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The more boost you run, the shorter your motors life span. You are running the motor with more air and 12psi over standard. It's like over clocking a computer. You shorten it's life to gain performance. You add more voltage, more timing and you increase speed and power output but you also increase heat and internal load on components working out of their safe zone. Sure, they can do it, but for how long?

Boost affects it big time. Your piston is doing one thing, compressing fuel and air then turning the crank. You double, triple the amount of air and the pressure of air, double the amount of fuel... A coke bottle can handle x amount of pressure. Drop the bottle you increase the pressure, introduce mentos, the bottle can't handle the pressure and it pops. Peter has been working on these type of motors for 20 plus years, he said he has seen almost everything that can happen, happen. Now don't show me those couple, few people running huge boost and what not, look at all the people upgrading, rebuilding and replacing motors. It's more often someone on high boost will pop their motor as the introduction of more boost, air and fuel introduces the unwanted side effects...

Edited by SargeRX8

Boost is not a measure of air volume, which is what is important. I could put a tiny turbo on my car, run it at 25psi and make 100hp. That's not going to stress the motor. On the other hand, a TO4Z at 10psi is probably going to be a bit more stressful.

My point is, power and poor tuning kills motors (relatively speaking). I can't see how boost alone would have any affect what so ever given that what affects the motor is the volume of air going in, not the pressure. Your engine would be drawing more air at 15psi under full load in 4th than it would at 19psi at 3500rpm in 2nd.

Boost does have an effect on dynamic compression, yet its probably not what I would call a real world variable (as noone would really run much beyond 30s on a mild setup).

The more important thing to note is heat, generally compressing air is also superheating it. More boost is higher pressure and more heat. Also, it is generally accepted that high boost levels are pushing the boundaries of the compressors map in which would also look to create excess heat.

Say were talking a turbo built on EFR like technology, I would be happy to run it to say 30psi on a factory motor provided it was efficient at that level and did not exceed the motors given threshold (call it 280kw for the RB).

It isn't the psi that kills motors, it is the torque that kills them. If you get a tiny turbo off a starlet and run 30psi (providing you cool the intake charge enough) it won't blow the motor up because it will make absolutely stuff all torque.

If you keep the power under 280kw, temperatures down and the tune far away from detonation there is no reason why you can't run whatever boost you want. Obviously there is a torque limit where the pistons just cannot take it any more, but it is well above 280kw.

There are people running 400kw that haven't destroyed their pistons, so I see no reason why you would destroy them at the 270kw you were talking about. It is temperature and detonation that kills pistons, and revs that breaks rods and rod bolts/bearings, detonation also kills bearings as well.

He makes a reasonable point, because at 270kw if you get the intake charge too hot, run slightly lean etc then sustained detonation at that torque level will almost certainly kill something, however if you tune properly with a coolant temp and intake temp trim table that pulls timing (boost if possible) then you should never get detonation and hence 19psi at that power level on a stock motor will be fine.

I guess if you want to be 100% safe then you should limit boost, but if any of the above happens even with forged pistons it will kill the motor eventually anyway, it will just take longer.

edit: Actually if you get sustained detonation even on 15psi you will kill the motor anyway, so I think it is a moot point, it should be set up and tuned so safely that det never occurs, and hence I would say 19psi is safe.

The more boost you run, the shorter your motors life span.

Boost affects it big time. Your piston is doing one thing, compressing fuel and air then turning the crank. You double, triple the amount of air and the pressure of air, double the amount of fuel...

Not entirely correct, 15psi on a large turbo is more airflow than 20 psi on a stock turbo with steel wheels, boost isn't the issue, mass airflow and hence torque is the issue. But the MAIN issue is poor tuning that causes detonation, if you get sustained detonation on even a stock turbo at 12psi, you will kill the motor eventually, so providing you avoid detonation and keep the peak torque under the pistons limit you will be fine. If that means running 400psi with a tiny tiny electric compressor then that is no issue.

