Building the Ultimate Response RB!!!

[Murph]

Provided the RB26 is in good nick....that's a total bargain. There's usually a reason such things are so cheap though.

So what sort of drivig do you do? What are your reasons for wanting good response?

[Murph]

Oh...and from what I've seen and heard, an RB20 will spool a given turbo, later than a SR20 will. That's just the nature of them. Mind you, it'll rev higher than the SR will.

Say my mates R32 with the RB25 turbo, it's making boost at just over 2000rpm, full boost (16psi) by ~3400rpm, then will rev hard right to the limiter at 7800rpm. That's a good 4400rpm rev range. Keep it up there and good power is always just a second or two away. But....there's always the lag. You back off around a corner, then get back on the power, it'll take a second or so before it's making decent boost again. In that respect, you simply aren't going to get good response from an RB20. With bigger turbos it's worse again.

Another mate had an RB20 in his R31 with a pretty big turbo on it. That thing didn't hit boost till~4500rpm. Now the lag with that thing was pretty bad. Eg cruising along at 80kmh, drop it to second and floor it. It'd take ~2-2.5 seconds for it to the spin the turbo up.

I suppose if you wanted good response a pair of small turbos would be good. VG30s for example will flick from vacuum to full boost in a flash.

[brianglawson]

yeah i hvae drivn a TT VG, it was nice, but the rb26 is a shop's asking price for the rb's they get in:) plus they are local so i could inspect:)

[symon]

Hi brianglawson,

I can´t help much with the other engines but as I have a R32 GTR Skyline at least I can give you some ideas. In a relatively heavy (1400 kg )Skyline the performance of the RB26DETT is astonishing. My car has had a light ECU work over and nothing else and runs 0 - 160 kph in less than 10 seconds. The car runs right up to the redline in 5th which is a realistic 305 kph. Now in a car which is quite a bit lighter and smaller the performance would be like the Enterprise at Warp Factor 9.6 ! Just do the right thing a fit a standard RB26DETT in your Z and get a radar detector ! And then use the car as you daily driver , you will even enjoy getting up to go to work !

Symon

[PROJECTRB240SX]

If You Want Real Response....

Ls1/t56 Combo With A Clutch Supercharger (for Disengagement) And A Twin Turbo System... I Know Its Alot Of Piping But You'll Have Instant Full Boost And Hold It All The Way To The 7000rpm Redline. You Just Have To Have The Supercharger Disengage When The Turbo Is At Full Spool... Best Way I Can See This Working Is With A Pressure Switch Hooked Up To The Clutch.

BTW: PLEASE NOTE SARCASIM EVEN THOUGH IT WOULD BE COOL.

[aRCH-Z]

haha, very very cool!

I think there was a supra in the states which has a twin function nitrous setup that was pretty original.

first stage uses nitrous to help it out while the single turbo spools, then once it's hit full boost the nitrous starts spraying on to the intercooler, snap chilling it.

Not sure if it'd be possible to overcool the air, but interesting idea none the less..

as for response rb... hmm.. RB26DETT with 30 block and twin hks GT2530s? yes please sir

with the extra displacement you could probably afford to go bigger then 2530s but considering how stupidly quick a vg30dett is with twin 2530s i'd imagine a 3.0 RB would be even more silly... aah *sighs*

[Murph]

Not sure if it'd be possible to overcool the air, but interesting idea none the less..

If you were on the power for exteneded periods AND your intercooling system could maintain low temperatures for that period of time, you could freeze your throttle body open. But over a short period of time, it's unlikely to be a problem. There are plenty of drag cars around using intercoolers packed in dry ice that will maintain ~ 0 deg c over a full pass.

[PROJECTRB240SX]

Water To Air Coolers With A Dry Ice Unit Have Been Used In Drag Racing For 20+ Years..... These Maintain Below Ambient Air Temps For Maximum Power.

I've Got A Buddy With One Of Those Co2 Systems That Have A Throttle Body Air Cooler, Fuel Rail Cooler, And Ic Cooler.... I Think Its Made By Dei. Well Anyway He Has Noticed 30 Degree Cooler Charge Temps When He Activates It. There Are Kits Similar To The Co2 System But Instead Of Co2 And A Ic Cooler Its N20 And Air Stream Injection For Maximum Cooling.

