1991 Skyline Gtr

[Dakota_gsx]

This guy has the same pump as me. I'm guessing it is an older model pump and that they did not mark them ten years ago.

http://www.zerotohundred.com/newforums/the-malaysian-skyline-club/181119-used-hks-rb26dett-oil-pump-for-sale.html

[archaeic_bloke]

Archaeic_bloke I dont think you understand the whole oil pressure thing quite right. Having a smaller/narrower passage in the oil pump doesn't increase oil pressure. Well, not where you want it increased. It would actually have decreased pressure (after the restirction) compared to one with a larger passage and identical flow rates.

hahaha ya your right, pressure is always correlated to volume, I just meant the pressure in THAT specific channell would be higher than in the channel of an OEM pump... from the photo Id say it probably is the HKS as you suggested... good pump!

[Dakota_gsx]

So got some news from the engine shop a couple days ago. the pistons even coated will not be large enough to reuse. they were measuring anywhere from 4-7thou and they said max was 3. looks like a set of new pistons will be ordered soon. Any suggestions?

[archaeic_bloke]

whats your budget?

most people rock CP or Weisco, but you can get some crazy good ones from tomei, greddy, Jun etc

[Dakota_gsx]

by budget is whatever itll cost to get the proper parts for this thing. so if getting weisco means there is a chance of them not being enough to handle what im going for, then i will spend more money to get what i need.

[GTRADDICT]

by budget is whatever itll cost to get the proper parts for this thing. so if getting weisco means there is a chance of them not being enough to handle what im going for, then i will spend more money to get what i need.

Hell Yeah. Do it right or don't do it!

[Dakota_gsx]

Exactly addict. the last thing i wanna be doing is taking this engine out again next year. no way no thanks eff that.
does anyone know what the wiseco pistons are rated at? i wont be pushing anymore than 700bhp.
And since all these internals have been a mystery, we have been trying to figure them all out.
We are pretty sure the crank is Jun, and we are thinking that the rods are Carrillo because the rod bolts were carrillo. but we will never know.

[Dakota_gsx]

So the pistons that were in the engine were a 87.5mm piston. all i can find for these engines are 86.5-87.5. since an 87.5 will not fit anymore, we are going with a custom made piston that will be 87.5mm plus about 5thou. dont know the company name, cant remember, but the guy at the engine shop said they make pistons for top fuel and alcohol dragsters. as well as the fastest evo x uses their pistons.
My valve guides are also done along with three valves. i will be picking up some Ferrea valve guides and oversize valves.

[Dakota_gsx]

When they took apart the head, they said they have never seen valve guides in this shitty of shape out of an rb.
There was also so much oil blow by that there is a rubber/silicone like skin on the exhaust ports of the head that didnt come off in their tank. it will come off with a little scrubbing though.


Exhaust valve and Intake valve. (neither valves were cleaned after they were pulled.)

[DJ]

87.5mm..i wouldnt want to go over 87mm , the wall are getting a little to thin for comfort after that.

[Dakota_gsx]

Yeah my engine builder is saying the same thing. What does everyone else think about that. Are there people running 87.5mm bore or higher without problems?

[gtrjon]

i havent really heard of anyone running over 87mm. i went with 86.5 just so if i need to i can still bore over one more time and have pistons be readily avaliable since 87mm are pretty easy to get.

[Bruizer]

87.5mm..i wouldnt want to go over 87mm , the wall are getting a little to thin for comfort after that.

Lots of guys do. It's the same myth/rare occurance of a failed N1 pump or exploding front diff. You'll be fine. 87.5 is the limit though.

[Super_Dude]

Exploding front diffs is an issue with high power and hard launches. A genuine n1 pump works good. I wouldn't personally run 87.5 or 88 but its personally not a huge deal. Unless your planning on making a crazy amount of power. Hks, apexi and trust used to make 88mm pistons but discontined them a long time ago.

[Dakota_gsx]

Well like I originally said, I am getting the pistons custom ordered so they will be 87.5mm plus like 4though. I won't be running more than 650 horse to the crank. What would even happen with having too skinny if cylinder walls?