Nistune Forums

Hi Pete,

Yes ... fair enough.


Midrange to me is 2000 to 4500 (but there is no official rule for what it is)
(Or anything I use in city traffic)


For a Diesel 4500 might already be redline

Cheers,

Andrew

many years ago when I was running an S14 SR20DE engine with an S13 loom and ECU and an RB20 turbo I did a few tests for the optimum VTC changeover points.

I had the solenoid connected to a manual switch, and after overlaying dyno runs with it on and off the ideal turn off point was 6300rpm from memory.
In the end I just drove around with it turned on all the time since it was rare to go over 6300 in day to day driving (especially with a turbo that made full boost at about 2200rpm!)

Later on I swapped out the ECU and loom for a complete S15 loom, PowerFC, coil packs, and CAS (and an RB25 turbo) for easier tunability and hopefully more power.
It did gain some drivability, but would only ever make 160rwkw (10:1 compression is not ideal!)

One day (at a Hillclimb event) the turbo died, so I decided to convert the engine back to n/a since I had some extractors sitting around.

Back on the dyno for a quick touch up tune it made 110rwkw, and I think the VTC switch point ended up around 7000, with the rev limiter moved up to 7500.

I then installed a set of Tomei Procams (12.5mm, 270°) and valve springs, and made 122rwkw, with the VTC point set to 7500 and rev limit at 8000.

That engine was a lot of fun in a sub 1000kg S13

Hey Andrew,

That's pretty decent for a (blood from stone) DE! Very decent indeed. And you've even managed to get some top end without totally destroying the midrange!

I'm with you about the VCT. In reality you rarely use the rpm range above where VCT turns "off" so it's not the end of the world if it's not there. Good for making dyno numbers though....

I was recently talking to a guy who runs an R33 RB25DET with an R32 RB20DET ECU. This is a cheap and easy way to get programmable management on your '33. But the downside is that you lose the VCT. But as he (and you) explained - just wire the VCT on all the time. The little bit up the top is rarely used on a street car.

Naturally this isn't an option if you just gotta have that top end power. For some reason...

PL

On the DE I found the peak power was always in an area where the VTC was still on, so really I didn't gain much by having it turn back off.

Ideal possibly would have been an adjustable cam sprocket set somewhere in the middle, which may have given a little bit more peak power slightly higher up.
That setup worked really well though so I didn't do anything more (apart from a much better exhaust and intake once the car became race only - I reckon 125-130rwkw in that spec)

I think it would have been possible to recover the slight losses in the midrange with some more tuning too, but never really bothered.

It was also making more power than any of the fully built DEs getting around (that I knew of) back then - 6 years ago now!

Funnily enough, that engine is now in a street car making 109rwkw with a quiet exhaust - running Nistune

It's amazing the punishment it's handled.
I ran it for about 18 months with the turbo setup, then n/a for a couple of years of hard track use before selling it to someone who also thrashed it at a bunch of track days, and it's still going strong

Yeah they seem to be a bit like the old L Series engines - capable of taking crazy amounts of punishment.

I had a similar experience with my old S13 SR20DE which I fitted to my 1600 in 1995. Thrashed it around for a couple years, sold it to a mate who fitted it to his Stanza. He thrashed it around for a bit (he's quite good at this!) and then sold the car. It got thrashed around a bit more by the new owner and crashed.

Then a friend bought the engine from the wreck for his dirt track car. He bolted a T28 to it and fitted DET injectors. I tuned it for 180rwkw on conservative boost. Last time I heard from him it was still going strong. That's 16 years worth of work. Bloody incredible I reckon!

As long as you don't let them starve for oil or detonate they'll just keep going!

PL

PL wrote:Yeah they seem to be a bit like the old L Series engines - capable of taking crazy amounts of punishment.

I had a similar experience with my old S13 SR20DE which I fitted to my 1600 in 1995. Thrashed it around for a couple years, sold it to a mate who fitted it to his Stanza. He thrashed it around for a bit (he's quite good at this!) and then sold the car. It got thrashed around a bit more by the new owner and crashed.

Then a friend bought the engine from the wreck for his dirt track car. He bolted a T28 to it and fitted DET injectors. I tuned it for 180rwkw on conservative boost. Last time I heard from him it was still going strong. That's 16 years worth of work. Bloody incredible I reckon!

As long as you don't let them starve for oil or detonate they'll just keep going!

PL

Yep you reckoned right indeed