SimonR32

i was also getting 15psi by 3800rpm on my rb20 on flat road in 4th gear

All correct Except for running 7psi, that's just gay

way too much lag for the turbo, looks like your boost controller would be the first problem... had one (snozzle now owns it I think) on my rb20 about 4 years ago. made 305rwhp on 18psi dropping off to about 15 with a turbotech boost controller and stock actuator im pretty sure the problem with not holding boost it due to the actuator being blown open at high revs

Adam here is Perth ran close to 300rwkw for about 2 years before stretching the head studs I'm hoping for at least 260rwkw and wanting more like 280rwkw, lets see how long that lasts...

They are not talking about a drop in exhaust manifold pressure (that is what a wastegate effectively does to hold a consistent boost level). They are discussing too high exhaust manifold pressure caused by restricting the wastegate movement Actually as pressure builds in the exhaust manifold it pushes the turbine wheel faster and harder (this is why if we run a turbo without a exhaust manifold pressure release aka wastegate then turbos will run almost unlimited boost)... It also pushes harder back on the engine which is what is causing some people concern.

Similar to the point I was trying to make

I also don't see the difference between a "Wastegate controller" holding the actuator flap closed or something like a stronger HKS actuator holding the flap closed... both will cause increased exhaust manifold pressure

made and assembled not same same

Can you elaborate? I wouldn't mind improving mine if possible

ive got a set of cheap ones... very well made, the bolts were shocking so i just replaced them with a set of stainless steel ones from the local fastners for under $10

got around to installing (or half installing) the turbo ATR43G3 0.63 rear on my R32 RB20det last night! bolted fine onto the manifold, but the compressor cover was just fouling on the heat shield. was very easy to fix with a few taps of the hammer to bend it back a few mm and now there is just enough clearance. The braided oil line was a very easy install and the water line on the block side of the turbo lined up very well. The oil drain also seems to line up well and shouldn't be a problem to bolt up tonight. The water line on the chassis side seems to be low by about 15mm but is held on by a solid metal bracket which im pretty sure i can bend and line up well. overall it has been fairly basic to install ps. my JJR dump was hitting on the wastegate controller by a few mm, but used a angle grinder to take a little metal off the flange and it fits fine now

Your screaming down the hill on the back straight of Barbs in 4th gear at 6000rpm on gate... Vacuum?!?

A car in 4th gear at 6000rpm making 18psi going downhill will be under a lot less load than a car going up a hill at 6000rpm making 18psi... BUT they will both be using the same amount of air from the turbo!!! The same car in 1st gear at 6000rpm making 18psi going up and down the hill will also be using the same amount of air as well! Same amount of air is same amount of power!!! You are getting confused with load causing a turbo to spool up... Of course a turbo will spool up faster in longer gears due to additional load on the engine but once a boost limit is achieved then the load on the engine does not affect the amount of air the turbo flows... This is governed by the type of boost control used. Thus yes, turbos are laggier in lower gears but if they are falling over top end they do it in all gears (assuming they are not complete dogs of turbos that don't hit the boost control in early gears)! Read what I wrote again! Just because you can’t feel the turbo falling over after 5500rpm in 1st and 2nd doesn’t mean it isn’t... It just means that because the acceleration in those gears is faster and your “seat of pants” dyno can’t tell that it is dropping off!

we are on the same page, i was just trying to point out his flawed logic myself personally, i dont mind a bit more lag to get a bit more power if you want a bullsh1t fast car, get a GTR with a t04z

same same

sorry but you are just as wrong as he is... a turbo flows as much air as needed to build up a set pressure caused by the restriction of the engine (as set by a actuator/wastegate and/or boost controller), it has nothing to do with the load on the engine! thus once the turbo reaches its set boost (and stays there) the power it makes in any gear should be fairly similar. a engine flat out in 4th gear will flow very similar amounts of air into to a engine as one flat out in first gear (assuming same boost level) if a turbo falls over in 4th gear at 5300rpm when its running 18psi, then it will also fall over in 2nd gear at 5300 when its running 18psi... just because you can not feel it doesn't mean it isnt happening

im putting a 3076r sized turbo with a 0.63 rear on a standard 20 as we speak... stay with a 3071r with a 0.6 rear if you want less lag, go a 3076r if you want a little more lag but a lot more kick in the kidneys

shimming is better than welding

smash a shim in if you want it to be tighter and dont have a lot of spare cash

wtf... just buy a proper mechanical diff

I see you have changed the position of the wastegate controller, much better

sorry my bad 4th... 3rd was a few hundred rpm higher and 1st and 2nd too fast to get accurate readings

fair enough... to give you a rough idea of what i was getting on the road (6-boost, z with split 0.84 rear standard stroke 2.6l) boost would hit 24psi (shown on both sbc idiii and defi recall and both tacho and recall of max revs on power fc were usually around 3800-4000rpm when ramping up from just under 3000rpm on a flat road

interesting... r32-gts t04z was making 520rwhp on 16psi and mine made over 500 on 17psi both were also making loads more torque between 4000-5000rpm compared with the graph you posted... something wrong with the setup?

is that the same as mine stao?