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The mkiv Supra Owners Club

Boost Leak Dangers


Scott

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It is very important to check your car every now and then to make sure you don't have any boost leaks. The small ones are actually very dangerous for your turbo's (J-Spec especially).

 

If you have a very small boost leak you may not notice any difference in the readings of the boost gauge but you might notice a slight difference in power. The reason for this is the boost being generated by the turbo isn't making it all the way to the manifold and into the engine. This means your turbo's have to work harder than they would normally and they will generate more heat, leading to less power at the same boost reading.

 

Think of it this way, in a healthy BPU drive your tubby's will quite happily produce 1.2bar. If however you have a small boost leak, in say a dump valve actuator hose, you might lose 0.1bar of pressure from that hose. Your boost controller won't see this so will keep your wastegate closed until it see's the full 1.2bar. When it does your turbo's are actually working harder to produce effectively 1.3bar. Of course the bigger the boost leak the harder the turbo's are having to work to get you the 1.2bar your boost controller expects in the manifold.

 

Symptoms of this happening to you are:

 

Increased lag

Lack of power

Strange noises on and coming off boost.

 

Of course with the bigger boost leaks you will notice straight away due to no boost being created. There is very little load and back pressure being created so your turbo's will easily overspeed. This is very bad for your ceramic tubbys so be very careful how much you floor it when trying to troubleshoot.

 

The best ways to find a boost leak are the baked bean can method and the inflatable tyre method. They have been quite extensively covered through this forum so I won't go through it all again. Basically they create a seal through the entire +ive pressure side of the tubby's so you can add pressure and listen out for air escaping. If you are runing 1bar make sure you use the pump to mimick 1bar when you follow these methods.

 

HTH

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scott are you feeling alright pal? your up on the technical things as of late :D

 

I generally always am bud, I'm a very technical guy as it happens :p

 

Most things I understand without asking. When I feel the need to ask something I do ;)

 

With regards to this post, with all the talk of boost it made me think about the dangers with a leak. As it happens I had a leak where my BOV actuator hose came away from the BOV. It didn't make much of a difference for me as I don't have a restrictor ring so have been keeping off boost. Thought it might be useful info for others though.

 

Losing 0.2bar through different means could mean blown tubby's if they are set to put out 1.2bar.

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