[Murph]

A question for the Americans. Over here in australia while most people are still using large air to air ICs, there seems to be a trend towards using water to air ICs. Is this happening over in the US too?

Really, it's an excellent idea for street, drags or sprint type racing.....maybe not so good for longer races though.

[PROJECTRB240SX]

Its Not Smart For The Street..... Its Only Super Effective For The Track (Also Has Been Around Longer Than I Have Been Alive). Water To Air Ic's Are The Only Way To Go When You Want Super Effective Cooling For The Air Stream.

On The Street Its Not Effective Because The Water Would Heat Up Over Time And Then You Would Need A Radiator For It And You Could In No Way Keeping Up The Same Cooling Rate As A Good Air To Air Ic.

What I Was Thinking About Doing Is Hooking Up A A/c Compressor With R12 Freon And Sealing A Ic Core And Evaporator Core In One Box With A Fan Blowing Air Through The Evap Core And Over The Ic Core To Super Cool It Full Time..... With Proper Freon Levels And A Good Blower Motor You Can Realize Below Freezing Temps From A A/c System.

[Murph]

I can't say I've every heard of anyone using a water-air setup without a radiator? Other than purpose built drag cars etc...

They are actually a great idea for the street. The amount of heat that can be shed from a large air-air core will be greater than (what is typically a much smaller) a radiator....but that isn't all that important.

With an air-air core, the relatively small volume of metal in the core can only absorb a small amount of heat without it's temperature raising greatly. Heat transfer from the core to the ambient air is largely a function of the temperature difference of the which the heat transfer is occuring and the heat capacity of the medium to which it is being transfered. The ambient air blowing through the core has a low heat capacity, so simply can't remove the required quantity of heat until there is a large temperature difference between the core and the ambient air.

With a water-air setup, the water has a much much higher heat capacity, so you have a greater heat transfer rate from the core to the water, at a smaller temperature difference. On the street you wont be boosting too often, so you don't need a particularly large radiator to be able to shed the heat from the water, over a longer period of time (without any great rise in water temp). This is their downfall for circuit racing and such where you're on the power almost continiously. You'd esentially need a radiator with the same surface area as the air-air core to be as effective.....which makes for larger, heavier system that's no more effective than a large air-air core.

To sum it up, the main point is that a water-air setup has a much greater capacity to store heat than an air-air setup. As such, on the street you'll be seeing lower intake temps with the water-air intercooler. Of additional advantage, the cores needed for the water-air system are much smaller making for a much more space efficient setup and also allowing a very short (read RESPONSIVE) inlet tract.

[Murph]

I just want to point out that my explanation above is a rather simplified version of how it all works. So any other engieers out there....don't pick it to shreds.

What I Was Thinking About Doing Is Hooking Up A A/c Compressor With R12 Freon And Sealing A Ic Core And Evaporator Core In One Box With A Fan Blowing Air Through The Evap Core And Over The Ic Core To Super Cool It Full Time..... With Proper Freon Levels And A Good Blower Motor You Can Realize Below Freezing Temps From A A/c System.

The problem here is the AC system simply wont be able to shed the quantity of heat that you're trying to pull out of the inlet air stream. This is where you again need to go to a water/glycol etc - air based system. You need to have smothing that can quickly absorb all that heat. With such a system, if you refrigerate the water then you'll be able to get some pretty low intake temps for a limited time. It'd probably work out fairly well for street use. But keep in mind:

•extra weight

•power being sapped by the compressor

•greater fuel use

•and it'll only keep temps down for a limited time

If you went for a high speed blat down the highway, or went to race on a track, you'd have that water up at crazy high temps in no time....the ac compressor simply wouldn't keep up. Maybe if you had it bypass the water from the cooled core to a radiator when the water temp raises to above ambient. Too much fuss for my liking though.

There was talk of this sort of setup being used on some yank SUV a while back....don't know if they ever did it though. I also remember reading about such a setup someone had installed in their car. I think they found that it simply tool the ac system far too long to cool the required quantity of water.