Turbo lag or lazy shifting?

[akMcat]

So here’s what I’ve got going, I’m trying to determine if my lag is a product of the turbo I’m running or if it is caused by my clutching.

Turbo: I’m running a 2012 ‘153 800 with a Push Tial setup and vipec, this comes with a Tial external gate 2871 w/HTA billet compressor I’m not sure on the A/R of the turbine housing.

Elevation: 10,500’

Clutching:
82g cat weights with 122-285 titanium spring
36/46p helix with the plastic washers on both sides of an orange cat spring(don’t remember the spring rate)
I don’t believe I am having any binding in either the primary or secondary, clutch temperatures are hot but not IMO excessive, running the 084 belt.

Symptoms:
During normal riding when in and out of the throttle dodging trees and whatnot the sled is very responsive, tachs right up to 8250-8300 and goes like hell. Boost comes up very quickly and hits 9.5 and stays there, virtually no lag.
When moving very slowly, kind of crawling around and you hammer the throttle, again boost comes up quickly, very little lag.
When cruising at steady speed 30-45mph about half throttle and you hammer down it takes close to 2 seconds for rpm to come up to 8250-8300 and boost responds much slower than situations described above. At this speed and throttle position I am indicating around 3psi boost before opening up the throttle.
I have considered going to a higher finish rate primary spring but this would in turn require heavier weights to control rpm which would exacerbate the midrange laziness I think.
Any thoughts or suggestions?

 

[kanedog]

Clutches are worn. It only takes less than 500 miles and you are chasing your tail trying to tweak clutching. Rebuild both and report back.

 

[Hardass]

Im fairly new to all this as well but im wondering if when your in the tress and what not it feels fine because your in the 36 of your helix but when your cruising at a higher speed your in the 46 part of your helix and your motor is not making enough power at that point to pull the 46.I have a 800 cat turbo that i run at 9/9.5 psi i tried the 46 and thought it was to lazy feeling at that psi.Im using a 36/42p for my application. of course i have different weights and springs than you as well . Just a thought.

 

[akMcat]

Im fairly new to all this as well but im wondering if when your in the tress and what not it feels fine because your in the 36 of your helix but when your cruising at a higher speed your in the 46 part of your helix and your motor is not making enough power at that point to pull the 46.I have a 800 cat turbo that i run at 9/9.5 psi i tried the 46 and thought it was to lazy feeling at that psi.Im using a 36/42p for my application. of course i have different weights and springs than you as well . Just a thought.

I was kind of thinking along the same lines too, I have a straight 40 deg helix I can try but I thought it would sacrifice too much on the back shift. My setup worked well at low elevation at 7psi and 77g weights, but off boost power was better being at sea level so maybe low elevation I could pull the more aggressive helix but not at high elevation. This was my first season in CO riding high elevation which changes things up a bit.

Clutch rebuilds are probably due, 1500 miles on the primary, and about 400 on the secondary. I was planning on doing pistons and reeds this summer as a preventative measure as well.

 

[Hardass]

Obviously the lighter your weights the more responsive youll be. i try to go up in helix angle to to keep rpms in check but you can only go so far or you you create belt problems. I actually added 3 dagrees of timing which works great with no det @9.5 psi Im running the stock 09 head and about 35% 110 to 91 octane @5500 feet thing ripps hard great backshift im using the mds weights @ 81.5 gs with that set up.

 

[jim]

sounds to me like the secondary is splitting open too easily at that range. I'd try easy things first like anther spring spacer in the secondary and cleaning both clutches up. Rock rollers have worked well for me too.

 

[WyoBoy1000]

Need to know rpm when cruising, and gauges egts? A/F? Readings before and after.

Could be pv are sticking,
Fuel is to lean and not spoiling turbo
Turbo is dumping boost
There are many things
Reeds
Temps
Fuel pressure
Needs some more data

I would lean against clutching because it seems to be working but you should clean them, check all rollers for play or grabbing. Make sure weight pins are in right.

Inspect turbo,

Alway try a new primary spring and 83 belt

 

[akMcat]

Need to know rpm when cruising, and gauges egts? A/F? Readings before and after.

Could be pv are sticking,
Fuel is to lean and not spoiling turbo
Turbo is dumping boost
There are many things
Reeds
Temps
Fuel pressure
Needs some more data

I would lean against clutching because it seems to be working but you should clean them, check all rollers for play or grabbing. Make sure weight pins are in right.

Inspect turbo,

Alway try a new primary spring and 83 belt

I never thought of fuel being too lean and not spooling the turbo, cruising those speeds RPM is between 5000 and 6500ish A/F is still up in the high 15 and comes down to 13.5 at around 6500 RPM that's about where the sled comes back to life, and then down to 12 or so at WOT. I'v added fuel twice in 2% increments in this area of my map, I was planning on adding another +4% before the next ride to try to get my AF down into the 14's. I'll clean my PV's and see what happens then. I don't know on the fuel pressure or EGT's I'm just running A/F and boost gauges.

Hopefully this spring storm keeps dumping snow and it lasts until I get home in a week. I've been trying to hook up with Matt from F.R.A.C. all winter for a ride but schedule just hasn't worked out for me.

