M8 track speed

rcaustin · Sep 8, 2009

I am running an 08 M8 with a boondocker race gas turbo kit. Last season I had a few problems with boost leaks but I have them fixed now and I am able to make lots of boost with no problems what so ever. The issue I have is making track speed. typical M8's running 12-13 lbs boost (what I am running) are supposed to pull 80-90 mph track speed while climbing correct? Well I am only pulling 45-50 mph track speed. (153" track) I haven't had much time to play with clutching due to the boost leaks I was trying to fix so I was wondering if anybody has some clutching specs that allow them to pull those kinds of track speeds? I am running stock gearing, 75.3 gr weights, straight 44 degree helix. can't remember spring colors off the top of my head.

I think I have it tuned fairly well right now, I am running 1250-1300 on my egt's and my air fuel ratio is good as well so i don't think its a tuning issue. I know once I make the turbo work harder I will have to increase the fuel requirements to prevent it from getting to lean.

If anybody could help me out if its an aero or garret or any turbo kit out there for clutching specs that would be great... I think I need to throw a bunch more weight at it... 80 grams for starters?

Any help is appreciated.

Thanks,
Ryan

x-5 · Sep 8, 2009

Ya you need clutching help...I would pm snow jw he knows how to set them up...We have a pgt 09 m8 with a 162 running 60 to 65 on 7 to 8 psi

lightening800 · Sep 8, 2009

60-65 at 10-11 psi on long hard pulls pm me if you want some clutching tips.

hatchers · Sep 8, 2009

a stock sled will see 40-45MPH
a optimal TM8 will see 60 or more
a straight 44 cut is a hill climbing helix

- do you have stock clutching?
- something is waaaaay off to see such a low track speed, you need to take a marker to both primary and secondary and see where your belt is shifting to
- your secondary spring can be too stiff
- or your primary too stiff for the lack of pin weight...add weight or change to a lighter springs....it all depends in how you want the sled to react

JHG · Sep 8, 2009

It sounds like your primary weights are to light. I talked to Dale Cutler last week about clutching mine and he was saying 79 to 80 gram weights @ 12 lbs, and something like a 36/46 helix. His clutch kits and springs are a little different than the others so this might not work unless you're running his stuff. He recommended a straight 44 helix for drag racing.

twsandrew · Sep 8, 2009

I haven't heard of any TM8s in the 80s but you should see high 60s and maybe low 70s on good boost with the right clutching. As everyone has said, you likely don't have enough weight in it now that you aren't leaking boost.

lightening800 · Sep 8, 2009

also at 10psi at 7000ft you probobaly only a honest 190ish on a 800, so anywhere in the 60s is going to be good track speed. now my apex set at 290hp will hold 85ish mph in altitude, just an eg what 100hp will do lol.

winter brew · Sep 8, 2009

I agree....clutching! And maybe gearing. You setup is what I ran in a 170HP M7 bigbore. And what's the deal with EGT's in a turbo application? I understand there are some much different numbers to aim for than with a N/A engine?? Do you have access to a A/F gauge? Might make it easier to compare tuning notes with others since that seems to be the popular method for tuning. :beer;

rcaustin · Sep 8, 2009

Yea I have an A/F guage on it as well... running between 11.0 and 12.0 WOT... slowly creeps up to the 12.0-12.3 range on a long pull.

So i guess the first thing I should change is add weight... somewhere around the 80 gr range and possibly change the helix to a compound angle 36/46 or something.

I want it to pull hard on a hillclimb but be responsive for boondocking etc. I know it won't be as snappy due to the spool time needed but you know what I mean. I am also runing an ovs secondary clutck kit... so i can crank up the torsion or back it of to make it upshift harder or slower etc.

I will look at my spring colors when I get a chance and report those as well... see if you guys think those should be changed as well.

Thanks,
Ryan

SSWIM · Sep 9, 2009

Wow. You guys are getting some serious track speeds out of your sleds. I guess maybe it is our elevation that "kills" my track speed. At 11000-13000' my TM8 at 10lbs. of boost will pull approx. 55-60MPH. My TAPEX at 19-20lbs is in the 70-75MPH range.

I must be doing something wrong.

