Ok, been a VERY long time since ive been on here. the KLZE swap build has been on hold for years now due to kids and other priorities however we bought my wife a miata and i got it built up and tuned (self tuner). long story short, signature has the mod list, i tuned the car to come on to 14psi give or take and then ramped it up to nearly 20PSI at redline with 13* timing at redline. i stuck the log into virtual dyno and it came back with only 283whp. this seems a bit low for 20PSI. ive compared with others with the same turbo but nearly all are on E85 and running much more timing than i am. does this number seem realistic?
anyone got a comparable setup NOT ON E85?
keep in mind im still fine tuning this tune and still on the 5speed NB trans (tuning above normal boost levels incase **** hits the fan)

 

Hard to tell with a single VD. Log could be taken from a road that isn't flat, could have wrong car weight or tire Dia.

My black Miata had the same turbo, 8.5cr ported head, fm2 kit, 93 octane. Don't remember exactly how much boost, but it was 19-22psi typically.

This picture is over 5 years old and I'm too lazy to find the old tune so no idea on timing, nothing crazy though it was tuned by 18psi (vlad)

The one pull is stopped short, but trending with the rest. So I'm comfortable saying that car made anywhere from 300-320 depending on variables.

 

Looks reasonable to me, though probably some power hidden in there with a proper dyno tune and more timing. My gt2860rs + bp4w car made 315whp at ~18psi for reference, and ran out of air and I couldn't push it any harder. That was on e85 with all the timing (stopped adding once gains diminished).

Though I do expect more from the GTX turbo, I'd imagine it's not maxd out airflow wise and there's probably more on the table for you there as well.

 

FWIW I've read this thread How to Use Virtual Dyno a couple times and found some good tips in there.

From what I've seen playing around with virtual dyno, there are a lot of things that will make a 5-10 horsepower gain or loss. Weight, tire height, diff ratio (say 3.6 vs 3.636), SAE correction, etc... can all make a ~5 HP swing pretty easily. Personally I still think it's probably pretty accurate if you pay attention to all the details, but I've also never seen the numbers I expect from it.

 

Like any dyno, I don't trust numbers to be absolute but rather a reference against the same measuring tool. It's good for determining the result of changing things sometimes but not good dyno versus dyno.

 

this I completely agree with. The speed shop I worked at and used to tune at we had a dyno jet and I would always tell people this same thing it’s just been so long since I’ve tuned or been in that industry that I can’t remember how much timing is too much on these cars and how much power they make at what psi with so and so turbo haha.

absolutely love the way this turbo drives just always remembered making 250whp with gt2860 at 15psi and more timing and now that we have a gtx2860 gen2 i guess i was expecting to make more at the same boost level. Maybe im just conservative in my timing table and its more power on the table than i thought

 

The GTX should respond earlier and be more efficient in a broader area. Maybe double check cam timing then base ignition timing? I say this without scrolling up and rereading your thread.

Other variables like air filter, EBC, MBC, boost leaks, exhaust leaks, etc. ?

I had boost leaks at the injector to cylinder head rubber rings. Turns out there are at least two thicknesses and I would never have found it unless I put compressed air to the intake system.

 

Very comparable setup here, sounds alright. I hit 300whp on premium fuel @20psi and 15°.
take a look at a thread I started a while back: https://www.miataturbo.net/diy-turbo...-times-109074/
If your car is competitive, you should be fine. Invest in a Dragy or P-Gear, it's a lot of fun!

Edit: These turbos shine at higher pressure ratios. Up to 20psi the advantage is negligible, but up to 28-30psi they absolutely rip and are real 400hp turbos.

 

ya we still have the 5speed NB trans in the car and aren’t going to go over 17psi at redline (keeping torque under 250) until we can fund doing a bmw swap. For now I’m dailying the car while I fix my daily so gotta keep it alive. Probably gonna limit the ramp on to about 13psi and then taper to 17-18 at redline

 

It's all in the ignition timing. Why don't you put a little e85 in the tank bring it to like a E30 mix. Then add the fuel % you can find calculators online. Then you can probably run at least +3* timing+ the cooling effect from the increased ethanol. You'll pick up +35whp I bet

 

there is no e85 fuel available around us unfortunately

 

Mine made 330 at 240 kpa, but that was on 100 octane and it's a GTX 2863R so a slightly bigger compressor. (other differences: P&P head, +1mm intake valves, BP5A intake cam, stock BP4W intake manifold, EWG exhaust housing).

A few thoughts:

- IMHO, while virtual dyno can be effective for tuning if you are careful to control as many variables as possible, it is useless for comparing with other cars. If you want to do that you need to get on a dynojet at sea level (altitude compensation is totally broken for turbo cars). It's not perfect, but it's the best option around.

- Assuming you controlled for variables, something funky is happening at 6200 RPM on your chart. Torque should not drop and then go back up. Do you have a hole in your timing curve?

- Why are you only revving to 6600?

- What valve springs do you have installed? I logged exhaust manifold pressures and at the top end it was high enough to blow the exhaust valves open during the intake stroke. Installing supertech heavy doubles fixed this.

All of that said, my guess is that the biggest factor is that you can't run enough timing on 91 octane. Maybe try water/methanol injection?

--Ian

 

I guess that is a hint for me to go ahead and list the two meth injection kits I've got sitting on my shelf. Give me a few days.

 

Wishing I didn’t sell the meth kit from my wife’s speed3 build lol. We have a stock bp4w head on the car. No port or anything. Bottom end is eagle rods stock pistons. We have an eBay cast manifold but I have the flanges and **** to make a tubular manifold hopefully this winter. I could always turn up the boost but the transmission won’t like that. The car feels great just remember back when I used to tune Miata’s all the time that a gt28 turbo at 15 psi I could be over 250 and this car VD is claiming less at 15psi with better head. Better turbo. Better manifold etc. makes me feel like I’m missing something in the tune or maybe one of these parts is a massive restriction

 

What exhaust housing are you running? I ask because we ran into a wall with the old internal wastegates on the T2 garretts on our SR20 cars. It seemed to happen around 15 psi or so. We ended up deleting the internal WG and using a 38mm Tial and picked up about 40whp.