Drive pressure readings

oldsmokey

oldsmokey

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Jun 28, 2007
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I finallly got around to installing a drive pressure gauge and I am wondering what drive pressure should read from 0-20 psi boost? Should it be 1 to 1 all the time or only at peak boost? Im using a he351 9cm exhaust housing over a BHT3B 26 cm housing, and a 40 mm external gate.

Joel
 
oldsmokey said:
I finallly got around to installing a drive pressure gauge and I am wondering what drive pressure should read from 0-20 psi boost? Should it be 1 to 1 all the time or only at peak boost? Im using a he351 9cm exhaust housing over a BHT3B 26 cm housing, and a 40 mm external gate.

Joel
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sorry to get off the subject for a minute, but how is that twin combo working out for you? spool quick and still make big power up top? i am doing a similar setup and wanted see how other combos do. thanks
 
On my first set of twins, my drive pressure was lower than boost up to about 50 lbs. That was a 66/65/12 on top, and an HT-60 on the bottom, no external gate.
 
On my setup, I show drive pressure about 2 PSI higher than boost throughout the range.
 
Any test I've ever done (BD twins) was below 1:1 up to about 40 psi........... 1:1 up to 55............. and TIP read 67 up to 65 psi boost!

RJ
 
Thanks guys, what is everyone using to tap into the manifold. I just blew the fitting that I used to screw into the manifold. The threads are still in the manifold . My drive pressure is pretty high right now at about 50 psi i boost see about 70 for dp.
 
1/8"npt threads, remember dont run the tap all the way down since this is a tapered thread.
 
oldsmokey said:
Thanks guys, what is everyone using to tap into the manifold. I just blew the fitting that I used to screw into the manifold. The threads are still in the manifold . My drive pressure is pretty high right now at about 50 psi i boost see about 70 for dp.
Click to expand...

Do you know if your HT3b is the high flow version? If not that might be your problem.


On edit: If it's not a holset 3b I would suggest switching over to a high flow holset...3bs are not all equal!
 
carcrafter22 said:
1/8"npt threads, remember dont run the tap all the way down since this is a tapered thread.
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Yep thats what I used, it didnt pull the threads threw it it broke the fitting in half. I think it might have been a bad fitting

LReiff said:
Do you know if your HT3b is the high flow version? If not that might be your problem.



On edit: If it's not a holset 3b I would suggest switching over to a high flow holset...3bs are not all equal!
Click to expand...


Its a BHT3B, the same one that Piers used to use in there towing twins. I ran drive pressure to the top of the gate and boost to the bottom, but I dont think its opening enough. Im only seeing about 17-18 psi from the 3B and about 50 psi total with no smarty.
 
oldsmokey said:
Its a BHT3B, the same one that Piers used to use in there towing twins. I ran drive pressure to the top of the gate and boost to the bottom, but I dont think its opening enough. Im only seeing about 17-18 psi from the 3B and about 50 psi total with no smarty.
Click to expand...

You lost me! What gate?
 
My first suggestion would be to check for boost leaks i had higher drive pressure then wanted i then ended up finding a boost leak, when that was fixed it made it closer so i atleast had a good baseline. I also think that you need your gate to open sooner therefor it should decrease drive pressure and raise boost on the 3b
 
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