nixon_2wd

Got my new setup running and all is good except I experience turbo surge at full throttle (pull) and part throttle (static load).

2wd cossie

Current setup:
- GT3071R.63 fullsize 60mm turbine wheel, 4" compressor housing (NO antisurge)
- 2wd Reyland modified external wastegate manifold
- Tial 44mm MVR ext WG
- 200block 0,5mm
- Stock camshafts
- Piper vernier pullyes
- 750cc Siemens injectors
- 4x4 modified inlet with 15mm spacer
- Slightly ported head by the valve seats by removing some material (about 10mm on the diameter taken off the curtain behind valve seat
- RS500 cooler, 3bar map, 3" pipe etc.
- MSD6A Digital ign amp.

What would you recommend me doing to this setup to avoid the surge?

1. Order a .82 turbine housing as the .63 seems too small, but Im not sure if itll solve the problem on its own?

2. I could machine the comp housing to antisurge spec?

3. Electronic boost controller? If so, which one?

Thanks!!

bigchez

isn't a bigger housing just gonna make the problem worse? granted boost will be higher up rev range so VE up but from a layman's POV i don't think that's the answe (but will prob be proved wrong shortly!!)

nixon_2wd

A bigger turbine housing will make the compressor spool up slower, hence reducing the surge, but it may not be enough to eliminate it completely (make turbo laggy). Thats why im thinking to maybe controll the boost with an EBC?

bigchez

but when it does spool there will be even more boost so you may just make it worse. surge is when the engine can't physically consume the air so boost capping might be a work-around but sure the answer is to properly fix it - poss cam timing or more headwork? I'm not an expert fella. who built/mapped it? ask them?

nixon_2wd

I built it, and currently live mapping it with a friend. It only goes into surge. Dont want to fiddle too much about the camtiming all though more overlap may help it (std cams have a specific timing). It is as you say a work around, but what do people do on this as clearly its a popular / modern setup?

Fudgey

iTrader: (4)

im far from an expert but if your making more air than the engine can consume (VE) then you will get surge.

you say your on standard cams, maybe get some higher lift/longer duration cams and possibly more headwork if that doesnt cure it

Fudgey

iTrader: (4)

or fit a smaller turbo lol

nixon_2wd

Fitting longer duration cams will not help as it will not increase the VE by much at these low RPMs. Headwork as you say will, however its expensive and I dont want to pull the engine out for it.

The turbo is a gt3071r which people say its a good turbo for the YB?!

jamie's

good turbo if properly spec'd engine,
but on standard cams and head/ports its defo a tad overkill
you could poss map around it but i wouldn't know how
but in my experience you need the head off to get ported and bigger cams to get it flowing better
but i'm no expert so thats just my experience
but i highly doubt any of the big tuners will comment as they have spent many many hours
researching this problem with builds and wont want to give away their time and effort for nothing

J1mbo

iTrader: (1)

Inlet cam and head work, if the head is slightly ported that should help but deff a inlet cam needed. If you have valve pockets in pistons stick a bd16 on the inlet. If you don't your best off getting some as the likes of a ab07 (only updated cam on STD pistons) won't really help.

nixon_2wd

I believe a EBC with the ability to map boost at different rpms will allow me to controll the WG, keeping the compressor right beneath the surge line at lower rpms. I have studied the boost maps on a couple of engines here, and none of them are boosting 2 bar before 4100rpm. Mine is currently boosting 2 bar at 3750, so Im guessing some work around has had to be done on these engines aswell.

Fitting an antisurge compressor housing will clearly help with the issue. Its probably the best solution here, but it will kill turbo efficiency and take away some of the top end power duo to turbulence created by the antisurge design itself.

nixon_2wd

pistons only machined down 1mm unfortunatly so I believe BD14 is as far as I can go, even with this cam I will not be able to fully advance the cam without hitting the pistons i think. Anyone of you know if 1mm is enough?

nixon_2wd

Fitting a larger AR turbine housing will decrease the backpressure (the larger AR flows more gas), making less resistance for the compressor to work against, and therefore the engine can flow more air. Its all about the pressure differential across the compressor and turbine.

CossieRich on here made 460hp on std head, only using a BD14 inlet cam. (480hp with MAD special super secret inlet cam).

Seeing as the BD14 is a "top end" power cam actually makes the lower end loose VE.

I think the solution is anti surge compressor housing combined with the 0.82 turbine housing, and a EBC.

