China 2871 dyno run built 1.8l 280hp 250tq 20psi
 

Here is my recent dyno tune. It's a load Eddy steady state dynojet 224XLC. I was going for a safe tune that would give me no risk for detonation. I was hoping to break the 300whp mark at 20psi, but it didn't happen.

There was a strange intermittent drop at 6k rpm that we think is coming from my cop harness. I've bought some replacement cop connectors with wires already attached to eliminate my shoddy craftsmanship.

Two runs are logged. The "clean" run and one with the drop.

Where do I go from here? I'm going to get a Map Daddy sensor so I will feel comfortable going to 24-25psi. I think the standard diypnp sensor is only good for 21-22 psi. Someone correct me if I'm wrong. Before increasing the boost to that level, I am going to dial in the closed loop boost settings. The steady state tuning of the none boost cells made for a very nice drive home.

My diypnp psi and the dynojet differed by about 1 psi. The diypnp was about a pound higher. He pulled his point from a vac port on the front of the manifold. I pull my MS reading from a port that is shared with the fuel injector rail. Should I change mine to a different spot?

Feel free to add ideas, areas for improvements, thoughts on what could cause the intermittent drop at 6000rpm.

Also this is with an intake cam gear retarded by 7 degrees.

Fourth gear pulls with 6sp and 4.10 rear



https://www.miataturbo.net/picture.p...pictureid=1346

https://www.miataturbo.net/picture.p...pictureid=1345

GREAT power, and wow, almost 300 lbs of torque at the wheels, congrats!

As much as I'd like to stroke your ego, 280whp at 20psi is a little lackluster, especially with an ARtech setup and retarded intake cam. Your timing map isn't particularly conservative either (16 degrees at 240kpa) - I'm only 2-3 degrees up on you (~19 degrees at ~220kpa). Before the Honda IM and E85, I was seeing ~265whp at 14psi, and on the old '99 motor it was 300+whp/wtq at 18psi.

Two theories: Either there's some .64 A/R housing phale occurring, or the chinabay 2870s aren't performing like a genuine Garrett does. Phil had the same thing - 2870, 26psi and water injection producing less than 300whp/300wtq.

The setup looks good - good manifold, good exhaust, I like the retarded intake cam gear and all the rest of it, but something is lacking for sure.

This has been said already by many actually.
Specs aren't the same, so output is not the same.

Still not bad IMO.

I was thinking the exact same thing. I was a bit surprised that the 300HP mark wasn't surpassed.

I think it is what it is. The china turbo seems to spec close to the 2871, but maybe there is more to it than impellar/housing size. At least we are getting some data on these turbos. On a positive, the turbo only costs $300.

Maybe after a hardtop and 3.6 R&P I will venture into.

My IC piping is only 2", I don't know if that would be an issue. IAT was just shy of 100 degrees.

BB turbo's always make more power. Even with the same specs. From what i've been told. Even a Garrett 2860 potato will make more than that at 20psi. But for the $1000 saved, I would say your doing pretty well.

The cost to power benefit is why I'm not seriously pissed. It's hard to complain about saving a $1k, Plus my built motor can handle all the boost this can throw at it. I'll just take it to 24-25psi

Car must be a handful to drive now. I just got a chinabob2871, hope i can look forward to close to the same numbers

I hit 298/296 on a mustand dyno with my inferior 1.6. I would add some water injection to your setup and go back.
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We were hitting 260rwhp (dynojet) on newbsauce's .020" over 1.6L with a true 2871; only 17psi.

I don't know what to tell you guys. My options appear to be: raise boost or new turbo. I'm not going to buy a new turbo.

Water injection.... retune (and add boost if necessary)

all of the above.

I'm not going to hassle with water injection. How does my tune look? Rides really smooth through all of the cells up to 20 psi. I'm currently trying to pull out the extra enrichments that were present when I was tuning. This is proving to be harder than i expected.

enrichments/trims are a very finicky part of the tune to mess with. be careful. save the map often (under new file) so that you can always have a "restore point" so to speak

I found that out on the way into work this morning. I made too many changes at once. As soonas it came out of warmup I had to pull over and use my good dyno tune. I'm going to start slower this time.

Warm up was constantly adding 13% after it reached temp, so I figured I could just shut it off and add 13% to my ve table.

Without seeing a log file of how the AFRs react to your VE table I can make the follow assumptions:

It goes hella rich as it's building boost and it leans up as the RPMs increase in boost.

go back and do it in the right gear. 4th gear if ur running a 5 speed. 5th gear since ur running a 6 speed.

doesn't matter on a dynojet. youre just pushing a concrete drum and it calculates the gear ratio.

Water injection is so easy buffon could do it.
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