KiwiRS4T

Well you're doing better than me - so far I only have 230awkw at 15psi. I have a GT3540 with .63AR. I will be getting it retuned soon to whatever it will take - probably around 25psi and I iwll be happy if I crack 300awkw. If you have a similar compression and turbo your extra power must be down to the RB26 head or do you have twins?

This is getting tedious but I hate being misrepresented. I never said that the stated CR on a box of pistons was 100% accurate. I just said that you could use the manufacturer's listed CRs as a guide. Your impressively long formula will not give a 100% accurate CR either because of the irregular shape of most compression chambers and some piston crowns and the variations in the compressibility of the head gaskets etc. The correct measurement is actually quite simple if the spark plug hole is at the top centre. With the engine fully assembled put the piston at TDC. Using a pipette measure the amount of liquid needed to fill the combustion chamber and subtract an amount equal to the volume of the part of the spark plug if any that protrudes into the combustion chamber (quite easy to determine). Call this volume x Take the piston to BDC and measure the additional amount of liquid required to fill the cylinder to the top of the combustion chamber. Call this volume y. The static CR is (x+y)divided by x The product of this calculation will be sufficiently accurate for most purposes.

Plenty of people have done it before - read the RB25 turbo upgrade thread above. 300kw is easy... the next 50 will take a bit more doing. Allegedly the auto can be rebuilt to handle that sort of power (e.g. MV Autos in Blackwood Adelaide - poss others) but I would be going manual with that sort of power.

Everyone agrees that the early short crank collars should be replaced to safeguard the oil pump but there is a theory that the later full length collars and therefore the Jun and Tomei collars (and the ones that I sell) allow too much clearance and therefore destroy oil pumps. I don't accept that this theory is by any means proven but those that believe it either weld up their cranks and machine them down to allow less clearance or else get bigger (than 40.7mm) collars made up. I don't know how they pan out.There are hundreds or probably thousands of RB engines with stock full length collars that have not destroyed their oil pumps so I remain unconvinced. In any case the collar you have bought will just replicate the collar you already have so that is why it is not worth fitting.

I have one only GTR bov for sale. Great upgrade if your C34 bov is leaking...the GTR bov is much more robust. The flange is the same so bolts right up - vacuum line is the same but the outlet is bigger so you need to step it down to fit stock return (I just pushed the bigger hose over the smaller and clamped it but a reducer would be more elegant! Price $60 posted to anywhere in Australia

No one's going to pay you $195 for a crank collar - your best bet is to see if your supplier will take it back less a handling fee maybe for a credit if not a refund so that you can buy something else off them.

cutting power is not the solution to anything -it is an emergency measure. I have gone to great lengths (won't detail them again) to fix the known RB oil control problems - having the ecu cut the power in case of a failure is a last resort in case everything else fails which i plan not to be the case!!

Just so you don't confuse the punters you will agree that you can use the tables supplied by the piston manufacturers/sellers to work out which will give the higher compression ratio e.g. Spool sell pistons for the RB30/26 - one labelled 8.2:1 CR and one labelled 9:1 CR and the latter will result in a higher static CR which is all that I was saying (I wish I had the higher compression i.e. 9:1 pistons). You are quite correct to say that the resulting static CR will not necessarily be exactly 9:1 as there are many variables but you will agree that just changing the piston specs can increase the CR.

The new collar will be 40.7mm so you have probably just bought a collar for nothing. Don't waste any more money by getting it fitted. Yes it would entail machining off the old collar and replacing it with one exactly the same. Its only worth doing if you have the older style shorter collar that only partly engages with the pump.

Can't you just drill and tap some holes in the thermo sandwich plate?

A few of the track RB30s have the Link watching for lack of oil pressure. I bought a high quality 0-150 psi pressure sensor from Rips (they are widely available) and my G4 will be loaded with minimum oil pressures for each gear and cut the engine if they are not maintained. There was a video on U tube of a GTST with an RB30 and you could hear it stuttering at a couple of points at Hampton Downs as the oil surges away from the pickup. No doubt it can be made to switch an accusump. My plug in G4 has spare inputs - The wire in Extreme will have more as well as more computing power.

Either some piston suppliers are telling porkies or you're mistaken. If you have two pistons with generally the same dimensions and pin position etc then the one with a domed or raised part (various shapes are used sometimes with allowance made for the valves) crown will have a higher compression ratio - the swept volume will be the same but the volume of the chamber will be reduced by the amount the crown intrudes into it ergo higher static CR.

Haven't seen any evidence of that. The Nelson built gearboxes have been failing though.

Well its reassuring to know I am not alone but in hindsight I would have preferred to get the 9:1 pistons but they were not available in standard size and would have involved a lot more expense. 9;1 pistons with a Neo head would be great and with a 26 head even better - maybe next time!So what power are you making with your low compression and 26 head?

Motec has been the ecu for many motorsport applications but the Link G4 Extreme is now being used by the new NZ Supertourer series: http://www.linkecu.com/newsfromlink/v8-supertourers-are-go

I guess you're running on E85?

Maybe but you can't get 4 wheels, floor jack, tool box and 60L of fuel into the back of a GTR!

Well I've only got a 30/25. (132psi) What did you get?

You could have bought an identical collar from me for $70 delivered! But I really wanted to say forget the head drain but be sure to drill and tap two 20mm holes as high as possible in the sump for breathers (necessary for an RB30 - don't know if they are for a 26 but you can always plug them if you don't v having to pull the motor to add them later) and I would go 1mm on the restrictors (just one on a 26?)with your Tomei pump.

5 minutes? That's a bit modest I am sure they can crack ten seconds.

I wish I had a Neo head. With stock pistons and the 33 head my compressions are 132psi (leak down test is fine) so I am guessing about 8:1 if I'm lucky. Only making 230-awkw at 15psi so soon to be retuned to 25 psi or as much as poss till it stops making more power (GT3540). I'm using a Tomei metal head gasket.

Does your RS4S have forks like the GTR at the back or eyelets like the front?

Like this: Locate the "air bleed" wire behind the drivers kick panel, it's a plug with a single wire either side (usually green socket, white plug). Disconnect it. Start car. As key comes back to the ON position, within 10 seconds, depress brake pedal 5 times, 4WD light will start flashing to indicate you are in 2WD mode. To go back to 4WD mode, turn car off, reconnect plug and off you go. I have hooked mine to a switch in the centre console.

Just go to a shock shop and they should be able to offer a number of alternatives after having a look at yours.

Are they supposed to? Have you changed your dampers/shocks? I have Tein springs but also changed to Nismo labelled Bilsteins at the same time and they determine my ride height. Here ya go: http://www.trademe.co.nz/motors/car-parts-accessories/nissan/suspension/auction-482758760.htm