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Discussion Starter · #1 ·
I have a VOD boost gauge on my 4BTA in the M37 under construction. Its getting the boost reading from the 1/8" pipe thread port on the intake manifold. The truck can not be driven as its not complete. But with engine running at 2000 R's I get no reading.

I was told today it wont read unless your driving on the road. Is this true and Why wont it read with engine at 2000R's sitting still. I know the gauge/tubing is good as I tested it prior to install

Paul's Confused
 

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Paul,
I know this sounds crazy but recheck the brass farrel in the fitting @ the intake,I have had them turn a bit and it pinches the line or it leak out the fitting and it won't read any bost.You'll see boost when you go to rev it up just a bit ,it won't be a bunch.

Thanks
CrewCab59
 

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Discussion Starter · #4 ·
Thanks Guys.

I dont have a boost gauge on the Carryall. What pressure boost shoudl i see with a Stock H1C turbo under acceleration and then also crusing on the flat at say 60 mph.

Paul
 

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To generate boost you must have a load on the engine. The Turbo works on temperature. At a no load situation the exhaust isn't producing much heat. Once you get the engine in a loaded situation you will start seeing boost.

my $.02
Yep, need engine load to create boost.
I can't get anything by revving my engine either.
 

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Discussion Starter · #10 ·
Thanks Guys. I guess there is a lot more thermal dynamics taking place inside the turbo than I guessed. With this new knowledge, I am sure I will have boost showing once I am able to drive the truck.

I guess what I dont understand is if you have the truck not moving and the engine at 2000 RPMS or if the truck is moving at 2000 RPMS you have the same amount of exhaust gas spinning the turbo. So how does temperature make the turbo spin faster ? Not questioning, just trying to learn.

Paul
 

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Turbos take energy from expanding gas on the exhaust side and transfer that spin on the tubine impeller via the shaft to the compressor side to increase boost. The higher the temperature of the exhaust coming out of the cylinder the higher the pressure. Thus the higher load on the engine the higher the boost.

That make any sense to anyone but me? :rasta:
 

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I found I could get some gauge movement (light - upto maybe 2-3 and 5-6 when floored - on a setup that could go as high as 25 psi when running) only with the smaller housings and larger turbos... With the stock turbo no movement at all.. I actually had the same concerns when I first got mine started... Congrats again on getting it running, must be a great feeling!
 

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Yep, need engine load to create boost.
I can't get anything by revving my engine either.
Every Autometer gauges that I have install will show boost when you rev it up,not small but will move!!!

some gauges might not all be the same.

CrewCab59
 

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It takes more fuel to keep the engine at 2000 rpm while driving than freewheeling the engine at 2000 rpm. More fuel burning = more heat and expansion to spin the turbine
 

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I was out for a evening drive in the 4bt jeep tonight and the turbo was spooled up about 15 psi when boom!!!!! One of the intercooler elbows exploded. Scared the sheet out of me. But when it is parked and I crack the throttle iImay be able to get 5 psi out of it with no load .
 
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