Tran

I forgot to add that this car has 9:1 pistons which would say it's even more retarded. Apparently it made 315hp with that spark map.... Another "professional" tune from the UK....

sixshooter

iTrader: (12)

If tuned properly the EGTs will be fine.

Miata events? Some of the local Tampabaymiatas forum guys meet up every week. Check that forum for details.

Highly retarded spark causes skyrocketing EGTs.

I didn't get to see his spark map because I'm still using the mobile app.

Tran

Thanks, I meant more as in any kind of Miata Autocross or Track day or even a cars and coffee. I'll take look at that.

Is the consensus here that my spark is so retarded that my EGTs have gone mad?

sixshooter

iTrader: (12)

High EGTs are often caused by retarded spark and Brain says your spark is very retarded... ergo...

I'm not doing any events right now because my car is apart for upgrades. Chin is doing a track weekend at Sebring this weekend.
http://chintrackdays.com/subevent.aspx?q=xVL48cM4P6w%3d

NASA and PDG aren't running locally in the next two weeks.

Hooked on Driving will be at Palm Beach International Raceway on the 27th.
HOD PBIR

Cars and Coffee is too dangerous.

lol.

There's a huge classic car cruise-in at Old Town in Kissimmee on Hwy 192 on Saturday afternoon and evening unless it's raining.

Tran

Thanks for the helpful response. Lol at the Cars and Coffee... I got a car that would be very suitable for that... I got really excited when I saw an ND Miata at the rental place, though less excited when I realised it was an auto and even less excited when I couldn't fit either of the large suitcases in it. So got a mustang but it's not cars and coffee drift spec (ecoboost auto).

I'm tempted to go to Sebring this weekend. Do you know what the Chin events are like to just pop down and spectate? I assume trying to blag a passenger ride is totally out of the question. I'll give the Old Town cruise a look too, though maybe next weekend.

Back on topic, is there a recommended base spark map to try? If mine is that far off, it probably doesn't make much sense to continue with it.

Thanks,

Tim

Tran

An update to this to whom may be interested.

I had checked base timing, but I hadn't checked it with RPM. I did this and it revealed that the timing was retarding with rising RPM. It wasn't a huge amount, but needed 75us on the MS3 before it held steady. By my calculations, this is worth ~3 deg of retard at high revs.

Also, I took the car to be mapped for the better fuel I'm going to run in it (99 RON, looks roughly comparable to US 93). Even with keeping a decent knock margin and doing painful 25 second det checking pulls, it was possible to reach MBT up to 16psi, which is where the tuner stopped since EGTs were hitting 900C in a 25 second pull. This needed an extra 4-5 degrees even with the latency correction.

I'm not quite sure what the limit of the OE VVT valves are, but don't really want to find out the hard way. I wish I had inconel exhaust valves, but the car feels plenty quick as is. (I'll see how I feel about this when my friend finishes his forged build with inconel valves...) I ran a full trackday yesterday at Brands Hatch Indy and EGTs were fine all day, though admittedly conditions were bad, so I was on low boost (10psi). We'll see how it fares at Silverstone later in the month....

sixshooter

iTrader: (12)

Do you have the settings enabled that pull timing with MAT? I had that and it killed two turbos on the track because of high egts.

Tran

I do have those settings, but they don't pull timing until 45C (113f) and the IC will hopefully keep MATs below that even in a UK summer. I've got the MS set to cut power if EGTs reach 900C which should hopefully save my valves and turbo if EGTs do creep up for whatever reason.

Which turbo did you melt and do you have an estimate of what your EGTs were when it happened? What exhaust valves were you running at the time and did they survive?

sixshooter

iTrader: (12)

They were Chinese 2870s. Method of failure was cooked bearings and hotside seals. Flapper rod for IWG started sticking, too. It stopped being a rod and began acting like a noodle above a certain point. I also had multiple fastener and downpipe failures.

I'll advise you to raise your threshold for MAT timing intervention and only remove timing fractionally when it becomes active. 140*F is not unusual for a factory turbo car driven hard on the track and superchargers can get higher. Pulling timing will make the entire engine run even hotter and will often overheat the cooling system.

I'm still running the same head and factory valves. I'm using the Supertech double springs. About 320whp according to virtual dyno, so 350 European horsepower, haha.

Running excessively rich can cause high EGTs because of the unburned or still burning fuel entering the exhaust. This can be exacerbated by a late spark.

Tran

Thank you for the information. It's good the head is still going strong. Is hard to know whether the quality of the turbos was a factor in that, or perhaps the stock exhaust valves can take more than my somewhat guessed limits. I'll start a thread in the engine section on that. I'm on the supertech doubles too now

How do you recommend to avoid knock at say 140F MATs if there is minimal spark retard there? Do these engines not really need much MAT retard?

sixshooter

iTrader: (12)

You don't need much MAT retard. I'm using pump gas on the track in hot weather in Florida. I'll look up the values I'm using when I get to my laptop if you want to see them.

Cold air is more dense than warm air so some tunes actually detonate more in cold weather. Cold MATs create a lot more cylinder pressure (and power).

Tran

Thank you for the offer, that would be great please when you get a moment.

sixshooter

iTrader: (12)

It pulls 0.5 degrees at 170 degrees and 1 degree at 190.

Tran

Thank you!