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Rb20det Minor Performance Mods


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hey guys ive started to modify my rb20 finally with the following mods: turboback exhaust, front mount, pod filter, walbro 255 fuel pump, rb25 turbo, yellow jacket coil packs, boost controller, soon coming are injectors (mainly because new means they're running at 100%) and a nistune along with 14psi boost, was wondering if i needed any more mods for this stage of power (around 200rwkw) such as z32 AFM, anything else i cant thing of at the moment
thanks :)

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You might get 200rwkW from a stock RB25 turbo, but you won't do it with the standard ECU, AFM and injectors. The injectors are actually the worst of those. If you're going to buy new injectors, then obviously buy something quite a lot bigger than stock, and quite a lot newer (Bosch EV14 based injectors are the usual recommendation).

The stock injectors, AFM and turbo all get pretty close to running to 100% at around the same sort of power level, 170-190 rwkW. To aim for more, ie 200, is a waste of time. Seeing as you have to replace all of the ECU-AFM-INJECTOR stuff anyway, you're better off aiming for 230-240 with a proper turbo upgrade. So your list above all makes perfect sense.

Be aware that running an RB25 turbo at 14 psi, even on an RB20 where it should spin a little slower, could end in tears.

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I was going to go for 550cc injectors,honestly I'm not fussed if I don't get exactly 200 or more, the tuner I spoke to said running 14psi on a 25 turbo is fine along with a nistune, at this stage would an afm benefit me or will the factory one suffice?

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Hey bud my old rb20 r32 made 207rwkw at 12 psi on 98 with: custom highmount mani, wastedspark setup, custom 3" no cat exshaust" 550cc injectors and 040 fuel pump, nistune and a new zealand made turbo i cant remeber what it was called but its a little bit smaller then a 3076r.. this was before i fully build it... hope that helps

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I was going to go for 550cc injectors,honestly I'm not fussed if I don't get exactly 200 or more, the tuner I spoke to said running 14psi on a 25 turbo is fine along with a nistune, at this stage would an afm benefit me or will the factory one suffice?

The tuner is right....as far as the tune and the engine are concerned. The turbo itself though will have a much greater likelihood of shitting itself if you run it at 14 psi. Those ceramic turbos are all old, and they are all a lottery as to how long they will last. The only thing that is absolutely knowable is they will die earlier if you run high boost, and 14 psi is high enough to significantly add to the risk of it coming to pieces. Or, it could last for years. Luck of the draw.

No, the factory AFM will reach ~5v long before 200 rwkW. If you want to tune safely, you would be well advised to upgrade to Z32.

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If you have the yelloe coil packs then stick with them. But if you are yet to buy them do std or Splitfire

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Forget a boost controller. Not needed, just use the wastegate actuator off your std R32 turbo and the money you saved on a boost controller make sure you have a decent cat in yout turbo back exhaust. The thing will spin to 14psi off the spring from the R32 turbo. Just make sure you are measuring boost at the outlet of the turbo and not inlet to the engine.

If you are running the std Nissan ceramic you may experience 1-2psi pressure drop through your piping and intercooler and frankly you dont want to be running 15-16psi on the std turbo so make sure you are controlling boost with a reference pressure off the turbo outlet. As an obersvation those that blow the R33 turbo on the RB20 arae running boost controllers sampling inlet manifold pressure trying to spin the turbo up to ensure the set pressure in the manifold is achieved. And like I said, it is possible 14psi in the inlet manifold is actually 15-16psi at the turbo...so far riskier than knowing/ensuring you are only running 14psi at the turbo...which if your cooler and pipes are all in good order should be damn close enough to 14psi given the relatively low cfm fo air

I would not waste your money on injectors or AFMas most likely you will be making 180-200rwkws and they are fine at that level. Only really become questionable in the 200-220rwkws....in whcih case the R33 turbo is not going to get you there

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I already have a boost controller in there set at 12psi by the previous owner,and I will be getting injectors because standard injectors over time will not run at 100% and it only costs slightly more to get new ones than to clean out the old ones so why not, so the general consensus is that I don't run 14 psi, get a z32 afm and opt for a better turbo?

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I already have a boost controller in there set at 12psi by the previous owner,and I will be getting injectors because standard injectors over time will not run at 100% and it only costs slightly more to get new ones than to clean out the old ones so why not, so the general consensus is that I don't run 14 psi, get a z32 afm and opt for a better turbo?

Sort of. Your choices would include;

A. Leaving the AFM (and realistically the injectors) alone, use the 25 turbo and tune it carefully to run up to the limit imposed by either the AFM or the injectors, which likely will be less than 200rwkW, but will be fun.

B. Getting bigger injectors (and take recommendations for Bosch based injectors, not drilled out bullshit old tech ones like most 550s are) and a Z32 and a better turbo running a lot more boost (like 20+psi) and pushing it up to 230+rwkW, which will be more fun and cost quite a lot more.

Both Roy and I have already said as much as the above in different ways. Read what Roy said about boost control signal source and intercooler pressure drop carefully, because it is good advice.

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Yeah that makes sense, I definitely won't be going above 12 psi to be safe, I'm thinking for now I get the injectors and AFM, get it tuned at low boost and down the track if I feel like it get another turbo and up the power and I'll already have it setup for when that time comes, which I'm sure as every turbocharged car owner knows eventually will haha

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