StockyMcStock

man the dump pipe clearance to the firewall must be tight. when i was looking at making kits for the 2jz supras i had a good measure up of it all, everything seemed far too tight at the back and you couldn't fit a GT42 compressor in between the engine and strut tower, but they've managed to jam it in behind somehow. dump pipe must be TIGHT! what sort of blower is it? looks like one of the TRD ones, which are (as far as i can tell) enlarged and revised SC-14's. i hope it has the capabilities to produce the required boost and not run into the redline of the blower. p.s. if the guys need any tech support, let me know. i trust they're using a bypass gate?

USA ebay dude. there's heaps of them in the US. consequently the prices are substantially lower.

well i built the bottom end myself with new pistons, so that was super cheap. had the head reconditioned, ported it myself. made the exhaust manifold for $150 all up the only real extra costs above a single turbo setup are the blower purchase price ($300), modifying the drive snout ($200), billet drive system ($500) and belts ($40) the steel was basically free and the idler bearing was cheap as chips. it would cost a LOT if you asked a shop to do it. not to mention they would have NFI how to make it work. even the bloke who tuned it on the dyno didn't understand it.

erm....... no it's not. see the wastegate high mounted at the back of the engine bay? here is the manifold: here it is with just the turbo: which is fairly large: here is a youtube video i made of it: this engine shits all over a turbo-only setup in almost every way. p.s. i was thinking of making kits but it's too expensive and nobody could really afford it.

cheers mike, sounds like it will be okay. although in a race car, you probably use the mix up at quite a prodigious rate, and that rate would not drop to zero for long periods. in my street car, i would set it up so that it started going around 7psi and increased up to full boost. now i probably only spend about 1% of total driving time above 7psi, so the pump would not be working for long periods. my concern is then that there could be large air pockets in the line, which would delay the speed of actuation when next i boosted. i guess the answer is to run a check valve right at the nozzle, and a check valve right after the pump.

question for you guys: how long are your actuation paths for the water/meth kits? I am probably going to install a decent kit on my vehicle eventually, but the reserviour would need to be in the boot of the car due to space constraints under the bonnet. would 2-3m of piping be okay? do they have check valves?

i am absolutely unsure on that. i wouldn't take the decision lightly either because the different balancers are designed for different capacity engines. ps i guess nobody clicked on the link in my first post so here you go: yes 303rwhp on 9psi

it will not make a noticeable difference at all. but if you were starting from scratch, i'd advise to go to split pulse manifold, split pulse housing.

hey guys. http://www.performanceforums.com/forums/sh...ght=contraption any specific questions not answered in that thread, let me know. it's a ripper of an engine. waiting for a stronger gearbox before upping the boost. p.s. the biggest drama with the RB25's is that the harmonic balancer doesn't run any wide belts, and has no threads in the end face for mounting a billet drive pulley. so it is not easy to bolt a pulley onto the end like you can with the RB30 balancer. the only other easy option is to run an extended belt off the 4?PK drive for the p/s pump to drive the blower, but you're in for a bit of belt slip there unless you can get the wrap up near 100%

so the problem was the hole in the induction piping the mike? good stuff!

split pulse manifold and split pulse housing (all else being equal) is always better than open collector and open housing. less turbulence at the gas merge, less chance of a cylinder's exhaust valve being caught open when another one is pulsing as well (so less pressure spike variations across all cylinder's exhaust runners = lower average backpressure when the valve is open). i would only go an open collector if it was significantly cheaper, or there was no other choice. manifold must be split pulse as well though.

it certainly will, as long as you cut the flange off and weld on a new one to match the bigger throttle body.

