meckert

iTrader: (11)

I like them-- other info on them here.
https://www.evolutionm.net/forums/ev...274-278-a.html

Can't remember who, but there were some big numbers up on these as well.

wingless

iTrader: (15)

OG 7460 from the cam and valve spring promotion here. 1800$ for the turbo, valve springs and 274/278 cams. Not to many stock frame BB turbos under 2k$ alone.

Built 2.0 + head, about 1.5 years/ 20k + of daily abuse no issues yet.

With a 3port, V7 boost control and a tight Tial QR it was pretty tricky riding the surge line up through every gear and % TPS to get it dialed in, but well worth it. I run the stock exhaust except for a down pipe and about a 25 PSI peak with a big ol' IC. Its a pussycat in traffic and ****ing brutal and instant from 2.5K RPM on when you get after it. Coming from a 10.5 "TME" 16g this was one of the "biggest" turbos that I could stomach on the street. The tiny hotside works better than most with my mostly OEM exhaust.

tl;dr: I<3 this turbo, no problems yet.

SKILMATIC

iTrader: (1)

Just curious and this may be a bit off topic but do any of you have issues with surge? I initially had it bad when I had a crushed stock dv. Then i switched to a synchronic old style bov recirc. It seems to help but still get surge when going up hill and try to maintain a certain speed. Has anyone cured the surging entirely? And if so how exactly? I keep hearing different things just curious if someone has some first hand personal experience.

wingless

iTrader: (15)

So... Yes, but... And someone please correct me if I'm wrong, but as I understand the dynamics, "surge" is when there is a greater volume/pressure in the cold side charge pipe/IC than can force passed the obstruction of the butterfly valve throttle body (or not enough vacuum in the IM due to the VE of the motor). Small turbos that can move a lot of air quickly can create a pressure differential on either side of the throttle body and back flow air into the compressor creating the chuffing noise we know so well. The stock diverter valve has a bypass to mitigate this on a 16g and the intake system also helps slow down the compressor on the stock set up (crushing it closes this bypass).

As I mentioned above with ultra responsive turbos (small hot side+ bigger compressor), a tight (non-leaking) BOV and a free flowing intake filter you will be able to move air quicker than it can get past a partially open throttle body and surge will occur.

Very precise gear by gear boost control is an absolute must with an after market BOV and filter. Another feature in V7 very few people use and even the stock setting are all 100% is waste gate control by %TPS. This is very sensitive and even going 90-99% lets a lot of power through the WG but helped me with a couple problem part throttle areas.

So yes this turbo surges. Other smaller turbos use the (surge port) vented bypass in the compressor cover, and OEM uses a leaky BOV and restrictive intake, but personally I prefer fine programable control. You are done when you can matt the pedal at any RPM and not hear that "chuffing" noise.

Big turbos are less prone to surge as they are always behind the spool curve until higher RPM and into more VE of the motor... Other fixes are bigger TB /intake manifold, but I have not personally experimented here.

tl;dr: Yes, but good boost control solves the problem.

SKILMATIC

iTrader: (1)

I was contemplating utilizing a surge cover on the turbo but I haven't heard anyone using one and it curing the issue. I will have to look into the electronic control method. I do have tephra but im not sd.

wingless

iTrader: (15)

SD or MAF should not matter although I do prefer SD, all about tuning boost control by gear/boost/RPM. None of Sean Ivey's 7460 cars surge for a reason V7 boost control is awesome and with properly set up error correction you can get a pretty square boost profile.

SKILMATIC

iTrader: (1)

I really appreciate your feedback on this. Now according to Sean does this method tamper with overall performance as far as making power and or reliability? I am actually going to be eventually changing setups anyway going for more power but I would like to know anyway. I will probably utilize this setup for another yr. But sd is something I looked into but due to the altitude changes in California I was a bit weary of switching to sd. I actually got all the parts for it and everything lol.

wingless

iTrader: (15)

I have honestly never talked directly with Sean. I am a hopeless tinkerer and tune myself. When these turbos came out Sean, being an factory HKS dealer and tuner, just had the most experience with them and the most intelligent feedback on the forum at the time contributing to a couple "surge" threads. having pointed me in the right direction I muddled through the rest. If I had lots of money or lived closer to NJ I would have loved to have it professionally tuned.

