Hey guys, Getting my rb30et rebuilt atm and the rebuilder reckons its guna end up with a comp ratio of around 7.5:1. Sounds a bit low to me but what are you guys running? Cheers Ryan.

bit to low u want at least in the 8s

Im very instrusted in what other people run to. I would think 7.5 would be to low as i wanted to put a rb25de head on my rb30, but desided against it because it would lower my compression to 7.8:1

Yea i thought around 8.2 would be on the money,what do you think it would be like to drive with it as low as 7.5? What does a std rb30et run?

8.5:1

Quote: Originally Posted by rusty577 8.5:1 For a standard turbo engine?thats seems pretty high.

Na 9.0:1

Fark,that makes 7.5 seem way low.

Standard is 7.8:1, not 8.5

Quote: Originally Posted by jordy Standard is 7.8:1, not 8.5 Thanks mate,seems more realistic. So 7.5 wouldn't be all that bad,especially if its got sum other mods that will more than compensate for the loss in compression.

the manual says turbo 8.5:1 mate and na is 9.0:1 thats stated in both my manuals for the vl turbo rb25 head on my rb30et block was gunna make 7.8:1 Do a Search

Quote: Originally Posted by rusty577 the manual says turbo 8.5:1 mate and na is 9.0:1 thats stated in both my manuals for the vl turbo rb25 head on my rb30et block was gunna make 7.8:1 Do a Search you do a search, you are so wrong its not funny. TURBO is 7.8 NA is 9.0

Quote: Originally Posted by rusty577 the manual says turbo 8.5:1 mate and na is 9.0:1 thats stated in both my manuals for the vl turbo rb25 head on my rb30et block was gunna make 7.8:1 Do a Search Ok I've done a search, and you're wrong. It's 7.8:1 compression for the turbo. Mate.

yes turbo is in the high 7s. but that technolgy was back in the 80s. things have come along way since then. alot of peopl are running big power and good time with as much as 9.5:1 some where in the 8s is a good place to start. somany different engine builders have there own ways on building a powerfull engine, and none of them are really wrong, it just comes down how you want your car to respond. most people are running in the mid to low 8s, but not all. i would be looking for that comp if i where you as it will be much nicer to drive off boost. you wont find to many people running in the 7s anymore P.S i thought na where 9.5:1 well in the skylines any way. i maybe wrong though

Righto,i had a look around,its def 7.8,so with mine around 7.5-6 is it really going to be that noticable from when it was std?I cant see .2-3 making a huge diff. Guess i'll jus leave it n let ya's all know how it goes. Thanks for all the help.

I would seriously consider a CR of around 8.5:1.. CP Pistons wil get you that figure with the standard head gasket and RB30E(T) head. Ive been in cars with 7.8:1 and in mine which had a gt3540 on it with 9:1 CR.. spools up so much quicker and is simply more driveable.. Really.. with such a low compresion your goingot have to run more boost to make the same power compared to higher compression and low boost setup..

I'm runnin cp's,cometic head gasket at 74thou thick,maybe i should get the 51 thou gasket,that would bring it up to around 8.1 i think.

I'm runnin cp's,cometic head gasket at 74thou thick,maybe i should get the 51 thou gasket,that would bring it up to around 8.1 i think.[/QUOTE] definitly do that. you will regret it other wise. if its all still apart and you only gota buy another head gasket why wouldnt you. here use this link ive posted, it hepld me out heaps http://www.csgnetwork.com/compcalc.html

Yea the head isnt on yet,after hearin sum other opinions i mite giv the the higher comp a crack,could be sum easy hp in it i guess.

lol i was wrong. i was reading the data on the NA6 verse V8 compression ratio in the manual