I have been a member to this forum for awhile, but this is my first time posting. I have tuned my 90 Miata on the street for 3 years using my butt dyno, but after having numerous people ask what it puts down for power I decided to do my first dyno session yesterday. The dyno I was running on was an inertia style, and very heavy to get rolling: http://http://www.carzcustom.com/dyno/dyno.htm The heavy load resulted in my knock sensor going off more than on the street.

The question I have is can too much ignition retard cause knock? I found this thread: http://https://www.miataturbo.net/showthread.php?t=30244&highlight=timing+map+compar isons and it looks like my map is retarded about 5-10 degrees compared to the above. See my map attached below.

I got some light knock in the 4-5k rpm region around 20-22 psi. I decided to pull timing and the knock got worse (pulled 5-7 degree range all down to 2). On the next run I added some back in and it decreased. By the way the AFRs are all 10.8-10.4, and the knock was ignition not fuel. Does this make sense? Has anyone run into too much retard can lead to knock? Convention states that you pull timing to get rid of knock, but adding? I have seen this before on the street with this car, but it was just augmented by the heavy dyno load. Is my map just too retarded?

I would like to get your thoughts on the ignition curves and please post any maps you can share.


Thanks,
Adam
Car:
94 1.8 block with stock cams and mild porting
9.8:1 compression
Wiseco Forged Pistons with Carrillo Rods
MS Extra with KnocksenseMS
NGK plain jane plugs – 2X colder BKR7ES-11
Ported EVO3 16g with FMIC
Ran 91 with no ethanol

 

Are you sure what you were hearing is knock and not some phantom noise? Also, are these turbos still efficient at 22psi? 6 degrees seems awful low.

22psi + stock ignition is asking for problems.

 

yeah you should be in the 20* timing range.

 

I've never seen anything like this. You should check your static timing by assuring the pulley didn't slip, then check cam time. I've seen more than one slipped pulley and several cars one tooth off on the belt. Then, make sure you don't have some weird CLT advance.

Are you using detonation headphones? I suspect that spark time is so retarded that you're hearing the ignition event so late in the decompression stroke that it is masquerading as knock. From previous experience with people who leave static timing at 10*, maybe fuel is lighting off from a similar scenario.

Infant guess at a bunch of other variables, but I won't.

You can always use a phone or MP3 player to record the noise from the set cans too, then play it here. Be careful of course.

 

What specific plug are you running? I've changed from BRK5E to 7 and added 5* of spark on an NA car before.

Are you at 9.8 or 8.8 compression on the pistons? I could see a heavy propensity for detonation on a 10:1 engine with 91 octane at the MAP levels you're running on that turbo.

 

well EGT could be going up high with the retarded timing as well also why 10.x for fueling?
How were you hearing the knock? det cans? just listening to engine noises? some spiffy knock system setup?

 

Could be pre-ignition. The scenario is that you have a hot spot in your cylinder (usually the spark plug tip). By igniting late, less of the heat goes into the work of pushing the piston and more goes to waste -- i.e., heating up your combustion chamber hot spot and your exhaust.

You should try some colder plugs and see if that lets you get your timing back to normal. At 22psi with no Water/Meth injection, even 2X colder may be too hot.

 

Sorry everyone I forgot to mention that I have Toyota cops and KnocksenseMS (knock sensor). I completely agree with the stock coil pack being too weak. I have to swap to the stock ignition come colder temps due to the cops not sparking, and I cut the boost to around 15 psi because they break up.

I have wondered about phantom knock in the past but I am sure this was knock. I have MS set up to pull 1 deg for every sec of knock noticed. If I see 1 deg pulled, I typically don't get worried, but on one pull that we ended short I saw up to 3 deg get pulled.

As for the EVO3 16g, these turbos are great as long as the hot side housing has been ported. The DSM guys typically run these to 24 psi on their 4G63s, and swap them out due to the turbo not keeping up with the demand of the motor (psi tapering off with RPM). Yet this guy holds steady to 22 psi on my 1.8. My manifold air temp located in the outlet of the FMIC registered a max of 129 deg F thru all 11x dyno runs. If you are looking for cheap decent turbo for a build definitely give one of these a look.

Good questions!

