Tuning my DR750s on Chrome

[Ninja Performance]

Ethanol likes closer to 12.0 than 11.5

-Chris

[Trevor]

Anyone with much e85 experience have input? Is 11.5 AFR a lot harder to light off than 12.0? I was trying to produce a safe tune, but if leaning it out will give me some ignition headroom I will.

It makes a huge difference in ignitability at high boost/power. You'll see misfires / pre-ignition go down considerably. You're not going to get true knock in the low/mid 12's on E85 at 8.0-9.0:1 compression unless you're trying to run 40+ psi.

[J. Fast]

100% stock 99 vr4 timing map:

2687.5 21
2718.75 19
2750 17
2781.25 16
2812.5 15
2843.75 14
2875 13
2906.25 12
2968.75 12
3000 12
3031.25 12
3062.5 12
3093.75 12
3156.25 12
3187.5 12
3250 13
3312.5 13
3406.25 13
3406.25 13
3468.75 13
3531.25 13
3562.5 13
3625 12
3718.75 12
3750 12
3812.5 11
3875 11
3906.25 11
3968.75 10
4000 10
4093.75 9
4125 9
4187.5 10
4250 10
4312.5 10
4343.75 10
4437.5 11
4500 11
4562.5 12
4625 12
4687.5 14
4750 15
4812.5 16
4843.75 16
4906.25 17
4968.75 17
5000 18
5062.5 18
5187.5 18
5187.5 18
5312.5 18
5312.5 17
5343.75 17
5406.25 17
5468.75 18
5531.25 18
5562.5 18
5625 19
5687.5 19
5750 19
5781.25 20
5843.75 20
5875 20
5906.25 20
5968.75 21
6000 21
6062.5 21
6093.75 21
6125 21
6187.5 21
6218.75 21
6281.25 22
6343.75 22
6375 22
6437.5 22
6468.75 22
6500 22
6562.5 22
6593.75 22
6625 22
6687.5 22
6718.75 22
6750 22
6781.25 22
6843.75 22
6843.75 22
6906.25 22
6937.5 22
7000 22
7000 22
7062.5 22
7062.5 22


I have not pulled the plugs yet, maybe tomorrow.

You'll know if you're in the ballpark when you see the strap. Log numbers look like there's maybe another three degrees of advance left in there. Like Trevor and Chris also mentioned you have lots of room with a pump gas afr. I'm a full afr point lower than you. I run 12.5 at peak tq all the way thru and I tip in from 13.5.

[Chris@Rvengeperformance]

It makes a huge difference in ignitability at high boost/power. You'll see misfires / pre-ignition go down considerably. You're not going to get true knock in the low/mid 12's on E85 at 8.0-9.0:1 compression unless you're trying to run 40+ psi.

Thanks Trevor! I'll lean it out and report back.

[NOMIEZVR4]

5 star thread

[futurevr4man]

lookin good chris! i wish i had some flat road around here that i could do VD runs with. i cant find a single one though (and i have kept my eyes open for one)

[Chris@Rvengeperformance]

Haha we'll ran into some issues. I just joined the SBC today.

Before I even got out of town, just putting around the cel was lighting under some light loads. I figured maybe the tune was slightly lean in that area, I subtracted .4 afr pretty much over the map and smoothed the transitions to closed loop, so maybe it needed a little more fuel there. Well I don't think that was the case, we did one long pull and I knew it was down on power, started knocking bad.

Probably shouldn't have, but I limped it home and it sounds like a bag of hammers. Oil pressure is way down. We must have hurt it yesterday. This was a 98K motor that I replaced the rod bearings with clevites in. The clearances were pretty good, but I guess something was wrong, like the rod was out of round or something.

I'll drain the oil later and cut open the filter, but I'm positive at least one rod is spun. Looks like it won't make the NG.

[JasonY]

what the fuuuuuuuuuuuuuuuuck.



Jason

[OhioSpyderman]

Damnit Chris, and I just signed up yesterday and was looking forward to seeing your new beast

No chance you might get here rebuilt in a month?

Ugh....

Bob.

[Greg E]

This was a 98K motor that I replaced the rod bearings with clevites in. The clearances were pretty good, but I guess something was wrong, like the rod was out of round or something.

Noisy engine shows false knock at low loads. I never posted a thread about how to "tune" the knock sensor because my fear is it opens the door to people messing their engines up.

At any rate, you were probably just making too much power for that tired old engine. It seems right around when you get to the sweet spot with these turbos, the stock motor gives out...