R33 Rb30 Conversion

[Cubes]

yes.

[shanef]

For the price fo $1400 just for the Greddy plenum, you can save that and buy an rb26 head like i'm doing.

The rb26 heads also flow better.

[lukits01]

How much better is the RB26 head compared to a RB25? Assuming similar setup offcourse.

Thought I'd ask when buying a head, how can you tell if the valves need reseating? Is there any way to tell if the head needs to be reconditioned?

[Cubes]

For the price fo $1400 just for the Greddy plenum, you can save that and buy an rb26 head like i'm doing.

The rb26 heads also flow better.

<{POST_SNAPBACK}>

Thats also my thinking. Its not so much they flow better its the better factory cams + the added bonus of the solid followers = higher ramp rate. higher lift for a given duration.

Providing you can pick up a rb26 head and manifolds for a reasonable price.

Edited October 7, 2005 by Cubes

[Roy]

Every 6 months i end up in the same position...I want the thing to look completely std, heat shields and all. So what is so difficult about getting a few offset braces made wo that it goes behind the throttle body??? Does it clear the actual manifold.

Be great is someone could put a telescopic aeiral on their rocker cover and measure the height to the top of the plenum & top of throttle body. Then close the bonnet and measure the ehight to the underside of the bonnet. Liek to know the clearance to th eunderside of the bonnet as well:)

[Cubes]

I'll take a few measurements Troy.

[Cubes]

I've done a few measurements.

Just in front of the throttle body the plenum has 20mm with the motor lowered 13mm.

If you drop to your knees on the drivers side of the engine bay you will see where the cross over pipe is higher than the throttle body and plenum, it almost v's up a little, I had a good look at the cross over pipe, its not touching the under bonnet lining but must be damn close as it too sits 20mm higher than the plenum section where the strut brace would pass over.

The strut brace will no way fit over the throttle body and cross over pipe. I suspect one of those flat tubular style strut braces will fit providing it passes in front of the throttle body/cross over pipe.

All else fails you could always grab a r33 rb25 or rb26 stuffed bottom end (piston oil squirters a must for cast pistons that see track work), Rebuild that with cast pistons and throw a r32 rb25de head on it. That would look 100% stock.

Edited October 7, 2005 by Cubes

[Scribble]

I take it the rb25/20 covers dont fit on the 26? what about the front cam cover?

[Cubes]

It really is a hard decision.

When purchasing my head I found a 26 head and inlet manifold for 2.5k.

The 25 head was $750 + $1100 for rebuilding and port/polishing.

I decided the 25 head rebuilt was a better option for reliability. I didn't want to try my luck with a second hand head even though it would have no doubt been fine.

I wonder which would flow better, a 25 head that has been ported polished, the suitable valve jobs, inlet valve deshroud, port match and 260duration exh. cam or a stock 26 head.

The reason for a 260 duration exhaust cam... From flow tests i've seen its the exhaust side of the rb that has issues. Not the inlet.

I could be wrong. Its only my observation.

[GTR-Ben]

For my brothers RB30DET he got a RB26 Head for $1500. Happened to have some high performance HKS cams already fitted. score!

[Cubes]

They can be picked up for quite a bit cheaper these days.

The same place I looked at 3years ago when buying my rb25 head who wanted 2.5k had one for 1.6k including all manifolds etc.

[Bl4cK32]

Thats the thing, CUbes and myself were looking for the heads for our motors almost 3 years ago now...a lot has changed in that time for skylines. Especially prices for parts.

Saying you can buy GTR heads for $1500 now doesnt reflect the almost $3k price tag back then

[Cubes]

Definitely a bit of a bugger.

Ahh well there's always the next rb30 when this one throws a rod out the side of its block.

lol

[Bl4cK32]

thats my thinking....series 2 rb30det will be definitly be a refinement

[lukits01]

If you did decide to change from RB25 to RB26 head, would you bother to change the loom to a proper RB26 loom or just addapt the RB25 one to suit the new head?

[Cubes]

The only difference between the two looms (being an r32 without vct) is the inlet air temp sensor addition.

After all all you need to do is route the existing loom plugs to the new rb26dett locations. Not too hard at all.

Edited October 8, 2005 by Cubes

[the_tonkau]

Warning!!! ACL PRODUCT WARNING. Were supplied new race series forged ACL pistons, rings and bearings for an rb30/25 hybrid. Engine built buy a reputable engine builder and run in by ex Perkins engineering mechanic/tuner. Rattled from new and finally pulled it down at 2000Klms to discover massive wear on the drive side of the bore. Piston to bore clearances measured at 7 tho and within spec. ACL denied refund/replacement and rolled out these excuses in this order. 1. Detonation (cleared after hardness test) 2. Foreign substance in bore (brand new engine run in on dyno with standard air box and new filter) Cleared after excuse number three. 3. Over boosting causing rings to break down and cause abrasion on bore. (Stat decs signed by engine tuners stating run in boost set to max of 14psi). ACL now tell me that there FORGED race series pistons are only rated for 10PSI. This engine has a comp of 8.2:1. Standard engine runs 9:1 with cast factory pistons at around 9psi...do the math. Currently taking legal action. Any questions regarding this "race designed product" PLEASE contact me @ [email protected] .This is not a rant, but an opportunity for other people to learn from my experience.

[retrotec]

ACL now tell me that there FORGED race series pistons are only rated for 10PSI

Theres a reason why they are rated at 10 PSI, they aint forged pistons!

I've been selling ACL parts for years and they are yet to make forged pistons. Someones been feeding you bs.

Alot of people take the RACE series brand to be forged when they are a better grade of cast.

Edited October 11, 2005 by retrotec

[StockyMcStock]

on a side note, i find it hilarious that a piston can be "rated" at 10psi.

does that mean the piston will be okay on a motor with 10psi, huge back pressure, poor camshaft design and 14:1 compression? or does that mean that the piston will be okay on a motor with 10psi from a blower, with no back pressure, a perfectly selected camshaft and 7:1 compression?

[platinum]

on a side note, i find it hilarious that a piston can be "rated" at 10psi.

does that mean the piston will be okay on a motor with 10psi, huge back pressure, poor camshaft design and 14:1 compression? or does that mean that the piston will be okay on a motor with 10psi from a blower, with no back pressure, a perfectly selected camshaft and 7:1 compression?

<{POST_SNAPBACK}>

it's a bit like wankers who ask you about your car and their first question is "how much boost u running bro?"

But I think this guy is talking about the acl hyperlite series of pistons, I was considering them for my conversion, but my engine builder talked me out of them.