wolverine

Your link doesn't load. On an RS4S there should be a torque, battery voltage and boost gauge in the centre. The seats and door trim should be identical to an R34 GT-t skyline. There are a few other things but this will usually rule out most of the aftermarket conversions. It sounds like an aftermarket heavy duty clutch....and yes the car is much heavier than an R33 so they are doggier off the line.

If you can get 350rwkw out of a GT3071 core then I need to get my cars on that dyno asap. They are a 450hp cartridge assuming you use the 56 trim comp.

If the GTX wheels work like their maps show then mated to a 0.82 turbine housing should be the right combo for and RB25.

You can't directly compare a 0.73 non-native housing to a garrett housing. It is based on a ratio and it won't be same when you compare housings.

There are a few AVO housing results around if you search but most don't make the most of the compressors potential from what I have seen with the exception of one outlying high result. Pretty much this subject has been covered a few times over the years and most people are going to suggest the native housing for the turbine for best results.

The turbine wheels were designed with a garrett housing so you are compromising turbine flow. If you are determined to go this way then post up the results as soon as you are done. The good news is it will bolt on to the factory dump pipe.

A shame about Bahrain.... ....perhaps Bernie can organise something in Libya to make up for it.

I imagine the fix is in the cold fuel enrichment tables. Colder weather is is going to make it hard for fuel to vapourise.

Don't want a manual stagea in the right colour with the stronger running gear, bigger sway bars and better motor?

I would simply tighten the covers with a big fat screwdriver. The covers on the R33 were a little loose and leaking a small amount of oil but it had 200,000kms on it at the time, it now has 235,000kms. 1x big fat screwdriver = no leaks and no money spent in my case.

Surely during combustion in-cylinder pressures are much higher than manifold pressure....like 50 to 100 times higher.

Good to hear it is internally intact.

and....

We need more test pilots, so go for the GTX3071

No idea why it failed, it was name brand and fitted by reputable workshop. Stuff happens.

The mechanics expected they were going to take the head off but figured it was worth trying to fit a belt and idler bearings and then turn it over by hand to see what would happen. It turned ok, so they cranked it and it started like normal. There is no joy in getting the bill for a new timing belt (etc) but in this case it beats the hell out of a new engine.

We all want more power but there is a point where you start losing somewhere you just have to figure out where you can live with the compromise.

Come on Duncan don't be a spoil sport, I am pretty sure JP showed you the timing belt that came off my R33 when the idler bearing seized and stripped the timing belt. New belt fitted, it started and purred like a kitten. I have no chance of winning Powerball now.

Try this...

Why is it a weak point? The gaskets don't fail. Good tuning with proper knock sensing & using quality fuel doesn't require a drop in compression. There are lots of higher comp cars out there nowadays that run without issue so 9:1 isn't exactly pushing the boundaries. Poor tuning will kill any engine at any power level. Issues like cooling start to become part of the problem at higher power levels and over 300rwkw for prolonged periods you are asking a lot of stock parts. I run 280rwkw on and internally stock R33 and chose to stop there rather than going further for a big number out of sympathy for an older engine so I definitely agree that there a point where prudence should take over. I personally wouldn't pull the head off a perfectly healthy RB, just in case, as it is money that can be spent on tuning or other more performance enhancing mods. I believe the RS4S driveshafts are the same as an R33 GTR (I haven't checked part numbers on FAST so this should be taken with a grain of salt).

You don't need a metal headgasket or studs for this sort of power level. The RS4S (ie manual series 2) has the larger driveshafts.

Much of this is going to depend on what the pre-dyno and post-dyno figures show. I have seen some results from an SA workshop that all seem pretty high so the final figure might not be comparable to other results. Full boost at 4000rpm is GT3076 territory (perhaps even the smaller 0.63 turbine housing on a GT3582). This doesn't sound like a small frame GT turbo. Wringing the neck of a GT3071 or GTX3071 might get you there. Duncan is echoing what I said earlier a solid 250rwkw is a lot of power for a stagea and much more power can compromise the drivability day to day.

Be careful with the GTX3076 there is almost no data out there for how well they work. On paper they should be sweet but the only plot for it that I have seen showed that it put out similar numbers to an old school GT3040 aka GT3082. The GTX3071 is the more likely candidate as it seems to flow the same as the old 76mm compressor wheel but we haven't seen real world results yet. If you get bored and compare the GTX specs at the Garrett website you can see that the new billet 76mm wheel looks like the smallest gain over the old one. The HKS turbos are more money but come with all you need to they bolt on. You won't pay for the stuffing around sourcing parts and paying extra to make them fit. If you go for a Garrett turbo and want to be a bit of a test pilot then definitely go the GTX3071 as it should do everything the old GT3076 does and hopefully spools a whisker earlier. If I was upgrading my GT3040 on the R33 this is the way I would go but I would be using a twin scroll turbine housing as I already have the divided HKS manifold and it would be a relatively easy change.

This sort of thing has been covered to death in forced induction so if you really want 300rwkw then you need a GT3076 or bigger if using 98ron. If you are willing to use E85 you can probably go down to a GT3071 sized turbo. On a stagea there are a few other issues to consider and weight is one of them. Larger turbos feel even doggier on a heavy car with 2.5L displacement so you need to think carefully about where and how you use the car. In the bolt on upgrade range a high quality hi-flow will get you 250rwkw or thereabouts and is definitely worth considering. It is a lot more power despite what forums seem to imply. A HKS GT-RS is very similar to hi-flow but comes on a little quicker. A HKS 2835 ProS or the new HKS 2835 Kai slightly larger turbine and a whisker more compressor flow than the GT-RS and is probably the standout turbo for 2.5L RB's. Then you are into the not quite bolt on turbos like Hypergear which will require a few more mods but will make good power quite cheaply. They are bushbearing which can affect transient response but will still make numbers. Then the Garrett range comes in with all the required changes they need intake, oil water lines and dump changes. I would look at the HKS 2835 kai but it might not reach 300rwkw.

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