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Rb26 Light Rebuild

full_stick

By full_stick,
in Engines & Forced Induction

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full_stick

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I've just had 28060-5's installed in my R34 GTR. The engine has done close to 100,000km so I recently changed the timing belt and did all the other maintenance mods such as spark plugs, ancillary belts, water pump etc.

Anyway I want to put in some cams to bring the -5's on song a little earlier in the rev range and as the motor is stock I thought I'd ask what internals can I change while I'm doing it so I don't blow the engine. I don't want to spend too much as I'd like to stroke it one day but just can't afford to at the moment. Just a light rebuild or can I just change a few small things to make the engine a little stronger so there's less chance of it going boom with the -5's...

cheers...

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Brockas Proficient

Brockas

Posted
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A well maintained 26 wont just fail if everything is kept reasonably sane. A standard '89 shitter 26 with 140,000kms has done 590rwhp here in Perth, and is still going strong.

Keep the boost at 20psi or below, and ignition timing conservative.

Usually if a 26 fails, it will be due to the oil pump failing, or a bearing failure due to poor servicing. You might be unlucky enough to bust a piston ring, but don't rebuild it until you really need to.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

^ Agreed. Stock heads are pretty good - it is entirely dependant on the initial condition. 100k kms doesn't mean a lot in overall terms, just get it inspected really.

If things are A-OK you could easily get 50,000km's from it. I know a few cars have done 35,000km's+ over a few years with 330-350rwkw 18-20psi... so no drama's there really.

Also another thing is turbo's failing - but you've eliminated that one as well so all is well.

Keep the power to around 300-330rwkw (16-18psi) and it should last quite a while without much drama until such a time as you are ready to build and chase the power the -5s are actually capable of

300-330rwkw is a walk in the park for them, easily 50rwkw shy of what they can do on a good motor.

IMO its very much debatable if cams offer any benefit in that regard.

All the Racepace 380-400rwkw -5 cars are using STOCK cams due to the fact they give better response where it counts - on the track/street, which is something you cannot really measure on a dyno at all.

Something to think about as if it were me, i wouldn't be doing cams based on the above. (i used stock cams for my 370rwkw RB25 as well, great response)

full_stick Collaborator

full_stick

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R31 Nismoid, you talkabout the use of stock cams giving better response where it counts - street and track but I've analysed the dyno results of two very similar setups to mine, both cars using -5's, one with cams and one without, and the vehicle with aftermarket cams seems to have much better power delivery all the way through the rev range.

Now I know you mentioned that this response can't be measured on the dyno. I'm just wondering whether you can elaborate a little as these dyno results were really my basis for this discussion. I thought it logical to change cams provided that I'm going to get better power consistently through the rev range.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Loaded up motors on a dyno are one thing.

The other is on/off part/low throttle, transient response between gear changes, mid throttle and similar.

None of which is at all easy to measure on a dyno if at all.

The cars were faster around the circuit, can't really argue that.

I've used stock cams in two setups now. Honestly i cannot say i have any less response than those with larger cams.

By Racepace's own testing the larger cam cars "feel" like they are faster, but reality it is not the case. A number of cars HAD larger cams and reinstalled the stockers.

Seems most people north of the Victorian border have a different view on the matter, so there are always points for and against, however that is what R&D is all about.

Finding what works for your setup.

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