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Discussion Starter #1
Hello guys

Just wanted to know if i'm totally wrong here. Please correct me if im wrong

If you have a stock engine (RB26) and you give it some mods.

First if you change the stock airfilter box with some aftermarket filters like A'PEXi. That would help unload the turbo's a bit,
so it don't have to work that hard to get air, I don't know how much it would be, but the shaft in the turbo would have less load
apon it imo. So this is a mod you can do without you having to change any other parts.
Next up is the intercooler and pipes:
If you replace the stock IC/pipes the total volume of air that can be inside the system,
would be alot more, that will result in, the turbos would need more time, to fill up after you press the gas pedal(turbo lag)
If you stop here you would, get a slower car.
So you would have to change the boost on your turbos to get the same respons as stock right?
If so, then you would get more air in the engine = more exhaust come out, but with stock exhaust, would that not be a
bottle neck in the system?
If so, you would have to replace the complete exhaust sustem, that have higher flow rate.
Now we have to use more fuel as the you let more air in, so with a stock ECU, you can't just replace the injectors right?
If so then you have to go for a ECU like a Power FC.
But what about timing on ignition, that would have to changed too ?

What im getting at, is that you can't really just give the car a single mod like IC/pipes, you have to go the whole way, if you
want it to have the same/faster response and the power gain.And the stock turbos is limited so they need to be replaced too.
Hey i am a mechanic but i work with alot more power and turbine engines for aircrafts, so the turbo thing is easy as the turbine
works almost like it.
The engine i'm studying now(to get my certificat on that engine) is a small but powerfull engine max shafthorsepower 7600 max
torque 35000NM. (too powerfull so they wear like rubber on a F1 car)


8,804 Posts
the RB26 can be done in stages.

1) exhaust, from downpipes all the way back.
2) intakes
3) ecu/boost control
4) injectors
5) fuel pump
6) turbos
7) cams
8) pistons/conrods

in my opinion, replacing the stock FMIC on a GTR is utterly pointless until you are over 600whp, unless you like crappy throttle response. The stock unit is the same one that Nissan went racing with in Group A, so it's more than up to the job. Also, along that path, one will have to do supporting mods as well, such as the oil system and water system.

1,969 Posts

In theory, yes you have it right, but in practice........
On standard cars, new air filters make very little difference, the stock airbox is pretty good, so only marginal gains in airflow there.
The injectors fuel supply is dictated by the ECU reading the AFM/revs. If you were to marginally increase airflow through the engine, the stock ECU and injectors can supply the extra fuel available without any need for outside intervention (to a point).
A free flow exhaust makes a big difference to a stock engine. The stock ones are quite restrictive.

You only need a PFC once you start upping the boost. Some people run up to 1bar on the stock ECU. It doesn't run well, overfuelling and danger of det, but is possible.

So for an exhaust change and a filter change, you don't need to have new injectors or a pfc. Certainly don't need a new IC.
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