If your boost is...
- Thread starter EZmoney
- Start date
My a/f and boost gauges are mounted below the bars which makes it difficult to monitor them continually. I have never seen my boost spike. It always ramps up proportionately to the throttle. I read something about an arm or rod freezing up on the turbo. Is that it. I have a skid plate between the track and the rear mounted MCX on my Nytro. I am just fishing.
Your boost should not spike at all if your wastegate is set and working properly.
This usually only happens when you add some sort of manual boost controller.
You can reduce spikes by installing wastegate designed for the boost you want to run, and skip the boost controller.
Manual boost controllers can do a good job if you only adding like 3-5 psi over wastegate setting.
Also Keeping your hoses for your manual boost controller as short as possible helps a lot.
Boost spikes can and will destroy and engine.
That reminds me there is a small (tiny) hole on the bottom of my manual boost controller. If that hole ices up it will over boost.
Spikes are common. I know lots of guys that there sleds are doing the same thing. Myself included. We all run the rear mount mcx on Apexs and Nytros with all the same results. That quick flash will not hurt anything as long as it isn't holding that over boosted pressure. Make sure it is settling back down. The over boosting generally comes from lack of deep snow. If you rip on it in really deep snow you will find that it won't over boost because you aren't reving up the motor as quick so you won't get that burst from the turbo.
mine does not spike (rear mcx) a 4 lb spike puts you at 16lb and if your only running pump gas (assuming thats why only 12) your in bad territory. does the motor respond funny? sounds or bogs? when does it do this? how fast does it come down? i agree with addictedtoboost. more of a chance of a jumping rod
Mine spikes too mcx nytro goes from 14 to 17 lbs just runing pump gas going to switch to av gas cheap insurance. I also am installing a boost memory too hard to watch the gauge all the time. What is the waste gate set for boost from the factory and how do you tell if it is set properly mine only has about
1/4" of thread showing.
1/4" of thread showing.
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EZmoney
Well-known member
I set my waste gate like the alpine video said,i believe it was a 1/8 inch of pre load I do have a bd turbo but i watched the alpine one as well when doing my install. "good vid". I run a turbo smart controller and seems to work good.For fuel i never run straight gas always 50/50 at the least, av gas and 94. I wanted to know if this is normal having a boost spike like this, i read about the guy running 18 pounds on pump fuel??
but any way i dont want to have a blown motor as well with these boost spikes, you start running 16 well heres twenty at ya with a stock motor.
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JSCC
Well-known member
We have a Turbosmart on our Nytro, I think that is your problem. We had to bypass it completely for the same reason. If the wastegate was set at 8lbs, we were seeing spikes on the Bd box to 20, and on the analog to 15. Then it would hold 15 for a couple seconds, then drop down. Or if when we got into it, we would blip the throttle, then ease back into it, it would not spike.
I dont think that controller is worth a crap. We bypassed it to make sure, and while it still spikes, as all turbo's do to some extent, it solved the problem.
I dont think that controller is worth a crap. We bypassed it to make sure, and while it still spikes, as all turbo's do to some extent, it solved the problem.
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EZmoney
Well-known member
Jscc. i dont run a bd box i have a pl.So your saying dont run a boost controller ? I dont like that idea at all, or maybe i read that wrong .I talked with a buddy that runs a mcx on his apex and his also spikes. Im hearing from some its normal and others its not?? Some one asked if my sled bogs or makes noise. No it pulls hard sounds good once in a while hits the rev limiter though, i need to add a little weight.
J
JSCC
Well-known member
I did say to remove the controller, to see if thats your issue. Every turbo has some spike, but it you are seeing it on an analog gauge, its excessive. The Bd box would tell you your max, and peak boost numbers if you still had it. That was my reference.
The spike will not hurt you at all if you are running good enough fuel for it. But dont run fuel for 12lbs and have it spiking at 16lbs.
It also matters how long is the spike. With that controller, ours was seconds long. One second is too long, let alone seconds.
My Bd spikes about 2 lbs. But it is not noticed at all on my analog gauge. Just on the Bd box. I use a hallman controller though.
The spike will not hurt you at all if you are running good enough fuel for it. But dont run fuel for 12lbs and have it spiking at 16lbs.
It also matters how long is the spike. With that controller, ours was seconds long. One second is too long, let alone seconds.
My Bd spikes about 2 lbs. But it is not noticed at all on my analog gauge. Just on the Bd box. I use a hallman controller though.
No spike on mine. I'm using a turboxs 2 stage controller with really short hoses. If you're using a controller that has a ball and spring, spiking is common. If the hose between the controller and the turbo is too long it will spike. Any more than one psi is too much.
I have a turbo smart boost controller.....I never hammer the throttle off the line too scared to see what it would spike too....always thought that it was the nature of the turbo's waste gate.....but it makes sense that the boost controller doesent help....I never could figure out that some tmes it seems to hold boost fine then sometimes its hold for a bit at 15psi and drops too 12 psi......must be that controller.....
If I never run the boost controller how much variance would there be if you set it at 15psi @ 5000' if you riding 7000 would it drop lots?
If I never run the boost controller how much variance would there be if you set it at 15psi @ 5000' if you riding 7000 would it drop lots?
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BigFish BC
Well-known member
you should not get boost spike its not good for the motor at all.for some reason the apex is the worst for spiking but it seems the nytro is bad to by the sounds of it.if you are running 12lbs on pump gas on a hot motor & hot turbo,then you hit 16lbs for a second you are getting deto . do this 10-20 times in a day of hard riding guess what it starts to hammer on the piston & rod bering sooner or later it will give up.this is one of the few manual boost controlers that work & not a bad price you can get them on ebay too.
http://www.addictedperformance.com/hallman-pro-rx-kit-p-2.html
http://www.addictedperformance.com/hallman-pro-rx-kit-p-2.html
Well spikes are more common than people think. I even turned mine down once to 8lbs to see what it would spike to. It would spike to 11 or 12 then settle to 8lbs. The only reason that I could see the cause of the spike is from being on some hard pack snow and the sled revs so quickly and is spinning that you get the spike. But it settles back down in the blink of an eye so no big deal. I have 2000km on my sled and know problems. Set at 12lbs.
If it's only spiking for a second it shouldn't be at a high enough temp to cause deto.....if its longer then your looking for trouble....I not a expert by any means, but your cylinder temps probably vary a large enough difference that boost spike wouldn't cause deto right?
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BigFish BC
Well-known member
it just isnt good in the long run not something that will take a motor out fast but it will just ask any turbo car guys, just not a good thing to have for motor longevity.a couple of thing that help with boost spike are ported wastegate & double or divorced down pipe or exaust pipe but i only know of 2 guys using that in there kits.
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