Negative Boost Question

[sleslie]

I just got my MCX low boost turbo installed on my 09 Nytro MTX and took it for its first run on the weekend. This is my first experience with a turbo and am super happy about how it turned out. My question is that on my boost gauge when i was idleing or just cruising along was showing about -12lbs boost pressure, when i hit the throttle everything seemed normal and my pressure would come up to approx. 9lbs which is where it should be i think. I was just wondering if something might not be right with so much negative boost or is this normal? I was riding in Golden at Quartz and Silent and it did the same on both days. Thanks

 

[tfitz]

Yeah Negative boost is normal, all 4 stroke motors create a vacume when ideling or not under load, I have a 09 Nytro with the 240 kit on it and it does the excact same thing

 

[Apextenn]

Ditto what he said a turbo will not creat boost intill it is spinning at a certain rpm usually 100000 and at idle their isnt enough exhaust to spin it that fast where as a supercharger is a mechanical air pump so even at idle it will create boost. This is why if you notice when you pin it their is a little bit of a lag intill the rpms get up then she is a rocket.

 

[yami]

negative 12 lbs seems excessive. i get a negative 3-5 lbs max.

 

[Modman]

negative 12 lbs seems excessive. i get a negative 3-5 lbs max.

Where's your boost gauge plugged into?

 

[sleslie]

I'm not 100% sure where the gauge is connected to, and unfortunately i am up in northern BC working for the next couple of weeks and won't be able to check until i get home. I just thought it was a lot of negative pressure when compared to the 9lbs or so i am getting at max throttle. Thanks for the responses so far.

 

[NM]

Vacuum is displayed in inch pounds, so it really minimal actually. The range your running in is normal. Who's kit is it?

 

[sleslie]

Its a MC Express 180 kit installed by my dealer in west central Alberta. The install was great and it seems to run like a dream, just seemed to me like a lot of negative pressure but maybe thats the way its supposed to be, it is my first experience with a turbo.

 

[drew562]

Its a MC Express 180 kit installed by my dealer in west central Alberta. The install was great and it seems to run like a dream, just seemed to me like a lot of negative pressure but maybe thats the way its supposed to be, it is my first experience with a turbo.

its normal All 4 strokes sled bikes cars make vacume at idle and 12 lbs of vacume is normal. I have a stage 2 nitro and a low boost nitro. Both the same vacume