EricYellow

Here's the thing.
Just fitted a T38 running 1,5 bar (instead of my old t34) to my BD10, 750cc injector powered engine and got a strange place to find compressor surge....
It's to far up the rev range if you ask me...
I only get it at about 4750 to 5250 rpm, everything below or above is fine...
I would expect it to surge at lower rpm's but no problems there only higher up the revs.
Even at 1 bar I get a slight surge.
With the t34 at 2,4 bar I had no problems at all.
Is it possible to change the BD10 setup to lose (some, or all of) the surge ?
Don't want ot get a remap to "map around" the surge, becuase over here I don't trust anyone enough to do it.

Billabong

Are you saying you've swapped T34 for a T38 without a remap?

EricYellow

Nope, not without a remap, fitted the 750cc's and sorted the fuel setup to suit the T38 myself.
It's running perfekt afr's but I'm kind of stuck with a bit of surge.
Must say I haven't played with the cam timing yet.

reality

Sounds a bit Cowboy to me

Stu @ M Developments

iTrader: (12)

Its a Turbo Technics T38 then i take it?

EricYellow

Nope, haven't got any exact specs of it, it's been used in Sweden on a Rally car so most of the AR markings have "strangely" dissapeared.
Only thing I know is that it's got a .63 ex housing.
I compared it with a T34 turbine and the T38 one is about 1 cm bigger in diameter, so the ex housing is large enough I'd say.
That's also why I find it strange to get surge at all.
Compressor diameter is about 74 mm, not enormous either.
I get full boost from about 3500 rpm, would expect it to surge around that rpm.

Is it possible to try and lose the surge by playing with the cam timing ?
Like retarding the intake and advancing the exhaust cam a bit ?

Billabong

A workaround could be to lower boost at the surge point, so the turbo is back in an efficient area of its' map?

AndyRST

Forget the surge, Love that avatar

reality

Surge is not necessarily a result of engine speed, it's relative to a) the turbo and b) the amount of air flow.. and different turbos surge at different places EITHER side of the surge line! Only testing demonstrates!

wimwerf

don't you need a modified head for getting a t38 to work properly..

EricYellow

Not always, but mine has been "worked on"