Thread: Size x Rpm

Right lads lets discuss size vs rpm limits, whats gonna work best, more displacement or higher revs, i was planning a 2.3 build but been told i cant rev it as high as say a 1.8 or 2.0 setup. and i really like the idea of a high redline.

I'd go with the 2.3l build, remember you won't be making that much torque on the top end, so its pointless.

remember- Horsepower sells cars, But! Torque wins races. Go with the 2.3

There are a few ways to build a 2.3L SR motor

92mm bore x 86mm stoke = 2.286

90mm bore x 91mm crank = 2.315

These 2 motors are both 2.3L motors but will resond diffrently.

92mm x 86mm = 2.286 will rev just like a standard 86mm x 86mm 2L setup safely to 9000 RPMs. They will both have the same RPM capacity or piston speed.

90mm x 91mm = 2.315 will still rev nicely and safely to to 8500 RPMs

Each 2.3L motor will do a diffrent job. The 2.3L motor with the bigger crank would be better for small track racing with lots of turns and also rollon racing.

The standard crank 2.3L will work better for top speed racing and also will work well for drag racing because you will be out of the weak point of the power band once you launch the car.

I went for the large crank setup as it will work better for a street car in my opinion.

the biggest problem with a higher reving motor, say a sr16 crank, is being able to fully take advantage of the rev's. By that I mean gearing. The lowest gear ratio's, final drive and all the gears, are in the 6 spd gear box. There are 4.133, 4.429, and 4.75 final drive's available.

the sr16 crank with a 92mm bore is a 1827cc motor. this engine would have reliable piston speed at 11,000rpm but you would have to have the rest of the motor up to par and built correctly. Engine management would be the other draw back. Calum, JWT, or any factory ECU would not work as you would need to make corrections way above 8000rpm.

a 92x86 motor would be more for someone planing, or wanting the most power above say 7000rpm to 9k maybe, and a 90x91 would be better for the street or someone wanting to use readily available parts and management such as the calum ecu. You would not need to rev the 90x91 motor above 8500rpm because of how much power it would make everywhere else. This setup is more reasonable for the average joe.

good insights lads thanks to ye both, i will be using it for track and street mostly track. this cars going to be my baby. someone is coming looking at the gtr saterday so hopefully i will have enough for the n1 and some nice parts, i plan on staying 1.6 with boltons until i am happy with the chassis this will give me time to acquire the parts i need.

I like to rev high as long as the top end can handle it. You can make more power on less displacement this way. HP is all that matters. When and how much. TQ is not a derivative of work being accomplished, only potential. I agree that gearing is going to hold you back a bit on the high revving engine.

Highest AVG hp throughout shift points will win (same weight, comparable gearing etc). I would go with the big bore if you wanted top end power, but most people want to make their power down low like Andre. I like that approach as well. Less revs=better wear.

Basically NO race cars have more torque than horsepower, unless you're talking rally cars and that's due to rule restrictions.

An extreme example is F1 cars, 800+ hp and barely 200 lb-ft of torque. They seem to move around the track nicely.

To the average person, they'll rate the "responsiveness" on an engine by its torque characteristics, not its peak horsepower figure. Torque is what you feel pulling away from lights and tooling around town.


hp=tq*rpm/5252. This is why every dyno plot has hp cross over tq at 5252 rpm. Show me a rally car dyno or any car dyno that contradicts me. This is an argument about physics without any engineers or physicists in it. Why even debate and waste each others time.

Stock ecus are capable to correct fuel and ignition way above 8000rpm.

Not the B13 and B14s

That capability ends at 8000 RPMs and all that happens after that is the same timing and fuel last seen at 8000 RPMs to whatever you rev to.

Only a few Nissan ECUs can work properly above 8000 RPMs.

1. SR16VE and SR16VE N1
2. KA24 89-90 ( I am sure I am correct with this )
3. Skyline R32-R34

Theoritically rescaling can go up to 12500rpm although I haven't tried it for real.

What I have tested and I know it works, is rescaling to 8800rpm in N14 ecu and 10000rpm in VE ecu.