Cr Advice For My 30/25 Build,

[tm_r33]

+1 for 9:1 static comp. I have just had my engine built with 9.2 aries pistons but the nice big mls head gasket brought it back to pretty much 9:1. Isnt half the reason for switching to 3 litre to gain some down low driveability??? I know obviously the extra exhaust gas brings on early spool and you have the increased torque as displacment grows to name other benefits buts whats the point in adding extra displacement and then lowering the compression. One gives u low rpm drivability and the other hinders it. nothing wrong with the 9:1 cr that rb25 have to start with. Especially for a car with regular street duties.

My 2c

[psi]

I'd pay big money to get even more response and more torque..

Like the everybody has already said, the RB25 has 9:1 comp, It makes no sense to spend

good money to build and fit a 3L to REMOVE response?

That poor dude needs to get out of his shed a little more often.

(Lots of honda drivers add turbo's without decompressing their hi-comp engines.)

[JonnoHR31]

we have a crx here with a b16 (around 9.5:1 i think), its loving 10psi of boost and drives very nicely down low. compression is awesome

[DaveO74]

Hey Guys,

Thanks for keeping my old thread running, fwiw I still haven't got my sh1t together and taken the plunge into dirty 30 land yet but the the car is half stripped out and I am still trying to make up my mind on wether to go the 30 or just stick with the 25 and chuck a 2835 pro s kit at it for a nice 280 odd killer wasps.

I have decided to not go with the original person that wanted to build the 8:1 cr and have been shooting emails to RIPS and they have suggested a pretty nice sounding package for the power I am looking at achieving (<350rwkw) using one of thier special non-forged bottom ends which they assure me is good for 650 odd hp so I am considering this.

Xmas cleaned me out a bit and I bought a nice interior so I'll have to wait a month or two to make the move...............spend 5k on the 30 bottom end or 5k on the2835 pro s, decisions decisions decisions

there are pros and cons for both options

[joe blo]

when rips says there good for 650hp does he mean rwhp? or at the motor

and on youtube when he says that one has 650whp is that rwhp or flywheel?

i mean the standard bottomend ones

[DaveO74]

I'll look through the emails when I get back home tomorrow night and let you know, I do remember him saying that 330rwkw would be fine with his proposed setup (with proper tuning etc etc)

It's not a totally "standard" bottom end so to speak, it has a few mods that I can't remember off the top of my head but dosent run forged pistons

[wolverine]

Is the CR of RIPS standard bottom end builds pretty close to 8:1? I seem to remember this is about where they come out.

[JonnoHR31]

sounds like the 1st block listed here, doesnt have much details but says stock internals. so 1 must assume stock pistons, which would mean ~8.3:1.

http://www.ripsracing.com/products.html

would be 600-650hp at the flywheel

[DaveO74]

So still too low, I'll have to check the emails I have been sent

[works 510]

I would of gone with 9.1:1 CR but went for 8.5 mahle pistons insted mainly due to budget.

Have to look after the ol' bank account

[The Mafia]

Stay above 8.5:1 at least mate. We're in 2011 now. Its a no brainer. I had no issues in my rb25 running a factory 9:1, so why would issues in a rb30 running 9:1 come up? You're building s better more refined motor ( ported, deburred, etc) so you're actually improving your motors ability to prevent detonation.