boost creep.

Discussion pertaining to positive pressure E28s.
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red535t
Posts: 204
Joined: Jun 03, 2007 4:53 PM
Location: auckland,new zealand

boost creep.

Post by red535t »

hi all,
its been awhile since i last posted here,but
certainly have checked up on all the progress's
of everyones projects over the last couple months

after leaving the 537 project for all most a year,
its getting love thrown at it again ($$).
and its had its dyno day and its
incouraging and alittle depressing in the same breath
250 oddkw at the wheel at 5500rpm.
had a reasonable amount of spark blow out
so the tuner decided to pull the pin,and rightly so.

spark plug adjustment is not a biggie and already
taken care of.
main problem 'boost creep', had a 7psi spring
and was/is at song at 2900rpm, then carries on up,
building upto 15psi- at 5500rpm,probably cept on biulding
but its not recorded
Image

Anyway,knowing i have a full length wastegate tube running to the back on the car,i have cut that bad idea off and have
joined the waste back into the exhaust just after the sway bar,
could/should have merged higher up but space is not a
commodity i/we have.RHD.
Image
the exhaust size is 3 inch from turbo to a very empty can/muffler at the back.
wastegate has been 'tested' had in screamer mode and it definatly opens.....ears are still bleeding
the other thing i can think of necking down the exhaust
before the waste tube merge in a hope to build some
back pressure and encourage more diversion.
wastegate size is a 46mm tial.

any more ideas would be very appreciated.
ideally want to run a 0.8/12psi spring and re-tune it soon,
kinda keen to see how much this project is going to
put down on the tarmac

cheers marty
T_C_D
Posts: 7733
Joined: May 27, 2009 11:42 AM
Location: Twin Cities
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Post by T_C_D »

You don't mention the size of either the wastegate entry piping or downpipe but it looks like the entry pipe should be located over the top of the turbo entry instead of off to the side.
red535t
Posts: 204
Joined: Jun 03, 2007 4:53 PM
Location: auckland,new zealand

Post by red535t »

good point Todd,

the wastegate entry has an ID of 45mm,and the
down pipe is ID 40.
could there be a chance of the waste down pipe
to restrictive over the length of it?
T_C_D
Posts: 7733
Joined: May 27, 2009 11:42 AM
Location: Twin Cities
Contact:

Post by T_C_D »

red535t wrote:good point Todd,

the wastegate entry has an ID of 45mm,and the
down pipe is ID 40.
could there be a chance of the waste down pipe
to restrictive over the length of it?
Those sizes are big enough. Check to make sure the WG is functioning properly and then revisit the entry point.
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