109.65mpg :ugh: Running standard 93 pump.

I think I'm losing a lot in the back half. For example, I was running 10+mph faster than a stock/new WRX in the 8th, and by the end of the 1/4, i was still only about 10mph faster than him.
I had a best of 89mph in the 1/8th which could/should have put me around 112 in 1/4.

ridethecliche has me wondering if my $20 Amazon boost controller has anything to do with it.
I may also be swapping out my upper down pipe (i.e. turbo exhaust elbow) but I doubt that'll do much and going with a smaller A/R exhaust on the turbo. We'll see though.

Something's definitely not right. Here's part of a log from the 109mph pass. With each gear change, the car drops boost down to <5PSI, and then takes 1K rpm to recover back to peak boost. That doesn't seem right?


My waste gate flapper may be getting stuck against the inside of the upper section of the down pipe. I've tested this and know it COULD happen, but I didn't think it was opening enough to actually cause it. Taking it apart as we speak.

https://cimg8.ibsrv.net/gimg/www.mia...c67a646297.png

What's wastegate for you?

This is something I was told to do to test spool:

-set boost cutoff at a level just around what you're tuned for. Mine was set to 12. You can also be more conservative here and go a few psi below that because you want to see ramp up.
-disconnect vac tubing to the wg.
-do a pull in 1:1 gear starting at 2k.
-let off when your boost cutoff kicks in

This shows your best case spool scenario. If you're way under this, then it shows that things aren't optimized. Obviously I'd only did this once or twice and only if your shit is working by testing at a lower cutoff with everything plumped properly first. Danger to manifold! But it gives a best case scenario you know? A benchmark of sorts.

I posted a few logs on my thread recently.

Also EBC!



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I'm running a 1.5 bar (21.7psi) wastegate spring.

What you're proposing makes sense. And just so I'm clear, it would confirm there:

• Is not an issue with the the wastegate opening early/staying stuck open, correct? It would not be proving anything boost leak related.

Yeah, I don't think it would show anything leak detected. You have to listen and use a boost leak tester for that. It just shows you a theoretical max spool speed since the wg never really opens.

I'd wait for a senior member to chime in before doing the above though. I know why this works and think I'm correct but id rather have someone agree with me first lol. This isn't the best thing for your turbo, which is why it needs to be done once and done right. I did it 2-3 times on the same strip to make sure I had good data. But it's definitely a thing where you get to where you test, stop, disconnect, run test, then stop to check the log and see if it's good and reconnect if it is.

I'm not sure how much it helps with an mbc, but it basically showed me the theoretical max I can get with ebc tuning. I found out I had far more work left to do than I anticipated!

Do you hear anything that sounds like a leak when you pop the good while idling? I know my BOV leaks. I know colipto just went through and chased down and fixed a lot of leaks on his setup and the bov was one of those spots leaking.

That's partially why his spool is slow.

I'm 100% confident I have no leaks BETWEEN the turbo outlet, and the throttle body (which obviously includes the BOV). I made a boost leak tester and that entire section can hold 30+psi for minutes on end. I wonder if my BOV is set too tightly, not opening long enough, and is stalling the turbo between gears.

In any event, I ordered a flyin' miata upper downpipe section (turbo exhaust elbow). This will stop the wastegate flapper from interfering with my current turbo exhaust elbow (and possibly getting wedged open), though I'm still not convinced this is my issue.
I guess I should also order a quality boost controller as well....b/c at this point, why not :facepalm: (ffs)

I'm also actively going to try and trade my A/R .86 for an A/R .64.

Try what I said too. The mbc is out of the equation at that point.

What's the highest wastegate pressure you can run? If you can reach that faster without the mbc, well then you've found your holdup!

Thanks for the tips!

Remember the boost leak i was 100% sure i didn't have? Well.... turns out I had a slightly deformed intercooler pipe that was causing the coupling to leak only if the band clamp was clocked a certain way.
In addition to fixing that, I replaced my homedepot boost controller with a Hallman Pro (extreme waste of money in my opinion), and my eBay turbo elbow (upper down pipe) with a Flyin Miata cast unit (again, a waste of money considering my issue was a boost leak).

Spark notes: Spent nearly $400 on replacing working parts, trying chasing a boost leak :facepalm:

The car should be together by Tuesday night and back to the track by Friday. My arbitrary goal is to put down some solid hp numbers across the RPM range and trap 112mph.

How's it going? Any progress with the changes?

Mehh...I guess it's going ok.

I swapped the 2.5 inch / 300 cell / ceramic / megaflow cat (that comes on Flyin' Miata's 2.5" mid pipe), with a 3 inch / 100 cell / metallic / mil.spec cat.
Below is a VD comparison pull between the two cats (same stretch of road, both in 3rd gear). The blue line (old cat) was from the morning before going to the track mentioned earlier in the thread.

While it helped boost/spool a bit, overall power is still lackluster (compared to the imaginary numbers I've got in my head from reviewing other people's setups). The power flattens out so dramatically after 5K

I'm going to make one more road tuning session one night this week and see where I land. I'll then be either setting up a dyno session, requesting paid tuning help, or both i guess

https://cimg6.ibsrv.net/gimg/www.mia...725d89f097.jpg
https://cimg8.ibsrv.net/gimg/www.mia...eb6689737a.jpg

Talk to vladdddd

Though he might be overbooked at this point lol.

EBC is faster and better spooling than a spring, as big as it might be.

I'm curious about your eBay turbo. Looks like a T3 copy to me from the compressor wheel (size/fins)- completely different from your Garrett GTX2867R. Did you pull housings to measure the wheels and check fins/contours?
Here's an eBay t3 compressor on the left (next to a Garrett T4 compressor). The wheel sizes will make a bigger difference than AR. I narrowed down my poor spool to a housing swap- from a Garrett to eBay turbine housing (both stage 3 t3). Turned out that the turbine wheels (though same specs) had different contours. In my case the blade to housing gap was excessive at the turbine inducer.

I scanned the thread and dont' see it: what is OP using for boost control?

At the start of the thread, I was using a $20 diy special off Amazon. About a month ago, I upgraded to a Hallman Pro.

I thought you were only using a 20 psi spring. Anyways, ebc is also better than a manual :)

While true, the difference is nowhere near as drastic as many make it out to be.

Yeah, but there's about five strikes against this car showing good boost response. Too-big A/R, too-small exhaust, lousy cat (OK, one is fixed), no EBC, and pulls in 3rd instead of 5th.

--Ian

Let me attempt to grab a 5th gear pull tonight and report back