Terrible top end only 140whp?! Doesn't make sense
 

Not sure if I should just throw more boost and timing at it to try and force the graph to look proper when there is most likely an underlying problem. The log shows with RPMdot that there is something fishy unknown going on. I could really use some help please
obviously but something is not how it should be.

In a third gear or above pull the RPMdot always shows several points where the value is negative. Especially above high 4k to 5k RPM. It does not do this in a 1st or 2nd gears pull.

Several things tried already: I've gapped the plugs down to 0.032" all the way down to 0.027" as well as tried increasing the nominal dwell settings up a sensible amount with no good improvement. I can still shorten the spark duration although I wouldn't be SHOCKED if that doesn't help. ;) Anyways, also when dragging the pull logs into Virtual Dyno, it shows how the tq/hp looks (not good). Not only the peak figures but the shape of the graph overall doesn't look right for the boost, timing and setup I'm running. It should be more around 200whp+ and continue to climb as the boost slightly tapers higher towards redline.

Summary: I don't know what's causing this. Could detonation cause this? I checked in the combustion chamber with a mini HD camera and there is no pitting or signs of detonation other than a healthy looking engine. The compression is 182 on one cylinder and 195's on the other 3.

I'm running 93octane and using conservative boost/timing. Is that what a misfire looks like in logs? If it is a misfire, it's happening right when 1-2psi of boost builds but is intermediate. Enough to create a lack of power but not enough to ruin the livability a noticeable amount (at least until I can experience how it runs after this problem is fixed) Not sure what it could be. Wants those normal/good peak hp numbers for the top end!!

Oh and it's also important to note that I've checked for spark latency correction and the timing stays fixed properly at 10base timing with the value of 40 that the Megasquirtpnp.com turbo base map included so I've left that how it is (it shouldn't be latency correction).


https://cimg6.ibsrv.net/gimg/www.mia...1fc4f8366a.png

I just did two more pulls today with the boost turned all the way up, got the AFR's between 11.8-12.0 so there is no excuses. 16.5PSI and only 170wTQ?!!!! What the bleep.


That is definitely way too much boost for my stock internals and it still barely takes the numbers up to what you'd expect out of ~5-7psi power levels.

Soft top is up, windows were up, pop-up headlights were down, flat road and 3rd gear pulls.

3" free flowing exhaust, turbine and exhaust housing should be more than large enough for 300whp, 2.5" FM cast downpipe, cast log ebay manifold, stock coil packs, NGK plugs and wires, MS2PNP, Flowforce 640cc's which by the way, show a duty cycle of 89% at the peak of the boost it hits.

Anyone know what's causing this?

I should certainly have a 4.10 Torsen, 5 speed gearbox, 205 50 r15's on 15x8 rims. Weather is usually between 80-90degrees outside lately. That's everything I can think of right now.

virtual dyno?

https://cimg1.ibsrv.net/gimg/www.mia...905e005248.png

I mean, at 17 psi you're only asking what, 10 degrees of timing? I don't think you should be surprised.

Add 4* from 100kpa up, see what happens.






<---not responsible for what happens.

Add 6 degrees at 100kpa to end up where the spec Miata guys run. Get some det cans and try what Curly suggested.

Is virtual dyno set up properly?
Vehicle weight and wheel/tire size settings make a HUGE difference.

What's overboost protection set at? From the jiggly psi log right at 180kpa and seeing VD set at smoothing level 5 I feel like that's likely the issue.

From all of the other timing maps I've seen that others run to get anywhere from 230-250whp at the same boost levels i ran previously; 10 degrees at 200kpa should be completely good enough for for a baseline 200whp pull...

10 degrees should definitely make some proper power (above 270whp) when u throw 16.5psi at it.

This is all from my understandings.

I'm fairly sure that if i start adding 1 to 4 degrees at it, It should lively it up in increments and overall engine sound but something tells me based on ^^ up above, it's not the fix to the problem. And won't bring me to where i should be. At the very realistic risk of doing perminant harm to the car.

I need to make some det cans soon but i can't really go forward when the timing and boost should make atleast 40% more wtq/whp

Like i bet u if i added 4-5degrees it's not ganna bring it up to 210whp @ 16psi.

Idk i just think it's risky to do that when it should've made tons of power at 15-16psi with that spark map!
Right??!

I turned it up to like 230kpa? Just when i recently tested bringing up the boost by a large amount. It's plenty above where it needs to be.
16.5 should be borderline limits of stock rods even with 10degrees timing. Right? It was only a test

11.5psi made like 160whp
16.5psi made 169-179whp

As long as overboost is above the psi you're running then that shouldn't be an issue. It just looked like a possibility when I saw the log.

Inb4 op posts "blew my motor trying to make 200whp"

Sounds accurate haha. The timing boost is beginning to sound like a decent enough idea..

If i have time tomorrow after work if the weather allows, I'm ganna aim to first set the boost controller back to start at ~10psi with a less aggressive taper = ~12.5psi peak.

