Turbo clutching ?

[mmsports]

Okay so recently I had a guy contact me with clutching question. I was blown away at his clutching on a 08 M8 race gas turbo he is running a straight 36 helix and 77 g cat weights and under tacking. he has since ground 1.5 g off to try them to see if its better. So since I have never under clutched a turbo so much has anyone else ever seen this kind of clutching?

My theory is its like how a turbo will not build more than like 3-4lb of boost on a jack stand do you think that if you under clutch you get same results?

I believe that turbo's love load and must have it . I have road like a BD turbo with 80G cat weights and I think the run good but very week same with OVS clutching runs good but does not pull at all.

What have you experienced?

 

[diggerdown]

You already know the answer Kevin. Turbo's need to be loaded to make boost. High rpm and no load only makes you exchange the air in and out. Put it under load and the R's come down which slows the amount of air taken in at the same time you get more exhaust gasses because of more fuel being fed. Put it together and you get more boost pressure. Maybe a poor explanation but in my twisted mind it makes sense!

 

[Tonysnoo]

I agree ya gotta load a turbo!

I think this has a lot to do with peeps trying to reach some imaginary RPM that "Joe Bag-O-Donuts" said is the best RPM to run. I got caught up in the light weight scenarion for the first little bit of my turbo education trying to get to a certain RPM. I had to buy weights that were way too big to run.....no how....now way................hmmmmmmm....... way!

I say load the clutch till the motor pukes(drops too much rpm), then back off a bit and start tuning(primary and secondary, and fuel) around that RPM. There are too many variables in pipe tolerances, port tolerances, and especially Tach tolerences to assume you will run the exact same RPM as someone else.

Big Fat Weights is where it's at for my sled.

 

[w2bridin]

When you say load it down with big weights how big you talking 85-90? I am running 80s with a 36-46

 

[mmsports]

Not just weight

IT IS WERE THEY ARE LOADED THAT MATTERS .

For example cat 80g weights are light tips and my turbo weights are very heavy tipped. both 80G weight

When you say load it down with big weights how big you talking 85-90? I am running 80s with a 36-46

 

[WyoBoy1000]

I was running a twisted setup that worked well and responsive, 10000ft 6lbs dalton 72g weights and a 36/44 helix. Held rpm but lacking top end pull. Put MDS weights in with all the weight in the tip with a 36 and gained huge amounts of track speed and pull and perfect rpm/backshift. Worked well with the 36/44 helix to but didn't have the top end pull. over 9psi the 36 wasn't enough though. I think around 10lbs with the weights fully loaded and a 36/40 helix at 10000ft would have been perfect.

But I can't see how he is not reaching rpm, has he tried a new spring or is his secondary f cked.

 

[flatlandsledder]

Heavy tips?

Hey guys. Got a question. Would heavy tips affect the low end? Give it more of a lag than it already has?

 

[Tonysnoo]

When you say load it down with big weights how big you talking 85-90? I am running 80s with a 36-46

OVS sold me some D&D weights that look similar, but they have four holes to put the magnets in. They have a set that maxes out at 83 grams and another set that maxes out around 97 grams.

I ended last season at 88 grams but had run as much as 92 at lower elev(6000). Certainly, not all setups will need to run as much weight nor will they all want the ends loaded. We often move weight around the various holes to see how it affects part throttle response and backshift.

 

[WyoBoy1000]

Hey guys. Got a question. Would heavy tips affect the low end? Give it more of a lag than it already has?

On the MDS weights, if you load the end it has a lot more track speed on top and a little less off bottom. But you can take a little out of the tip and add to the middle, it will pick up the bottom end and only leave a few mph track speed on the top, worth it in most cases.

 

[snobyrd]

Those using mds, post your weight configuration , elevation and turbo output.
mine was
Tip washer,drilled short bolt
Mid 2 washers, long bolt
Black pol spring, 36 helix
8t pg 4000'
This setup I couldn't really feel the boost, seamed abit lame, so today I changed to
Tip long bolt, 2washers
Mid short bolt
And I've got a 36/44 Dalton comming in the mail
My old setup made lots of noise but no great power to the Trax