 

[WyoBoy1000]

You can ride with me anytime,

The pv open at 6200rpm, I'd say look there. Make sure cables move free and adjusted properly.

 

[Polarisrocks]

Cat and a few others did a really stupid thing to help clean up their emissions. They lean out the cruise rpms 5500-6500 I am sure whats happening to you is the sled is tooo lean to accelerate and build boost fast.. Mine coughs if I cruise too long with pumping the throttle and demand boost with a jab of the throttle. If you have an accelerator pump function in your fuel controller use it help in that area. When most guys turn down the fuel pressure to clean up the bottom end they make this condition worse. I would also do a boost leak check everytime boost builds slower than normal..

 

[WyoBoy1000]

when you cruise in that rpm, even if you add fuel it makes it worse. What happens is the pipe sensor is trying to hit temp and the ecu will pull the fuel. then when it comes out of that range the ecu plays catch up because you have adjusted the fuel without it knowing and its just trying to hit pipe temp to burn the fuel.

That's why a lot of pipes actually lean out the mid then the ecu adds fuel for you.

It will also adjust the timing

 

[akMcat]

I'll have to look a little deeper into how my correction tables are setup and see what I can come up with, I have full control with the VIPEC I'm running, just lacking a little on knowledge but the more I tinker with it the more I learn about it.

 

[Polarisrocks]

So with the vipec you do have accel pump feature, turn in on and add a fair amount till the sled isn't clean anymore then back off 1-2. Accel pump is the only adjustment we use on our boost it boxes if needed. It gives just enough squirt to get on boost. If we use the actual table and add lots of fuel in that lean range it just isn't as affective with different loads. I didn't know the ecu was playing hell with us too at the lean spot. Maybe that's why I gave up on the direction I was going and went back to accel pump.

Where do you ride? I have chatted with Bryce a bunch and want to learn more about that vipec.. and ride a sled with one.

 

[akMcat]

I'll check out the accel pump feature and make some tweaks to my map. Ive just been in CO for a year and pretty much just rode the snowy range since it's close. I rode pinedale once and made a trip to island park early this season.

Vipec has amazing capabilities, if you can dream it up it can pretty much do it. It's just a little overwhelming when you get into the software and you've got to bring a laptop to make changes. I've got mine pretty close but not perfect yet.

 

[Bacon]

Try a straight 36 with a lighter secondary spring. Not sure on the rate. Dakota Performance gets them custom built. Those multi- angles don't work worth a darn at high altitude. I've also noticed that turbos just will act a little more laggy and not as crisp when you get over 10,500-11,000.

 

[Polarisrocks]

Try a straight 36 with a lighter secondary spring. Not sure on the rate. Dakota Performance gets them custom built. Those multi- angles don't work worth a darn at high altitude. I've also noticed that turbos just will act a little more laggy and not as crisp when you get over 10,500-11,000.

The higher you go up in elevation the turbo has to work harder, more heat. The air is also less dense and makes less power so this what most are seeing as lazy. If you had a smaller turbo it might spool faster at those higher elevations and maybe more timing. I have ran a 36 and its a zippy off the bottom but doesn't load the turbo on the big end. If you don't load that turbo it doesn't make REAL power, pull your arms off power. Like MMsports says load it too soon and its a dog and load it too late and its over.

 

[Betterview]

If I understand you situation correctly you are getting a quick response when travelling at low speeds or while under load, but get a slow response when travelling at a moderate half throttle speed under light load. If that is the case I am guessing that with the light load the secondary has up shifted to the steeper part of the helix and you are not producing enough power to get a quick down shift.

I have found that a brief stab at the brake when needing back shift while under a light load and less than full rpm's will give you that back shift.

 

[akMcat]

Update

So I cleaned and inspected my clutches, no glaring problems. I left everything the same except for switching to a straight 40 deg helix, then I cleaned and checked adjustment on my power valves, all good there. This seemed to help a little bit with the light load cruising lag, but it was hard to tell since it's been a few months since the last ride.

Then I added 10% to my boost fuel in the 0-3 psi range from3-6k rpm and added an additional 10% accel pump fuel in the same rpm range. I'm still getting the super lean O2 sensor readings but the lag I was experiencing is virtually gone and the sled has never ran better. I think i am going to add some more fuel in that 5-6k rpm range to try to get my O2 readings at least within the range of my gauge and see how the sled reacts.

Thanks for the suggestions

 

[wwillf01]

So I cleaned and inspected my clutches, no glaring problems. I left everything the same except for switching to a straight 40 deg helix, then I cleaned and checked adjustment on my power valves, all good there. This seemed to help a little bit with the light load cruising lag, but it was hard to tell since it's been a few months since the last ride.



Then I added 10% to my boost fuel in the 0-3 psi range from3-6k rpm and added an additional 10% accel pump fuel in the same rpm range. I'm still getting the super lean O2 sensor readings but the lag I was experiencing is virtually gone and the sled has never ran better. I think i am going to add some more fuel in that 5-6k rpm range to try to get my O2 readings at least within the range of my gauge and see how the sled reacts.



Thanks for the suggestions

What is the reading that you are calling lean ..


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[akMcat]

I'm using the NGK AFX O2 sensor and 16 is the upper end of the range and that is what I am seeing cruising at 5000-6000 rpm.