High Rpm Performance - Rb26

[nisskid]

Hey everyone, just looking for some info into setting up an RB26 for high RPM, mostly interested in setup for the head, however any info on bottom end would be helpful as well. Currently the plan is oil accumulator setup, balanced crank, forged rods/pistons, restrictors, additional oil drain etc. the turbo will probably be a TD06 25G, with a power band from 5-9500 rpm. Some ideas as far as manifold setup, cam setup, springs, whether any head modification is worthwhile etc etc.

anything would be appreciated.

thanks.

[Joshbigt62r]

You want a decent oil pump with a crank collar if it's a early rb26 engine. I suggest a Nitto or Tomei oil pump. Have your oil drains drilled out bigger. Set of double valve springs and some 260* by atleast 10 lift camshafts. A good rebuild and tidy up of the head will be benificial as well. I could go on and on but do some research

as there is plenty of info on here already. Why do you wish to rev the engine so hard for? With a TD06 25g there is really no need to rev 9.5rpm. I would limit the engine to 8.5-7rpm. That's plenty enough for that turbo. Any more revs is not needed and only puts extra stress on components for no real gain.

Cheers Josh

[nisskid]

sorry, it will be running nitto pump. yeh that's seems to be around the mark with camshafts, but wondering what off the shelf cams people would recommend, there might be only a small difference in specs, but im sure there are guys out there who will have tested them back to back and can give some insight.

revving the engine the same reason any race car revs their engine, basic maths. yes on the dyno it doesn't look any more impressive, but when you're able to run a 4.9 diff while still increasing your speed limit in each gear from a 4.1, it shows on track.

revving to 7000rpm would defeat the point of the build, i enjoy revvy, peaky engines.

[Joshbigt62r]

Yeah but your wasting your time revving a TDO6 25g to 9.5rpm. There really is no need to rev anymore than 8.5-8.7rpm with that turbo. It's just a waste of time spinning it fhat high with that turbo in my opinion.

Cheers Josh.

[nisskid]

there is room to go bigger, if the turbo runs out of puff then that is obviously an issue, which we're currently looking into, however the idea is not to make more torque or power, but to be able to run the gears out longer with shorter diffs is where the benefit comes from. remember, this is not about power figures, it's about how it gets put to the ground. i will be running to around 9000rpm, that part isn't up for debate.

[R31Nismoid]

In more accurate terms - the TD06 simply will not have the airflow to hold boost, and thus torque will die and die hard.

RPM and turbo selection go hand in hand. You cannot just set a RPM range and hope the turbo works within it. Same as camshafts etc.

R34 N1 turbos, a more common example... From 7,000rpm onwards they will fall from 24psi down to around 17psi by 7,500rpm... By 8,500rpm you'd be lucky if you have 12psi... You're going slower than you would've if you put the car back into the meatier range so not being interested in power or torque is a bad way to go about it, without them you'll be slower

More RPM, lighter/better aligned things need to be, especially in a race scenario.

[Joshbigt62r]

Pretty much exactly what I was getting at... ^^^

R31Nismoid knows. Listen to what your being told and research my friend. There's plenty of info around.

Cheers Josh

[GTSBoy]

Yuh, at this point you'd be far more likely to enjoy driving the car, even on the track, if you aimed to bring the boost on earlier and extend the rev range DOWNWARDS, not upwards. Stao's VNT option looks to be promising in that regard. Go with E85 to keep exhaust temps a little more sensible and it should do well.

[Roy]

Twin TD06-25G will pull to 9,500rm EASILY

[Lithium]

9500rpm is really really working the motor hard - hope you have a really good block and are not worried about breaking things, its a really counter intuitive way of building things... especially if you want to run it as a track car.

You say you don't want to make lots of power etc, but at the end of the day you need a dyno/drag -queen spec head if you want a turbocharged engine holding power to 9000rpm. The reason being is to maintain good enough volumetric efficiency for power to hold at those rpm you will effectively be redesigning ports, going silly cams and doing fun things with the combustion chambers - and all the supporting stuff to keep the valves being actuated they need to be etc. If you are holding VE at those rpm then hp per psi will be higher than if you were only spinning to 8000rpm, so if you ran it at the typical 20-24psi people tend to with a build motor you will make a lot of power. Well unless you run a 25G compressor, in which case it will try and spin itself to bits trying to maintain that boost at that flow level and pump all sorts of disgustingly hot air etc.

If you are spending the money to make this kind of thing happen and are not after big power then you're probably going to be sensible to consider a MUCH better turbocharger than the 25G and a nice big hotside on it - you should be able to afford it if you are aiming at racing an RB which spends a reasonable amount of time in the 9000rpm range. I'd be looking seriously into the likes of an EFR8374 turbo which has a pretty broad range of efficiency, good turbine flow, good response etc - with something like that and VERY good electronic boost control you should be able to build something with a strong midrange and then bleed boost backwards through the rev range, ie 24psi from 5000-6000rpm and then bleed back to 1bar at 9000rpm... something to hold the engine's flow requirements below the choke line of the compressor, and give you a more or less flat power curve (torque dropping for most of the rpm range).

You WILL need to go a decent crank trigger setup, amongst other not cheap things...