There is a ton of information on the ECUflash forum about how the SD barometer routine works from Mrfred. I don't remember off the top of my head, but I recall lot of testing and I don't think varying altitude was a huge problem...

nollij

iTrader: (21)

All turbo compressors have surge lines from high pressure ratios in relation to flow.

At low rpms the flow is pretty low and it is possible to have too high of a pressure ratio for the particular flow that the engine allows with a turbocharger that spools up early.

http://en.wikipedia.org/wiki/Compressor_stall
Things that will help (probably):

• turn down boost in rpm range where surge is occuring using ECU (This is what I have done; stock turbo, surge at 3200, turned down WGDC in the 3000 rpm cell until it stopped surging)
• less MIVEC (I don't know specifics)
• more open intake (decreases pressure ratio across compressor)
• compressor cover with anti-surge cover
• more restrictive exhaust (slow that turbo down!)
• create boost leaks! (everywhere! get that pressure ratio down!)
• anything else that can be done to slow down the spool of a turbo (large intake manifold, long runner exhaust manifold, cams that are way too big for the turbo to sensibly run, etc.)

So, cheapest would be to just address it in the tune or create a more open intake.

wrx2evoIX

Agree with comments above regarding gear based boost control and MIVEC tuning, for those with MIVEC.

I run 10% WGDC below 3000 rpm in 5th and 6th and have no surge with this turbo. I have to be a little bit careful in 4th as well, currently using 47% WGDC settings from 2500 rpm. I also call for less Boost Desired Engine Load in 5th and 6th. I can flatten the gas pedal in 5th and 6th from less than 3000rpm and just get smooth acceleration.



In 3rd gear I'm seeing 27PSI at 3400rpm and spool driveability is perfect.

I don't run MIVEC values of more than 19.2 during spool. The MIVEC settings depend on CAM type and setup. With more agressive MIVEC I've seen >25PSI at around 3000 rpm but make for a jerky spool zone and make less power.

I did have some issues with partial throttle lift flutter but I recently changed from the stock metal DV to the small Synchronic DV with softer spring and now the part throttle stuff is perfect too.

keath

Aaron from english racing tuned my 7460 with 2.4 and it does not surge at all. he did something with the mivec if i recall. maybe he can chime in

SKILMATIC

iTrader: (1)

No offense but that entire outlook defeats the premises of buying and utilizing a quick spooling turbo in the first place. We of course want the best of both worlds in quick responsiveness and drivability. I want my cake and eat it too...

nollij

iTrader: (21)

You can only shove so much food down a goose's neck at a time when making foie gras. Half of my suggestions were sarcastic (boost leaks, restrictive exhaust, etc.)

Surgeline is just an aspect of a compressor. You want to have your cake and eat it to? Get a small turbo with a better surgeline. BW EFR turbos supposedly have great surgelines. Talk to FP about their turbos and their surgelines. I am sure you will find that their compressor cover and compressor design result in a lot of surge reduction.

God forbid you buy a turbo for its transient response or other reasons that don't show up in a dyno plot.

meckert

iTrader: (11)

I have only had surge when I was in the wrong gear and loaded up at low rpm. ( this doesn't mean this is your case) that being less then 2000rpm and attempting to accelerate under boost and not in 1-2 gear. Never had issues otherwise with this turbo. Thinking tuning is playing a large role.

wingless

iTrader: (15)

In order to get as much power out of a 2.0l motor as quickly as possible you get a turbo that can shove air quicker than you can suck it up and pump it through the motor in some places on the map.

You need to tune around that ****- To use a more direct analogy than force feeding geese (which was awesome BTW).

Rest assured that by backing of WGDC and allowing RPM to build you will still make power sooner.

Won't impress the MBC and 35r crowd, but it will huck you out of corners with thoroughly terrifying quickness.

If I had a **** load of money I wanted rid to get rid of, the little top mount Full Race IWG EFR is choice #1 for me.