I was going to comment on the 2.5 but he's externally gated so shouldn't be too bad

My old 2560 saw a big jump in spool performance when I went 2.5" -> 3", and the gate is closed for that.

--Ian

I've raced several 5th gen GTs stop light to stop light in town without issues, I've not raced the newest one my town it littered with the older ones, you are right I probably won't touch the vett just yet.

I have spool data from my logs. spool starts at 3700rpm 18psi happens around 4300rpm. 8/10 times boost stays solid at 18psi 2/10 times it bounces between 16-19psi

I'm about to order a 3" from Abe. From what I have read here that could give me 5-10% more power with better spool, is that still correct?

I did a compression test with a cheap gauge, 190 across the board I think one cyl ran 188 but nothing scary. After that I didn't think a leak down was needed?

AIM tuning is helping me go through the tune. We are still tweaking it. I'm not sure on MBT I won't pretend to know tuning. I can post my tune.


No but I'm thinking about getting one

I'm not running a cat, just s resonator and muffler.

Edited to fix the post that mt.net ate.

You might want to go compare your spool data to that in the spool data thread https://www.miataturbo.net/diy-turbo...ool-data-26641, there are a few other 3076s in there. That might shed some light on how well the basic stuff is working. You're doing this pretty close to sea level, right? If you're up in the mountains then that changes everything.

If it's the exhaust that's holding you back, a 3" one is potentially a much bigger win than just 10%. It's got 40% more internal volume for one thing, and is even more than that when talking about the flow that's not next to the walls of the pipe. I don't know if it is the limit or not (the EWG with the dump pipe complicates things), but my hunch is that there's significant gains to be had there.

If you're data-inclined, you can measure the backpressure in the various parts of the exhaust system to determine if there are real problems there. On my car, I pinpointed a bad "high-flow" cat that was severely impeding my power by doing this. Swapping out that component for a test pipe did this: (same boost (16 psi), same car, same dyno, only difference is the cat vs test pipe).

http://www.codrus.com/dyno/synergy-O...ompare-215.png

One other thing you can see in that graph is the rapid rise in torque that's characterstic of a larger turbo. The torque curve is basically in three parts -- 2000 to 3500 where it's slowly trending upwards, 3500 to 3800 where it goes nuts and rises very rapidly, and 3800-redline where it's using the wastegate to keep the boost at the target level.

Yours is a 3076, that's larger than my 2863R and yet it doesn't do that. I don't know why.

EBC will help spool, but it's not a huge effect. You have a Hydra, right? 2.6 and lower don't have great EBC in them, 2.7 might have fixed this, I'm not sure.

As far as tuning goes, the basic principle of spark tuning is fairly straightforward. Ignoring some details, every cell in a 3d spark map has an ideal value that produces the maximum amount of torque, both below and above this value make less torque. This value is referred to as "MBT", and the goal of dyno tuning is to find it. One way to do this is to start with a good basemap and make a run across a given MAP row (need good boost control for
this). You then bump all of the timing values up by a couple degrees, repeat the run, and compare the results. Cells where it gained torque aren't at MBT yet, those where it didn't (or even lost torque) are at or above MBT. You then adjust the values and repeat this process until you have a row that's at MBT. You then adjust the boost value and repeat the process for the other rows, until you have an entire table at MBT. You then typically back this off by a couple degrees to be conservative, and you're done.

Of course, you might hit detonation before you find MBT, and if so then you have to decide if you want to accept less than MBT, or if you're willing to shell out for race gas/E85/water injection/etc in order to get better timing numbers.

--Ian

spool sure, but he's down on quite a bit of power

I feel like it has to be in the tune with some in the exhaust. I think the 90 behind the turbo is a huge issue. It is a very tight bend.

Thanks, I will look into that. I love comparisons.

I hope my move to 3" would be that much. I'm def sold on it.

If all the mechanical things seem correct then I lean to the tune. Unfortunately remote tuning is my cheapest option. Although there are dynos all over here, no one around here feels comfortable looking at it.

Last time I talked to FM they said the 2.7 was better but still didn't recommend it.


I'm trying to learn this stuff, what you said makes sense. It will be a while until I feel conformable making any changes without the advice of someone knowledgeable. I want to keep this at 93 which is common in the areas I drive. I do a lot of back road driving in the middle of nowhere Arkansas. I'd hate to tune for E85 then not have access to it.

