Aerocharger stumble

gsxr1k2 · Dec 21, 2014

Here's the background on the sled.

2011 pro rmk 163" with 170 miles
Aerocharger 66 with air to air cooler set at 9.5 psi
Running dolbec controller (I think it's a 3)
Almond spring with 10-70 weights and I forgot what helix..
Running straight vp 110 and riding 10,000 ft
Tried new plugs (br9)

The problem I am having is a bottom end stumble. I can't seem to tune it out. For instance say you stop on a side hill and will have some track resistance to get moving again the sled will stumble for 2-5 seconds before the turbo lights and rips your arms off. AFR during the stumble is around 13.5 to 12.9 and around 5300 rpms.

Any thoughts?

RedRider · Dec 21, 2014

How many turns is your turbo set at. Should be around three.

gsxr1k2 · Dec 21, 2014

Assuming your talking about the controller... Yes it is still currently at 3 turns from tight.

RedRider · Dec 21, 2014

Three turns from tight?? Back it all the way out then three turns for when it touches the diagram.
Aerocharger has some vid on youtube on how to set the controler

gsxr1k2 · Dec 21, 2014

That's what I meant. Three turns from when you feel pressure.

J almont · Dec 21, 2014

VP 110

Way too much octane. Mix it down to 100 with non ethanol 91.
50/50 mix. At 10k 9.5 psi. this is plenty of octane. This will cause bottom end
bog. Or switch to AV.

Aerocharger_jerry · Dec 22, 2014

We agree, your octane might be rich for the type of riding your doing, if you're on and off the throttle in the trees and not at WOT.

Also, make sure the area around the exhaust outlet is sealed. Use high-temp silicone or header wrap to fill the gap, otherwise exhaust might get back into the compartment around the muffler and cause a bog.

Give us a call if you need anything. 913-829-3400

Silber · Dec 22, 2014

what are your control box light settings?

gsxr1k2 · Dec 22, 2014

GREEN....6
ORANGE..6
RED........6
GREEN/BLUE...6-8
ORANGE/BLUE..3-8
RED/BLUE.....4/5-8

Sled runs great other then takeoff. Afr is 12.0-12-3 at WOT.

gsxr1k2 · Dec 25, 2014

Am I close?? Lol

Spaarky · Dec 25, 2014

You guys that are screaming too much octane. Why didnt we have problems 10 years ago with carb sleds? They ran just fine.

It very well may be the octane. Especially at 10,000 ft. Just saying in the old days it wasn't a issue.

Others things could be the controller. Those Dobek controllers can do crazy things. Seen it on a scope.

Second is clutching. Most guys today try to calm down the top end with big weights. Your motor struggles enough at high elevation, then you throw some fat Azz weights at it. It's like putting a gag on your mouth. I will say it till I am blue in the face. Set the gearing/clutching up to run almost the same as stock weights. I have seen it too many times, the turbos run better with light weights.

Could be turbo set up too. I don't remember the ins and outs of the Aero. When it took a 1.5 years to get one back from repair we quit using them.

Boston Racing · Dec 25, 2014

I am not sure how much different the aerocharger code is than the Silber but I heard they are very similar. If it is your tuning is off.

J almont · Dec 25, 2014

Octane

Outlaw, quit being such a drama queen. No one is screaming anything regarding octane. I guarantee you he does not need to be running 110 at 10k.
If I need to give you a lesson on octane I sure as heck can get into that for you. Start with the simple obvious things first. You must have stock in VP
or something. Oh yeah I'm screaming now.

Spaarky · Dec 26, 2014

Oh FFS.... It was a figure of speech. If you want to educate me go right ahead. I have not learned much in the last 15-20 years of running boosted sleds.

fredw · Dec 26, 2014

Having 6s on the first three fuel control settings is huge fuel.. Off the start, on the doo aero with same dobec fuel box we are 0 and still a bit on the richer side, I would be trying that with much smaller numbers

As for fuel at 10k feet you don't relly need much over pump fuel up to eight pounds..

A higher octane fuel Is a much safer controlled burn in the head, but the down side is that it is less volitile burn, and can be more associated to burps or stumbles when not needed

m1kflyingtiger · Dec 26, 2014

What injectors do you have? Some of the '11s were known for going bad. Sounds to like if you can't tune it out you should look a your reeds. A little chip can really screw up your bottom end.

gsxr1k2 · Dec 26, 2014

fredw said:
Having 6s on the first three fuel control settings is huge fuel.. Off the start, on the doo aero with same dobec fuel box we are 0 and still a bit on the richer side, I would be trying that with much smaller numbers

As for fuel at 10k feet you don't relly need much over pump fuel up to eight pounds..

A higher octane fuel Is a much safer controlled burn in the head, but the down side is that it is less volitile burn, and can be more associated to burps or stumbles when not needed

That's where the sled seems the smoothest with those settings @6. Not saying it's right. What afr are targeting for when light accelerating or heavy accelerating but not at max rpm?? I was taught to under light acceleration to run around 13.0-13.9 and heavy acceleration to shoot for 12.0-12-5 afr.

gsxr1k2 · Dec 26, 2014

m1kflyingtiger said:
What injectors do you have? Some of the '11s were known for going bad. Sounds to like if you can't tune it out you should look a your reeds. A little chip can really screw up your bottom end.

The sled, engine and turbo system have 200 miles on it. To the best of my knowledge the injectors are '11's.

fredw · Dec 26, 2014

we found the a/f to be useless other than wot, we had put a a/f on a stock sled and drove around, it would come down to 13.3 on wot and any other throttle position it would go as high as 19 to 1, and this is what doo considers to be good

Also found that on wot anything under 12.5 your sled is running like crap on the etec, and best to be around the 12.8 to 13 2 for best running

If I added first three fuel divisions to 6 like you had it would stumble so bad that it would not even run

Talking with Chris at dobec he mentioned that we should keep it at zero and he would be releasing something soon to take more fuel out..

gsxr1k2 · Dec 26, 2014

fredw said:
we found the a/f to be useless other than wot, we had put a a/f on a stock sled and drove around, it would come down to 13.3 on wot and any other throttle position it would go as high as 19 to 1, and this is what doo considers to be good

Also found that on wot anything under 12.5 your sled is running like crap on the etec, and best to be around the 12.8 to 13 2 for best running

If I added first three fuel divisions to 6 like you had it would stumble so bad that it would not even run

Talking with Chris at dobec he mentioned that we should keep it at zero and he would be releasing something soon to take more fuel out..

Well I installed the new dolbec (3.5) and will be riding Sunday. I will try and pull some fuel out of the bottom end and will switch to AV gas mix with 110.

Aerocharger stumble

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