My SN95 build thread - ms3x with LS coil conversion

[awing]

I got my car running full sequential spark and fuel over the weekend. A few bumps in the road, like usual but it's getting better. This is a DIY MS3 V3, with the MS3x expansion.

Coil packs are LS2 style from GM trucks around 2000-2004, maybe later. These are pretty cheap out of some junkyards, I bought from LS fbook groups. This is the D585 heatsink coil, and while a hot coil it has drawbacks. These will autofire if over-dwelled. This is good for the coil, but very bad for your engine as it can dangerously increase your timing. Default MS settings will overdwell these coils. Currently I'm running a flat 3.5ms dwell with no battery correction. I ran some tests on my bench to see where exactly these will autofire, and I have another set to test still - to check my first results, to make sure it's safe. 3.5ms should be okay under all conditions, but I'm thinking I should have picked a different coil. They were cheap enough though, $100 typical for 8 coils. I'll try to dig up my data to post later.

Rest of the kit is hall effect crank sensor from 64 Bit Tuning, which I modified my balancer setup to fit. Kit is targeted at fox setups, but I like having an SN setup still. Distributor is replaced with explorer 5.0 style hall effect half-moon sensor.

Coil Conversion

• awing
• Nov 20, 2019
• 4

 

[a91what]

Sounds good!

I am running the D581 coils for the first time on my build, they should work well with similar dwell settings.

 

[awing]

I'm still here years later. Sorry @a91what for not following up with you after your first remote tune session - 2 years ago was it? I've actually made some decent passes this week - my best of the night 12.02 @ 114. And it's been a streetable setup as well. I've tinkered with your tune, added timing and let autotune do it's thing here and there. I have some track logs to go back and mess with in MegaLog for my next session, my AFR was around 13 on this pass. I know there's an 11.9 to be had here.

Engine and trans setup is untouched from my sig. This was on stock front suspension, with the sway bar still installed. Car was on a 28x10.5 slick with a skinny up front. Rear suspension has stock uppers with new bushings, maximum motorsports adjustable height lowers, eibach lowering springs and strange single adjustable shocks, with a sway bar. 3.73 rear gear.

Car weighs 3,400 on the dot with me in the car and a half tank of fuel. 3,200 without driver.

 

[a91what]

Thats not bad, try adding a touch of fuel 13.3 is lean best power but I have found better results using 12.5 for best power. What timing did you end up with? and does the timing slightly increase toward redline?

 

[awing]

Yes it increases, it's at 32 degrees at 6500 rpm and carries that until I shift. I was going as far out at 6800 RPM but I think my camshaft quits by 6500. I think you threw a conservative 29 in there to start. I kept bumping it and gaining MPH so I'll keep trying.

I'm the one who made my timing pointer and did my TDC 0. So I understand I could be off by a degree in either direction.

 

[a91what]

Thats the correct approach, try bumping it another half degree