Bottom end strength?

[400GTST]

Hey all, i searched and searched and didnt find much. I have an r33 Rb25det and i just reached 300 kw on the dyno yesterday after the next stage of my mods. Although it was only on 18 psi i am worried that i have pushed the standard internals as far as they will go...Without breakage.

What kinda power and boost is everyone running on standard internals?

Or does anyone know how much the bottom end will handle?(approx 90,000kms)

[gtst4d]

dont know for sure but things i have read you shouldnt push them past 300 rwkws on a standard bottom end . Iam in the hunt for those sort of figures and have just about finished my rebuild( flogged out valve guide) with fordged pistons and rb 26 rods so i hope it will be strong. Congrats on the figures to thats great.

[Sydneykid]

Hey all, i searched and searched and didnt find much. I have an r33 Rb25det and i just reached 300 kw on the dyno yesterday after the next stage of my mods. Although it was only on 18 psi i am worried that i have pushed the standard internals as far as they will go...Without breakage.

What kinda power and boost is everyone running on standard internals?

Or does anyone know how much the bottom end will handle?(approx 90,000kms)

Sydneykid Rule of Thumb (yes another one) for an unopened RB25DET is 450 bhp, that's ~280 rwkw. So you are already past where I would start looking for signs of distress.

[dnb]

313rwkw. will be at wsid next week

[R31Nismoid]

a 1/4 mile itll last a little while.

around track... unlikely it will last a long time at all

[400GTST]

Forgive me if im wrong sydney kid, but i thought 450hp was 336kw?

[sproosy]

Forgive me if im wrong sydney kid, but i thought 450hp was 336kw?

335.5 actually!

[BBQ]

Sydneykid Rule of Thumb (yes another one) for an unopened RB25DET is 450 bhp, that's ~280 rwkw.  So you are already past where I would start looking for signs of distress.

300kw is only 402BHP

450BHP = 335.5kw

[GIGOLO]

subtract ~60kw for drive train losses

[Sydneykid]

Over the years we have developed a standard around here.....

BHP = Brake Horsepower, which can only be measured at the crank, on an engine dyno if you like.

RWKW = Rear Wheel Kilowatts, as measured on roller dyno (Dyno Dynamics being the most popular in Australia)

BHP / 1.34 - losses = RWKW

PS; it is much easier if everyone uses the same language.

[400GTST]

Ahh i understand thanx sydney kid

[sky30]

SK:- What usually goes wrong if you go over your suggested power limit(280rwkw)?

What do you suggest are the most important parts to strengthen when aiming for 350RWKW??

[dnb]

id say the standard rods will let you know when they have had enough

[Sydneykid]

SK:- What usually goes wrong if you go  over your suggested power limit(280rwkw)?

What do you suggest are the most important parts to strengthen when aiming for 350RWKW??

Things I have seen fail;

Piston ring land

Piston crown

Head gasket

Little end bearings

Conrod bolts

Big end bearings

Main bearings

Exhaust valve and seat

The #1 part is pistons, #2 is conrod bolts, #3 is the conrods themselves. Head gasket can be an issue on older engines, head studs are a good solution. Upgrading the bearing material is important and main bearing studs are worthwhile.

Actually the only thing I have not seen fail is the crank, they are blooody strong suckers.

Hope that helps some more:cheers:

[R31Nismoid]

cranks are tough as

as SK said, totally agree. That what ive found myself hehehe

[sky30]

SK- What bearings do you use, and what studs do you use for the main bearing girdle?

[Sydneykid]

SK- What bearings do you use, and what studs do you use for the main bearing girdle?

We used to use Clevites but they must have done an exclusive deal with some Jap Tuning House, so we now use ACL Race Series, great results so far.

We only use ARP studs, never had a problem with an ARP product.

[sky30]

SK- have you ever used kings bearings, or heard much about them??

[Sydneykid]

SK- have you ever used kings bearings, or heard much about them??

Sorry, no to both questions:cheers: