Rb30, Realistic Na Power Figures

[Russ_T]

Hey all,

Been pointed towards this forum from some other Skyline forums. I have a Datsun 240z that I wanted to fit an RB30 into (seems the most logical engine to choose and looks right in the engine bay). I'm not into turbos so thought I'd go down the high revving throttle body route, make use of the vvt and some motec engine management. Try to build quite a trick engine.

I've been looking through the threads here at past builds, and there are some nice looking engines. However i'm a little disappointed with the performance put out. My L6 (original Datsun engine) is good for 250bhp, and I hoped the same money spent on the more trick, more modern RB lump would see 400. However looking at the builds here most seem to put out 200bhp or so (about 150kw I think).

Is this because these are in a low state of tune? I don't want to throw money away, but I don't mind going to town a bit. I know the v8 (VK56DE I think I'd use, if that's right) is good for loads of power, but I didn't really want a v8.

Anyway if anyone can advise as to what sort of power figures are obtainable, in a streetable engine, I'd appreciate your input. I have my heart set on the RB but if it won't make good power without a turbo I think I'd have to avoid it Unless I supercharge it

Thank you for your time,

Russ

[danielson]

Hey all,

Been pointed towards this forum from some other Skyline forums. I have a Datsun 240z that I wanted to fit an RB30 into (seems the most logical engine to choose and looks right in the engine bay). I'm not into turbos so thought I'd go down the high revving throttle body route, make use of the vvt and some motec engine management. Try to build quite a trick engine.

I've been looking through the threads here at past builds, and there are some nice looking engines. However i'm a little disappointed with the performance put out. My L6 (original Datsun engine) is good for 250bhp, and I hoped the same money spent on the more trick, more modern RB lump would see 400. However looking at the builds here most seem to put out 200bhp or so (about 150kw I think).

Is this because these are in a low state of tune? I don't want to throw money away, but I don't mind going to town a bit. I know the v8 (VK56DE I think I'd use, if that's right) is good for loads of power, but I didn't really want a v8.

Anyway if anyone can advise as to what sort of power figures are obtainable, in a streetable engine, I'd appreciate your input. I have my heart set on the RB but if it won't make good power without a turbo I think I'd have to avoid it Unless I supercharge it

Thank you for your time,

Russ

rb30de lightened and fully balanced strengthned bottom, rb 26 top, open the head right up on both sides, and see what happens

[Cubes]

When you simply stroke out a motor and do nothing to the head it will make the same power as the smaller motor but at a lower rpm.

As the same power is at a lower rpm the motor will be making more torque to make that power as Power = Torque x RPM / 5252.

But.. Peak power isn't everything, the car will accelerate quicker to that peak power as the average power will be higher.

So if you want to really make use of the rb30DE you will need to keep a nice high comp 10:1+ and drop a set of nice cams in it.

This is where the 3ltr is worth while over the smaller motor, a 3ltr with big cams is more streetable than a 2.5ltr with the same cams.

Go the VK56DE its a nice motor, you won't regret it.

If you want something a little revier go the VK45DE.

[NA_R33]

MMMM VK56DE thats something i see in my fantasies....

Neways Naturally aspirated the only way to make power is REVS and lots of them, i was talking to Sydneykid quite some time ago about this and he said that the problem with high revving RB30's is they seem to get some wierd harmonics through which will eventually cause excesive wear on just about everything.... cant remember if he mentioned neways to eliminate this best u pm him i think, he's super friendly and like a nissan dictionary.

[Russ_T]

Thanks guys.

Really though what I'm trying to find out is am I ever going to see 400bhp (300kw) at the fly unless I spend about $5 zillion at 10k rpm? My friend makes 250bhp (180kw) with his 30 year old 2.8 L6 engine, the spiritual father of the RB, and with a SOHC. He has mapped EFI, nice throttle bodies etc. I'd had hoped that with VVT, twin cam, modern head design and better modern metallurgy I'd have trumped that. There are even L6s in Japan with 300bhp. I have yet to find (with my basic google skills) a really well performing NA RB, please prove me wrong.

Was aiming for about 10.5:1 comp, 97 RON fuel, depending on what parts are available.

The RB engine looks so right in the 240 engine bay, and I wanted a NA engine Think I'll cry myself to sleep tonight if the answer is no

Edited May 25, 2006 by Russ_T

[hmj]

Thanks guys.

Really though what I'm trying to find out is am I ever going to see 400bhp (300kw) at the fly unless I spend about $5 zillion at 10k rpm? My friend makes 250bhp (180kw) with his 30 year old 2.8 L6 engine, the spiritual father of the RB, and with a SOHC. He has mapped EFI, nice throttle bodies etc. I'd had hoped that with VVT, twin cam, modern head design and better modern metallurgy I'd have trumped that. There are even L6s in Japan with 300bhp. I have yet to find (with my basic google skills) a really well performing NA RB, please prove me wrong.

Was aiming for about 10.5:1 comp, 97 RON fuel, depending on what parts are available.

The RB engine looks so right in the 240 engine bay, and I wanted a NA engine Think I'll cry myself to sleep tonight if the answer is no

People generally havn't bothered with working RB's purely because there always has been a Turbo option.

That being said. If you do the right mods, 300kw at the fly would be obtainable... maybe with the assistance of a supercharger for the last 25kw or so....

[Cubes]

NA_R33,

The harmonic issue isn't a problem providing you fit up a crank collar and throw on an ATI balancer. All though just this in itself will set you back close to 1.5k. :S

[NA_R33]

NA_R33,

The harmonic issue isn't a problem providing you fit up a crank collar and throw on an ATI balancer. All though just this in itself will set you back close to 1.5k. :S

Thanks for that, i couldnt for the life opf me remember what sydneykid told me was to fix the problem, looking at building a RB26/30 high crompression NA at the end of the year for a friend... after my car is finished..

[slip]

well look at how much people spend on rb25 turbos to get that much power....

All you can do is your best. 25 or 26 head, throttle bodies, internals lightened/balanced/blueprinted, management. you'd really need to talk to nizpro or another experienced RB builder.

Look at what M3's are putting out. That is one amazing engine and they are 252kw or something. Good luck getting close to that.

what you could do, its just build a good tough fun engine without worrying wether its gonna make 400hp or not. I had a hoot in my 31 when the RB30 was in there, and it was pretty slow. Get the compression right, fat cams, throttle bodies, bit more rpm and have some fun. People get so caught up on numbers. MX5's on paper arent very well specced, but drive one and you have an absolute blast, and thats what its all about.

[Russ_T]

Look at what M3's are putting out. That is one amazing engine and they are 252kw or something. Good luck getting close to that.

That's a really good point, and something I hadn't thought of.

Im not getting hung up on numbers, but a few of my friends have just spent a lot of money developing their L6s, gotten to about 250bhp, and then hit a wall. Now they are wishing they'd started with something with more potential so they could keep going (v8 with more capacity probably). We run a nice club drag league, and I'd like to build something that would allow me to take it as far as I wanted (within reason), and if 3ltrs of RB is going to realistically stop me at 225kw then I'd probably be better off opting for a VK engine instead, much as it pains me to do so.

Thanks for your help, I think I'll let this one run a bit longer and hopefully someone will come along saying "yes 300kw is very doable".

[BADR33]

my rb30de went on the dyno in the weekend. running 0 timing(cus i forgot to advance it as i had knocked it back ages ago after the last dyno showed it was running lean) and it still put out 121.7rwkw so i lost 2rwkw and 100Nm of torque. from running 20deg advance to 0 or less.

it really needs an aftermarket ecu. but im just waiting on earning enough $$ to pay for one and get it tuned.

if i wacked some larger cams, did some porting, mb 6x throttle body and another exhaust manifold set up for peak power instead of good low down torque. i reken it could be close to 150rwkw. its one of those things that you dont really know untill sumbody has done it.

when i can find that dyno sheet ill take a photo and put it up for you.

im still trying to get a sound recording of my car it just sounds pretty insane and nobody can really pick what it is unless you know that i put that motor in my car

[slip]

even if you got 180rwkw out of an rb30de, itd be fun, but a 200rwkw turbo 25 motor would be so much quicker/cheaper/easier using tried and tested parts/methods.

ive done things the hard way with my car. yes ive got an extremely tough 31 now, and id happily put it up against any 31 in the country in an allround test of car-ness, but its been a long expensive road. i could have just bought an S14 or something. Would have been so much easier and better value.

