R33 Rb30 Conversion

[cordiapower]

I'll try to find out which part number pistons they used, anyway according to dyno graph car makes lots more power down low than standard engine at the same boost, like 20hp more at 2500rpm and 80hp more @3500rpm and 100hp more@4500rpm, with heaps more torque...what could be downside of lower compression pistons?

[shanef]

responsiveness. from what i understand, lower compression means u can run more boost safely, than you would with higher compression. But on the downside however, u lose responsiveness.

[SLIMVLT]

mabys the cam timing is out alowing some of the compresion to blead out. this can be a problem

[Craved]

rb30 rear main seal the same as say RB25 and rb26 ??

[shanef]

nope, and they differ between models of RB30's (ser 1 or ser 2)

[Craved]

nope, and they differ between models of RB30's (ser 1 or ser 2)

thanks for the heads up

[cordiapower]

I checked the piston numbers and it seem that they are ones with 7:1 compression, they are nothing like those cubes used, they have much bigger channel on top hence lower compression, i redid compression test myself today and testing with full throttle it shown 120psi dead even on all but cylinder 3 and 5 which were bit lower around 115psi, and without throttle 115 on all but 3 and 5 which were 110psi, i dont know which method is more correct but as you can see cylinders 3 and 5 are lower on compression by 5psi, is it acceptable? and is there any resonable explanation why 3 and 5 are bit lower...?

[Adriano]

Yep its ok for a low comp motor, test should be done with motor at operating temp with throttle open.

[r33_racer]

well i can say then that series 2 rb30 rear main seals are the same as rb25s. Cause ive changed them myself when we built the 30 and then when i built my 25 a few weeks ago i used the spare one we had for the 30.

Chris your not getting it from Nissan are you? Go to a bearing shop and get one from them, will be cheaper and probably better. Same with cam seals and they are the same as oil pump seals.

[shanef]

Another heads up re seals, Repco have them aswell

[shanef]

well i can say then that series 2 rb30 rear main seals are the same as rb25s. Cause ive changed them myself when we built the 30 and then when i built my 25 a few weeks ago i used the spare one we had for the 30.

Chris your not getting it from Nissan are you? Go to a bearing shop and get one from them, will be cheaper and probably better. Same with cam seals and they are the same as oil pump seals.

The rear oil seal differs between models of Rb30's, one is of a larger diameter and one is smaller.

[Guilt-Toy]

I HEARD that ACL bought out Marley and are using there specs and design etc so its a ACL made piston but designed by marley ???

Something like that - this was only recent.

i was certain that acl didnt make a forged piston that worked for the rb30det. their shop in nz said they didnt and when i contacted acl in aussie they also said they didnt???

[kaige]

Hey guys, I just rang nissan about getting the Inlet and Exhuast manafold gaskets on their own and they are asking for $190 just for the two.

Does this sound right?

[shanef]

unfortunately yes, it does sound right

[r33_racer]

and lucky for you thats probably cheap too. Nissan charge a heap to buy bits..so if you can outsource them from other places that have the same thing or a different brand its normally way cheaper.

[Orphan]

Just wondering if using a rb26 crank in the rb30 bottom end strokes it out at all? And also have many people put together dohc (rb25) RB30DE's? and if so what is the success/performance of them? I've had a look around but didn't find much information on this.

[r33_racer]

i dunno about it stroking it out...wouldnt make sense to put a crank in with a shorter stroke. I know a bloke on here did the exact opposite, a modified 30 crank into a 26 block and got it to 2.9 litres i think. Is that right? Someone fill in the blanks who remembers better

[Craved]

well i can say then that series 2 rb30 rear main seals are the same as rb25s. Cause ive changed them myself when we built the 30 and then when i built my 25 a few weeks ago i used the spare one we had for the 30.

Chris your not getting it from Nissan are you? Go to a bearing shop and get one from them, will be cheaper and probably better. Same with cam seals and they are the same as oil pump seals.

Yah i was - $58 LOL lucky they sold it on me hahah

Another heads up re seals, Repco have them aswell

Nice- its a S2 from an R31 so should be alright

one local to me so i'll check out repco.

---

Extra question, has anyone replaced the water fittings on the inlet side of the block ? anywhere local sell them? since nissan said they are ex japan

the one near the thermostat and one near Cyl 6, since the rb30 one is different to the rb25 ones.

oh and thanks again Shane and Michael

Edited November 9, 2006 by Craved

[Orphan]

Ah k cool, sorry I don't know any specifics to this kinda stuff and was just wondering but it would make sense that the 26 crank would stroke out the smaller engines but not a 30. So any info on a RB30DE with a 25 head? Thanks.

[r33_racer]

Chris i just used the rb25 fitting in no.6 and the rb25 water fitting from the back of the water pump. It has that nice little 90 bend in it for the turbo water feed. If you dont have any rb25 ones, maybe try a wrecker for them? Is your rb25 in your skyline still being used? Cant you pinch them off that?

Heres the photo i posted ages ago of the way we set ours up in the race car, using both the rb25 fittings.