Sam

JHG · Sep 9, 2009

SSWIM said:
Wow. You guys are getting some serious track speeds out of your sleds. I guess maybe it is our elevation that "kills" my track speed. At 11000-13000' my TM8 at 10lbs. of boost will pull approx. 55-60MPH. My TAPEX at 19-20lbs is in the 70-75MPH range.

I must be doing something wrong.

Sam

I don't really think you can look at track speed for a measure of anything. I think everyone an honestly say it should be more than 40 mph w/ a turbo but past that there are to many things that change it. I know one day it's high and the next it's low and no changes to the sled have been made. It's all about snow conditions. I've also never been on a snowmobile at 13000' so I have no idea what difference that makes.

rcaustin · Sep 9, 2009

I agree there are many things that change after 40 mph... but every day i rode it after i got the boost leaks fixed... (6 days of riding in mountains) I was running the same low track speeds. 45ish mph. Just looking for some clutching req's that get me in the ball park... after that I can fine tune for each day as required.

WyoBoy1000 · Sep 9, 2009

I've never seen less than 40mph on my na m1000. I don't know much about the tm8 but I saw 60+mph out of a pg tm8 at 9,000ft. it was the rtr m8 kit from boonedocker on 5-6lbs and pulled my modded m1000 easily. I would start by calling some of the pro turbo builders: Cutler, twisted, bd ect....

rcaustin · Sep 9, 2009

No the boosted sleds run a higher degree angle on the second half because you have twice the hp's when your turbo spools up vs when you are at an idle... low angle for NA condition @ idle and high angle for boosted condition. I don't know why I am running a striaght 44 after I just wrote that....

Jkinzer · Sep 9, 2009

i may be comparing apples to oranges here, but on my sled D8T i was having trouble getting track speed last year so i geared up 2 teeth higher, and added some polaris series 10 weights (heavy heel profile) that were about 2grams heavier than i needed, i then ground off 1.5grams to make the arm of the weight a little lighter and make up for the excess weight, while keeping the heavy hitter style of weight... this was the fix for me, took my track speed from the low 50's to mid 80's at about 13lbs of boost.

deaner · Sep 9, 2009

Jkinzer said:
i may be comparing apples to oranges here, but on my sled D8T i was having trouble getting track speed last year so i geared up 2 teeth higher, and added some polaris series 10 weights (heavy heel profile) that were about 2grams heavier than i needed, i then ground off 1.5grams to make the arm of the weight a little lighter and make up for the excess weight, while keeping the heavy hitter style of weight... this was the fix for me, took my track speed from the low 50's to mid 80's at about 13lbs of boost.

That is kind of charactaristic of polaris clutches though isnt it? All of the old school tuners I know always swear by gearing up to gain track speed on a mountain sled. But.........these guys all run P85/team setups regardless of the sled they are running. I know this theory doesnt work with Doo clutching. Ive tried. But boosted sleds are probably a whole different ball game too??

bigbull · Sep 9, 2009

Jkinzer said:
i may be comparing apples to oranges here, but on my sled D8T i was having trouble getting track speed last year so i geared up 2 teeth higher, and added some polaris series 10 weights (heavy heel profile) that were about 2grams heavier than i needed, i then ground off 1.5grams to make the arm of the weight a little lighter and make up for the excess weight, while keeping the heavy hitter style of weight... this was the fix for me, took my track speed from the low 50's to mid 80's at about 13lbs of boost.

I basically did the same thing with the M7 Turbos we built a few years back. They worked great.
BB

KAWGRN · Sep 10, 2009

where did you grind the weight ,,off the tips, sides, bottom??

Jkinzer · Sep 11, 2009

i ground the weight off the outside... made the arm skinnier... i needed the heavy tip to get all i could out of the top end

RockyMtn.Kris · Sep 11, 2009

SSWIM said:
Wow. You guys are getting some serious track speeds out of your sleds. I guess maybe it is our elevation that "kills" my track speed. At 11000-13000' my TM8 at 10lbs. of boost will pull approx. 55-60MPH. My TAPEX at 19-20lbs is in the 70-75MPH range.

I must be doing something wrong.
Sam

You are. You are riding too high! Hahahahaha

M8 track speed

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