Building the Ultimate Response RB!!!

[brianglawson]

Now ive been doing alot of reading on higher compression turbo motors, and im really liking the idea of it, i posted this on www.zilvia.net too, but i wanted to get some opinions here as well

im looking to put an rb 20-25- or even 26 in it, but what i want is the ultimate response maching

i know on sr20's its possible to put the natural aspirated pistons to up the compression a little, yielding better response

Option:1

RB20DET

N/A SR20DE Pistons (giving 9.5-1 compression)

Equal length tubular manifold

3 inch elbow

full 3inch catless exhaust

custom intake plenum, maybe ITB's if feasable

Light Flywheel

Aluminum driveshaft

4.11 gear r200

electric fans

s15 t28 bb turbo at about 16 psi

spearco intercooler

recirculated BOV

now this is assuming the piston interchangability

option 2 will forthcome if 1 is shut down whats everyones opinion on this? i can get rb20's for 1500$ all day long. So this might be a good way to make 350whp or so decently cheap plus then i would have 2 2.0 240's

[PROJECTRB240SX]

I Hope You Know Of A Way To Bore A Motor From 78mm To 86mm.

Why Would You Step Down From A T3 Flange To A T2 Flange?

My Suggestion Buy Either A Rb20de And Turbo It Or Build A Rb30dett Using A Rb26dett Head With Small Turbine And Large Compressor Turbos If You Want Resposive.

Also You'll Get Better Response Froma Log Style Manifold Over A Equal Length Because The Exhaust Pulses Will Be Hitting The Turbo All The Time Rather Than In Intervals (although The Are Small Intervals).

[sblake01]

How long would that motor live with a 9.5 c.r. and 16psi boost?

[brianglawson]

its all in the A/F mixutre, proper tuning is the key to succesi was under the impression rb20's cam with a t25 stock, if not what did they come with?

[PROJECTRB240SX]

Rb20's Have A T3 Flanged T25.... So You Are Better Off Sticking With A T3 Flanged Turbo.

There Are 10 To 1 Turbo Rb's Running Around. A Guy Here In Az Has A Turbo Rb25de Thats Putting Out Decent Power. I Know Of A Few Turbo'd Rb25de Neo Motors. If You Have Proper Tuning And Enough Octane You Will Be Fine. I Personally Would Build A Rb30det Or Dett If I Was Going To Spend The Time Turboing A Na Motor.

[Murph]

The simple answer if you want more response is to go a larger capacity RB. The RB20DET is simply never going to be a responsive motor AND make a decent output.

[brianglawson]

but i like the aspect of the rb20's short stoke design, plus its price

[Gav240z]

Yes but an RB30 will rev nicely depending on the ignition curve sure small strokes work well in terms of revving but you can overcome this with balancing and reducing rotational mass Ie: light flywheel etc..

The L28 with an LD28 crank will rev to 9000rpm if you want it to. It comes down to the ignition curve alot of the time.

[PROJECTRB240SX]

You Need To Figure Out If You Want Responivness Or High Rpms? They Are Two Ends Of The Spectrum..... If You Want Response Build A Torqueir Motor; If You Want High Rpms Build A Long Rod, Short Stroke, And Large Piston Motor... Or Build A Two Stroke!

[Murph]

I'd say if you really want response.....ditch the turbo idea and build yourself a RB30DE with some slightly more aggressive cams. You'll make the same power as you would with an RB20DET with a "responsive" sized turbo. That's all relative of course, IMO most turbo motors will never be "responsive". There's talk of people making ~190kW with a basic unmodded RB25DE headed RB30DE (just higher compression). No reason why you couldn't make a very streetable 200+kW.

For example I was out doing naughty things in my mates R32 (RB20DET, RB25 turbo, FMIC etc) the other night, and I was finding the lack of power after lifting off and getting back on the accelerator quite off-putting. Where as, with a NA motor there's no waiting for it to build boost or any such nonsence....it just does what you tell it to.

[Victor Laury]

These guys are giving you proper advice. For Responce (Drag) racing, the addage "There's no replacement for displacement" IS the absolute. Why else would they build the 500 ci monsters. They build for torque first and HP secondary. Get off the line and up to speed in the fastest possible. RB30+ block. Square stroke builds for high rev horses are specific to road course, where your'e gearing to keep it in a narrow powerband. even if you need a push to get out of the pits.

[brianglawson]

im a turbo person, but i also dont drag:) but i also have seen an sr20 full spool at 2500rmp making 350rwhp! with proper fuel tuning, but guess what else i saw last night and the shop is local, rb26dett, with rb25 tranny for 4200$!!!!!!!