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VF-52 - When does it Spool?


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I recently got tuned up for a VF-52 on my 5EAT 05 Outback XT. Even with a pro dyno tune, its a dog off the line. I don't recall the exact RPM, but it doesn't really hit until about 20mph. I don't launch the car so maybe that has something to do with it. I'm in the process of trying to get a better tune. I'm currently on my 3rd etune revision with Tuning Alliance, and I'm not seeing much of a difference. I let them know about my concerns ahead of time.

 

Here are my mods: VF-52, GrimmSpeed Uppipe, Invidia Catted Downpipe, GMS Catback, GrimmSpeed TMIC, Tomioka Racing Inlet, HexMods Valvebody, DeatschWerks 65 C Fuel Pump, DeatschWerks 740cc Side Feed Injectors, GrimmSpeed 3-port, Grimmspeed CAI, 4454 Tranny Cooler

 

Maybe its performing as expected but I just want to get some input from others about how their VF-52s perform. Thanks.

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I have a VF52 on my 5MT OBXT. It spools slower than the VF46. That was expected. The VF46 hits with a sharp torque spike and then dies higher up. The VF52 seems to come on a little more gently and keep pulling harder. It feels close to 3500rpms before my VF52 actually feels like it's pulling.

 

I don't know how many revisions TA does (I did 12 with Cryo), but I would absolutely not consider the 3rd one anywhere close to done or worthy of analyzing the behavior of the Turbo.

 

If you look at WRX USA graph (his mods are more similar to yours). It's really obvious the drop in early torque.

http://legacygt.com/forums/showpost.php?p=5412274&postcount=53

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Oh hey, you live near me and were tuned where I am planning on bringing my car. I don't know if an etune will give you better results than a dyno tune would, I've heard nothing but good things about Quantum.

 

Some amount of sluggishness at low revs can be explained by it being an automatic. You could always just launch the car off the torque converter if you really want it to haul ass.

 

But looking at the dyno graphs in the thread Rhitter linked, there's no real getting around the fact that at 3100rpm, the VF40/46 is at full blast and making ~75 lb-ft more torque than the 52. It's what has me apprehensive about a 52, and more likely to go with a custom vf40 instead when I get bored of being stage 2.

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Funny you say that, I was actually thinking of the custom 40 while I was writing this thread. I do like the extra highway and passing oomph though. There is always a tradeoff with a turbo I guess.
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I have been considering an equal length header for quite some time now. I wonder if that would reduce the Spool RPM (how much if any)?

 

They typically make boost threshold (your issue) worse. More volume, less velocity to the turbo. If you wanted to try this the Killer B and Perrin have smaller tube diameters and thus better spool. Former is super spendy but bulletproof, latter has some fitment issues.

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For a fast spool the oem manifold with ceramic coat and wrap is hard to beat

 

I wouldnt bother with header till the rest of the exhaust, along with upgraded intercooler and fuel upgrades and tgv deletes have been done. The vf52 is capable of more than the stock injectors can dish out and its not uncomon to make over 300 TQ

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I have been considering an equal length header for quite some time now. I wonder if that would reduce the Spool RPM (how much if any)?

 

The graph that Rhitter posted is mine. I do have the KillerB Holy Header and my VF52 is a JMP custom but it was also ported/polished by Grimmspeed before. The porting/polishing on the hot side has a direct impact on the spool. As much as I'd love to swap in an unmolested hot side to see if that helps spool, I will most likely go with the AVO380 that I just bought since either requires another tune. Also I don't miss "the rumble" at all.

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I'll have a grimspeed ceramic coated PNP manifold + cross pipe + up pipe set up for sale in a few weeks if spool is your only goal :lol:. I'll even throw in some DEI titanium wrap. Not sure how much it helps though because I installed it at the same time as going stage 2.
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For a fast spool the oem manifold with ceramic coat and wrap is hard to beat

 

I wouldnt bother with header till the rest of the exhaust, along with upgraded intercooler and fuel upgrades and tgv deletes have been done. The vf52 is capable of more than the stock injectors can dish out and its not uncomon to make over 300 TQ

 

I have everything mentioned installed except for the TGV's and of course the header. For me its not worth the $ or hassle to delete the TGv's at my current HP/TQ level.

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My vf52 tuned by TA is awesome.

 

Here's what I would do. Make sure you don't have a boost leak, do a boost leak test. When your sure the engine is in good shape, fresh spark plugs if they've been there for a while, change the oil, drive down to meet Mike and have him street tune your car. The 90 minute drive or so will be so worth it.