You double, triple the amount of air and the pressure of air, double the amount of fuel... A coke bottle can handle x amount of pressure.

The pressure is dependant on the compression ratio and how much air is in there, the amount of air in there isn't dependant on the boost pressure, that is dependant on how much air the engine can swallow and the turbo in use. The x amount of pressure the coke bottle (piston) can handle is based on amount of mass air (eg turbo AND psi) but it is also based on HEAT which makes it far more complicated that just plain on psi.

Edited by Rolls

Boost is not a measure of air volume, which is what is important. I could put a tiny turbo on my car, run it at 25psi and make 100hp.

:rofl:hahaha no that won't work on Rb25det unless you got another car with 0.2L engine. Hot air would not pump out a tinny turbine housing and wheel combination, which traps inside combustion chamber causing detonations. So depending on size of engine as well as sizes of the turbo, bigger engines would need larger turbine housing and turbine wheel to maintain stable at certain boost level.

R33 rb25dets should be alright around 280rwkws mark at about 18psi without getting valve spring or lifter issues.

I think the main point peter was trying to make is not that 19psi is going to kill your motor, but the fact that it is not a good idea to be running 19psi as a low boost setting, all day, every day. He said sure run your 15/17/19psi but run a lower low boost like 10 or 12psi. Right now I'm only on 9psi and ill admit I am very happy with the performance. My old car with a garrett high flow would make the same power at 14psi. He thinks also that the front compressor housing is too small for the flow and that high boost and thinks that on extreme use the thing will roast and get red hot. He didn't mean it literally but he was saying what everyone here is saying about smaller turbos trying to do big work becoming inefficient.

None the less, back onto the original topic of this thread. If anyone is thinking about getting a hypergear turbo, I highly suggest you put it up there in your preference list. I was initially going to go Garrett with genuine garrett front and rears. From the graphs Ive seen I'd say the extra pain in the ass of fitting the turbo on and having to make a custom dump flange, spacing the turbo and what not is not worth it. These hypergear turbos literally bolted straight on(obviously not as easy as it sounds but yes it bolts straight on). The only change is the connecting pipe from the compressor outlet and the intake pipe. You can use standard but Stao doesn't recommend it.

Happy customer here. 9psi and I break traction between first and second and chirp third with fat 255 tyres. Very nice 0 - 100 even though I haven't tried it out I know it will get there quick. My old car was in low to mid 5's I'm sure this one is on par if not better. Cant wait to tidy up my tune and run more higher boost.

:rofl:hahaha no that won't work on Rb25det unless you got another car with 0.2L engine. Hot air would not pump out a tinny turbine housing and wheel combination, which traps inside combustion chamber causing detonations. So depending on size of engine as well as sizes of the turbo, bigger engines would need larger turbine housing and turbine wheel to maintain stable at certain boost level.

R33 rb25dets should be alright around 280rwkws mark at about 18psi without getting valve spring or lifter issues.

Lol no I know, it was a hypothetical situation. All other things being equal, boost is relative. Higher boost on one turbo could still be less air flow than lower boost on another turbo. You can't just say nup, 20psi is too much for this motor. If anything, you could say running 20psi through this turbo is creating too much power for this motor. Which I imagine is what the mechanic/tuner in this case was getting at.

another factor to be considered is the use of the right foot :P

This lol. Who honestly drives around at 20psi all day everyday in top gear? I might give my car full stick in 1st, 2nd, maybe 3rd and by then I'm breaking every speed limit in Australia. On the track I'll get to redline in 4th, but that's where the quality of the tune makes the difference.

Anyway, good to see another positive result from Hypergear. Makes me hopeful that I can sort out whatever gremlins my car has and see the promised result :(

Thinking to upgrade my stockie and every one pointed this thread.

Wahoo this is a very informative thread. Filled with real experiences, real results, real feed backs, DIYs and plenty of recommendations based on solid out comes. And you guys's works looks great, must been taking lots of practices to do that sort of welding and machining work.