 

I jacked with Knocksense for countless hours and I believe, without a doubt, that it's a total waste of money. Use your ears to listen for knock, not that knocksense.

I had trouble keeping spark above 16psi on my car with the Toyota COPs. I'd like to do LS1 coils one day. How much plug gap are you running?

 

I have the same plugs you mentioned in it – BKR7ES-11. Agreed on wilder mpas with these.

The motor is 9.8:1. Long story here. The short of it is I got a deal on high compression pistons from Wiseco (I think these were like 12:1), talked with Wiseco, and finally milled the dome/tops down to get the compression listed above. I was shooting for 10:1, but the end mill walked and the clean up passes ended up in the compression listed above. By the way I was able to keep the oil squirters with these – more fun.

I have KnocksenseMS keeping an ear on the knock – see my previous post. I will have to check the cam sensor and base timing again. I know the crank pulley is spot on. I had that thing fly off 2 years ago, and I dowel pinned it – no problems since. More to come on base timing…

 

double check cam timing.
get ignition timing back to the mid teens.
lean AFRs out to around 11.8
and the throw the knocksense out the window.

report back.

 

I got a .025" gap. This seems to keep the Yoda COPS happy. LS coils do rock, I just remember scratching my head on intergrating them with MS. I am going to get rid of the COP, due to the cold start issue. I was going to try these next: http://www.diyautotune.com/catalog/i...oil-p-394.html If they are good for that Huber 9 sec stang, they should be good for my ride.

The dyno guy and I were able to hear the knock, and knocksence agreed. Knocksense can be miss leading at times, but with it turned all the way down and on the lower portion of the block it is not too bad. Since my car is so loud it is nice to have as insurance.

What are you running for coils now?

 

thats way too small a gap too.

go back to .040"


jeez dawg. what you probably heard was the car disagreeing with everything you did wrong.

 

Agreed on the knocksense. Also, same for me with COPS. I had spark blow out at 14psi, and now with my LS1 coils at 17PSI I have no issues whatsoever.

 

11.8? That seams pretty lean. What boost psi and gas are you running at this AFR?

I have seen guys up here claiming this, but seams espically low with the 91 winter crap gas out now in Denver. My back ground is the DSM world and that is way too lean for them. My buddy has an EVO9 and that is tunned to 11.0-10.8 and puts 320 hp/375 torque. Any leaner AFR and he gets knock. My goal was to start leaing the Miata out on the dyno, but didn't quite get there.

I will definetly check base and add more timing. More to come...

 

Integrating LS1 coils is exactly the same procedure as COPS. Only dwell is different, wiring is the same as the LS1 coils have an internal ignitor.

 

Will the pull up resistor in there now drive the stock tach?

 

First of all, thank you for running man levels of boost.

22psi on 91 octane is kinda pushing it but you have some other issues to take care of before determining if you are knock-limited by your fuel.

Here are my recommendations:

-Gap to .025, not .04. You won't be able to reliably run a .4 gap at 22psi. BTW I like NGK race plugs, the ones FM sells with no protruding insulator/tip. They have been good to 35psi for me. Nothing wrong with what you have now though- those were fine for me at 30psi.

-Your map is WAY too retarded. There is a limit to how much timing you can pull and you've pulled it so much you probably still have fuel burning on the intake stroke haha

-For your highest load row, I would start with 18* @ 7800 RPM. @ 45000 RPM I would run 13* and start ramping above 5500. That is not very much but your fuel isn't that great.

-Run low 11's AFR. You are not running a subaru and you are also not running 40psi. No need for low tens. You are loosing power by running that unnecessarily rich.

-If you have logs from your pull check out your AITs. I wonder if your IC was heatsinked.

-Also as you realized, dyno tuning is not the same thing as road tuning. Ideally you have both. And yes, air resistance loads the car differently than rollers does. Road tuning can get you 90% of the way there though.

 

And yeah, I was serious about the AFR thing. Different motors like different AFRs for max happy and safe power.

I could and have run my miata at 12:1 @ 25psi without knock (93 pump) but can easily make it knock with timing.

 

I will add more to your thread later, but for now I want to say skip the coils DIY sells and get the LS coils. Wiring them in is reasonably simple and the bracket FM sells for them are really nice. I will be doing an LS coil write up in a couple of days.