Compressor surge question

[archangel]

Hi guys,

Have a hypothetical question. I have a rev1 turbo with forged Pistons, cometic head gasket, etc., bmic, 880cc injectors, sard fuel rail, motec m4 ems, and a gt3071r with .063ar turbine housing. All running dandy but I haven't finished sorting things out so its not yet running its target boost. It was fine running up to 1.2 bar during the fensport mapping session but it was getting wet and I didn't think it was safe given the crappy tyres and suspension it had on at the time. Now that things are closer to being ready for another tuning session and cranking up to 1.4-1.5 bar I'm concerned whether im likely to hit compressor surge during boost with this turbo due to restrictive flow.
Do you think I will need to upgrade cams and head components to create better flow or do you think the existing setup will be able to support that level of boost?

Also if it did happen to be getting compressor surge on boost will it be easy for me to hear in the cabin or will I need to record with a camera or microphone in the engine bay?

[ashley]

What compressor housing have you got on there- is it one of the 4 inch intake, ported shroud ones?

I'd have expected you to be well away from the surge line with a 71 compressor wheel, even with a stock head and cams, and the .63 turbine housing. What kind of rpm are you seeing peak torque at?

I've seen these engines running the 82mm compressor wheel with the same exhaust housing as you've got, so you should be fine!

As for detecting it- should be obvious from in the cabin, and from standing next to the engine bay- you'll hear it...and Fensport are easily experienced enough to spot it when mapping


Have a read (if you haven't already):

http://www.turbobygarrett.com/turbobygarrett/surge_line

[archangel]

Thanks Ashley that's great. Just a stock compressor intake that fits the standard intake pipes. When fensport were mapping the m4 I told them to keep a fairly reasonable 7500rpm limit but I won't be bouncing off the limiter anyway. This setup will produce enough power for my liking so as long as it's running within safe limits at target boost then I'm happy choppy.