[Russ_T]

Really I wanted a very high performing version of this (my mates L28 engine) and the RB seemed the way to go for it's twin cam etc. Also it'd look so right in the engine bay, sound beautiful, etc etc. However I'm really chasing pretty high hp figures and so it looks like I either go v8 or turbo

Hmm I'll see what his 250bhp (190kw) feels like (currently manages a 13.83 quarter) and make my mind up. There are other cars I can build for dragging I suppose.

Cheers

[scathing]

I have yet to find (with my basic google skills) a really well performing NA RB, please prove me wrong.

The thing is, because turbo RBs are a lot more popular for performance applications that's where the scene and the aftermarket has gone. Why spend big bucks to make mild power gains when you can spend fewer bucks on bigger power?

That said, one of the big Japanese tuning houses (can't remember which) made a hardcore RB26DE with ITBs and the rest, as a homage to the L26. Maybe someone can chime in with more info on it.

[Russ_T]

The thing is, because turbo RBs are a lot more popular for performance applications that's where the scene and the aftermarket has gone. Why spend big bucks to make mild power gains when you can spend fewer bucks on bigger power?

I see your point. I just expected to find a lot more on them, you know usually you can search for something even really obscure on the net and find a torrent of info on it and loads of fanatics. I was hoping the NA RB scene was going to be bigger, but alas we'll have to make it bigger.

That said, one of the big Japanese tuning houses (can't remember which) made a hardcore RB26DE with ITBs and the rest, as a homage to the L26. Maybe someone can chime in with more info on it.

NOW YOU'RE TALKING! That sounds exactly what I'm after. If anyone has any info on this, or what magazine it might have been in etc then I'd appreciate it. Not so much because I want to rip their ideas of, just as a proof of concept of what can be done.

I've been thinking about the power of the RB and I think I just want it bad enough that even if it doesn't make big power I don't care, it'll still be bloody quick. I'll just have to do a lot more lightening

Thanks bud.

[slip]

dude, if you want to do it, go for it. its a completely sweet idea, will be great to drive, and youll pull chicks with it*

i looked into doing it myself but went turbo. would love to see it done.

*no you wont, car broad minded persons are the worst.

[Russ_T]

dude, if you want to do it, go for it. its a completely sweet idea, will be great to drive, and youll pull chicks with it*

i looked into doing it myself but went turbo. would love to see it done.

*no you wont, car broad minded persons are the worst.

Mmm, broad minded persons. NOW WE'RE DEFINATELY TALKING!

I've listened to some audio clips you guys have put up of the NA RB, and I'd probably sleep with you and I'm of the heterosexual persuasion, who knows what effect it may have on a woman. I'll have to fit big bumpers to get them out of the way when they throw themselves in front of the car.

[Eug]

ohh yes do it..

i went through a phase where i was looking at it, reading up on it and dreamt of doing it...

if i had the cash to spare i would jump at the oppurtunity to build something RB based to the near equivalent of the m3 motors...

it would sound and go like a greyhound with heat rub on its nuts!!

[Kaido_RR]

RB25DE OR RB25 Block With 26Head

then put this on it

"They are 6 connected throttles of RB26. The manifold for NA. It is the HKS delivery pipe attachment. Funnel kernel funnel 70 millimeter."

For the N/A rb25 you will need a Blitz Adoptor plate To make it fit

Just to let you know that they are VERY VERY VERY Rare and the last one that was for sale had a price of 100,000yen

Cheers michael

[NA_R33]

' date='31 May 2006, 11:55 PM' post='2217991']

RB25DE OR RB25 Block With 26Head

then put this on it

For the N/A rb25 you will need a Blitz Adoptor plate To make it fit

Just to let you know that they are VERY VERY VERY Rare and the last one that was for sale had a price of 100,000yen

Cheers michael

Or u could just make one, theres not a great deal of difficulty for someone with a little know how. If someone where to supply the parts id happily make them up for people, i love tough NA 6's!