what sort of 1.4 mile times is everyone running?

[nando]

ive been messing around with stock ignition curve shapes and others.. dont know if its my mods or what but i seem to be running the strongest on something alot smoother than the stock shape...

heres a comparison graph i made a couple months ago.. im running something like the one marked experimental in black. i removed the degree numbers from the side of the graph so people cant go and copy the WOT ignition maps im posting here but the black line peaks at like 38-39 so that should give u some idea of where the other ones are in comparison. i was originally basing my tunes on the AA tune and tweaking from there but once i cracked open a dinan fine and saw the shape didnt drop back nearly as much as all the others did in the mid range that got me started with experimenting in the mids.. i havent run into knock yet and its starting to look like i could probably a nearly straight line from the first peak all the way to the end of the map without knock.. dont know if that would lose me anything in the mids tho.

that has to be a ton of advance. I've seen the Jim-C map, and tried it, it's too much for my engine. Also, just because you don't hear knock, doesn't mean you'll make more power, or that it isn't knocking. MBT should come before the knock threshold (hopefully). You can only find that on a dyno.

the reason you drop timing in the mid range is that is the peak torque area. If you look at a dyno graph of an M20 you'll see the obvious torque plateau. Overlay that on top of a timing curve, you'll see an inverse correlation - the knock threshold at peak torque is much lower, so timing must decrease at peak torque.

also if you redline much past 6200, the scale of the stock map sucks. at 7500 you would be using the same timing as you are at 6200. Not good.

[kamotors]

not saying this is accurate, and it could be off, but...... with my accelerometer and a confirmed 1/4 mile my car did it in 15.2 seconds @ 90.4mph, with 195/60s, a 4.27diff,shift kit, MAF conv.,CAI,headers, and about 130lbs removed.

[Jaxx_]

not saying this is accurate, and it could be off, but...... with my accelerometer and a confirmed 1/4 mile my car did it in 15.2 seconds @ 90.4mph, with 195/60s, a 4.27diff,shift kit, MAF conv.,CAI,headers, and about 130lbs removed.

I could see that, but I trapped 90.6 in a FWD car at 14.9, pulling a 2.2. If you can get a better launch you could be in the 14s for sure.

my DD ran a 15.1@92, damn ECU holding back the launch. :-\

Didn't get a good run in with the e30 because of issues with hard launches and ignition, but I believe my 318 ran 18.3 @ 78mph

[DmcL]

btw if you run 16 seconds in a 1.4 mile drag race you have one fast mother fucker.

lol typo, meant 1/4 :razz:

that has to be a ton of advance. I've seen the Jim-C map, and tried it, it's too much for my engine. Also, just because you don't hear knock, doesn't mean you'll make more power, or that it isn't knocking. MBT should come before the knock threshold (hopefully). You can only find that on a dyno.

the reason you drop timing in the mid range is that is the peak torque area. If you look at a dyno graph of an M20 you'll see the obvious torque plateau. Overlay that on top of a timing curve, you'll see an inverse correlation - the knock threshold at peak torque is much lower, so timing must decrease at peak torque.

also if you redline much past 6200, the scale of the stock map sucks. at 7500 you would be using the same timing as you are at 6200. Not good.

yea i dont like that about the redline being after the end of the maps but its not that much of a problem because power drops off before 7k anyway.

also noticed the link between ignition WOT graph and a dyno graph myself.. its probably retarded back to give a more linear pull up the revs instead of being peaky in the mids and dropping back a little after that. im running a bit rich but even with an unshielded intake with an exposed filter i wasnt running into knock anywhere. i do have one of the later M20B25's with lower compression tho so thats probably part of the reason why.

at the drags on sunday i tried the current ignition curve (similar to the black line) and also tried the aplina B3 curve which is WAY lower and didnt notice any huge difference, i think the B3 felt a little weaker on the butt dyno down the strip. i also tried increasing/decreasing advance in some areas between runs on my current ignition map but i couldnt feel any difference and of the 9-10 runs i did all of them were trapping between 82-85mph and running an average of around 16.8, looking at the 60 foot times, most were around 3 seconds give or take 0.1-0.2 of a second so im pretty sure the 60 foot is what affected my overall times and not any tweaking of the map.

not saying this is accurate, and it could be off, but...... with my accelerometer and a confirmed 1/4 mile my car did it in 15.2 seconds @ 90.4mph, with 195/60s, a 4.27diff,shift kit, MAF conv.,CAI,headers, and about 130lbs removed.

that sounds about right..

