Stock compression ratio on my 07d7 was 12.8 to 1 . Ran 13.5 to 1 with porting, slp single, vforce reeds at sea level. I ran 50/50 90 premium/av gas. No issues at all.
Performance Polaris Cfi Cylinder Heads for Turbo and Non-Turbo applications
- Thread starter 1200psi
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Stock compression ratio on my 07d7 was 12.8 to 1 . Ran 13.5 to 1 with porting, slp single, vforce reeds at sea level. I ran 50/50 90 premium/av gas. No issues at all.
09' D8 w/ updates what kind of gains could I expect w/ the 12.5 head? I am under 2K elevation.
1
1200psi
Well-known member
Alot more throttle response and about 5-6 hp overall
J
JesseJames
Active member
So, if the stock 700cfi is 12.7:1, and your head design is alot less prone to detonation, we still wouldn't be ok to run your 13.5:1 heads at 1000ft on 91 ocatane? Jesse.
1
1200psi
Well-known member
The 700 stock are like 13.4 or something close to that . I would personally If you were going to run at 1000 ft all the time I would do like 12.8 -13.0 for that altitiude. I recently just sold some to customers for that same application and i reliveed a little out the heads they are about 12.9 to 1 and should work real nice for that altitude. So the answer to you question It will work But If you got real cool dense air and ****ty fuel It could be a setup for a disaster. You may want to run like 1 to 2 gallons of 110 or equivelent.
Brad
J
JesseJames
Active member
Brad, I ride this around 1000ft all the time, and it runs great, no detonation to speak of. If the stock head is 13.4, and your head is 13.5, why would I need to run some race fuel to be safe? I was under the assumption from earlier posts that your head design was less prone to detonation than the stock design. Not trying to put you on the spot here, just trying to understand the difference between the two heads. Thanks, Jesse.
1
1200psi
Well-known member
They will work but it is on the edge If you were to get some bad gas like maverik gas or 7 11 I would say they dont have real good gas as far as octaine. The 13.5 heads will work but for insurance i always say to run a little higher octaine so that you would not need to worry about it. When we dynoed the 800 we had the 13.6 domes on the motor and it did not show a lick of detonation period at sea level and 92 octaine fuel. But That isnt always the case. Say if the air is like 10degrees it is really dense and cold and if you got some cheap fuel that is not that great you probably would see a little det so I always say for guys that want to run that compression at sea level I would recomond that you run a little higher octaine.
Now i own you I would recomond the 13.6 head for pump gas no problems for that elevation and 14.5 for about 2 gallons race.
Hope that helps out.
Brad
I am running the 13.5:1 heads at sea level, but not with stock pipe or porting. Also, i am run a little 100ll every other tank just to be safe.
On a stock motor at 1000' you should be fine if you are running good gas. The hp difference between the 12.5 and 13.5 on the dyno was much less than if the DET kicks in. So you can base your decision on that too.
Neil
On a stock motor at 1000' you should be fine if you are running good gas. The hp difference between the 12.5 and 13.5 on the dyno was much less than if the DET kicks in. So you can base your decision on that too.
Neil
What, if any, changes to performance could did you expierence after installing the heads?
C
Clarke673
Somewhere between too dumb to quit and flat earth
Hey brad, i am doing one mod every two weeks when i have the cash. First week was HPS can, this week it was the PC IV, now i am looking at heads... and serious this time.
I have been researching and it seams that the LOWER compression heads on these engines make more horsepower......? Huh?
How long would it take to have one anodized orange? I am assuming a week or two?
I have been researching and it seams that the LOWER compression heads on these engines make more horsepower......? Huh?
How long would it take to have one anodized orange? I am assuming a week or two?
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Lower compression better designed heads will make more power then a poor designed hi compression head, which is what the original Polaris hi-comp head was. That is why all of the results show an improvement on lower compression versus the stock head. That said, if you have enough octane to support the compression and the heads are of similar designs, then the hi compression head will always produce more power. That is why race sleds run hi compression and hi octane fuel.
As for a previous question about the difference in power that I experienced...as mentioned earlier, i am ported and running a modified slp pipe, i never tested the exact same combo with a stock head. I can only tell you that a stock, significantly lower horsepower motor detonates at a much richer fuel mixture than i needed for max hp. Indicating that this head is much less prone to detonation, even at elevated performance levels.
Neil
As for a previous question about the difference in power that I experienced...as mentioned earlier, i am ported and running a modified slp pipe, i never tested the exact same combo with a stock head. I can only tell you that a stock, significantly lower horsepower motor detonates at a much richer fuel mixture than i needed for max hp. Indicating that this head is much less prone to detonation, even at elevated performance levels.
Neil
Curious how many are running this head on N/A CFI's?
J
jholer
Member
Brad, I'm looking for more info on the performance gains (HP, etc) for a head for my 09 700 running at 6-10k. We start off down the trail at actually 5800 ft but ride much higher. I only run good 91 octane, no ethanol, with slp pipe, carls y-pipe mod, clutch kit, big air intake, etc. Is one of your high comp heads going to be a real noticeable power improvement in deep snow at elevation, or will I just notice subtle improvement in throttle response. I'm trying to piece together an slp-like high performance kit for the 700, without permanently modding the engine. Thanks for the info!
C
Clarke673
Somewhere between too dumb to quit and flat earth
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