Question on building RB25det head

[BlockHead]

I am in the US so I dont have alot of info on this. I was looking to put springs retainers and solid lifters in the head so I can rev higher safely. I plan to rev to about 8500rpm. Any suggestions on brands or anything to help me out?

[GTRgeoff]

Word from the guru...the fabled sydneykid ... is that 8500 rpm is ok on the stock head, which I plan to do.

I wouldn't trust the stock conrods though so I changed to GTR conrods which will be safe at that rpm and only cost me $300 plus resizing the big ends for fresh bearings.

There is a thread discussing this, i think on the bottom end limit....

[BlockHead]

So the conrods wont be able to handle that many rpm's but the head will be fine?? Well I was also going to do cams too, and would rather build it while I have it apart.

[GTRgeoff]

It's probably on the limit with stock pistons and marginal with lightweight forgies.

I'd suggest most of your parts are available on this very forum, such as GTR rods (which I got for $300 AUD for the lot). I also sourced bearings locally from ACL using their heat treated race series of RB30 mains and SR20 Big Ends (tricky huh?).

Sk suggests the stock cams are okay as well, and the lash adjusters will pump up slightly at that rpm but not enough to make a real difference. It's not some crap subaru motor . Just clean up the combustion chambers and maybe port match but otherwise leave the head alone.

Worth doing the seals as well and RB30 oil pump seals are about $20 each and also fit the cams, while the rear main is also RB30 compatible at $25.

The key was getting a really good engine shop to machine, 'O' ring the block, balance everything and x-ray as well as straighten the crank slightly.

A good enlarged sump and baffles/gates will be of benefit for you particular application as well.

[BlockHead]

wow that just seems like alot to do to just get some more revs out of the block. I am used to working with hondas that we rev to 9k and higher on a built head with no problems.

[GTRgeoff]

This engine would be good for over 300 rear wheel kW for quite some time, and launch a 1400kg car from 0-100kmh in under 5 seconds consistently, but more important, pull 200kmh in around 11 seconds.

With 30% drive loss that equates to about 430 kW at the flywheel or close to 600hp (what our 5 litre V8 supercar racers put out). Consider the 5.7 V8 in the HSV here is only 300 kW with a 1800kg car, this is a serious piece of machinery.

Also the more cylinders, the more work to get high rpm. The available tirque of the nissan RB's usually means you don't need massive rpm, but i want the flexibility on the racetrack. The cost is not high. The machine work was $1200 AUD...less than the Arias Forged pistons.

Honda do a fairly good engine, but they won't stack up to the potential of the nissan RB series 6 or the toyota 6's with forced induction, which have pushed more than 1000hp (1300 in one case). Their S2000 engine is a treat though.

[maximajim]

What is the weak point of the RB25 rod? the "neck" area or the bolts? I only polished the rods and used ARP bolts. I plan on reving to a maximum of 8500rpm.

[GTRgeoff]

There is some good detail to read here

http://www.skylinesaustralia.com/forums/sh...ead.php?t=34860

I believe the 25 rod will be weaker at the bottom of the neck due to the lack of material used which was discussed in the thread below. I am yet to get off my butt and FEA the rods.

RB26 rod

http://www.skylinesaustralia.com/forums/at...achmentid=10064

RB25 rod

http://www.skylinesaustralia.com/forums/at...achmentid=10063

Thread on the 26 rod limits

http://www.skylinesaustralia.com/forums/sh...ead.php?t=31078