Changing compression to 8.5:1 -- How will this affect performance?

[**DONOTDELETE**]

I am planning to rebuild my motor soon and going to upgrade the bottom end (beef it up a bit) using forged pistons, piston rings, crank, and get the crank assembly knife edged and balanced. by changing my pistons to one with compression of.. 8.5:1 how will this affect my performance before I go turbo in early next year?

Thanks,
Jon

You will be very slow http://forums.freshalloy.com/forum/images/icons/smile.gif Some of this might be offset by the lighter weight of forged pistons and rods...but your performance will definitely decrease.

Asad

<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by simple008:
I am planning to rebuild my motor soon and going to upgrade the bottom end (beef it up a bit) using forged pistons, piston rings, crank, and get the crank assembly knife edged and balanced. by changing my pistons to one with compression of.. 8.5:1 how will this affect my performance before I go turbo in early next year?

Thanks,
Jon<HR></BLOCKQUOTE>

[**DONOTDELETE**]

whelp.. i have the piston and everything ready to go.. all i need to do is take out the motor and put it in.. i am planning to run nos with the new (8.5:1) piston, piston rings, crank, crank assembly.. until i get the turbo in december or so.. how much will performance suffer? will i still be able to drive around town? i really hate to do internals and turbo at once too much work all together.. so i was wondering can i drive it around with the internal in until i get the turbo?? and with that kind of bottom end upgrade and possibily a higher flow injectors and fuel pump how many shot of nitrous can i run??

Thanks,
Jon

I'm not sure how well the engine would run. A compression change is a pretty drastic change in the operating parameters of the engine. My guess (and this is just a guess, I have no experience with this) is that when you drive around without squeezing NOS...With the lower CR, the engine will not be able to burn all the fuel that is injected into the cylinders (because of lower combustion temperatures due to the lower compression ratio) and the engine will run rich. And you'll get horrible gas mileage, and you may ruin your catalytic converter. But you probably won't damage the engine.


<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by simple008:
whelp.. i have the piston and everything ready to go.. all i need to do is take out the motor and put it in.. i am planning to run nos with the new (8.5:1) piston, piston rings, crank, crank assembly.. until i get the turbo in december or so.. how much will performance suffer? will i still be able to drive around town? i really hate to do internals and turbo at once too much work all together.. so i was wondering can i drive it around with the internal in until i get the turbo?? and with that kind of bottom end upgrade and possibily a higher flow injectors and fuel pump how many shot of nitrous can i run??

Thanks,
Jon<HR></BLOCKQUOTE>

He was asking about how his car would run until he gets his turbo in December http://forums.freshalloy.com/forum/images/icons/smile.gif

And read the "Turbocharging KA24E/DE" thread...makes some good points for both lowering CR and keeping it the same. For running high boost, a lower CR is a must, but will give you soggy off-the-line response until the turbo kicks in.

<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by 240fan:
asad, dont you want lower compression on turbo engines? I agree it would suck on a KA24DE N/A higher is better. <HR></BLOCKQUOTE>

[240fan]

asad, dont you want lower compression on turbo engines? I agree it would suck on a KA24DE N/A higher is better.

[JonCarson]

If you're going Turbo, then yes you do want lower compression.
If you're going NA tune, then higher compression is what you're looking for.