Ok a pretty good ? [Archive] - GrandAmGT.com Forum

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grandam01
09-22-2007, 08:00 PM
Since I am in school now and am spending all my money there, It will be a bit before I get a turbo setup for my car.

I have a friend who has a stock block, well the it is the stock two bolt mains, otherwise it is bored over .030 and stroked. the car is an 87 GN it runs a very solid 9.5 sec 1/4. I was talking with him about turbos the other night while we were both at the track. Now he said that almost No body on the GN sites have a blow off valve on the their GN's because an auto trannied car does not need a BOV. On the manual cars when you shift you release the gas pedal to shift closing the throttle plate, that creates a back pressure against the turbine in the turbo, causing problems, soo the have BOV's to release that excess pressure. On Automatic cars there is no need to release the gas when shifting so there is no excess pressure built, or not enough to do damage. Even when you release the gas in an auto the engine winds down and doesn't create enough pressure from the turbo to hit the throttle plate and return to the turbine.

Has anyone tried not puting a BOV on their Auto GA. I will possibly try this. The engine builder for my friend confirmed what he was saying is true. So before any ridiculous flaming please take this into consideration that it is not like everyone else does.

bp's97gagt
09-23-2007, 11:59 AM
Well, I have a bov on my auto tranny. Why? because the pressure needs to be released when the throttle plate closes and if there is no bov, the pressure returns to the turbo which will eventually result in a $650.00 paperweight. You were mislead with the information you were given. The trans type does not matter, why? you have to let off of the gas at some point and the trans type has no effect on what happens to the pressure inside of the charge pipes.

grandam01
09-23-2007, 06:12 PM
OK well then why do most guys with GN's running high boost even not have one. when you let off the gas in either auot or stick there is no BOV any car I have seen with a BOV does not whine when you release the gas. it is only the wastegate pushing out the excess air that is built up over the psi you set for it to allow.

grandam01
09-23-2007, 06:23 PM
I completely understand teh purpose of the BOV, I now it is a great investment, I am offering it up as I really don't like the sound it makes, I don't want anyone knowing I have a turbo on my car till after I beat them.

SpyhunteR
09-23-2007, 06:33 PM
if you don't want the bov noise then you get a bov that recirculates into your intake tract.