Pinging at track

[jerrah]

I thought I had my car running fairly well with a road tune but I found at QR monday that I couldn't use more than half throttle without inducing pre-ignition which was to say the least - a little frustrating.

With the car cooled down the car ran fine on the way home and no amount of being brutal on the road can induce pinging so it has to be to do with the continuous high load boost running at the track.

I currently have no undertray and my ducting is pretty much non-existant. With my head in the mouth I can see out the wheel wells so air is definitely bypassing my radiators.

I've pulled 2 degrees of timing from 6psi up which has left the car feeling flat but should be safer at the track, would fitting ducting around the mouth~intercooler~radiator make a significant difference or do I need to run retarded timing and a bigger intercooler? Currently using a 12x18x2.5.

I datalogged my runs and I'm not running lean anywhere in boost with a solid 11.5:1. Intake temps didn't look outrageous but the coolant temp goes up to the high 90's but comes down quickly as soon as the load is removed.

[Steampunk]

...would fitting ducting around the mouth~intercooler~radiator make a significant difference.. .

Yes, but I would say it's more your timing.
This is the reason that other car blew a head gasket.
Very restrictive front grille (poor air flow) + no air redirection plate (compromising flow through the radiator) + bypassed heater core = very hot engine.

High 90's coolant temps is within normal range. I'm assuming in deg Celcius?

You didn't bring your laptop to the track to play around with the tune did you?

[NitroDann]

Post ignition map or msq.

Do you have a reroute?

And yeah good ducting is very very good.

Dann

[Ippa]

If you datalogged your intake temps and they dont look bad then it will be your timing. On the street you are in boost for much shorter durations and hence you will be running a much lower egt. you could consider buying an egt gauge as this is one of the best tools to use to avoid pinging and burnt exhaust valves.

My advice is to first fit your stock undertray if you still have it, you will have to cut any holes required. The next step would be to make up the top radiator cover. This will stop the air flow escaping above or below your intercooler and rad. If you want to get really excited you could make up some custom ducting to box the whole mouth area. I would also consider making up a mania style intake if you do not already have one, as this will greatly reduce your intake temps as opposed to sucking hot air in from the engine bay.

[Ippa]

I agree with Dann, post your msq or ignition map if you are running an MS and i can compare to what i am running.

[jerrah]

I think there was probably a number of reasons why the NA8 blew a head gasket, and the split radiator probably had a large part of it.

No grill on my car, mouth is wide open but air can cleanly pass straight past my intercooler and radiator. I also have an air conditioning condensor in front of my radiator so it's not an ideal situation.

Don't have MAP or MSQ with me, timing is similar to Flyin Miata base timing for their turbo kits with a few degrees removed. I'll try to get ahold of the MSQ soon.

Yes I have a reroute.

I have a cover over the opening above/in front of the radiator.

I'm thinking of boxing in the mouth and around the radiator/intercooler and making a new undertray.

I don't think I'd have room for a 'mania style intake' with the supercharger in the way.

[jerrah]

Ignore below 100kpa (because I'm running completely different numbers there) I copied this for my boosted section. Runs great on the road and even getting the car really really hot and pounding it up steep hills won't make it ping. But a moderately warm day at the track after one flying lap I had to limit myself to around 6psi (WOT is about 10psi). Car ran fine at 6psi and was still making solid power.


re: Braineack in http://www.miataturbo.net/showpost.php?p=745010&postcount=12

[timk]

I seem to recall an IAT compensation table on the MegaSquirt where you could pull timing relative to IAT. Wouldn't this be the best way to do it?

[NitroDann]

Timing map doesnt look stupid, but its off a turbo car right.
Anyways, long story short its an ait issue, either use the ait ignition trim like sab says, or get some water/meth/e85 or just get some ducting so air actually gets through the intercooler.

See my ducting pics. Mine works incredibly well. Stock rad, no fans, and on a normal day I have trouble getting it up to temp.

I can sit still, reving at 4k until it boils then immediately row it through the gears and by 150kph im back to regular op temps.

Dann

[zoomzoom]

Jerrah,

Be careful there is IAT comp in the code. It is not anywhere in the tuning screens, but in the code is a IAT compensation built in, which removes fuel for rising intake temp. This is meant to help maintain the correct AFR but what I found was it does just that, when you want/need the excess fuel for cooling charge and safety from pinging. In MT there is a IAT comp which can be set by the user, when I was having problems I turned this on as it wasn't as default. I graphed the inverse map of the compensation built into the code and put it in the comp in MT, so the ECU wasn't pulling fuel for higher temps. This helped a little. Keep in mind this was for MS1 and I havn't played with MS2 or MS3 but I would imagine it would be similar.

Cheers,

Tim

[zoomzoom]

I found this on my old HDD, this is the std correction you shoulod be able to find this in your source file under airdenfactor, the numbers down the LHS are the correction factors for the coresponding temp. I found the inverse of this and put it in the correction map in MT to stop it pulling fuel at higher temps.

[NitroDann]

Sure, thats a good point.

But I must say that theres 2 common ways to reduce det. Adding water is one, and the only worse way is adding fuel.

You really need to tune the ait ignition curve.
Some of the issue is that your blower is nowhere as efficient as a turbo, it creates a lot more Intake charge temperature. So if youve taken an at; or close to the limit turbo ignition map, youll definately ping due to your blowers low efficiency.

Just taking a few degrees out across the board to make up for this isnt really perfect as your blower isnt just 20% less efficient across the board, it may be 15% inefficient at 240cfm and 22% down at 270cfm etc etc.

Do you have access to a dyno?
Do you have a good mate to drive and a big abandoned very steep long hill?

Dann

[Steampunk]

....a bigger intercooler? Currently using a 12x18x2.5.

.... the coolant temp goes up to the high 90's but comes down quickly as soon as the load is removed.

Intercooler seem like a good size, but I'm intrigued as to the quick reduction in coolant temp as soon as load is reduced.
To me this seems like under heavy load, intake charge temp is really up there, because even after a cool down in the pits, it still takes a few minutes for the coolant temps to decrease.
Is the intercooler flowing properly? possible blockage?
What does your datalog look like in MAT? (manifold air temp)

[Ippa]

All good comments here. Definitely sounds like its a combination of issues causing it. Just a few other things to reduce pinging.

Install an oil catch can if you dont have one.
Stick you hand in the end tank of the intercooler, im assuming you have the original engine with a fair few kms on it, if you do you might find that you will have a lot of oil all through your intake and even possibly inside your intercooler. Most of the time its not that bad, however, you are still blowing oily vapours into your cylinders, this effectively reduces your octane rating.

install colder spark plugs.

Good luck

[jerrah]

Install an oil catch can if you dont have one.

Done.

im assuming you have the original engine with a fair few kms on it

Nope, NB6 engine with low km. Pistons and bore still look new.

if you do you might find that you will have a lot of oil all through your intake and even possibly inside your intercooler.

Oil in the intake but not in the intercooler, it's clean as a whistle. Intake oil was coming through my dud PCV.

oily vapours into your cylinders, this effectively reduces your octane rating.

Possible, I installed a GTX PCV day after the track day and the old one was well stuffed.

install colder spark plugs.

Using NGK BKR7E-11.