So I will machine my own comp housing to antisurge in the next couple of days while I wait for my 0.82 housing.

botters

iTrader: (2)

your going to have to get headwork and a cam change unfortunatley mate, an anti surge housing is only a way of masking a problem without the benefits of actually curing the problem in the first place

nixon_2wd

What spec is that based on?

Mark Shead have written himself recommending this turbo fitted with both anti surge and 0.82 housings.

I am open for suggestions, but I think there is more to this than just porting the heads as many on here are getting great results without headwork.

botters

iTrader: (2)

not based on any spec specifically just saying that if you fit an anti surge housing then yes you will get rid of (hopefully but not definatley) the surge but you wont get the benefits of actually getting rid of the surge correctly ,better cam, better exhaust, larger better shaped head ports etc...ultimatley giving more power and torque plus a better breathing and performing engine compared to one that is choked but being slightly dechoked by an anti surge housing which in my opinion is a compromise at best

nixon_2wd

agreed!

CossieRich

iTrader: (1)

I did indeed

However i had an anti surge housing and the .82 exhaust housing and a mental inlet cam

nixon_2wd

Tell us what you know about surge problems you may or may not have experienced; CossieRich? And how you solved it.

CossieRich

iTrader: (1)

I didnt have any surge at all. Foot down at 2000rpm in 4th and 5th and zero surge when the boost arrived. I have no idea why but Mark may know. My only theory is because of the anti surge housing and larger exhaust housing. Adding a larger inlet cam would increase the chance of surge as would a plenum spacer im guessing?

xr2wishy

iTrader: (2)

i have the same turbo in a zetec turbo and also get surge over 1.6BAR, just need to map around it or swing with timing a little.
i also have no anti-surge housing but on a similar setup no surge that i know of.
must be a way round it with some effort though, i do suspect it could be too much overlap though just getting too much air through when exhaust valves are just closing.

stevieturbo

So exactly what boost is it making, when does it surge, how much boost when it surges etc etc ?

And why vernier pulleys on std cams ? Are you sure cam timing is correct ?

What ecu are you using ? Cant it control boost ?

Bigger turbine housing may help...or so might a more restrictive intake before the turbo.
Although even a ported front cover doesnt mean there is no chance of surge, although it should help.

Shouldnt cost that much for a ported cover ?

Karl

Gt3071r (56 trim) does have a tendancy to surge under 4500rpm on standardish YB 2.0 engines when running over 1.8 bar.

Sounds to me like you allready know the answer:

Changing housing to 0.82 will increase spool threshold to 4000rpm and reduce turbine back pressure. This alone may cure your surge.

Changing to anti surge housing will reduce compressor efficiency. However you should have chosen a different compressor wheel in this case as why have the larger 56 trim wheel, only to reduce its efficency with a ported anti surge inlet!

Cap the boost via your ecu mapping until it can take full boost.

All your other options require the engine coming apart Im affraid to build something a little more suited to the turbo! (Should have chosen a suitable turbo for a standard engine!!)

xr2wishy

iTrader: (2)

what i'm experiencing is an oscillation, say at 1.6BAR hold, it is actually fluctuating from 1.4-1.6BAR back and forth throughout the revs.
most peculiar, didn't do this on the last turbo, but changing to the gt3071r has started this, i may have a cam swinging session to see if that is an issue, then move onto the wategate springs possibly not sitting right with each other and go back down to one spring again.
my head is an area six one with porting to exhaust side and uprated cams.

nixon_2wd

Original cams are not timed perfectly for their capabilitys on std pulleys, bought them for a later camshaft upgrade. They are currently set to std configuration though.

Using L6 ecu so no boost controller.

Hits surge at about 3700rpm, hard to say exactly because of the surge making the MAP signal go wild but about 1.7bar when it stalls.

I think I will get the head ported and fit a 0.82 housing on it, leaving compressor cover as is.

Thanks guys

xr2wishy

iTrader: (2)

could it be an idea to pull some timing out so there is less efficiency causing the turbo to spin a little less, or more timing?
i'm not sure, but will get out in mine and pull timing out and pop it back in to see how things are going.

GARETH T

What about changing the turbo?

nixon_2wd

Not an option. The GT3071r is a great turbo, with a bigger range than most. A smaller turbo will not give us the top end power. It just needs some tuning.

xr2wishy

iTrader: (2)

there must be a way round it, changing turbo isn't the answer as mine was fitted to a similar engine previously and didn't suffer like this.

GARETH T

So you change the exhaust housing, maybe port the compressor, play with the boost control and a head job. You gain one nice big bhp number but have you gained a nice driving car?

Mark Shead

You need to change the exhaust housing and a inlet cam.

Mark