Cubes

I've found the biggest influence over where peak power lands and how power holds after peak is to use a shorter runner plenum the the std rb25 item. i.e GTR. Already being a gtr head = ftw. Even the Rb25 head with its std cams is able to makes its peak close to 7000rpm and holds power basically flat without drop off until a shade over 7000rpm then by 7500rpm its begins to smoothly drop off. Std runners/plenum power peaks and then drops off hard. Mine with the port matched inlet and plenum, port matched exhaust manifold, mildly ported r32 rb25de head, valve deshroud and gt30 .82 iw made its peak 268 @ 6000rpm 15.5psi BUT it does drop off fairly hard after that. By 7000rpm its making 252rwkw. So 16rwkw over 1000rpm. No point reving past 7000rpm BUT it does pull to 7000rpm comfortably.

With those cams and if you run a shorter runner plenum it will most definitely want to keep making power past 7k well in to 8k.

I believe only 1 other is that I know of. But in saying that I really don't know; ordering from nengun takes a good 2-3months so time will tell. Its fairly simple. You just need a circuit that at a preset rpm triggers a relay then at a second rpm it disables the relay. Mallory do a window rpm trigger switch that is suitable. Tracking down how much I can get them for.

I'll take you back to and my reply of.. It will be sorted.. Just in my spare time. If you get edgy why not research and start fiddling also.

Hey Disco, 270rwkw is a fair fetch away from the 300-320rwkw brick wall of the std exh. manifold. Its still got a little more left in it yet. The problem 90% sure lies with the std cams but more importantly its cam timing/centerlines. I am running GTR valve springs so they 'should' be ok but I wouldn't be surprised. As I think I mentioned in another post a mates GTS4 making 270rwkw with a GT35r .82 hit the exact same brick wall at 270rwkw with the std cams. Pushed more boost in the curve went all lumpy. The problem was literally IDENTICAL!! No detonation problems just the power curve began getting all shakey. And funny enough Z32 afm voltage sitting at 4.7volts as is mine so identical airflow. Sky30 ran a similar setup gt35r .82 BUT he ran with the slightly larger RB20DET exhaust cam (240duration 7.8mm lift) + it has a difference centerline; he pushed a touch over 300rwkw; he then dropped in a set of 260degree cams which only improved spool. No real peak difference with regards to rpm and power. So hit the limit of the std exh manifold. I really don't believe scroll inlet pressure is a problem with my spiky/lumpy curve. The gt30 rear with decent fuel has pushed 360rwkw odd without resulting in a lumpy curve. The problem of excessive scroll pressure shows as not being able to run decent ignition timing and the requirement of better fuel. Of which isn't happening. At 15.5psi making 268rwkw we pushed in another 2degree's of ignition timing and only picked up 2rwkw; pushed in another 1 degree' picked up no power pushed in another 1 and saw a little bit of detonation. So its fairly happy where it is. Definitely not an indication that there's excessive scroll pressures. By dropping the larger turbine housing on the GT30 when pushed to its limit I would only see an additional 20hp peak power. But the trade off being off idle spool, part throttle and low load (1st & 2nd gear) response and general lively feel of the car is most definitely scarified; much more noticable than the 20hp increase at peak. Tune the boost curve to suit how well the car is hooking up. Makes for a much nicer drive. There's nothing worse than a lazy feeling motor at part throttle. Of which the larger turbine housings do cause. I was told if I want the 1.06 sell the turbo and drop a GT35r .82 on it as its spool characteristics will feel the same BUT offer a hell of a lot more top end. I'm not after more than 300rwkw as the cars not 4wd and relatively light so I don't see a need to run a turbo that offers such power especially when it sacrifices mid range. But yes.. I have this gut feeling its the valve springs. I've seen that wobbly curve many times before.

It will run fine. A Gt3082r on an rb20; you wont have to worry about seeing boost unless you were to pull it out past 4k. It will drive fine just plodding it around. -- I always prime the turbo with out before starting. Disconnect fuel pump or igniter and crank her over until you see oil coming out of the drain; connect the fuel pump igniter back up and then the oil drain.

Just received a reply from Noltec. So there we have it.

Kralster. I noticed u randomly posted Rock Lobster in another thread. Was that a hint as to who you really are?

Which is why I said wait until the VCT controller has been sorted before buying one for your R33. Its something I am doing in my spare time so when its finished its finished.

Short shift. Hold the gears out and it will still drink as much. Max 2500rpm.

Power to weight.. GTR needs around 40rwkw more to have the same up and rolling pace. BUT the gtr does have twins which offer better response so once making decent 300rwkw+ the twins will get up and go quicker in the lower gears; say second gear from a rolling run the twins own! TWINS FTW!

