Help with surge under part throttle

[Tom Tom Turbo]

Wondering what I can do to eliminate surging under part throttle. I'm running a billet wheel 6262 with the ported inlet. It's fed by a 4" aluminum inlet and a 4"x14" filter. I'm using the SD chip, so there's no MAF to interfere.

I'm set at 22 psi with an external gate and GN1 boost controller mounted under the good. At WOT it hits hard and pulls strong, but at 1/2 to 3/4 throttle and 12-18 psi it surges and flutters like crazy. Any thoughts on curing this? Could the alky be coming on too soon?


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[SCOOBY DOO]

I have the 6262 without the ported shroud...and I don't experience it. I did with a 6152 tho. Bison and a few of the more educated lads will be able to shed some light on this. Hang tight...and wait for them to chime in.

 

[1KWIKSIX]

PTE SLIC or Front Mount ?

Can't tell by your signature, not sure if it would make a difference with what would appear to be the compressor surge you are experiencing?

 

[Tom Tom Turbo]

Sorry, yes running a PTE SLIC.


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[TurboBob]

what is the base spring in the gate? with it running on the base spring, does it flutter?

Bob

 

[Tom Tom Turbo]

8# spring in the gate, it doesn't surge/flutter on the spring alone.


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[TurboBob]

how much boost can you set if for before its starts to flutter?

B

 

[Tom Tom Turbo]

It typically starts acting up around 12-14 PSI


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[Bescurred]

My 44 does this too, I also have the pte slic...curious what's the fix

 

[DavidM]

I have this happen as well on a TA49 .63 Garret.

It occurs around mid boost 12-16lbs. It goes away at higher boost.

Stock wastegate with RJC Boost Controller. Stock Intercooler with Duttweiler neck.
E85 25lbs.

 

[we4Mateo]

No easy fix guys. The compressor, coupled with the alky, is just feeding too much air for the engine to eat at that boost level. Change the turbo, port the heads, a cam change might help as long as exhaust energy isn't also increased. I bet if you turn off the alky, you won't have this problem. You won't be able to hit 20psi, but the problem will be gone at 15psi. The alky just makes the charge too dense and the engine can't eat it. I've tuned my alky so the window is more narrow for surge, but hard to eliminate completely. It's really only wot surge that you need to be worried about. Drive around it otherwise. A tornado pre-turbo in the intake might slow down flow just enough to help too. The tornado is the easiest fix. I used to take mine out for track days, but it made no difference. It is just enough of a restriction however to really help the part throttle surge. Try that and report back please.

 

[TurboBuRick]

Try running the wg tuner style. Boost hose directly to bottom port. Leave the top port open.



Rick

 

[Turbo Negro]

I believe this to be fairly common. One of the downsides to doubling a car's horsepower with bolt ons. I drive around it by slowly easing off the throttle instead of chopping it closed.

You may want to try a different tune for street driving, as well. Then turn it up to maximize the combo at the track.

 

[Mr.Spool]

a lot of air before the motor rpms's combined with a cool intake charge.you would have to slow turbo response time,larger ex housing or bigger turbine wheel.years ago I ran a 62/65bb but a cast wheel it surged with a .63 ex housing put the .82 on and the bigger ar took it out if surge,however it was faster with the .63.

 

[Mr.Spool]

when I ran a 49 it had plenty of surge but never hurt anything and the car flew.

 

[blackazz]

I also have this surge problem with my ta49 around 12-15#boost. I put a tornado inside the intake hose seems to help, but others have advised against using a tornado.

 

[Rodney87GN]

Saw this a few days ago on Facebook...
Buick Regal Turbo Surge Fix! (84-87):

Seems like a good idea...thoughts?

 

[TurboBob]

He's sorta right.

whats happening (in my opinion) with this part throttle surge is: High pressure and low flow.

The wastegate is set for ~ 20+ psi, and the turbo is creating 20 psi in the intercooler, but the driver has backed out of the throttle to limit manifold pressure.
So the turbo is running full boost but the flow is being restricted. This puts the turbo in the surge region of the compressor map.

2 solutions: dampen the surging (his resonator, a tornado, stock MAF, stock intercooler, whatever), or reduce the wastegate setting at less than WOT (there are a couple ways to do this).

__discuss__ ....

Bob

 

[Pronto]

Well, that seems like a simple enough mod to try. If it works it would certainly be a boon to those that are experiencing it!

 

[TTA976]

The only turbo cars that I know of that didn't come with a diverter valve.


Joe