MicroSquirt.com read only forum (Jan.15,2018)

im useing one of the spark tables from boost junkies web site and im haveing real problems with det so we retarded it by 5 deg and it still done it then we done that again still no different then we done it agian and it seemed to make it worse not better so my thinking is this as i have low compression am i going the wrong way ?? im running 8.0:1 on a t34 turbo and the turbo is glowing and i mean glowing !!! so am i correct on thinking that with lower compression i can run more advance the retard to stop the det
it got to 47 deg and was still doing it but i got another spark map i had on the laptop and turned the boost down it went to 172kpa and it was running less retard and seemed to run ok and i got no det
can to much retard cause det as well as to much advance ???

why does my turbo glow so much is it down to the spark map being out as i read some where that glowing manifold and turbo can be caused by to much retard


thanx for any help on this

and what about your a/f if you are running to lean the turbo and manifold will glow and you going to hear detonation.

11.5 -10.5 under boost i dont have a problem with a/f its a bit on the ritch side but i would prefer it that way than lean off boost it runns 13.5 to 15.5 its not a fuel problem

You need to post your .msq and datalog for info. Your spark map and any other info you can give might help determine what's going on.

Did you verify what your timing is doing with a timing light? Post more info also.

If you retard the ignition too much the spark will fire later and heat the exhaust side of the head up (valves etc) due to the hotter gasses leaving the head. Hot valves can cause detionation so you`re in a vicious circle at that point.

I can`t manage to run more than 7 degrees under load, under 3500 rpm on 12psi, after this I can gradually increase the advance to 15 degrees at 7000 rpm 15psi boost.

I run 2 grade colder plugs than n/a, that seemd to help slighly.

Running approx 9:1 cr.

right ive got it running so so now its running there abouts 12 psi and no det but my turbos glowing and i mean its glowing manifold and turbo are red this carnt be doing it any good can it ???


ive posted my msq so somebody ,might be able to tell me where im going wrong


engine spec

2.0 8v vaux engine

forged pistions running 8.0:1 c/r
steel forged rods
gas flowed head and ported and polished
arp bolts through out
2 1/2 in exhaust
t34 turbo
external wastegate

ive got and egt gauge and on idle it sits around 500 c
under boost its goes to 600-700 c

but if i give it a real raggging it goes over 800 and but drop quick to 600-700 c


this is the second turbo engine ive built in a year but the last one runns on standard vaux managment with a duel fuel pressur regulator to up the fuel on boost and it wont run more than 10 psi due to the fact there was no way of retarding it thats why i went m/s so i can have more boost and the engine on vaux managment newver glowed like this one does


whaty am i doing wrong ???

thanx again for the help

I may be new at tuning MegaSquirt, I have had a turbo car a long time with other management systems.The reason I went MS is so I can control spark under boost. you may want to try retarding the timing when you get in to boost. If i'm reading your spark table corectly, your putting in more advance under boost which I've been told is bad on the other hand, to much retard, will make a manifold cherry red as you say. My manifold runs red with normal timing( no retard and conservative advance).
Scott Bruce

I've seen a video of a turbo cosworth doing a pull on a dyno and the manifold goes from normal to bright orange in the space of one pull. Also parish's blue trucks manifold glows in one of the dyno videos on their site..

I guess whether it glows or not depends on what hp your shooting for..

screamer69 wrote:im useing one of the spark tables from boost junkies web site and im haveing real problems with det so we retarded it by 5 deg and it still done it then we done that again still no different then we done it agian and it seemed to make it worse not better so my thinking is this as i have low compression am i going the wrong way ?? im running 8.0:1 on a t34 turbo and the turbo is glowing and i mean glowing !!! so am i correct on thinking that with lower compression i can run more advance the retard to stop the det
it got to 47 deg and was still doing it but i got another spark map i had on the laptop and turned the boost down it went to 172kpa and it was running less retard and seemed to run ok and i got no det
can to much retard cause det as well as to much advance ???

why does my turbo glow so much is it down to the spark map being out as i read some where that glowing manifold and turbo can be caused by to much retard


thanx for any help on this

Ok we need some basic numbers here.........

Did I read correctly ? 47 degrees of advance? That much will grenade that motor in no time.

Boosted engines need less advance as boost rises. (There are slight exceptions)


At TDC it is 0
Lets assume this engine at full boost makes its best power at 20 degrees of advance. The spark is firing as the piston is squishing.

So what happens if you have too much advance. 47 degrees.
- Spark fires too early and you can have some serious knock.

Lets say we only have 10 degrees of advance.
- Spark fires and as combustion occurs a lot of it spills out the exhaust. PROBLEM. Burnt valves, turbo glowwing, EGTS way up.

If we have 10 degrees of actual advance and we say we are retarding by 3 degrees. Then ACTUAL advance is 7 degrees.


So the question I have .........What is your ACTUAL timing accross the 170kpa cells from 3000 rpm and up?

I would start with a solid value. Lets say 10 degrees (ACTUAL ADVANCE) across those cells.

I run a 2.5 with similar compression and run 18 degrees at FULL BOOST tapering to 23 degrees at high rpm for comparison.