Aerochargers etc: real back pressure numbers

[Jeff Meager]

urm, huh?  Hmmm, urm, yep, I'm a 180sx t25g owner who's a little
perplexed.....

I have the usual issues that nearly all turbos have which is small amounts
of blowby...but I see it in the intake (which would be unaffected by the
exhaust change.....

As it has been said....turbos work on pressure differential for flow, you
must have as low as possible BP in the exhaust post turbo to maintain a good
pressure differential to increase flow....

LJ


-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Dave Evans
Sent: Wednesday, 17 October 2001 6:55 AM
To: diy_efi at diy-efi.org
Subject: Re: Aerochargers etc: real back pressure numbers


Hi

Wouldn't lower back pressure increase oil blow by, past the seal?
Theirs some picture around of a Garret T25, verses a T3, and it would
appear from the casting point of view that its just the T3 has been
flowed.

I know on the T25 fitted to my car unless you've got cats fitted
(increasing the back pressure) oil virtually pours past the seal at idle
and on over run, I'm told this is a common problem with the T25, any
Nissan ZX?00/T25 owners care to comment.

Cheers


In message <Pine.SOL.4.33.0110161813480.938-100000 at tempest.gpcc.itd.umic
h.edu>, Frank F Parker <fparker at umich.edu> writes
>> Insightful info.  Thanks.  I am curious as to whether you had an exhaust
>> system downstream of the turbine in your TY during those tests (ie:
piping,
>> converter, muffler), and whether you data logged the EBP at the turbine
>> discharge?  Anyone else ever measure this type of thing?  I know this is
>> going to sound rather vague, but, what's an acceptable value for post
>> turbine EBP in a street car before seriously impacting a turbo's
capability?
>> Walt.
>>
>
>Yes, I had a complete exhaust, 3" downpipe back to a Flowmaster and 3"
>over the rear axle, but test pipe in place of cat.
>
>Sorry, did not measure EBP at the turbine exhaust but from tests others
>have reported, it seems turbos like the lower the better. In fact, in the
>early days of turbos, exhaust backpressure was often used to limit boost.
>( my old 66 Corsa turbo, for example). Also used an external HKS wastegate
>with it's output fed back to DP about 3x dia's down the pipe.
>
>regards,
>
>frank parker
>
>
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--
Dave Evans
Lotus Omega 3.6l,S6,412Bhp,186Mph on the clock.

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