I’ve just ordered an Atr43ss-1 for my 93 R33 GTT can't wait to receive it. Will post reviews of the whole package as its getting installed and tuned.

Thinking to upgrade my stockie and every one pointed this thread.

Wahoo this is a very informative thread. Filled with real experiences, real results, real feed backs, DIYs and plenty of recommendations based on solid out comes. And you guys's works looks great, must been taking lots of practices to do that sort of welding and machining work.

I've just ordered an Atr43ss-1 for my 93 R33 GTT can't wait to receive it. Will post reviews of the whole package as its getting installed and tuned.

very true, good on ya for going with the highflow! i havent made my mind up yet if i want that or the ss-2 (bit confused on the differences, will re-read). though will be good to get some more feedback and results from you. and hate to be a troll but you have an R33 GTS-t or GTS25-t, its the R34's that are called GTT, just to eliminate potential confusion in the future :happy:

Stao are you getting that new skyline tuned? I'll be very interested to see results of that from a untouched engine.

Add:

Also are you making any thing in between the SS1 and SS2? any chance of making 270~300rwkws mark with 2530's response?

Yes I'm getting both car tuned shortly, will post result when ready.

Regarding to powered up SS-1, I've made few drawings on different shaped comp and turbine wheels which I will cut them out on a CNC machine for trails runs. I think getting 300rwkws with stock response on factory setup and 98 fuel is looking very possible.

SargeRX8: The SS-2 is at its best with 18~20psi, but depending on what you and your tuner are comfortable with. Stronger actuator will improve turbo's response and on road driving ability as it doesn't "starting to open" so early. Looking forward to see more power.

When does the ss2 hit fullboost roughly on a rb25?

The answer is in the last 20 pages of this thread or in the RB25 dyno thread. Just have a quick read.

It's a VERY promising looking unit.

EDIT: found it in 3 seconds flat.

http://www.skylinesaustralia.com/forums/topic/55845-rb25-turbo-upgrade-all-dyno-results/page__view__findpost__p__5692653

3750 RPM for 20 pounds. Talk about a bullet.

Hi Stao,

i have a simple question about Shaft SPEED,

What is the Shaft speed at idel,

as i know the difference between BB & PJB on spool time from 40,000 to say 100,000 is same.

whats your take on BB V PJB,

BB Ballbearing , PJB plain journal bearing

Cheers Chuckie

On idle, the BB setup is obviously quicker with PJB where the opposing surge pressure is not present and oil pressure is low. Notice how the BB ATR43 Alfa units behaved off the car and on idle.

How ever once the comp wheel takes on opposing surge pressure then it requires greater forward spinning energy from turbine wheel. So based on the same turbo and setup I believe the shaft speed from 1 psi and above should be very identical.

Shaft speed on idle varies depending on the size of the turbo and idle rpm. Some of the large turbos don't even spin on idle. Generally cases looking at 50~200 RPMs or more depending on variances.

anyone in sydney who has one of these rb25 hiflows in their car and willing to take me for a spin?

deciding if i should ditch my twin setup (250rwkw) for a single as 1 of my turbo seals are leaking & it will be cheaper to go back to single then upgrade to -7s lol

anyone in sydney who has one of these rb25 hiflows in their car and willing to take me for a spin?

deciding if i should ditch my twin setup (250rwkw) for a single as 1 of my turbo seals are leaking & it will be cheaper to go back to single then upgrade to -7s lol

SS-2!!!!!!

I don't think many people have the flash options in Syd.. The dude who bought the prototype SS (now production SS-2) got tuned in Advan performance center and I rekon a quick read and PM will tell you what you want without waiting.

anyone in sydney who has one of these rb25 hiflows in their car and willing to take me for a spin?

deciding if i should ditch my twin setup (250rwkw) for a single as 1 of my turbo seals are leaking & it will be cheaper to go back to single then upgrade to -7s lol

I would if you are near parramatta. I got the ss2 running 9-11psi. Pm me.

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