Cheaper interstate. Foolboost bought his for 19k; mild cams, hks2530 turbo's, mint interior, good body/paint. Keep an eye out there are bargains out there.

A wrecker? I believe All Panels and Parts at Lonsdale do gearbox swaps etc so shove a s/h clutch in it?

Made 268rwkw @ 6000rpm on 15.5psi with the GT3076r .82 yesterday. Pushed more boost (up to 20psi) in but as it pushed past 275rwkw the curve got all spiky; no det issues just a messy curve. Shaun seems to think its the baby 232duration 7.3mm lift exhaust cam in these r32 rb25de heads. Pushed in another 2 degree's and saw 270rwkw peak but not worth the 2rwkw; there was no det but I'd prefer to pull 2degree's for only 2rwkw. Afr's are mid 11's dipping to low 11's after peak power is made. Not sure whats up with the clutch; shaun did say it felt high but was holding in ok on the dyno; so maybe it gets a bit hot on gearchanges and then starts to slip?!? :S Should see a fairly easy 300rwkw with the GT30 going by how much ign advance Im able to run and ~270rwkw being made on only 15.5psi.

No knock issues. It made the power super easy; so easy we thought bah an easy 300rwkw. Power started to get all wobbly and spikey once ~275rwkw was reached; from memory with more boost it was making around 275-280rwkw by ~5000rpm so I think its definitely got a 300rwkw in it once its sorted. If its valve springs or is indeed the std cams I guess I'll find out. Its interesting to note a mates RB30DET gt35r .82 running 17psi with ~8:1 static comp was making an identical 270rwkw power but with much less ign advance ~12degree's. The exact same thing happened to his; push more boost in it did very little and the curve got all messy. So more boost bigger turbo but the same power. So my slightly higher static comp + head work + hours spent port matching must have helped. Shaun is 99% sure its an airflow/cams problem. Feels strange reving the car past 5500rpm after driving it to 5000-5500rpm with the stock sized turbo for so long.

Straight off the actuator peak torque is around ~4500rpm. With the boost controller connected peak torque was ~3300rpm. Interesting we pushed in another 2 degree's advance, no power was picked up anywhere apart from the last 500rpm where it picked up 3rwkw. So pulled that 2 degree's out and left it as is. With 18-19psi in it made almost 550nm with 15.5 it made ~490nm.

At the moment its grabbling at the road in third on most road surfaces, some it just spins up but it is fairly controllable with the right foot; with the boost controller on it it was lighting up the rears. The boost vs accel position is quite linear; so when it begins to spin up you back off a little then feed it back in. BUT in saying that Im not running flash tyres nor is the diff in that good condition. They are cheapo Federal 535 225/50/16's. Throw a set of semi's on it and it will hook up much better.

Yes peak power arrives at 6000rpm which I am stoked about and there is basically zero boost creep. Maybe all that port matching and headwork has helped somewhat. The R32 Rb25DE heads are only different on the inlet; exhaust is the same size. The inlet ports are ever so slightly smaller and of a different more round cylinder type shape. The inlet of my head has been ported/port matched and valves deshrouded so no doubt definitely helps flow. Feels great to drive; at the moment I can't pick that power begins falling over after 6000rpm; feels as if it pulls strong until the 7k rev cut. The wavey is a sharp jaggered wave; the boost curve wave I think is because of the long feed from the plenum to the actuator. That will be sorted with an ebc. The cheapo ball/spring boost controller was next to useless; it would spike up and then tail off to a couple pounds above normal wastegate pressure. + If I left it on it would have most definitely smashed the rb20t gearbox to pieces rather quick. :S The tuner had another car on his dyno with a similiar setup and with a set of 256degree poncams it went from the same 270kw to 290kw on the same boost. He's got an rb30det same head etc going on in a couple of weeks with a set of reground cams so if that shows good results I'll go with the cheaper $220 regrind option. If results are not that crash hot I'll throw a pair of 260duration+ cams at it with decent lift as the buckets have already been machined.

Mine just pulled 268rwkw on 15.5psi @ 6000rp; power drops to 252rwkw by 7000rpm. Definitely has plenty left in it. Z32 afm @ 4.73v; 20degree's ign. timing at peak power. Pushing in another 2degree's (22) only picked up 2.5rwkw (270.5rwkw) so it must be near MTBT? If we pushed more boost in the power wouldn't really improve all that much considering and the curve began getting all lumpy. Its been suggested the std R32 RB25DE exhaust cam is too small (232duration 7.3mm lift) and has reached its limit. We did see 285rwkw but the curve was lumpy. Fingers crossed its not the onset of valve float. Feels awesome to drive; never bogs/lags even in first. Just gets up and goes with a strong linear pull that becomes more intense as rev's pick up. With the boost controller connected 3rd gear roll ons from 60km/h = lack of traction with boost peaking at ~3000rpm. The garrett actuator is quite lazy to bring boost on but it does feel nice to drive and most definitely helps those rears hook up and no doubt doesn't prevents the rb20t gearbox smashing near instantly. As it is now first 2 gears wheel spin but I can control it with the right foot; third gear over 4500rpm also starts to wheel spin up. Time for some decent tyres.