[Roy]

Or just put the 25G on an RB20 with solid lifter conversion and some springs and 260/10.25mm cams on a properly balanced bottom end. Will bag 350rwkws on E85 quite comfortably and because of the stroke and smaller, lighter pistons will pull those revs without anything near the piston speeds and big end loads of the larger RB engines

[nisskid]

cheers mate, like i said, turbo hasn't been fully decided, so helps to have some advice on that side of things. have a few blocks which will be sonic tested first to make sure there are no issues and that they are suitable. it's probably a better option to run a bigger turbo, but at lower boost, if anyone has any suggestions i'm all ears as that's part of the advice i'm chasing. i have some T04E's sitting around the place atm, i know they aren't a lot of people's fav turbo's, and i'd have to get specs, but they are are another option.

We are planning on using a crank trigger setup as well. thanks.

9500rpm is really really working the motor hard - hope you have a really good block and are not worried about breaking things, its a really counter intuitive way of building things... especially if you want to run it as a track car.

You say you don't want to make lots of power etc, but at the end of the day you need a dyno/drag -queen spec head if you want a turbocharged engine holding power to 9000rpm. The reason being is to maintain good enough volumetric efficiency for power to hold at those rpm you will effectively be redesigning ports, going silly cams and doing fun things with the combustion chambers - and all the supporting stuff to keep the valves being actuated they need to be etc. If you are holding VE at those rpm then hp per psi will be higher than if you were only spinning to 8000rpm, so if you ran it at the typical 20-24psi people tend to with a build motor you will make a lot of power. Well unless you run a 25G compressor, in which case it will try and spin itself to bits trying to maintain that boost at that flow level and pump all sorts of disgustingly hot air etc.

If you are spending the money to make this kind of thing happen and are not after big power then you're probably going to be sensible to consider a MUCH better turbocharger than the 25G and a nice big hotside on it - you should be able to afford it if you are aiming at racing an RB which spends a reasonable amount of time in the 9000rpm range. I'd be looking seriously into the likes of an EFR8374 turbo which has a pretty broad range of efficiency, good turbine flow, good response etc - with something like that and VERY good electronic boost control you should be able to build something with a strong midrange and then bleed boost backwards through the rev range, ie 24psi from 5000-6000rpm and then bleed back to 1bar at 9000rpm... something to hold the engine's flow requirements below the choke line of the compressor, and give you a more or less flat power curve (torque dropping for most of the rpm range).

You WILL need to go a decent crank trigger setup, amongst other not cheap things...

[nisskid]

Pretty much exactly what I was getting at... ^^^

R31Nismoid knows. Listen to what your being told and research my friend. There's plenty of info around.

Cheers Josh

Not when what i'm being told is to reduce the revs, this is the key part to the build, without revs i wouldn't bother with this project, may as well get an LS1 if all i was is low down torque.

[nisskid]

Yuh, at this point you'd be far more likely to enjoy driving the car, even on the track, if you aimed to bring the boost on earlier and extend the rev range DOWNWARDS, not upwards. Stao's VNT option looks to be promising in that regard. Go with E85 to keep exhaust temps a little more sensible and it should do well.

yeh this thing will be on pump jungle juice.

[XRATED]

I think some people are confusing what a TD06 25g is.... Think T67 not 20g. On e85, well over 300rwkw.

I think a TD06 25g with a 12cm housing would be a nice match to an rb26. I'm not sure it will still be making power at 9500 rpm though. It will still rev out, the power delivery will just flatten out though.

If you want to go top mount, a T78 would be what you are looking for... I'd suggest two 40+mm wategates too.

As for head... mild cams and any upgraded springs will get you to 9500rpm peak.

Cheers

Justin

[Lithium]

Pretty sure everyone who had commented are well aware of the 25G, and we haven't been given any detail beyond the engine needing to make good power up to 9000rpm. Not that I have checked compressor maps but I know a mildly hotted up RB25 can run to choke on a 25G within more or less stock rpm range and not huge boost so going up to 9000rpm on any kind of boost level is a tall ask.

T78, ewww haha

[NYTSKY]

Any setup that makes power up to 9500rpm without falling over is 800hp+ territory. With a side of lag.

Think of it this way, you have 4000rpm worth of usable power, where in the rev range do you want it?

[nisskid]

Hey guys, i appreciate you get a lot of clueless guys in here with tall dreams and stupid ways to go about things, i know, i have seen it all. But the biggest issue with SAU is a lot of guys believe there is 1 way to do things, and that is it. Generally it's an RB30, and the emphasis is almost always on low down torque. Believe me when i say, i know what i want, i have owned and thrashed (on track) almost any RB combo you can imagine, not to mention Jz's, V8's, SR's, CA's, 4AGE's etc etc, there are certain characteristics i enjoy whilst driving an engine, i don't need approval from a forum, i don't need dyno figures or 1/4 mile times, i'm building this engine to suit my driving, i enjoy high revs, responsive throttle, and i'm not a stranger to some lag.

the compression ratio we are looking to use will be around the 10:1 mark, high i know, but on jungle juice, maybe with a larger turbo on low boost, this would work quite nicely. t04e would be far from my first choice, but the fact that i have 2 around makes it appealing to me, even if i am sacrificing 200-300 rpm response.

thanks for the help guys!

[nisskid]

Pretty sure everyone who had commented are well aware of the 25G, and we haven't been given any detail beyond the engine needing to make good power up to 9000rpm. Not that I have checked compressor maps but I know a mildly hotted up RB25 can run to choke on a 25G within more or less stock rpm range and not huge boost so going up to 9000rpm on any kind of boost level is a tall ask.

T78, ewww haha

haha, well i have owned a T78 RB26 before, i don't think i was making the most out of it as some jap had tuned it and i didn't have a chance to change it whilst i was over there, but it was definitely fun, but anything under 5500 you could forget about it lol

[34GeeTeeTee]

Turbo technology has come a long way so there are plenty of good choices!