Megasquirt Tuning

[Caveman]

does anyone know the all in advance on a 4age smallport and a good all in advance with a smallport running itbs and free exhaust. Should I advance slightly more/less?

Thanks

[johntramp]

This may be of some help, http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_mki_toyota_mr2.htm

[matt dunn]

We normally set N/A race engine to 36 deg at full advance,
and ramp up from 6 or 8 at 1000rpm to max advnace at 1/2 max RPM.

thats normally on a dist setup with springs and weights,
but the theroy should be the same

[Caveman]

ahhh yep thanks from the bit of research I did it was around 36 all in but some had strange increments, I think matts idea sounds good. Just to confirm thats 36 from 10 degrees base timing? 20 degrees at 1000rpm sounds good too

edit: 20 degrees at 1000rpm meaning 10 base + 10 advance

[matt dunn]

Not sure how you are interpreting that? but

1000 rpm = 6 deg base + 0 deg Advance = 6 deg total
2000 rpm = 6 deg base + 7 deg Advance = 13 deg total
3000 rpm = 6 deg base + 15 deg Advance = 21 deg total
4000 rpm = 6 deg base + 23 deg Advance = 29 deg total
5000 rpm = 6 deg base + 30 deg Advance = 36 deg total

Something like that.

[Caveman]

Oh ok I got the 20 degrees at 1000rpm from garage dori

http://garagedori.com/forum/viewtopic.php?t=874&highlight=4age+timing

But im not running crazy compression like them

Im guessing for a smallport something like

1000 rpm = 10 base + 10 advance = 20 total
2000 rpm = 10 base + 14 advance = 24 total
3000 rpm = 10 base + 19 advance = 29 total
4000 rpm = 10 base + 23 advance = 33 total
5000 rpm = 10 base + 26 advance = 36 total
6000 rpm = 10 base + 26 advance = 36 total
7000 rpm = 10 base + 26 advance = 36 total
8000 rpm (limiter) = 10 base + 20 advance = 20 total

can you go slightly more than 36 on a 4age?

cheers

[QikStarlie]

depends on the fuel your running ? i can only get 95 octane up here. will start to detonate at anything more than 29 degress total. and less than that at lower revs of course. litstening for det with detset. stock smallport with slivertop quads, extractors, exhaust.

dout you would gain anything from going past 36. even if theres no detonation. go to far,and it'l make less power.

[spencer]

yea just sort it out as you learn to tune, Gives you alot more insight than just banging in someone elses numbers

[matt dunn]

IMO 29 at 3000 is a bit much.

Every engine is different,
If you want the most power get it done properly,

And remember, 15 Hp less is better than a buggered piston.

[mister2]

Dude, best way to learn is to stick it on a dyno, with appropriate knock gear. Most tuners will rent/run the dyno for you while you're tuning - it is a hell of a lot less dangerous/illegal than trying to road tune timing. Providing your fueling is ok (which is fairly easy to get right on the road) then you should only be on the dyno an hour or so which is cheap.

Then you know it is right.

Cheers

Nick

[Caveman]

Ahh yep thanks guys, im just looking for a bit of insight right now

Ive never tuned a motor before, thats the reason im asking the questions. Mistr2 it would be nice to dyno tune, however I dont think I can afford it...

After the cage is built ill be racing for a bit then hopefully installing a megasquirt and itbs, just getting info for now

thanks for all the comments, they're all really helpful

I could run matt dunns figures on startup and see how that runs, if its all good then ill probably leave it as that Although after talking to a few other people they recommend only about 32 degrees all in.

so...

1000 rpm = 6 deg base + 0 deg Advance = 6 deg total
2000 rpm = 6 deg base + 7 deg Advance = 13 deg total
3000 rpm = 6 deg base + 15 deg Advance = 21 deg total
4000 rpm = 6 deg base + 23 deg Advance = 29 deg total
5000 rpm = 6 deg base + 30 deg Advance = 32 deg total
6000 rpm = 6 deg base + 30 deg Advance = 32 deg total
7000 rpm = 6 deg base + 30 deg Advance = 32 deg total
8000 rpm = 6 deg base + 30 deg Advance = 30 deg total