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Do you know if there are any Problems with replacing the factory turbo dish pistons on a turbo car with flat top to rase the compression ratio to 8.5 instead of 7.?
The way I look at it is I will have more torque before the turbo kicks in and dont have to run as much boost as some people do, do to the higher compression ratio in turn less chance of detenation
If you got any suggestions please let me know ...
Thank you ,
Ron
 

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You will notice better off-boost throttle response. There are plenty of production engines that have 8.5:1 or higher w/a turbo. However, the detonation threshold will be lower. You will need to use higher octane fuel to keep from detonating. This is due to the fact that you are increasing the cr w/out changing the boost level. If the stock L28et is 7.4 to 1 and runs 6psi boost, the effective cr is about 9:1. With a static cr of 8.5 and the same 6psi boost, the effective cr is about 10:1. The difference of this one full point is a big difference in how detonation will occur. However, if you plan on leaving the boost level stock, then you will be fine. Make sure that your cr will be 8.5:1 with the flat-tops. I come up with 8.65:1 on a flat-top block, stock gasket, and P90 head. If I were you, I would cc the head to be sure, as there may be some variences. How do you know that the head has never been milled? You can also check the thickness of the head to find out if it has been milled. Make **** sure that you know your cr exactly. That way you'll know how much boost to run and what kind of fuel to use.

Flat-top pistons have another advantage over dished. They provide a better squish in the combustion chamber, resulting in more power. They will force the air/fuel mix toward the spark plug more effeceintly. This will be more so in a turbo motor. Bob Hanvey can explain this better than I can. May others will have an opinion on this subject. Good luck!!!

Ian

> Do you know if there are any Problems with
> replacing the factory turbo dish pistons on
> a turbo car with flat top to rase the
> compression ratio to 8.5 instead of 7.?
> The way I look at it is I will have more
> torque before the turbo kicks in and dont
> have to run as much boost as some people do,
> do to the higher compression ratio in turn
> less chance of detenation
> If you got any suggestions please let me
> know ...
> Thank you ,
> Ron
 
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