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Joined: Jul 2000
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Hard-core CEG\'er
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Hard-core CEG\'er
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What is the highest compression ratio that SVT cams and valve unshrouding can use? 12:1? 12.5:1? Say with 93 octane and some crazy ECU prog (ADC)
-Auto Mak or-
-Experiment or
-Station Wagon or-
-Computeriz or-
I have a foot that is bigger than a foot.
SuperChipFOR SALE
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Hard-core CEG\'er
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12:1 with a great tune ... I wouldn't go any higher on 93/94 gas.
Come on people ... this is a great deal that I don't want to loose out on!
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Joined: Sep 2004
Posts: 225
CEG\'er
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CEG\'er
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Originally posted by fastcougar:
Come on people ... this is a great deal that I don't want to loose out on!
I couldn't agree more! If you were thinking about doing an engine re-build next year (like I was) you need to get in on this NOW or you will hate yourself when you end up paying full price in a couple of months!
The Original Owner of 1998 SVT Contour #3384 of 6535,
Toreador Red/Midnight Blue, Assembled September 3rd, 1997
Also the Original Owner of a 1998.5 Contour SE Sport V6 5-speed,
Vibrant White/Greystone Sport Cloth, Assembled August 6th, 1998
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Joined: Jul 2000
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Hard-core CEG\'er
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Hard-core CEG\'er
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Add me to the list. 3L, 12:1 comp ratio. What is the price on rings?
-Auto Mak or-
-Experiment or
-Station Wagon or-
-Computeriz or-
I have a foot that is bigger than a foot.
SuperChipFOR SALE
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Joined: May 2000
Posts: 1,336
Hard-core CEG\'er
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Hard-core CEG\'er
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Originally posted by Chris Hightower:
Add me to the list. 3L, 12:1 comp ratio. What is the price on rings?
People are running around untuned on 11.2:1 ... that's why I say with a GREAT tune, 12:1 should be possible. I personally wouldn't gove over 11.5:1 just to be on the safe side. If I went 12:1, I would use 94 with octane booster just to play it safe 
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Joined: Jul 2000
Posts: 1,786
Hard-core CEG\'er
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Hard-core CEG\'er
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Originally posted by fastcougar:
Originally posted by Chris Hightower:
Add me to the list. 3L, 12:1 comp ratio. What is the price on rings?
People are running around untuned on 11.2:1 ... that's why I say with a GREAT tune, 12:1 should be possible. I personally wouldn't gove over 11.5:1 just to be on the safe side. If I went 12:1, I would use 94 with octane booster just to play it safe
I have faith that Chris can pump out a SCT chip that can make it all work with 93/94 octane that is available in Dallas. Hell, I can get 99 octane at certain places.
-Auto Mak or-
-Experiment or
-Station Wagon or-
-Computeriz or-
I have a foot that is bigger than a foot.
SuperChipFOR SALE
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Joined: May 2000
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SWEET! ... only one more person ... come on lucky number 5! We only have 14 days until the end of the year and prices will go up. Let's make this happen!!!
Current List:
1.Eternal One 3L 9.5:1
2.NVSVT 2.5L 10.5:1
3.FastCougar 3L 9.5:1 .5mm over (.020")
4.ChrisHightower 3L 12:1
5.???
Last edited by fastcougar; 12/17/04 04:45 PM.
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Joined: Jul 2000
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Hard-core CEG\'er
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Hard-core CEG\'er
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Originally posted by fastcougar:
SWEET! ... only one more person ... come on lucky number 5! We only have 14 days until the end of the year and prices will go up. Let's make this happen!!!
Current List:
1.Eternal One 3L 9.5:1
2.NVSVT 2.5L 10.5:1
3.FastCougar 3L 9.5:1 .5mm over (.020")
4.ChrisHightower 3L 12:1
5.???
Two more would be great, to get the price down lower. I wonder if 7 would lower it more?
-Auto Mak or-
-Experiment or
-Station Wagon or-
-Computeriz or-
I have a foot that is bigger than a foot.
SuperChipFOR SALE
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Joined: Sep 2000
Posts: 9,602
Hard-core CEG'er
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Hard-core CEG'er
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Originally posted by Chris Hightower:
What is the highest compression ratio that SVT cams and valve unshrouding can use? 12:1? 12.5:1? Say with 93 octane and some crazy ECU prog (ADC)
Originally posted by fastcougar:
12:1 with a great tune ... I wouldn't go any higher on 93/94 gas.
Not even remotely close!!!
Even the hybrids can't really run optimum timing on most pump gas.
I would say 10.5 to maybe 11 to 1 on good 94 octane can run best timing. Weather permitting. (SVT cooling system, 160 t-stat, OAT with WW or Evans coolant, et cetera are all a must either way!)
I could get the 10.3 CR 2.5L to best timing on 92 octane plus booster (real octane not the POS over the counter stuff or about 93.5 pump) or just straight 92 octane in cold weather. In hot weather I had to back the timing off a little even with octane booster.
Compression is not going to gain you much power though.
Figure maybe 1% over a 9.8-10.1 CR engine. That alone is a waste of money to just buy forged pistons & need engine balancing for!
Even if you went 12 to 1 and ran 104-110 octane race fuel you are only going to see a 4 maybe 5% (8-12 crank) increase in numbers. Good luck paying for race fuel every fill up!
High CR, pump gas, and optimum timing do not mix very well.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Posts: 759
Veteran CEG\'er
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Veteran CEG\'er
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The only reason to go high compression would be to compliment a set of cams. Going with a larger cam lowers cylinder pressures because of the increased overlap... thus usually you increase the CR to compensate for the larger cam.
Just increasing CR will NOT give you a noticable gain in performance. Usually, with JUST a CR change, expect 1% gain for every point you increase the CR. That will probably be negated by the amount of timing you would have to pull out to avoid detonation.
So, why is everyone so gung-ho on these pistons?? Just to add them to your sig?
If you have a set of custom cams, or are going FI then I can see the reasoning, but for a stock cammed, NA 2.5 or 3.0 it is a waste of money.
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