Chowcow

Hey All,

I just took my car in for tuning and was able to get 207WHP/185WTQ on a Dynojet with an FM 2 Kit. I was hoping to break 210WTQ but I'm way far off.

Looking at the logs, the car will take more timing and provide more power, but too much knock occurs. The tuner had said he has never seen anything behave this way-- the timing is pretty conservative to be knocking like that. Before turboing my car, I did a once over the engine and everything checked out fine. The only thing I can think of is that I used 91 Costco Gas (Forgot it was Costco). But I'm thinking "bad gas" couldn't be the explanation for 30 more WTQ.

Here's my build:

2003 Miata stock engine
FM2 Kit (GT2560)
Megasquirt 3 (REV built)
2.5" FM Exhaust (down/mid pipe)
2.25" FM Dual muffler (This might be responsible for some power)
FAB9 COP
Turbosmart BOOST Tee (MBC)
*My boost gauge reads 10-11 PSI when WOT, but the Dynojet reads 8.7PSI. The Dynojet was sourcing signal from the rear end of the manifold (the one where the check valve is located on the NBs). This might explain the discrepancies.. I'm going to assume that my boost gauge readings was more correct..

Here's my tune and log:



*The TQ curve dips down b/c my RPM readings gave an error so I lost the TQ readings for that moment in time. You can assume that TQ is linear from before it dipped.*

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One of the most noticeable things is the boost creep. I'm guessing this can't be controlled by an MBC, but the real issue right now is that the car knocks at more advanced timing.

Any suggestions on what I could look at/ change to up the WTQ to ~ 200/210?

Thanks!

fooger03

iTrader: (2)

My boost gauge is a little bit optimistic too. I'm willing to put my money on the $$,$$$ Dynojet over the $$ boost gauge, which means you're making 207whp on 8.7psi.

Either get an MBC, get a standalone EBC, or tune the Hydra EBC with my new and evolving method starting at post #26 here.

Chowcow

I forgot to add that I'm running an MS3 instead of the hydra.

Not sure if the Turbosmart MBC normally acts like this, but I'll have to rotate the thing a whole clockwise turn to turn the boost up .5-1 PSI.

Either way, I'm experiencing knock going up any further, so I'm not sure that turning up the boost would be helpful until I work out my knock issues.

codrus

The 2.25" muffler is probably a significant restriction, but I'd go with a 3" instead of a 2.5.

--ian

nitrodann

Exhaust is where I would start if you are sure the maintenance is up to scratch

Chowcow

My whole setup is 2.5" which I won't be changing anytime soon as I just purchased it all. Would it make sense to go from 2.5" --> 3"? exhuast muffler?

As it sits right now, I'm 2.5" --> 2.25". I still fail to see how that could translate to 20 more WTQ. But maybe..

patsmx5

iTrader: (16)

If you are knock limited, fix that and you'll find the power.

Too lean, run richer, then more timing and you'll make more power. I would add fuel first.
Wrong plugs? Wrong gap?
Air temps post-IC too hot?
Motor carboned up/burning oil?
Has the head or deck been shaved?

You have a MS3, see what boost it says you are running, it's probably right.

Also verify your timing is right. Also check timing latency. I had a problem with the latency on my MS3 PRO on my car.

codrus

The restrictive muffler is hurting your spool, a lot. You should be hitting 10 psi by 3500 RPM with a 1.8 and a 2560, instead it's 600 RPM later at 4100 or so.

3" muffler probably isn't worth it with a 2.5" midpipe, and the FM bits won't bolt up that way anyway. That said, I saw 10 hp and 300 RPM of spool on my old FM2 system going from a 2.5" to a 3.0" from the downpipe all the way back.

As for your torque, max torque values aren't only somewha sensitive to flow, that's more of a factor in how quickly the torque drops off with RPM and thus the max power you can make. You generally want to see around 70 lb-ft per liter-atmosphere. If it's 8.7 psi of boost you're getting 65 ( 185/(1.8*(8.7+14.7)/14.7), and if it's 11 psi then you're getting 59.

Why do you say the dyno says 8.7 psi? The chart you posted from the dyno shows between 9 and 10 for the entire run. What does your MAP sensor say? That's the number I would be concerned with. Did you run datalog the dyno run on the megasquirt?

How did you set up the VVT curve? That seems like a reasonably likely candidate for explaining poor low-end torque values.