Here are some of what I think the high points are on my tune

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begi #2 is a small and (restrictive for your purposes) core

Well, the spark table doesn't look like it's massively retarded due to detonation, your 200 row has 4-5 degrees more advance than mine. That might point to an exhaust restriction -- I have read that lower VEs tends to map to a more advanced MBT.

Do you know if your Hydra is properly compensating for spark latency? When I went from Hydra 2.5 to MS3 on mine I discovered that the actual ignition angle was off from the intended number by 8-10 degrees at redline.

--Ian

I'm not sure on spark latency. AIM tuning suggested I tweak the timing once the exhaust is on.


I've ordered a 3" from Abe today. Does anyone know what kind of turnaround he has?

Better ask him, could be a couple weeks, could be a couple months, depending on his backlog. He does good work though

Do you have logs showing actual timing to verify against the map? I agree with Ian, your map doesn't look bad

To check spark latency hook up a timing light and lock the timing at 10 degrees. At idle it should show 10 degrees. Now rev it to 5000 RPM, the timing should stay at 10 degrees. Mine was off by 6-7 degrees at 5K and even more at 7K.

Don't forget to unlock the timing afterwards! I wasted 20 minuets on a dyno trying to figure out WTF my changes to the spark map were having no effect the time I decided to confirm the spark latency numbers before tuning...

--Ian

Great info Ian. I never thought to check mine at higher RPM's.

I assume that's all due to timing belt slop. I bet crank fire would solve all that. I got the trigger wheel just need to get it hooked up.

Mine's an NB, no timing belt slop to worry about. I don't know what causes the latency, not sure if it's something in the sensor or something in the ECU itself.

--Ian

I'm going to check that out thanks for the info

So I have to quote myself on this because I'm an idiot. So when I was redoing my piping for the turbo, I thought it would be smart to get a heat blanket for the turbo. After seeing the price on name brand ones I thought I would get a cheapo and see if they are worth it. Well the heat difference was very noticeable but after a few weeks of driving it started to smoke, looks like I have to add that to my list of things to buy.

Attachment 180675


Speaking of which a few post ago I said my boost was stable 8/10 times WRONG, after driving the car everyday to work and doing some data logging I've noticed boost is not always stable. Sometimes it is, but most of the time not. After the initial spool it hits 18-19psi and backs down 3-5psi. From what I've read here a 1psi drop is typical for a MBC but not 3-5? The MBC might have debris in it but I'm tried of chasing down BS issues so I'm going to get an EBC. I've got an AEM wideband so I was thinking about getting an AEM true boost. Does anyone want to suggest an EBC. I've never used one before, I'd like to keep it under $450 I see that they can get pricey fast just like everything else in this addictive hobby. :facepalm:

In trying to chase down power issues I contacted Abe to have an exhaust made, he will need my manifold to get it all perfect and since I would be in a long line it could take a while. So that is on hold until fall. For me driving season is about to ramp up so I'd like to keep my car drivable for till November.

With my Hydra I used a GReddy Profec 2 Spec B. It worked pretty well.

(edit, or maybe it was a Profec B Spec 2. Something like that)

--Ian

Greddy Profec user here. Very happy. I think it is a Spec B or something. It has 3 knobs, fwiw.

Blankets made my flapper shaft lose its temper and stop opening and closing smoothly and cooked my CHRA turbine seal and bearings. YMMV.

The motor on my car was built in 2009, said to have less than 1k on it a year which I believe. But any who that was like 8 years ago so to play it safe I'm changing the timing belt, water pump etc. Boring miata.net stuff as some would say here. I plan on moving to a dual oil catch setup and adding some other goodies in the process.

I'm still committed to finding my power issue. We were talking about exhaust restrictions earlier and since I'm going to have to wait for the 3" I was looking at what I could do now. My car has this erh resonator on it that looks like a huge restriction. Its near impossible to get a good look at it, but on the inside it looks like it has a tiny passage for exhaust to push though. I though about just test driving the car without the midpipe to see if it is causing a restriction but I'm kinda afraid the heat could do some damage. Any thoughts? I'm thinking about just deleting it for now a throwing in a straight pipe for testing.

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This may be up for sale soon...
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Time to get frame rail covers, another gift from the previous owner.

Attachment 180674

:doh: that resonator looks like it has a 1" hole in the deep throat pic!

https://thumbs.dreamstime.com/x/big-...k-14198653.jpg


You can chop your exhaust right in front of it and just clamp on a turn down to see the diff.