Compressor surge

grim_d

grim_d

Member
Afternoon,

After upping the boost to 1.6 bar on the dyno I seem to be getting a touch of surge at WOT and partial throttle around 5-6k onwards, dropping the boost to 1.5bar cures it at WOT but not at partial. I know of someone running a 3071 at 1.85bar and not having surge issues so curious as to why I am?

I thought perhaps too small intercooler piping but I'm pretty sure it's 60mm at it's smallest parts in the run so shouldn't be an issue, what else might cause a bit of surge? It's not a massive issue as I'm looking to go full 3" on the exhaust and run less boost but would like to know why.

This video shows what I'm talking about despite the title, https://www.youtube.com/watch?feature=player_detailpage&v=_K0LFadOKBc#t=51

Thanks.
 
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M

Makaveli_se7en

Member
Lower following turbine stages inherently are more prone to compressor surge (about of work done by the turbine is greater at lower flows, leading to increase in boost at low engine speed/compressor flow, driving the operating point off the left hand side of the comp map into surge).

If you turbine stage is suitably sized then look for resistances, blockages and pressure drops between the compressor outlet and the intake. A cheaper intercooler core can be the difference between a turbo surging or not when coming on boost.
 
campbellju

campbellju

Moderators
Staff member
I had surge on my 3071 .64ar, sounded similar to the youtube vid you found. The solution was to enlarge the hole for the internal w/g.
 
red reading

red reading

Active Member
Greddy eo1 you should be able to map the boost and reduce the gain at the point it surges, prob a 2.75" inlet from memory and a.64 housing which was ment to only go to 1.5-1.6 bar or 420ish hp and 400lbft torque.
 
grim_d

grim_d

Member
Makaveli_se7en said:
If you turbine stage is suitably sized then look for resistances, blockages and pressure drops between the compressor outlet and the intake. A cheaper intercooler core can be the difference between a turbo surging or not when coming on boost.
Click to expand...
It's an HKS core and the pipe run is fairly smooth but there is room for improvement.

red reading said:
Greddy eo1 you should be able to map the boost and reduce the gain at the point it surges, prob a 2.75" inlet from memory and a.64 housing which was ment to only go to 1.5-1.6 bar or 420ish hp and 400lbft torque.
Click to expand...
Something I have not played with much is the EBC, will need to tap the RPM signal for that then, about time I did so to be fair. I'll grab a mate tomorrow and go and tune the controller and see what happens.

You are in a better position than I to have a hope of knowing what size the housing is, .64 is the ideal really. It made 382bhp @ 1.6 bar with the cams and a 2.5" from the cat pipe back, sound about right?

Thanks Guys
 
red reading

red reading

Active Member
It's about right, cannot remember what the turbo is I know he had trouble with one provided by a infamous seller that turned out to be a stock one,

stick the dyno graph up.
 
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grim_d

grim_d

Member
I don't have a proper graph yet due to some technical issues (read: duff printer/different operator) and I haven't chased it up, it was really just a run to sort out fueling, I only have a photo of the screen on a few bhp runs, its the top red line, not the best i know.

 
red reading

red reading

Active Member
Did they not do the overlay for rpm versus fuel AFR and boost pressure?, curve looks good for a road car ( as in mid range power) .
 
grim_d

grim_d

Member
Unfortunately the usual operator was unable to make the session and my mapper uses dynapack hub dynos so is unfamiliar with the DD software but as it was only a session to sort fuelling out to get back on the road I wasn't too bothered about getting a graph. Next time I will be.

It's pretty good but can probably be improved by setting the e01 up correctly.
 
M

MarkTurbo

Well-Known Member
grim_d said:
I thought perhaps too small intercooler piping but I'm pretty sure it's 60mm at it's smallest parts in the run so shouldn't be an issue,
Click to expand...
My intercooler pipes are only 52mm and i never had an issue on my 0.86ar 3071.

If you get underneath you should usually be able to see if its a 0.64 or 0.86 as its cast onto the outside of the exhaust housing.
 
grim_d

grim_d

Member
Ive had a good look about the housing for marks but i admit not from directly underneath. Ill give that a go.
 
grim_d

grim_d

Member
Had a good look on the housing only thing cast on it is "Garrett".

Good fiddle with the EBC today despite the weather, doesn't seem to be any surge at WOT just a bit if going through the rev range at partial throttle, I imagine the solution is to not go through the rev range at partial, with the butterflies only half open i suppose it's something that can happen?

Quite enjoying the rpm/boost logging function on the e01, achieving 1.5bar @ about 4400rpm.
 
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