 

My vf52 spools about 2400rpm and pulls hard to over 6000rpm. I'm on stock fueling.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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Mike should be sending you an email today.

 

If you wanted, you could upgrade your actuator / wastegate spring to a higher level. This will help spool, and let you hold higher boost at higher rpm (rather than tapering off). We can set you up with one if interested. I have a turbosmart on my legacy with 7 +10 lb springs (so 17lbs).

 

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Haha the VF52 did not last long. Looking forward to seeing your graph.

 

I got a crazy deal on the AVO380 that I couldn't pass up and it was the turbo that I was originally looking at before I got the VF52.

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My vf52 spools about 2400rpm and pulls hard to over 6000rpm. I'm on stock fueling.

 

In what gear?

 

OP's main complaint is with first gear acceleration. A VF40 will still spool early enough that you're getting a decent amount of boost even though the engine isn't really loaded as much and the revs are climbing fast enough to delay spool to a higher rpm.

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I can put the engine at 2400rpm in 4th and climb the long up hill without adding throttle. That's about a 1/2 mile from the house on my drive to work. I can feel the turbo spool and the car climbs the hill with no problem. The hill is close to a 1/8 of a mile long.

 

With the 5mt the car is never far from being in the spool area of the turbo. That's why I say the car responds to throttle input like an NA car. If I want more power I drop it down a gear or two.

 

In first gear the engine get' to fuel cut quickly if I'm not careful. Sometimes it make 1st gear feel short. It will also spin the snowtires in high end of 1st on cold pavement.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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In first gear the engine get' to fuel cut quickly if I'm not careful. Sometimes it make 1st gear feel short. It will also spin the snowtires in high end of 1st on cold pavement.

 

I have never really understood this (you have mentioned it a couple times) never have I felt close to spinning tires in anything but LOTs of rain and a clutch drop. I wonder if it has something to do with the larger diameter of my tires.

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I doubt you have pavement as cold as we do here when the temps have been blow freezing for day's on end. I run 17" snow tires.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I can put the engine at 2400rpm in 4th and climb the long up hill without adding throttle. That's about a 1/2 mile from the house on my drive to work. I can feel the turbo spool and the car climbs the hill with no problem. The hill is close to a 1/8 of a mile long.

 

With the 5mt the car is never far from being in the spool area of the turbo. That's why I say the car responds to throttle input like an NA car. If I want more power I drop it down a gear or two.

 

In first gear the engine get' to fuel cut quickly if I'm not careful. Sometimes it make 1st gear feel short. It will also spin the snowtires in high end of 1st on cold pavement.

 

 

 

The tirbo will always spool faster going up a hill due to higher load. It takes longer to accel up a hill so the turbo has more time to spool per given rpm.

 

You say you can feel it spool at partial throttle going up the hill, That is not even close to the same thing as spool !

First off spool means hitting max boost 18, 20, 22.... Whatever your max boost is set to. Second off dont go around claiming a 2400 rpm spool if your going by feel

 

Also if you are hitting boost cut your tune is no good. This is caused by wgdc being to high. If it happens only in first there is a 1st gear boost limiter you can adjust. Best thing to do is adjust the wgdc and possibly raise the boost cut. If the cut is due to mechanical creep you will need to either port exh housing, add a muffler or some type of restriction, or do an external wg. But seriously get that tune fixed !!!!!

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Fuel cut as in run's out of MAP after 7200rpm. There are some times when pulling out from a stop sign making a left or right turn where I go to WOT and the tires break loose in 1st gear and the engine runs out of MAP.

 

I always thought full boost was full boost, spooling is when the turbo begins to come into its its own and you can hear it and begin to feel it make power.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Fuel cut as in run's out of MAP after 7200rpm. There are some times when pulling out from a stop sign making a left or right turn where I go to WOT and the tires break loose in 1st gear and the engine runs out of MAP.

 

I always thought full boost was full boost, spooling is when the turbo begins to come into its its own and you can hear it and begin to feel it make power.

 

^He's right you know.

 

Spool is the act of building boost. This is why people talk about turbos starting to spool @ X RPM ... then reach full boost by Y RPM.

 

No one I've ever talked to has referred to full boost as spool. Nor has any of the literature I've read.

 

A spool is something that stuff gets wound around. Spool is also the turbo "winding" up to build boost. See how those relate?

 

See also: spooling up

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