Scooby

Where did the 850hp engine produce it's torque and power Matt? Does anyone know if there's a typical correlation of cam characteristics on long/er stroke motors in terms of lift and duration ie does a longer stroke generally mean more lift, or more duration? For good reasons in terms of the respective effect of lift and duration there may not be a typical correlation, just wondering. Not sure what the LS boys do when they go from 5.7 to 6.3 using a stroke rather than bore increase, presumably with a lot of street-built strokers due to mechanical limitations the rpm doesn't increase hugely, suggesting duration stays relatively mild but the extra capacity has to be filled somehow during the longer period of the stroke.

Mate seriously...they've been 'having a stab' for 'years'? Give Ray Hall a ring or send him an email. He's super responsive and has helped me out on two occasions when tuners have failed to achieve optimum results.

Yeah did some calcs on 3.5 diffs, top speed at 8000 would be 366k/hr but pretty sure it wouldn't get there unless it was 700rwkw. What did you get the 3.9s from, assuming Stagea is awd?

I've been looking for some 3.5 front and rear ratios from an R34 GTR, as soon as I can find them they're going in. I reckon 2nd with an 8k redline would be excellent.

Yeah I wondered that too, the RB30 oem cams were never going to cut it so I reckon they've always had to go down the custom path.

Cost wise you're better off with reuseable Tomei, one turbo change and they've payed for themselves.

-5s are good for 400rwkw, I'd have thought the exhaust housings wouldn't be a problem?

$500 for a full set sounds extremely good, at the risk of asking the obvious are they the real deal? Forged? Mine were somewhere around $1000 3 years ago from Faber when the dollar was strong.

I'm using them in a 26/30 with no problem. They were more expensive than most others when I bought them a while back. Supertech make some high end ie F1 gear from memory. I agree with what's said above, clearances etc are much more important than the value of picking one piston over another, and the well known brands have all proven themselves.

Mate it can only be a good thing either way. Are the Evos the same as the F series Brembos ?

How's it going with the conversion Chris?

Bugger, but I was thinking along the same lines anyway. Happy with the outcome? Did using custom cams come about as a general good idea or as a result of there being no dedicated 26/30 cams available?

Too late boys, next time you pull up next to a Commodore take a close look at the driver. See that heavy brow...?

It's understandable that people aren't keen to share that data but it'd be interesting to know the general direction people are going for the 30 when using a custom cam. Camtech mentioned the same thing re wanting to know specs, which is a logical place to start. Do you have an indication of whether in your case it was worth going custom compared to off the shelf stuff? I guess you'd have to go 'back to back' to figure that out. What specifically made you decide to go custom? Same reasons as I'm suggesting? That's true those considerations all play a part. Small changes can make a difference, hence I want to see if I can optimise the grind for the 3 litre and my usage. Camtech said they could get the same power at 5psi less in their 25/30 with a custom cam. Not sure what happens if they up the boost 5 psi after that but assuming there's nothing given away elsewhere I'd go custom to run with 5psi less as to me that represents an increase in efficiency for no extra cost.

I think the point has been missed. When a horse does a dyno pull it's a measurement of how far the horse can actually pull the dyno, converted into horsepower. This may explain the difference between dyno readings, as some dynos are heavier than others. I understand the distance can be improved by the fitment of a Polarhorseariser.

Didn't know that, any ideas around specs? I was able to find an old thread done by Cubes about 3 years ago but that was it. Spoke to Tighe and they said just use RB26 cams, Camtech guy was adamant that a custom grind is the way to go for a 25/26 30 and he has a 25/30. Of course he does sell cams, but then he wasn't simply recommending something like Poncam specs so he's probably pretty sure of what he's doing. Otherwise the results would go backwards pretty quickly. So I'm persuaded he's got good reasons for recommending a dedicated grind. Sure but those factors you mentioned are more of a known quantity in terms of their effect, cam timing is more of a black art and hence why there's probably not much discussion on the forums. That and the fact that there are lots of proven RB26 cams out there. In the case of a 26/30 most of us are putting cams onto an engine they weren't meant for so I'm keen to have a cam expert work out some specs for a dedicated twin cam RB30 based on the characteristics of that engine rather than something with 400cc less and shorter stroke. Most bigger RB26 cams have increased duration and stroke. Purely speculative but maybe the 30 needs something with greater lift but to the stock duration as they have a longer stroke (meaning the valve needs to be open for longer)but generally don't rev as high in most cases. Just speculating but that's the line along which I'm thinking.

G'day Just wondering if anyone has used custom grind cams in their 3 litre. I know there are people out there getting big power from using RB26 cams, but I've often wondered if, with the longer stroke of the 3 litre, we should be looking at cams that are more specifically designed for that engine. For example, should the cam duration reflect the longer stroke duration of the engine. That said I think the OS Giken kit uses RB26 cams so perhaps my suspicions are unfounded. Cheers

Hi Duncan Unfortunately no outcome yet. I agree it doesn't stop you from tuning but mine was moving around 500rpm at 6k, presumably it would have gotten worse at 7500. Yavuz said he could tune around it so that no matter which way it went it'd be safe, but not really optimised as the safety margin for timing would have to be significant. Mark PS you have PM.

I'd rather be at Bathurst watching this thing Steveo how reliable is your source?

Paul not sure how to answer as if the question is related to 'what is an EPA legal cat' that's different to 'what cat can I pass emissons with'. When I passed all they did was check the gas readings not the cat itself. Maybe ask whoever is doing your emissions tune what they prefer, its in the tune probably more so than the cat.

Hi A / Disco That's a great read. Sorry to go OT briefly but can you give us your views along the same lines on street turbos for the 26/30 please? Maybe here: http://www.skylinesaustralia.com/forums/topic/349467-5s-vs-rss-on-a-larger-then-stock-motor/page__st__160__p__5663461__hl__bigger+then__fromsearch__1#entry5663461 Cheers

is that a valve in the pcv line?

i always thought that was typically an air leak ie pushes water out but sucks air back in, but you've had a pressure test. maybe the rad cap is the problem and letting water out but sucking air back in. HG as suspected might explain why the water is being displaced.

I used stock spring hats with coilover adapters for the springs that came with the shocks.

Harey that test with the pencil gauge is good for absolutely nothing. Even if the cat had a piece of wood in it that pencil gauge wouldn't pick it up.