Dudemaaanownsanrx7

iTrader: (23)

I'm running a PFC/dataloggit, tubular divided manifold, 3" DP, midpipe, and catback, 50 mm hks open gate, short pipe front mount intercooler, and a large street port. I just went from a t61 small shaft with .84 hotside, to a masterpower t70 big shaft (i think) with a .96 hotside.

I never spent much time tuning the boost ramp because It was pretty much fully spooled by 3600 rpms. I could step on it at 3k and it would break the tires loose instantly. With the new turbo I can step on it at 3k and wait wait wait then it starts to kick in around 4000-4200 with full boost I would guess around 4500. At idle my old turbo would be spinning its *** off, the new one is just barely turning.

I like the new turbo, and it pulls like a **** once it gets spooling, but I would like to maximize my tuning to reduce spool to get all I can out of this setup.

I'm wondering what kind of timing people have experimented with at say 6 psi and under into vacuum, and below say 4500 rpms or whatever your turbo gets spooled by.

I used to use the PFC base map IGL timing for everything in this area, and changed it from 10 psi up to 17.5 psi. The split map goes from 0 split to 4* then gradually up to 12* split at higher boost.

Now I've bumped everything up a few degrees on the boost ramp, and leaned it out to about 12.2 afr. It seemed to make a noticeable difference. I'm thinking of going a little higher on the timing during and before spool up. To me it still appears pretty conservative.

So what have other people tried in these areas and with what result?

Dudemaaanownsanrx7

iTrader: (23)

does no one else tune this area? or is it a secret?

arghx

iTrader: (3)

I think I ran around from 25-20 degrees from 0-6psi, decreasing as boost comes on and varying with rpm. that's with 8.5:1 rotors though. I basically advanced the timing a couple degrees until I felt that the spool wasn't improving much--kind of a seat-of-the-pants approach. I'm hoping a dual EGT setup well help with tuning this. Otherwise you are just flying blind.

I think Howard Coleman was running like 1300-1400 degrees EGT during spool and 1550 at full boost

Dudemaaanownsanrx7

iTrader: (23)

Yeah when HC was first starting out with the alcohol system his EGT's were like around 1000* F and he mentioned advancing the timing to get them up higher which improved spool. He never said where his timing started and where he ended up putting it though. I'm sure it would vary from car to car, but I'm interested in what other people are running and the results they had.

Thanks arghx for sharing your numbers and approach. That's basically how I did mine too, I need to get a dual EGT setup just not looking forward to figuring out how to weld some bungs for the probes with the manifold still bolted up....

gusfd3s

Actually you will get higher egts by retarding the ignition, not by advancing it...
by retarding it you might lose 20hp but gain 1 pound of boost at same rpm, by advancing it you might gain 20hp but
you are down on boost.. i think you'll need a dyno to sort this out..

How about keeping a good advance and leaning it out a bit on spoolup for higher egts?

Dudemaaanownsanrx7

iTrader: (23)

Yeah I have the spool up area leaned out to low 12's. I don't think I would want to go much leaner then that, but it did help. Advancing the timing seemed to help too. I know there is mixed feelings regarding which way increases spool. To me it seems whatever makes the most power will generate the most exhaust, combustion pressure, and heat, therefore causing the turbo to spool faster. The car seems to preform better overall with the leaner afr's and more timing in this area.

Now there are antilag systems that retard the timing a lot and dump fuel which then allow for boost to be made at idle because the combustion process happens in the exhaust housing rather then the combustion chamber. This isn't really practical for a street car though.

I'll try retarding the timing a considerable amount to see if it does generate boost sooner, but i have a feeling advancing it is the way to go. I agree a dyno would be the best way to sort all this out, but where I live and my situation isn't practical. I am tossing the idea of getting one installed in my shop though, being the only one in town should allow it to pay for itself over a few years.

Maybe more people can share their results of retarding or advancing timing and the effects it had on spool. I like these kind of discussions.

fd_neal

iTrader: (4)

This is an area of the map ive barely played with but if it helps. I run 18-16* advance for the onset of boost. AFR's get tapered from 12.5-11.9 for the 1-6psi range.

I run an aspec 3574 with a 1.0 hotside and see full boost by or before 4000rpm

Dudemaaanownsanrx7

iTrader: (23)

That sounds pretty close to the PFC base map timing for the boost ramp under about 3400 rpm with it increasing to around 21* by 4k at under 6 psi. That turbo is the journal bearing gt35 right? with 74mm exhaust wheel. Sounds pretty close to my old turbo. I never spent much time on the boost ramp on that turbo either cause spool just wasn't an issue. Thanks for posting

Trots*88TII-AE*

iTrader: (11)

Well FWIW, this may or may not help you, but this is a text file containg the stock Leading, Trailing and Split timing from a 2nd gen N332 ECU. I know this is stock turbo, different motor, etc. But, interesting to note is that the IGL stays moderately high, 14-35, but the split is actually negative for a large majority of it. Firing your IGT before the IGL creates a lot of exhaust pressure, because I would say it simulates a pre-ignition event, but only under vacuum or VERY low boost (you wouldn't want to try this at even 5-6 psi)

Dudemaaanownsanrx7

iTrader: (23)

That is some weird looking timing compared to what i'm used to seeing.

Splits as high as 25* and some very very high timing under high boost high rpms. Though there is no reference to tell me how many psi it goes up to, or where vacuum ends and positive pressure starts.... so it could only be up to like 8 psi or something.

the negative split areas are very erratic also. jumping back and forth from no split to positive then to negative all within a few cells of each other. I'm sure glad i never saw that map when I was trying to learn about rotary timing, I would have been forever lost haha. Interesting factory map, but finding a definite pattern is beyond my abilities haha.

I'll post up my latest map later. I played with it for a little while but haven't tried running it on the car yet.

Trots*88TII-AE*

iTrader: (11)

Yeah, I don't know the exact "legend" to it, and you cant really use it as a direct reference "punch in the numbers". But it's just interesting to note that in almost all the vacuum or low boost (first 5 rows) they run negative timing, and in the higher load they run a pretty steady 15-16 degree split, even though the IGL is all over the map.

About the high timing in high boost/rpm, after peak torque, you can advance the timing some, but it's a completely different ballgame at 8 psi and 20 psi. Take it for what it's worth, cause you can be sure Mazda did a lot more research in figuring out a timing map to suit a large variety of built engines and to work well, produce power, be conservative and give good mileage.

Dudemaaanownsanrx7

iTrader: (23)

yeah I advance mine a few degrees at higher rpms but not anything like the 10+ degrees they have going on. It is an interesting map none the less.