you'll find that dyno RPM boost thresholds don't mean shit in the real world, especially with a manual vehicle. for example, my car made full boost at 3700rpm or so from memory when it was on the dyno. on the street, it's like this if you mash it from idle: 1st: full boost 4500rpm 2nd: full boost 4000rpm 3rd: full boost 3600rpm 4th: full boost 3000rpm so dynos aren't really very accurate when you compare it to a real-life situation. the only reason to be concerned is if the car feels bad on the street, or doesn't do what you want it to do. then you know you need to change things around to suit your driving style. for example, next time i get the car tuned for more power (up above 400whp) i'm strongly considering going to a larger supercharger drive pulley to push the turbo up to a faster spool and get full boost down to around 3000rpm on the dyno. after driving the thing for near on 2000km now, that's the only real change i have even considered making.

got mine, cheers mate.

yeah, that explains the presence of the coolant gallerys around the injector housings etc, but we're talking about the piping running through the throttle body here.

To stop the throttle body freezing shut. They serve no other purpose. i removed everything on my 25/30 and ran some 10mm fuel hose underneath the plenum to connect all the coolant galleries up. the flow through the throttle body is only necessary if you're seeing icy conditions - even then it's not really needed. remember to run a vertical hose up to above the radiator cap level, then plug it. you can use it to fill the coolant up to the very top so there's no air bubbles.

nobody does, unless it's a dedicated drag car. for a street car, you want optimum response across the midrange to be truly fast. that's why a skyline with a highflow turbo on 230rwkw will beat a skyline with 350rwkw and a laggy arsed T04Z (example only) in a street race. it's all about response on the street.

the rev issues with RB30's appears to be that around the 7500rpm mark (standard crank, mains cap, sump, block, oil pump) the system hits a harmonic which essentially distorts the geometry of the whole lot and means you break things. there are a number of ways around this, all things being equal: 1) billet mains cap 2) change the sump to something else - stronger, stiffer 3) dry sump it 4) forged, lighter rods and pistons with crank counterweight lightening 5) billet crank 6) block stiffening (grout filling, girdles etc) basically the stiffer you can make everything, the higher it will rev. if you can avoid that nasty harmonic (apparently it's very "focal" and if you rev past it quick enough, it goes away above 7500!) then you are in safer territory. having said that, revs are bad. revs create massive wear on bearings etc, not power. i'm not sure why anybody would want to build an RB26 just so that it can "rev hard". use a bigger capacity engine, fit a larger turbocharger and enjoy the off-boost response. fit taller diff gears to space out the gears and allow the turbo time to work in the first two gears. chasing revs simply for the sake of it is a bad idea.

from all reports they were a great little car to drive, very zippy and response - just how a twincharge should be.

i am interested in the answer to this too, particularly if people have any experience with sub-80 degree temps causing bore/bearing wear at an accelerated rate. i know my vehicle has a fair whack more power when it's at 75 degrees than when it is at 80.

i have an on/off davies craig 16 incher on my VL with 25/30, the VL cooling system is arguably worse than the skyline ones i believe. i don't even run a shroud on mine, but have a 3 core VL turbo radiator. i have it set up so that it switches on at 85 degrees, and i've NEVER seen temps go above 89 even when fanging it up hill. does fine in hot, stop start traffic, temps never go above 86 in that case. seems to pull an absolute arseload of air.

if it ran for 1 minute upside down, you will have bearing damage for sure. even if it was idling for 60 seconds, you would lose all oil pressure after 5 seconds and the rest would be destroying the bearings. try everything listed above, but don't be surprised if it has bottom end noise or very quickly develops it. it may already be totally rooted.

plain journal GT4088 1.34 rear housing on my stock headed 25/30 was on full boost around 4500 in 2nd gear, earlier in higher gears. they're a good thing i reckon with a smaller exhaust housing than mine. they have a HUGE compressor cover so watch your clearance to the strut tower etc. TA45 split pulse flange on em i believe.

piece of shit guage. i have the same one and it is wildly innaccurate. 9psi on the dyno's guage means 14psi on the boost guage in the cabin. get a decent one i reckon.

turbo fronts are far too small for it to be a drag car.