MSD Total Loss curve suggestions...

[Watty]

Hi guys,

I've just got myself a new MSD Pro Digital, and I thought I'd throw up a post to see what curves other people are running.

I've used pretty much every type of CDI out there before, Advent, Vilder, Inferno, Enhancer, modded stocker so I thought I'd give the total loss a go.

My engine setup;

- 61X cylinders at 83mm
- Heavy cylinder porting (race, but still has good bottom/mid)
- Stock, untouched 62T cases
- ADA head with 35cc
- 46mm Mikuni's
- R&D Dominator with VF2 Reeds
- Factory B - limited
- Used for both racing and freestyle (can't afford 2!)

In the past, I have had good results with the Advent curve Y701-6, with the excpetion of pulling the timing out at 4500rpm.

Based on my engine setup, does anyone have any reccomendations for curve setup? I was thinking of running pretty much the same as what I was running on the Advent, but I'm wondering if the curve might have to be ramped down a bit due to the lightened flywheel, etc?

I have some conservative settings of;

25 degrees initial, 4000 retard, finish timing of 18 degrees at approx 7000 rpm.

These seem very safe, but I think I might be missing out on a fair bit of bottom end with the low advance. I am going to try them for a start and keep bumping it up until I either get detonation that I can't tune out, or fic with higher octane fuel, or I start losing power.

We have some pretty good 98 ron pump gas here in Australia that is readily available, and alos access to Avgas, and methanol.

I'm very open to your input here, as I have ZERO experience with total loss systems even though they are the same as any other CDI.

Cheers.

 

[Matt_E]

I ran the following very successfully:
29 degree static
Start retard at 5000
RPM Limit 8250
Final retard 17 degrees of static

 

[Watty]

Awesome, thanks Matt.

I'm going to go with those settings.

Another thing, does anyone else find the MSD instructions extrememly vague and hard to follow?

When I'm setting my static timing with the trigger plate, 29 degrees for example, I can use the switch settings to lower this, right? So, basically, you set your max static timing and retard from there, yes?

The MSD instructions need to be put through babelfish I think.

 

[Matt_E]

Yes! Set the static to 35 and do the rest with switches (max 7 degrees off)

 

[1550]

Matt_E: is that 17 degrees final at 8250 rpm? And are you using normal 95 gas?

 

[Matt_E]

No, I said 17 off static. That means 17 degrees retard off the initial 29, making for 12 degrees @ 8250RPM.

I am using 92-93 octane ((R+M)/2 ), which is equivalent to your 95. (R only)

 

[1550]

i think i have way too safe side curve.

im using now 25 static, retard point 4000 and 15 at 7000 rpm and rev limit 8500... Almost same ski, only 34 cc domes and mach 2 pipe with vater injection

 

[Matt_E]

You can crank that up a notch.

 

[waxhead]

i run 34 degrees with it pulling back sharply from 4500 on to 17 at 7200

works well for me

 

[Matt_E]

Pull back later. :biggthumpup:

J/K. Wax knows what he's doing. I have ran both configs - I tried 35 degree static with start retard at 4500, and then my current setup.
I liked the 29/5000 much better.


PS Jared runs his carbs weird, too. :haha: :fingersx:

 

[waxhead]

Big advance allows for big jets and big hit

hahaha

34 with that slope gives you 31 at 5000 rpm as a matter of interest

 

[Matt_E]

I didn't find the 5-6 degrees to make a noticable difference (TO ME!) off the bottom.

As an interesting side matter, I recently found that I had to rejet when I switched back to stock electrics (coming from MSD TL). Had to jet up one fatter.

 

[SUPERJET-113]

Mine is pretty much like Matts:
30 static
Start retard @ 5000
RPM limit 8500
Final retard 17 @ 7200

Here are the specs on my Superjet:
http://www.x-h2o.com/threads/19557

 

[Watty]

Thanks for the replies guys.

The reason I asked the question is that I always ran way more advance than everyone else (apart from Wax) seemed to. I figured there was a reason for the low advance (30ish rather than my 38 on the Advent) but apparently not!

I'm going to try and run something around the 35 degree mark and see what happens!

 

[Watty]

Hey guys,

Just thought I'd throw up a pic of my total loss mounted on the plate. It might give you some ideas. I used 5mm acrylic sheet that has all holes drilled and tapped. Once I have the ignition set to how I want it, I'll put some nyloc nuts on the back to hold it on, better, although it's pretty solid now.

I used the acrylic sheet so it would be one less thing for the spark to short to. I'm not quite finished yet though, as I have just ordered a couple more Deutsch connectors for the pickup plate and battery wires.

 

[waxhead]

looks awesome

yeah 35 will be great and pull it back to about 17 at 7000
start pulling out at 4500