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720 Denso Top Feed From Rb26 - Fit Rb25 Neo ?

Sinista32

By Sinista32,
in Engines & Forced Induction

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Sinista32 Grand Master

Sinista32

Posted
Posted (edited)

So RB25 NEO runs 370cc top feed injectors.

My silly question - will 720 denso top feed from my R32 GTR fit in my NEO.

Will the fuel rail and/or FPR need changing? Fuel pump ??

Experienced with my GTR new to upgrades on the 34GTT - go easy..

Edited by Sinista32
GTSBoy Grand Master

GTSBoy

Posted
Posted

No. RB25 Neo injectors are the new 3/4 length ones. The rail from your RB26 probably won't be able to be bolted on to hold down the 720s, even if the injectors will physically fit in the holes (I don't know the relevant diameters). The FPR/damper setup on Neos is a bit more complicated than on the older engines (although it really just comes down to fuel in at one end and fuel out at the regulator end, so you can always find a way to set up any given rail and reg) so that will make it a bit more confusing.

Lastly, std R34 fuel pump is probably not big enough to support 720s. But that really does depend on the power level you're actually shooting for. Fair to say though that if you're doing any mods for power, then a new pump is a must anyway.

Sinista32 Grand Master

Sinista32

Posted
  • Author
Posted (edited)

Thank you GTSboy - Can I press you for some more info. Maybe PM if better

My OP6 turbo exhaust wheel seized recently. Sent it off to ATS in Adelaide for a high flow with garret CHRA. Should be 2871 equivalent.

I have an aftermarket FMIC, K+N pod filter, Splitfires. and 3" exhaust. Stock ECU. Boost controller plugged up.

Not looking for to much power as it's an Auto and my daily Tokyo taxi. But looking to take advantage of the extra kws (safe levels).

Not sure to fit and leave alone as is with a 12psi actuator or add some parts.

Was 170 RWKWS. Happy to have anywhere between 200-250.

Recommendations?

Shopping list

Edited by Sinista32
GTSBoy Grand Master

GTSBoy

Posted
Posted

12 psi stands a chance of R&R type misbehaviour. Right now I have my Neo (standard turbo) wound up to just shy of 12psi....probably just over 11 psi really. Last weekend I was experimenting with my boost controller (after a repair to it) and had the boost peaking just over 12 psi. The car was not running well up there. Whereas it will rev smoothly with a little less boost, it was getting rough when I had it slightly higher. I think that was R&R.

My ECU has Nistune in it but it is running the standard maps right now (until I can get around to getting it on the dyno). I know for a fact a few things. They are;

1) the standard fuel map runs out of load scale at 160,

2) at my current <12 psi boost setting the load (TP) is going up to about 185, which is well off the top of the map,

3) the last 5 or 6 load columns of the standard maps, from about 4000 rpm upwards are ridiculously rich and retarded. (The timing map actually extends out to a load index of 208, so I am still on that map).

So given that I am not even operating on the actual fuel map - that it is just extrapolating the fueling values from the last column, and the timing out in that part of the map is pretty much single figures, it's not hard to see that R&R is almost a dead certainty. It is also using a LOT more fuel with the boost turned up like this, because the fueling is so rich (and the extra power is addictive)

The point of all this? You won't be able to get good results just by highflowing (and or adding boost via a better actuator) because the ECU will get all emo over it. It is important to remember that with a highflow you will be moving more air at any given boost level than you would with the standard turbo. I am running at the limit of the standard ECU now, at 12psi, with the standard turbo.

So you will need to do something about management. Nistune is good, but it turns out that it can be a right pain in the arse to tune the R34 ECUs because they have a VE map which means that oxy feedback is switched on over the whole fuel map and there are vague calculations that go on in the background to determine if the ECU looks at the fuel map or the VE map to try to set the mixtures at any given time. I haven't actually tried to tune it yet, as I have said. But given that what I would want to achieve is leaner than stoich cruise mixtures, plus a general leaning off of the high load/rpm areas (just to claw back some power and economy), I may have some entertaining times ahead. I know people have done lots of R34 ECU tuning, so I'm not saying it's impossible...I'm just a little unsure how best to go about it. An aftermarket ECU would be easier to get the desired result. Nistune suits me though because it is nearly indistinguishable from stock. It's a tough call.

Anyway, to support your wished for power range (which your highflow will fall right into, should be getting up towards 250rwkW), you will need;

1) Metal turbo intake pipe. Stock one will suck shut,

2) ECU,

3) Fuel pump,

4) You may destroy the tranny if you give it a hard time. They can be toughened up, but at what cost/benefit ratio?

5) Sticky tyres are a good idea.

cheers

GTSBoy Grand Master

GTSBoy

Posted
Posted

Signal benders are to be avoided at all costs.

If budget is a concern, preference goes to cheap, proper ECU solutions first. These would be Nistune, cheap 2nd hand PFC. Then next preference goes to cheapish aftermarket new ECUs like Adaptronic or Megasquirt. Then onwards and upwards from there through the Haltech, Link, Vipec, etc stuff to Motec and Autronic. And caviar and champagne of course.

Missileman Veteran

Missileman

Posted
Posted (edited)

sorry that should read...

buy a aftermarket exhaust system, then a turbotech bleed valve and boost your positive manifold pressure until the stock computer says uncle.

Edited by Missileman

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