Jump to content
SAU Community

Recommended Posts

We went CP flat top pistons. But its upto you what pistons you want, to achieve whatever CR. Our tuner wanted us to go with a lower cr, while others tend to go for the higher cr.

The view is the lower cr makes the car less responsive off boost, while the higher cr makes it more responsive. However depending on tuning the lower cr helps with less knock and allows more ignition advance and boost without the knock, while the higher cr helps with more low/midrange power but in alot of cases ends up with more knock....but it all comes down to the tuner in the end or so everyone says. Prob abit in it with fuel economy and other bits and pieces, but .5 difference is like either choosing to run rb26 cr or running rb25 cr...in the end its upto you cause its your engine your building.

But then again it depends on what application your building this motor for.

Edited by r33_racer

howdy just about to order some pistons for 30det.

can get a good deal on acl rebuild kits and the new forged pistons they've produced.

does anyone have any experiance with these suckers? are they any good? or shall i pay a few hunj more and buy eg arais??? dont really wona spend teh extra dollars coz i will also be getting Hbeam rods.

also these acl forged pistons apparently produce a comp ratio of 8.5!

is this ok for a daily driver which will cop a bit of shit with about 420rwhp???

the car is a r33 is thats gona help.

except those pistons are suited for a rb30ET not DET. I think it will give a shithouse CR something like 7.1:1 its been said. You need the NA pistons to give a better CR around 8.2-8.5 or thereabouts.

No they are 8.5:1 in the RB30ET engine, so when used with the RB25 head they come in around 8 depending on combustion chamber size. I have used them in my RB30 with R34 Neo head ( it has a 58cc chamber ) and comp has worked out at 8.4:1

You are correct in what you said if you use the std oem turbo piston from the VL RB30ET. They were around 7.5:1 std I believe.

Best to use the CP pistons like I sell.

Edited by Spoolup
No they are 8.5:1 in the RB30ET engine, so when used with the RB25 head they come in around 8 depending on combustion chamber size. I have used them in my RB30 with R34 Neo head ( it has a 58cc chamber ) and comp has worked out at 8.4:1

You are correct in what you said if you use the std oem turbo piston from the VL RB30ET. They were around 7.5:1 std I believe.

Best to use the CP pistons like I sell.

So what compression do you get with your pistons SPOOL

CP make two types

8.5:1 and 9.0:1.

One has a flat top with zero deck height and the other has an 11cc ( from memory ) dome.

Thanks for that spool, just wondering Is their any issues using oil restrictors with VVT.

Edited by JMCY

seeing as ive got this motor apart

should i use restrictors if im using an RB25DE head and RB30 oil pump?

the isnt going to be raced very much at all, just a weekend cruise and a dyno run here and there

yes on an RB26 head block off one and use a restrictor in hte other, size depends on oil pump

i picked up my sump adapter on thursday and i'm going to install it this week, so i'll document the whole process (with pics) and post them up here

rb25 head with n1 oil pump and one blocked off and 1.5mm in other and we have oil problems. Circuit racing is a bitch for exposing problems.

oh and we have vct as well.

Refer to the table from SK's oil control problems in rbs info.

Edited by r33_racer

Hey guys been reading this thread for a while now almost an hour lol

just a few qik questions...

i have picked up an rb30 complete do i need a n/a rb25de head or can i use an rb25det head as there is one that has been ported and polished? vct or non vct

also this rb30 has been rebuilt to std specs like 400kms ago is it worth just fitting the head and fix it if it breaks. I work in a performance workshop so rebuilding it is no problem i was just curious if anyone has pushed the std n/a 30 bottom end to breaking point?

cheers

I would just bolt them together with the restrictors and remote oil feed to the vct. Cc your chambers and pistons( you dont need to pull them out) and chech your deck heights to find out your comp and squish, i would go for high 8's:1 comp amd about 35 thou squish, so you may have to deck the head or block of fiddle with head gasket thickness, get a steel head gasket and your done. Dont try to get 1000hp, and it will hold together. You may wish to put a good set of big end bearings in it though. This should be good for a safe 550hp if tuned well, as above this the rods go

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Yup. You can get creative and make a sort of "bracket" with cable ties. Put 2 around the sender with a third passing underneath them strapped down against the sender. Then that third one is able to be passed through some hole at right angles to the orientation of the sender. Or some variation on the theme. Yes.... ummm, with caveats? I mean, the sender is BSP and you would likely have AN stuff on the hose, so yes, there would be the adapter you mention. But the block end will either be 1/8 NPT if that thread is still OK in there, or you can drill and tap it out to 1/4 BSP or NPT and use appropriate adapter there. As it stands, your mention of 1/8 BSPT male seems... wrong for the 1/8 NPT female it has to go into. The hose will be better, because even with the bush, the mass of the sender will be "hanging" off a hard threaded connection and will add some stress/strain to that. It might fail in the future. The hose eliminates almost all such risk - but adds in several more threaded connections to leak from! It really should be tapered, but it looks very long in that photo with no taper visible. If you have it in hand you should be able to see if it tapered or not. There technically is no possibility of a mechanical seal with a parallel male in a parallel female, so it is hard to believe that it is parallel male, but weirder things have happened. Maybe it's meant to seat on some surface when screwed in on the original installation? Anyway, at that thread size, parallel in parallel, with tape and goop, will seal just fine.
    • How do you propose I cable tie this: To something securely? Is it really just a case of finding a couple of holes and ziptying it there so it never goes flying or starts dangling around, more or less? Then run a 1/8 BSP Female to [hose adapter of choice?/AN?] and then the opposing fitting at the bush-into-oil-block end? being the hose-into-realistically likely a 1/8 BSPT male) Is this going to provide any real benefit over using a stainless/steel 1/4 to 1/8 BSPT reducing bush? I am making the assumption the OEM sender is BSPT not BSPP/BSP
    • I fashioned a ramp out of a couple of pieces of 140x35 lumber, to get the bumper up slightly, and then one of these is what I use
    • I wouldn't worry about dissimilar metal corrosion, should you just buy/make a steel replacement. There will be thread tape and sealant compound between the metals. The few little spots where they touch each other will be deep inside the joint, unable to get wet. And the alloy block is much much larger than a small steel fitting, so there is plenty of "sacrificial" capacity there. Any bush you put in there will be dissimilar anyway. Either steel or brass. Maybe stainless. All of them are different to the other parts in the chain. But what I said above still applies.
    • You are all good then, I didn't realise the port was in a part you can (have!) remove. Just pull the broken part out, clean it and the threads should be fine. Yes, the whole point about remote mounting is it takes almost all of the vibration out via the flexible hose. You just need a convenient chassis point and a cable tie or 3.
×
×
  • Create New...