--Ian

Chowcow

I got confused with my last run where the boost stuck at 8.7. You make a good point about the VVT curve. I haven't played with that at all. I'll start searching for information on tuning it. If you have a good place to start, a link would be appreciated.

Also, I'll look into a 2.5" exhaust.

But one thing remains.. the engine shows a bit of knock when at WOT. So even if I begin to tune VVT, I still need to address my knocking issue, right? Or will the VVT help reduce that?

patsmx5

iTrader: (16)

Indeed sir.

Chowcow

My problem is that I don't know what's causing the knock. My AFRs are rich 11-12 during WOT (where the knock occurs) so I'm confident that the knock isn't AFR induced. However, it could be the "bad" tank of gas that caused early knock.. Although I'm not so sure that a bad tank of gas could rob so much power- however, I don't have very much experience playing with gas types.

Any other recommendations as to why knock would be occuring?

The timing has been pulled to a point where knock is minimized. If timing is added, more power is made.. So knock shouldn't be happening..

patsmx5

iTrader: (16)

11-12, you said earlier 11.5:1 AFRs in boost. If it's knocking, add fuel. Get it to 11.0:1. That WILL HELP!!!!!!!!!! More fuel will cool the charge better (reducing chance of detonation) and will slow the burn (shifting peak pressure to the right) which is artificially retarding the timing and will reduce the chance of detonation.

I made a list earlier of things that can cause knock, did you read them? You never commented on it. I listed several things that all could be causing your problem.

Chowcow

1) I'll try moving AFRs down to 11.0 and then see what happens. The reason I kept it at 11.7 is because I was under the impression that any lower wouldn't benefit the power. But I guess a richer mix would mean less heat and etc etc... How rich do people run their WOTs on this board? I usually saw 11-12..

2) Because I installed the FAB9 kit, I didn't gap my plugs at all (Denso IK22). I figured gapping had to do with the spark and that with the kit, spark will happen at any gap. If gap is related to knock, I'll re-gap them to the OEM specs (or is there a suggested gap?)

3) I'll check what the post-IC air temps are. I can't seem to find them in my log, but maybe its named something else. What's an "ok" temperature range for that?

4) Not sure if motor is carboned but I know it isn't burning oil. One thing its doing is leaking oil from the valve gasket. I recently replaced the gasket but can't seem to keep the oil from leaking out. I've used gasket silicone to seal the edges and have removed the valve several times. At the moment, I leak 3-4 drops of oil a night-- enough to notice something on the floor.

5) Head/deck has never been touched- at least to my knowledge.

6) I'll have a look at my timing again to see if its set correctly.

Thanks for all the suggestions pats

patsmx5

iTrader: (16)

My comments bolded.

Chowcow

I'll check those today.

The IK22 spark plugs are gapped at .0032 from the factory. I'll play with the gapping but my log doesn't show any misfires happening / I don't feel any. The COP kit also says its good for upwards of 22PSI with those spark plugs. I believe the plugs are the same heat range as the BK7RE -- sadly I can't use those plugs because they aren't pencil types.

One other thing that I just realized. I believe the tuner is looking at "Knock in" to see if there's knock. More specifically, he's looking at how the patterns appear on Megalog. During WOT at 6k RPM, the "knock in" peaks at 31.2 and oscillates from 30 to 20 at its highest peak and trough. I recall him saying that with this knock pattern, it wouldn't be wise to advance the timing anymore. Although when he did, more power was ready to be made. (Is this assumption correct?) I'm now remembering that I read somewhere on these boards that knock of up to ~30 is considered "normal/noise".

As a caveat, I'm looking for a DD tune. So I stressed a more conservative tune.

patsmx5

iTrader: (16)

I have never used a knock sensor to tune spark, so I can't tell you anything about that unfortunately. I'm actually trying to troubleshoot my own car as to why I can't get the knock sensor to read. Mine shows 0.0% all the time, it never moves. And I've tried everything twice. I'm thinking I either have 2 dead sensor that both test good, or the MS3 PRO knock module is bad.

Reverant

iTrader: (10)

Post a datalog showing the knock reading.

Chowcow

This is at WOT, the knock starts oscillating around 4k-7k.

Reverant

iTrader: (10)

That's not knock. This is knock:

Chowcow

I'm a bit confused. Are you saying the "Knock in" isn't a knock sensor? Or are you saying it isn't big enough to be of any concern? It looks like you're using a different sensor to display knock, where can I find that under my Megalog viewer?

Thanks again.