a head with a intake runner larger than 225cc.
Drifting
Joined: Jul 2007
Posts: 1,350
Likes: 19
From: In a house
Haha!
Don't waste the money and time on heads or dropping compression.
Put all that money into your drivetrain and suspension. Make it able to dead hook all that TQ your KB should be making and then see where it's at.
Or if you really have the power bug, sell the KB and put on any supporting vendors centri setup with a Flip Drive and make the car faster.
Just my .02
Put all that money into your drivetrain and suspension. Make it able to dead hook all that TQ your KB should be making and then see where it's at.
Or if you really have the power bug, sell the KB and put on any supporting vendors centri setup with a Flip Drive and make the car faster.
Just my .02
Banned Scam/Spammer
Joined: Oct 2010
Posts: 5,469
Likes: 20
From: West Bloomfield MI
I've been down this road multiple times. Save your money.
Put on a smaller blower pulley if you want to make more power.
There are guys running deep into the 9s with stock heads.
If you wanted to do worked over heads wait until you're building a forged short block. That would be the time to do it.
Put on a smaller blower pulley if you want to make more power.
There are guys running deep into the 9s with stock heads.
If you wanted to do worked over heads wait until you're building a forged short block. That would be the time to do it.