R32 GTST Standard Rods 87mm Wiseco Forged Pistons Mild port/polished head, port matched, valve deshroud and usual rebuild. GTR valve springs GT3076R .6 Port Shroud Comp Cover .82 Internal Gate 3" turbo back exhaust, Bell mouth 3" dump GTR Injectors with nismo adj. fpr running higher rail pressure 450w x 280h x 90d Bar/Plate FMIC Unfortunately 2.25" inlet and outlet Blocked Rear Oil Restrictor with a single 1.5mm Restrrictor up front Std RB25DE cams (240dur 7.8mm Inlet, 232dur 7.3mm Exh) Standard airbox with 100mm CAI Standard plenum Standard Exh manifold Standard R32 GTST RB20DET Gearbox (Hopefully it hangs in for a little while) No 3rd party boost control, standard lazy actuator boost level. Z32 AFM @ 4.795v. 268.5rwkwwith 15.5psi @ 6000rpm 252rwkw @ 7000rpm rev cut. Very nice and progressive to drive; doesn't lag, never has that doughy feeling just pulls from idle. Excellent part throttle boost/acceleration.

The 25t box has a slightly longer 5th ratio than the 20t box; unsure what the ratio is within the gtr box. But to give an idea. (Ignore what your tacho says; they read high. Consult the pfc rpm display) 4.363 ratio at 100km/h is 2757 (146km/h in third @ 7000rpm) 4.11 ratio at 100km/h is 2597rpm (155km/h in third @ 7000rpm) 3.9 ratio at 100km/h is 2464rpm (163km/h in third @ 7000rpm) 3.69 ratio at 100km/h is 2332rpm (173km/h in third gear @ 7000rpm) I went from a 4.363 to a 4.08 a noticed a drop in off boot torque; out of corners etc the car felt lazier and spent more time trying to accelerate through any lag. Essentially it made the car feel more laggier. Accelerating off the line the car felt much nicer in first gear and appeared to accelerate better even though it would wheel spin but second and third + didn't feel as responsive. So.. I dropped the 4.3 ratio back in and it is a much more enjoyable sporty drive. I don't do much if any highway cruising so the drop in 100km/h cruise rpm didn't affect me. Once making some decent power the longer ratio 'may' be worth while as it will help getting it hooked up. I noticed it felt as if it was easier to control wheel spin in first.

I didn't measure the internal dia of the crush tube but once up in position it was rock solid; wasn't moving around anywhere. Have you slid the bush up on to the stud to see how much movement there really is?

Well I didn't realize the little SR20 was such a capable performer. Ignorance is bliss. A little searching it appears the sr20's do usually see 280rwkwish but with stage 2 (260in 270exh) cams and the 3071 hanging off the side. 280rwkw on 15.9psi or what ever it is looks like with stage 1 cams & stock bottom end looks like good strong power. The SR20 essentially is 4cyl RB30 when you consider bore, stroke & valve size etc; would be interesting to see how the rb30det would perform with such cams and the 3076. As it is the rb25 head from factory runs quite small cams compared to the stock sr20 head so no doubt some big power gains are lurking if we were to run some decent cams. Sky30's rb30det is a good example; gt35r .82 17psi (@3400rpm) 380rwkwish with reasonable cams and plenum/exhaust manifold compared to his old setup 312rwkw (18-19psi gt35r .82) with std plenum, smaller cams, std exhaust manifold. Given the 460hp rating of the GT3071r minus the skylines usual 70rwkw drivetrain loss thats ~275rwkw. The Gt3076 @ 525hp; thats around ~320rwkw. So pretty much on the money from what I've seen over the years.

To Albert, Post the dyno sheet; yes spamming the thread a little but if you make claims u do have to back them up. Either way I did say a little over 250rwkw on the dyno I run on (and assumed as it is a skylines forum) with the rb and its driveline (the 25t box does soak a little more up than the rb20t box for example).

All bets are on having a gutted or no cat. Backfiring is caused by the blocked off bov. If the cat isn't already gutted my bets are on it being stuffed due to the backfiring etc. Have you connected up the pressure feed to the bov correctly? It may be that its blowing open a touch if its boost feed isn't connected. Block the bov back off; use a coke can, chop it up and see how u go. If it holds boost then the problem lies with the bov.