Custom/Hybrid msd tl curves for bpipe,pfp and RRP

[speedysprocket]

I just read the MSD 42351 manual again. I never noticed that HSR switch before. Seems kind of mysterious as to how it works and what it's doing. Not sure I trust it.

 

[masterblaster]

dont think anyone but a hardcore racer would take the time to setup a momentary switch for a hole shot rev lim. Im sure now that youve reread the whole manual your privy to all the nics and nacs. I memorize it and then forget by the next time i need to tune ign....

 

[waxhead]

My hx I used to run up to 35 degrees down low where the dynamic compression was low but when it came on then you had to get rid of that timing fast. Most big bore two strokes want to be at about 15 degrees at there max hp figure and a little bit higher at there max torque figure. When you start really big boring them you run less advance as they don't deal with the heat as well due to a longer heat path to the outer walls of the cylinder

 

[masterblaster]

I use to run 35 for a while and pulled it from 4500 up,got down to around 17 by 6800,never saw and det with that setup on a small stroker,but im moving to a 10 mill platform and trying some diff stuff.
Ive heard some say the larger motors need alot of timing for the flame speed across a longer distance,never made any sense to me. with no wide band or dyno info in this sport its really hard to say whats better. I dont really wana push it till visible det and then back off.

 

[waxhead]

Good luck with running more timing up top on a big bore I hope you have heaps of pistons avliable to you, The transfer flow over the top of the pistons is what is responsible for alot of the cooling and there isnt the transfer flow in a big bore in comparision to the extra heat energy being generated. This is another reason to not be reving a big bore hard and another reason why we should be running strokers over big bores

 

[WILKEY]

who pissed in your beer?

Yall and your retard talk.... hahaha

 

[masterblaster]

wax,your preaching to the choir with stokers vs big bores,especially with the price on quality 10 mills now.I think you may be surprised when you see what these asymmetrical transfers are capable of when its all dialed in.but i follow you on the big bore timing principle

what kinda rpms are you turning with the pipe your using. I dont have alot of experience tuning ign for big pipes,but i got the b pipe fig out with most the motors ive run and msd tl. Ive seen alot of older advent and vilder curves back off in the higher rpms where the big r&d, type 9, speed worx, and octane pipes sim to the pfp made most their torque,then go back up a little at the very end of their capable rpm. cant do this with the msd tl,but still thought it was interesting they were doing that with programmable ign and racing setups

 

[jetpilot36]

im trying to setup my TL. i just got the 42351. ive been using the 4270 for the last 3 years, which is dummy proof basically. can you guys give me your opinion on my timing curve? 28 degrees initial .pull timing at 4500 with a rev limiter @8500
total retard: 12 degrees. that should put me at 19degrees at 7500 rpm. ending up at 16degrees at 8500
that curve worked great with my last MSD.
701 83mm pistons
b pipe
stock pump 9/15 hooker
44mm black jacks
R&d pro series head 210psi

also can i just program everything on the dipswitches. AND THEN set my starter retard feature to ON? im not sure what the instructions mean on page 8 where it says " this will add 4000rpm to the retard begin speed when in the on position"

 

[masterblaster]

Good luck with running more timing up top on a big bore I hope you have heaps of pistons avliable to you

heres another quote from tpe..Bigger pistons need more advance, not to make up for anything but to give the flame more time to travel across the width of the piston crown. ever seen those transfers?

jetpilot..i assume at 210 psi your running race gas,you need to look at the curve more in the 7000 range and see where you would be there with a bpipe,you wont ever see those higher rpms under a load in the water with that b pipe to get to your safe low timing seting

 

[jetpilot36]

yes im running 50/50 av gas and 93 octane.

my question is does the starter retard feature effect the timing curve at all? i should be able to program my timing curve, then turn on the starter retard. am i right?

 

[Breese08SJ]

I don't have manual in front of me but from what i rem. Start Retard only has effect up to 1000 rpms. So if your idle speed is at least 1000 rpm it has no effect on the timing curve.

 

[masterblaster]

starter retard just makes the motor start easy,it turns the ign fire off for 2 revolutions of the pickup to magnet,does not effect curve. Use the curve map chart from msd and plot your curve so you are around 14 to 15 deg by 7000 rpm with the b pipe. you can push it a lil further with the av fuel your adding to 93

your other point about the plus 4000 rpm switch...that is for motors that operate in the much higher rpm range,makes the msd tl more usable for many diff applications