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2G Hx40 auto super laggy

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Lilslmj

5+ Year Contributor
126
44
Feb 8, 2018
Berwick, Pennsylvania
Ok wasnt sure where to post this but decided to post here since it'll get more attention. Anyway... I'm running a hx40 in a bep housing .55 and I've never really taken notice myself how laggy it was until ppl started pointing it out to me after looking at my logs. I just assumed it was normal to be laggy being auto with a stal .

So my setup is stock 7bolt motor recently reringed, 155 across the board, leakdown test was good showing 12% at most so the motor is healthy. Evo 3 intake manifold, bc 272 cams, mild port on the head, knife edged and gasket matched intake and exhaust, Old slowboy racing exhaust manifold with tial external gate on the manifold, 3" turbo back to apexi muffler, vrsf fmic.

Transmission is stock besides translab shift kit and forced four shift box with a sinister draginator 9.5 converter.

I've checked for boost leaks and only one is a very minor leak at tb shaft seal which I just rebuilt cpl weeks ago but its leaking ever so slightly. Being on sd I wasnt to concerned about it.

Driving from a roll i dont see full boost 32psi until 6300 rpm. I've tried brake boosting from a roll and still doesnt seem to bring full boost in any sooner. Maybe 200rpm sooner.
But from a dig with 2step set at 5500 and antilag enabled at 3500 I can easily build 20psi even more if my brakes could hold back more in 2.5 seconds.

So idk if it's the turbo to blame which it shouldn't be or the stall to blame or something else I may be missin . From a lot I've read I should have full boost almost 1000rpm sooner on an auto and 5spd guys I've seen having full boost as soon as 4500rpm.
I'm currently at work so I cant post a log but I will try to post one on break or after work or tomorrow.
 
Part of it is that crappy turbine housing.

Cam tuninng can net several hundred rpm as well.
But shouldn't the .55 housing help it spool much sooner at the cost of killing flow up top? And I wanna get some adjustable cam gears next to play with that to try and help it come alive sooner.
 
Man, it is smaller, but it is still junk. Guys are spooling faster on open t3 manifolds with the factory 16cm housing. Faster yet with a totally divided setup.

And when those housing really start being leaned on, expect a turbine failure.
 
Man, it is smaller, but it is still junk. Guys are spooling faster on open t3 manifolds with the factory 16cm housing. Faster yet with a totally divided setup.

And when those housing really start being leaned on, expect a turbine failure.

Already had turbine failure. Lasted about 5 years of abuse from me and idk how much from previous owner but yea shaft got bent and locked up so basically had this turbo built by justin.

I have a t3 manifold and was thinking of going t3 but I cant afford to lose anymore spool. My powerband is already short. Even though I'll be able to take the rpm a little higher I'll have to with spooling even later.
 
Even in the choked up housing you should see full boost before 5k. When I was running that housing I think I was seeing it around 4600 and it would hold to 8250. I broke a few turbos, they got too hot on my lean tune and just bent or snapped them. This was on E85 and Justin and I have talked about it. For some reason you don't see the failures on HX35s. I will be testing a .55 again soon on a build that is going on currently tho, so I am following along!
 
Part of it is that crappy turbine housing.

Cam tuninng can net several hundred rpm as well.

The .55bep is not going to cause the turbo to spool slower. It will make it spool faster, but less efficient up top. The turbo should not be spooling that late period.

OP I would be checking for exhaust leaks or cracks at the manifold or the turbo / turbine housing. I would also be inspecting the turbine wheel for damage of any sort if all else fails. Also be double sure you do not have any major boost leaks. I would also be checking to make sure the wastegate is functioning properly.

I am currently on the .55 housing switching to the .70 this weekend and I see 34psi by 4500
 
I had a 5speed but in third on my hx40 (62mm cast version) I didn’t see 30+ psi until 6300rpm either. I tried cam settings all over the place, tune, everything. I always chocked it up to the 62mm wheel from bae being trash combined with my .55 housing having seen a failure and had to clean it up with a die grinder so I assumed it flowed worse.
 
At 168 seconds, you can see that I was almost all the way in at 4800 with 36 lbs on this old log.

On the second log, I was on an 8 blade HX40 and it is the log right before I broke her. I was most of the way in at 4500 rpm.
 

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  • log.2018.09.26-01 571HP 482tq.elg
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  • log.2015.10.16-01 last pull before letting something go 540HP 27lbs old turbo.elg
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Here are some logs if anyone cares to look over of the slow spool up.. Ill post up a launch log as well but ignore the knock on that one as i forgot i had the ac on LOL... But youll see when stalling it up on the launch ive got full boost by 4500rpm..i have checked for boost leaks exhaust leaks and nothing that would effect spool up.. i dont have a vacuum or pressure pump to test the wastegate but i think thats working as it should.. i was tempted to plumb a line to the top just to do a wot pull until it starts to build boost and let out of it to see if maybe its leaking or cracking open a little causing slow spool.. anyway heres some logs.. maybe someone will see something im not seeing..
 