Do a base line then add about 1 to 2 degrees in two test runs and see how much it likes it. If it likes it by 2.0 - 5.0 whp per added degrees, then no. Not going further. Ganna put it back to where it first was & try to get LS coil packs soon.

But on the other hand if it adds at least 10-15whp or more per 0.5 to 1.0 degrees added then yeah I'll believe it was the timing all along /me shrugs.

In theory, if it is timing that's the problem, then adding only a few degrees should def bring me to 200+ easily no hassle

Thx | will be reporting back!! #WBRB

Back when i had the car on the stock ecu for a little while after freshly rebuilding the engine, i accidentally had the base timing set to 14-16degrees. There was 93 in the tank. I added some 89 to save some money, figuring nothing much of it. I drove to some backroads and it sounded happy during the trip there but Once i was in the twisties and put load on the engine, to get up hills and stuff, i felt the power disappear and heard the metallic rattle snake noise coming from somewhere lol. Realized after about 2 minutes what it was an limped home to fix it. It was only happening when i was going up any kind of hills.

Thankfully no damage occurred because it wasn't boosted and i wasn't really pushing it too far. That was way back last summer. Anyhow i know what the noise sounds like. I freaking felt it and heard it at the same time. But now days the car has aggressive poly engine mounts, tons of NVH, wind noise tire noise etc so I'm not ganna get as much of a notable difference if it knocks especially in boost. So i have to try and be smart about it and be as cautious as i can be. (KNOCK on wood)

You only hit 89% injector duty cycle when your shitty TPS signal spikes and triggers AE. You are, however, reaching 82% duty at 11.5 AFR with gasoline on 640cc injectors.

That much fuel should be good for very roughly 325-350 crank HP. Your logs look closer to what I'd expect a 4th gear pull to look like.

As for the excessive fuel spike due to AE; I plan on fixing that better once the fuel table is better once the timing is closer to what I will use. XD


I promise you it's third though lol thanks for looking into it tho. Forgetting the fact that if I did a 4th gear pull out to 6-7krpm, i'd be going 80-99+MPH. Nah I can't do that around here that many times lol or at least not without being seen. I can only do 4th gear pulls to like 5.8k without going too far over the spee limit RPM so i stick with 3rd gear for Virtual dyno logs

Got a random question. My tach is always kinda wobbly around 4k rpm but it seems to smoothen out above 6k to 7k. Do you think that noise is translated into a tuner studio log? Ideally I understand there should be no noise bcuz noise is in actuality a circuitry problem in the hardware that needs to be addressed rather than just tuning out the noise on tuner studio. But can that noise translate to the log and then its what's throwing off the power in virtual dyno? o.O

Idk I think I'm just missing fire and it's ruined the power. /me shrugs | Hopefully today I can add a little ignition advance to see if it adds tons of power per degrees (with the boost lowered a lot).

That sort of proves that it must be spark timing or misfire related (spark blow out)

So I brought the boost back down to the reasonable 200+whp levels I started off with today; like 11-12psi but also added around 4degrees in the 100kpa row. And anywhere from 1.0 to 2.0 in the 128kpa and above rows. The results of many logged pulls only yielded a net gain of a 2wtq peak more than the previous timing at the same PSI of boost. Therefore, if I were to chase more and more timing, I should most likely hit detonation before achieving 200wtq levels. Estimated. Doesn't that logic seem reasonable?

Doesn't seem like it should be so difficult to reach 190-200+whp with a standalone, 640cc's, semi large churbo, free flowing exhaust, running similar spark advance as others who are able to net much more than 200whp at the same boost, unless there is misfire the moment it runs above 100kpa; right? But if it was misfiring I'd expect to see the AFR readout in the logs and VE Table to hint more at it rather than looking kind of normal.

It's either intermediate spark blow out at low to high boost levels through out every pull OR the settings I have in virtual dyno are off by a lot. Has got to be one of the two o.O;; It does feel like it runs good.

In virtual dyno I noticed the RPM difference between the peak HP and peak TQ is a longer distance apart from each other now with the added timing. For example, before it was only 400-500rpm apart from one another. Now it's more like 1,000RPM different. That's probably good

When I added the timing advance, the IAT's / MAT's finally went up a whole lot more as the boost & RPM climbed in the logs. Rather than before I would never see more than 101 degrees f after several boosted pulls. Note that my intercooler is rather large 28" with 2.5" inlet/outlets. Where as today I finally saw 110degrees f during one pull and that excited me. It also feels faster but virtual dyno just says it barely added 2wtq at the peak. I'm still only at like around 173lbft and 179whp @11-13PSI. The added timing definitely increased MAT's somehow... Could that clue into any answers?

Don’t look at peak, that’s only half the story. Post the new graph. If you had a misfire, you’d see a dip in power and torque. Your issue sounds more like incorrect timing or some sort of clutch slip

What rear end do you have? Also 2500lbs seems heavy for an na8.