[nando]

the only purpose of the dip is to avoid detonation. I'd seen the stock/JC/Dinan maps with the dip at peak torque but didn't understand what it was. I tried a curve with flat timing through the peak torque area (thinking torque would increase) - pinging everywhere. Then I realized what it was for. :)

Basically through the fat part of your torque curve is the engine's best VE and the cylinder pressures are much higher. At peak power VE drops off quite a bit, but since the engine is turning more RPM, it still makes more power overall. If you could plot an engine's real VE vs the torque curve, the shapes would be nearly identical.

Cylinder pressures are still lower at peak power though, so you can use more advance, and indeed you should since it takes time for fuel to burn, meaning you have to start ignition earlier and earlier to complete the burn before the end of the cycle. So you can see why flat timing from say, 6000-6900rpm is not good.

[nando]

it also makes me wonder about that Dinan curve. Safety mechanism? There's no way it should drop that fast. I suppose the stock 325i is tuned for a 5800rpm peak, but still. Yuck.

[DmcL]

read up on VE and cyl pressure, etc.. also interesting how the M20's combustion chamber was designed. sort of swirls the air as its filling the cylinders.

its not ideal having no adjustment beyond 6200rpm but since power drops off around there its not as big a deal as it would be on something running a 288 and headwork, etc.

i did some playing around with my own maps after seeing the dinan one. what u cant see is that the fuel curve rises basically just the opposite of where the ignition curve drops at the end. i think its like that to create a rich condition on gearchange for faster pick up in the next gear but its not really something u can tell via the butt dyno. i did notice the occasional backfire and a friend said blue flames shot out of my exhaust one night when i was running my map with a drop in timing and a spike in fuelling around that point.

following on from that im going to try and build a flatshift module which will cut ignition when the auto kickdown switch thats still in there is pressed and the clutch is also pressed, the injectors will keep fuelling but ignition will cut for the gearchange so should make for some nice fireworks lol

really sucks that theres not really anyone on my wavelength here in NI. theres some smart folks on an irish E30 owners site and an english site but no one really local to help me get the mad ideas flowing.. u should move over here nando lol

also since the dinan maps were all scrambled i dont think many people will have seen them other than me and maybe a few other motronic nuts. i can tell u that the dinan part throttle maps S-U-C-K big time. both to look at compared to the strongest ive seen (Active Autowerke 1st followed closely by Jim C) and also in practise, car feels super weak driving normally running dinan part throttle maps. from what i can see dinans chip is like an on/off switch, its like stock everywhere but WOT.

[nando]

you'll be disappointed to hear that the "button" is not a switch at all, but just a detent that gives you some feedback for the kickdown function. but it wouldn't be hard to hook up a switch there.

as far as flatshift, be careful cutting ignition. it can be an easy way to break rockers.

[DmcL]

i thought the kickdown switch was an actual 2 wire switch? wouldnt be hard to mod/change it..

whys cutting ignition make rockers break easier? not as soft as a traditional rev limiter? dinans rev limits (u know the way there is a primary and secondary limiter right?) are both set at the same value so the cut is more harsh than the likes of AA, JC, stock, etc. as most others ive seen run the limiter at 2 stages to cut the injectors in stages for a softer rev limit.

the ignition cut device would work only when both the kickdown switch is pressed and when u step on the clutch pedal so ignition would only be cutting when the clutch is disengauging during a flatshift, not before.

[nando]

it can cause backfires, which is hell on rockers. a fuel cut is better for us. the stock cut is definitely fuel only. there's only 2 banks of injectors so it can't really stage anything. :p

[DmcL]

well it cuts 1 bank first then the second if revs dont drop after the first bank cuts. on the dinan chip both banks are cut at the same time.

plenty of boosted and decently modified M20's popping flames all over the place.. wouldnt think it could break rockers without hearing alot of stories on places like r3v where people are posting up how they broke rockers after the car backfired.. maybe im wrong?

[Dark Helmet]

my car ran a 14.6 IIRC w/ 155whp/165wtq... and about 350lbs removed.

[DmcL]

whats that in BHP? everyone over here uses figures at the fly instead of at the wheels. stupid imo but what can u do.

[nando]

who knows; pick a magic drivetrain loss out of the air to "correct" the real WHP #, and come up with as big of a BHP as you'd like. :p

so 155whp with a 30% drivetrain loss, that's 221 at the crank! ;)

[Wh33lhop]

whats that in BHP? everyone over here uses figures at the fly instead of at the wheels. stupid imo but what can u do.

What? Who the fuck is using flywheel hp? That's like measuring your dick from behind your balls.