Clutching for a good standing start apex mountain turbo

[mulot30th]

Right as it is now, my tpex get real good throttle response once already moving.

BUT

Thing are not that good from a standing start.

I turbo M7 get me out of the hole so badly I have to play catch on him all the time, which I do of course.

That is just too weird, when I look at my boost gauge from a start, I get ZERO boost until about 1 second after I snapped the throttle, then it jumps in one movement from zero to 15# (if I set boost to 15# for example) that results in 6500 rpms off the line jumping to 10500+ one seconds later... needless to say its a dog off the line.


Then I tried that turbo m7 just for fun. His throttle response is nowhere as good as mine once the sled is moving (his throttle feels mushy while mine is crisp and responsive)

BUT

From standing start, his throttle response is exact same as his rolling start throttle response, boost build progressively ans smoothly unlike mine (out the hole).

Is there something wrong with my clutching in this regard or is this a fact of live I must learn to live with?


I have 4 post clutch with supertips with two tunsten on bottom, 5 washers on middle and 2 washers on top. (total weight on my scale is 75.8 grams per ramp) and I am running a strait roller cam on rear.


thank you

 

[woodsrider]

From my experience, turbo sleds like to have the weight in the toe (or tip), not the heel. The more weight in the heel the quicker your sled will shift hence the 6500rpm shift when you first take off. Start weighting the toe first (generally your heaviest puck) and then some in the mid if need be. Run no weight in the heel.

 

[mulot30th]

From my experience, turbo sleds like to have the weight in the toe (or tip), not the heel. The more weight in the heel the quicker your sled will shift hence the 6500rpm shift when you first take off. Start weighting the toe first (generally your heaviest puck) and then some in the mid if need be. Run no weight in the heel.

so its would be to invert what I have done so far

thank you

 

[Turk]

I have clutched a lot of turbo sleds. Start heavy inner ; work lighter towards the tip & run a helix with about an 8 degree spread. This is for flatland riding. Running a lighter inner set up will increase any lag problems. This is using heavy hitter or supertip weights.Used both in turbo applications.

 

[Jonny Rocket]

I agree with Woodsrider. I have HH's on my RX with the heal totally empty, the mid is moderately weighted and the most is at the tip. This makes sense with a turbo'd sled. When you have no boost you only have ~150 hp which can't pull the weight. That is why I have my heal empty. Then as the boost and hp increase I add weight. Works for me.

J.

 

[zross1]

Good topic. So if do you get more mph on top end by loading the tip?

 

[Turk]

Your gonna get a crapload of low end belt slip setting up the weights like that.

 

[mulot30th]

I have clutched a lot of turbo sleds. Start heavy inner ; work lighter towards the tip & run a helix with about an 8 degree spread. This is for flatland riding. Running a lighter inner set up will increase any lag problems. This is using heavy hitter or supertip weights.Used both in turbo applications


I would like to know what are you meaning by "inner" and "tip" because if I understand correctly, it is similar as what I have done so far and it work great with EXCEPTION of standing start.

 

[woodsrider]

Weight in the heel causes the clutch to shift sooner than no weight. The more weight you add the sooner it will begin to shift. think of it as your shift pattern, the weight location is similar to your shifting , i.e. heel=bottom, mid=mid, toe=top end. You should run about 100lbs preload on your secondary to eliminate the belt slippage. I run an Arctic Cat green secondary with 30deg. preload. makes changing a belt harder but it eliminated the slippage. Ther objective is to keep your engine rpm's (higher engine rpm the higher the boost) up before you start shifting.

 

[mulot30th]

Right now my secondary is a 42 degree strait roller with about 100-120 degree preload (stock spring)

Primary engages at around 4500 rpm

WOT from standing start is like this:

6500 rpm at 0 boost for like 1 second
then 10500 rpm all the way to top speed when boost kick in.


The only part I do not like is the 1 second with no boost at start.


My supertips are loaded with two tungsten at heel, 5 washers in mid and 2 washers on top end

thank you

 

[woodsrider]

this is what I would do. Put your tungsten weights in the tip. Leave your mid weights as they are. Put no weight in the heel. Buy an Arctic Cat Green secondary spring. Buy a Shockwave Adj Helix (straigt helix not a multi-angle one) Preload secondary spring to 30-degrees. If your clutching was close before you should be able to "dial in" the top end rpm with the Shockwave Helix (the steeper the angle the faster it will upshift and this will decrease engine rpm, just the opposite if you decrease the angle). If you cann't adjust the rpm where you want it, adjust the weight in the primary weights accordingly. Keep as much weight in the tip as possible.

 

[srxguy]

What turbo kit are you running???...I have a front mount with ZERO lag and I started with the heel and worked my way to the tip!!

 

[mulot30th]

What turbo kit are you running???...I have a front mount with ZERO lag and I started with the heel and worked my way to the tip!!

ZERO lag, are you absolutely positively sure of what you're writing here?


I run BD kit with some modifications!

 

[Turk]

You should have zero lag. Clutching is not your issue. Check a/f ratios & look for an air leak.

 

[WesG]

Fuel controller

While I have not got my RB3 working correctly, it has shown me (28rs BD apex) that it will get you into the thick part of the power much faster than the pure logic box. With a slight amount of timing, pulling a bit of fuel, setting the accel pump, and the faster chips in the RB3 it is much more responsive. All those things add up to a nice improvement.

Wes


edit: I clutch heavy in the heel to grab that belt and help backshift on bigger pulls. heavy in the toe makes it respond fast for drag racing, but it is very hard on belts crawling around.