Rb26 Inlet on RB20DET ?

[discopotato03]

I came across an article in Zoom no 62 titled Killer Taxi Part 3 . This is basically about someone who put an RB20DET into a VR Commodore and I assume in part 2 has fitted an RB26 6 throttle inlet manifold . Does anyone have Zoom 60/61 that could tell me how it was done as I would like to do this on a non VCT RB25 head .

Thanks in advance Adrian .

[omp]

Apparently you lose low down torque on an RB20 with RB26 inlet manifold. But anyway they had to make an adaptor plate for it all to fit.

[Targa Tom]

As far as I know, the RB20 manifold is as good as even most AM jobs. Back to Back testing has shown that on a 20 they are very hard to beat. "if it aint broke....

Tom

[Roy]

The Grp A GTSR ran the std manifold with its RB20, dont know how much porting it copped though (if any)

On an RB25 though it may be a good thing

[R324D]

It works beautifully, you may lose some (not much at all) down low because of the short runners, however, up top all I can say is

http://www.skylinesaustralia.com/forums/sh...ead.php?t=49549

[discopotato03]

Are there any pics available from the Zoom article ie of the adapter plate . If not does anyone have picks of the RB26 head (inlet side without manifold) . Or failing that are there any pics of the R32 RB20/25DE inlet manifold gasket to compare to the RB26 gasket ?

Just for the record I was a Fitter/Machinist before Locomotive Engineman so am not scared of filing / grinding / milling / drilling - just can't weld aluminium myself , but others can so please guys how do I fit the GTR inlet on R32 RB25DE head . I am not concerned about the two litres because mine will go on top of three . Correct me if I'm wrong but I think RB20DET and R32 25DE use the same inlet manifold stud pattern so obviously can be done .

Chow Adrian .

[Roy]

As best i can gather, what they have done is cut the flange off the RB20 manifold where it bolts to the head, in your case you would want to be chopping off the flange from the RB25 inlet manifold.

Then the flange section that the 6 throttle bodies bolt to, cut the std RB26 head flange of, then weld the RB25 flange to it. You may need to match port the flanges etc, but an experienced aluminium welder shoudlnt have too many probs doing it. That way you dont have to muck around with head water galleries etc, and you can use the RB26 injector location etc etc.

[aybee]

in the next issue, they couldnt work out why the engine suddenly sucked. they traced it back to the rb26 inlet, so they ended up taking it off and concluded that it DECREASED performance.

[Roy]

But i ssuspect that it may not be the case here as he wants to put it into an RB25, though by the time you buy the manifld fiddle and setup, i dare say it may be worthwhile going to thr RB26 head, and sell the RB25 head to help fund it...modding the exhaust manifold is no biggie

[discopotato03]

Thanks Roy . In the pics I have the top water outlet (thermostat housing ?) looks different to RB20/25 (R32) . If thats the case they must have used a modified RB26 injector flange bit complete with the thermostat section and recarved it to suit . Someone here suggested they used an adapter plate . If anyone knows which workshop made it I am all ears .

Cheers A .

[Sydneykid]

Hi DP, I will post up the pictures when I get home. The dyno tests confirmed that the RB20 with RB26 inlet lost power EVERYWHERE, up top, down low and in the middle. It was SO BAD they couldn't drive it without stutter and stalling at low revs, as in traffic and parking. As I PM'd, there is more to an RB26 than just the inlet. It's a package, so don't expect to steal one bit and get a perfect result.

[R324D]

I would also be extremely keen to see the results, as I haven't had any dramas with this whatsoever and my top end power increased dramaticlly...

Can it come down to how the job was done to which type of turbo is used? I am no professional but I am really surprised at how negative some people are towards this...

Are there any other references where people have been disappointed with the results as I mentioned I have had no problems whatsoever with mine and the top end increased majorly...

[discopotato03]

I had a look at a 25 DET and a 26 head today . I can only hope that the R32 25 head is closer to the 26 especially as it does not have the 33's telegragh pole sized solenoid sticking out the side . I need to see a 20DET head to compare to a 26 manifold . The front water outlet is longer on the 26 head .

On the exhaust side no 3 and 5 ports have their studs diagonally opposite to RB26 . The 25 DET uses 10mm studs where the 26's are 8mm . No doubt adapting the 26 head to the factory single turbo manifold would involve the use of an adapter plate and oversized stud holes in the head . I think Joels DIY RB30DET PDF has a picture of an RB20DET head with the 25DE inlet gasket on it .

Chow for now , Adrian .

[Sydneykid]

Some info on the RB20 with RB26 inlet as per Zoom Magazine edition 64 and edition 62;

This picture shows the RB26 plenum being test fitted up to the cut and welded RB20 inlet. The throttle bodies go between the RB26 plenum and the modified (shortened) RB20 inlet but are not shown in this photo.

This is a picture of the RB26 plenum, RB26 throttle bodies and RB20 shortened inlet on the RB20.

This picture shows the RB20 with RB26 plenum, RB26 throttle bodies and RB20 shortened inlet in the car.

[N I B]

The best thing you can do with a GTR intake and throttlebodys is change them for a good single setup.

[Sydneykid]

The best thing you can do with a GTR intake and throttlebodys is change them for a good single setup.

I suppose I will get sworn at again, but I can't resist it ....

This car has the standard RB26 inlet and throttle bodies with a (larger) Greddy plenum and it runs 9's.

It also has AFM's and uses a standard Power FC, gotta love it for killing a few myths.

PS; Photo courtesy of HPI #47, thanks Ben.

[N I B]

Then again the Top overseas ones have single and some guys run faster than that N/A with push rods and a carb so does that mean we all should fit carbed V8s.

[Sydneykid]

Then again the Top overseas ones have single and some guys run faster than that N/A with push rods and a carb so does that mean we all should fit carbed V8s.

I agree with Munro it would be a damn sight cheaper, but not half as much of a challenge. :jk:

I guess if I had a GTR and wanted to drag it (what a waste, no corners) then I would spend my time elsewhere until I got into the 9's. Why spend money on stuff that you don't have to? :confused:

Theo's car actually is quite a good example of a package, it ONLY has ~650rwhp, H pattern gearbox, ~2.6 litres and AMAZINGLY uses Federal street tyres. But 9.8 at 145 mph proves what can be done if the WHOLE of the car (including the driver) is up for it.

If Theo is reading, nice reaction time

[discopotato03]

Sorry guys but the concept has now got me in , thank you SK for the pics . As I said I've looked at the RB26 manifold , just need to see a non VVT 25 manifold/head or gasket . SK the 1st picture didn't show very clearly the modified section of the RB20 manifold . I was looking at an RB20DET in a Commode Door and it had what looked like a spacer plate between the inlet manifold and the head . Does the 32 25 head have this too . Also in your pics the water outlet angled forward like an RB26 , so 20 and 26 must interchange ie to get around the plenum . I really should look at a Nissan R32 Engine Workshop Manual but I could not download it from this site .

Cheers A .

P.S Am still looking at RB26 heads but the block mods and exhaust side mods still require some work . Its a big if but if I can find the bits for reasonable money I'll grab them . The exhaust porting does look better and of course the better cams and springs would be good . With "pre loved" GTR heads is it common to have to replace valves and guides or are they pretty durable things .

Chow .

[lukevl]

Look at any decent race car - multi throttles. Gotta love response. Big single is a huge wank. maybe for tope end drag cars, but who wants one?

The only problem I have found with the RB25 lower runners is that 3&4 dip down to make them equal length which makes it hard to put a flange on them. Still deciding on which way to go at the moment in terms of attaching the throttle bodies.