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  • pull clipped 6200rpm spool.elg
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  • launch clipped.elg
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I would pull timing at 4K up to 5500 down to 3* and see if your spool comes in any different. I told my son last night to do the same, as he was complaining about he couldn't get up on his converter after putting cams in his motor (they were stock, and he could get up on it, but not with his BC280 cams, currently).
What converter is in your car? It looks like you were able to get up on it after the antilag came in.
It looks like she comes in like a freight train tho, once you get her lit, which is how my HX40 came in.
 
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The .55bep is not going to cause the turbo to spool slower. It will make it spool faster, but less efficient up top. The turbo should not be spooling that late period.

OP I would be checking for exhaust leaks or cracks at the manifold or the turbo / turbine housing. I would also be inspecting the turbine wheel for damage of any sort if all else fails. Also be double sure you do not have any major boost leaks. I would also be checking to make sure the wastegate is functioning properly.

I am currently on the .55 housing switching to the .70 this weekend and I see 34psi by 4500
And I would be willing to bet you will see less lag with the t3 housing vs the .55. like the early precision dsm flanged housings, the bullseye isn't great either. Yes it's a "bolt on" piece, but it sacrifices a lot everywhere to "bolt on".


O.p. is your housing machined for an internal gate with a flapper that's welded or tied closed?
 
And I would be willing to bet you will see less lag with the t3 housing vs the .55. like the early precision dsm flanged housings, the bullseye isn't great either. Yes it's a "bolt on" piece, but it sacrifices a lot everywhere to "bolt on".


O.p. is your housing machined for an internal gate with a flapper that's welded or tied closed?
Im running external gate off manifold. Flapper was welded shut from extreme psi but it wasn't really welded that good so I welded it agai .
 
I would pull timing at 4K up to 5500 down to 3* and see if your spool comes in any different. I told my son last night to do the same, as he was complaining about he couldn't get up on his converter after putting cams in his motor (they were stock, and he could get up on it, but not with his BC280 cams, currently).
What converter is in your car? It looks like you were able to get up on it after the antilag came in.
It looks like she comes in like a freight train tho, once you get her lit, which is how my HX40 came in.
I'm running the sinister draginator 9.5 which is
Drag DSM ( 7-8 Second E.T.) with Nitrous or
Small turbo (14b-16g) looking for a better flash stall and more MPH than the stock converter up top
Showing sub 3% Slippage at 140mph on a GT4202 at 38-40psi
 
Are you using both top and bottom ports on the external wastegate? And have you edited the settings in ecmlink to keep the wastegate closed longer?
 
No I'm only using the bottom por . I'm not running ebc. Running a dual stage turbo xs mbc but only running it single stage right now until I can get this figured ou . Then I wanna set 1 stage for lower boost and under 95% throttle for launching and 2nd stage for once I'm off the line and 100% throttle
 
I've got such a heavy spring in there that i highly doubt its cracking open early unless my backpressure is insanely high. So running both ports isn't gonna help. I thought about that as well and asked several big ppl in the dsm community and they all said it's not gonna change anything.
 
I run a heavy spring combo in mine to. WG pressure is somewhere around 28 or more. My Tial stays shut.
 
So you don't hear your wastegate open at partial throttle? Only at 27 psi?

I hear my wastegate chattering. To my knowledge, its bleeding off excess and "controlling" the boost. Based on Throttle Position.

Using both top and bottom ports can help spool by keeping the wastegate closed LONGER.

I have a stock rvr engine, 2.0, auto on a bastard 20g turbo. I eventually got to the point with all these bolt ons that my wastegate was opening at 14 - 17 psi. I switched the vac lines to dual port, and threw a T in there like ecmlink suggest for that partial setup. I've been on 27 psi ever since.

So, based on my research for my turbosmart external gate, that is why I am suggesting it. I literally swapped the lines over while in my work parking lot. And the difference was immediate.

Not every car is the same.... no matter if the setup is identical.

PS - 17 lb spring here.
 
You done a boost leak test? My old hx40 had a leak at the back of the compressor
Cover causing mass lag til I fixed it Something to think about.

You should definitely be seeing 30psi by 4800 max, I made 40psi on the .70 AR at about 5500. Theres definitely something going on. It should be a quick spooler, but drop off at the top end. Or be knock happy past 30psi on pump gas. But absolutely no reason to be seeing it at 6300
 
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