2G Slow Spool B16G Turbo 4500+ RPM

1slowhatch · Jul 4, 2016

Just installed a used Big16G OEM Mits turbo. No free play, spins freely. I ported the stock 2g manifold, 02 housing, turbine housing, etc. I have done a boost test, double checked exhaust leaks, new gaskets, etc. The turbo makes good boost around 4500rpm (15psi) in my car. I am at 4500 ft elevation. I was expecting spool to be much closer to 3500ish RPM.

I did some testing today. I've read that a bad WG actuator can cause problems. I tried shimming it away with washers under the mounts (to insure the flapper is closed) and it made no difference. With no boost controller hooked up, I only get around 8 psi. With the controller maxed out, I get a 17 psi spike, falls to 15 or so.

Does it sound like a bad wastegate actuator? What else could be causing the slow spool? I have stock exhaust less the rear most muffler.

1slowhatch · Jul 4, 2016

Forgot to mention, this is in a mostly stock 96 Talon TSI auto. It makes full boost around 4500 rpm no matter what gear I'm in.

Ferp · Jul 4, 2016

I think the stock wastegate pressure on a big 16G is ~10psi. If you're only holding 7 with an mbc hooked up it may be a wastegate related issue. Something you can at least check.

1slowhatch · Jul 5, 2016

No I'm getting 8 psi with no MBC. Around 15psi with my MBC maxed out. Anybody tried these cheap ebay actuators? http://www.ebay.com/itm/90-99-Mitsu...ash=item43e7e0103e:g:RWwAAOSwYHxWPm8F&vxp=mtr

ThunderChild · Jul 5, 2016

Those ebay actuators are garbage. Get a used stock one or the like.

How much did you port your parts? I know my 14b with ported 2g mani, ported 8cm turbine housing and ported PR stainless o2 housing hits full boost (18psi) in 3rd @ ~32-3500, which is later than most. Before I had my hallman pro, I maxed out boost at 9-10psi @ same rpm, give or take 100rpm.

Seems like porting the manifold and turbine housing too much drops spool pretty drastically. Granted I'm happy with how my setup works right now, but seems like your setup is lacking.

Where are you getting you're oil feed from?

1slowhatch · Jul 5, 2016

tametalon92 said:
Those ebay actuators are garbage. Get a used stock one or the like.

How much did you port your parts? I know my 14b with ported 2g mani, ported 8cm turbine housing and ported PR stainless o2 housing hits full boost (18psi) in 3rd @ ~32-3500, which is later than most. Before I had my hallman pro, I maxed out boost at 9-10psi @ same rpm, give or take 100rpm.

Seems like porting the manifold and turbine housing too much drops spool pretty drastically. Granted I'm happy with how my setup works right now, but seems like your setup is lacking.

Where are you getting you're oil feed from?

The manifold ports at the head were barely gasket matched. The outlet of the manifold to turbo was opened up to (gasket match) 7cm gasket. The o2 housing outlet had the step taken out. The turbine housing was just matched to the gasket. NO way 4500+rpm is normal right!??

Oil is coming from the oil filter housing via e-bay stainless line.

Why is my turbo making boost over 1k rpm later than most!??

Nate355RS · Jul 5, 2016

Are you using one of those ebay actuators? If so do you really have an genuine 16g?

If your actuator has a threaded rod, try adusting it. I usually get it so it will just slip onto the flapper, then tighten it three full turns. You usually have to give the actuator rod a good solid pull to attach it to the flapper, but it tends to hold boost better and limit boost spikes.

1slowhatch · Jul 5, 2016

No, genuine Mits B16g with OEM wastegate actuator.

I'm considering going to an ebay adjustable WG actuator. IS 4500 rpm spool speed normal for this setup!?

1slowhatch · Jul 5, 2016

I've read that FP red's spool not much slower than this. This 16g won't be on my car for long working like this. On a cool night, I'm seeing as much as 26 lb/min on mass air. How much power should that be good for? I think I'd see 22ish lb/min on the stock t25 at 18 psi.

pauleyman · Jul 5, 2016

Did you use the fire ring between the manifold and turbo? Ive seen those get in the way as they dont fit ported units.

EvilGST · Jul 5, 2016

1slowhatch said:
I've read that FP red's spool not much slower than this. This 16g won't be on my car for long working like this. On a cool night, I'm seeing as much as 26 lb/min on mass air. How much power should that be good for? I think I'd see 22ish lb/min on the stock t25 at 18 psi.

I have hit 30 lbs/min on a 14b

EvilGST · Jul 5, 2016

Did you actually physically look at the flapper? I had a similar problem recently and after taking the O2 housing off noticed the flapper arm and flapper somehow walked forward causing the flapper to not align with the hole. However my hot side is a turbolabs piece and not genuine MHI so im not sure this would happen on a MHI piece. Just something to check.

chrysler kid · Jul 5, 2016

If you are running the stock bov it is leaking and causing your problems. My factory bov would cause that exact same problem

1slowhatch · Jul 5, 2016

EvilGST said:
Did you actually physically look at the flapper? I had a similar problem recently and after taking the O2 housing off noticed the flapper arm and flapper somehow walked forward causing the flapper to not align with the hole. However my hot side is a turbolabs piece and not genuine MHI so im not sure this would happen on a MHI piece. Just something to check.

Yeah, when I had it apart for porting, it looked like the flapper opened and closed correctly.

1slowhatch · Jul 5, 2016

chrysler kid said:
If you are running the stock bov it is leaking and causing your problems. My factory bov would cause that exact same problem

No boost leaks (checked to 20 psi). I have an all metal Evo 8 BOV.

I'm thinking it must be a WG actuator problem? Lazy boost response, only holds 8 psi without boost controller...

I'm considering this one as well. More money, but looks like it's set for 15 psi out of the box. http://www.ebay.com/itm/Turbo-Actuator-4G63T-TD05H-14B-16G-EVO-1-3-Galant-VR4-DSM-1G-1-0-bar-15-psi-/182162619254?hash=item2a69bcfb76:g:0DsAAMXQVERS5u3h&vxp=mtr

hollywood_ikr · Jul 5, 2016

Were you experiencing any of the lag before the turbo swap? I had the same thing happen to me on a project last year. I ended up swapping to a good 14b and problem solved. At the boost level you are running I wouldn't even upgrade turbos yet

1slowhatch · Jul 5, 2016

No I had a T25 on it before, and I think it was working correctly. It spooled wayyy faster. I could foot-brake 15+psi on that turbo.

1slowhatch · Jul 5, 2016

pauleyman said:
Did you use the fire ring between the manifold and turbo? Ive seen those get in the way as they dont fit ported units.

I made to sure to leave the fire ring out.

doubleclutch · Jul 5, 2016

I completed a E316g (same as B16g i believe) this winter and with running on wstegate spring pressure alone I get 8-9 psi. That being said with the controller working correctly the thing builds boost like a mother after about 3200 RPM. No reason you shouldn't be building boost before 4500. Either the wastegate is too weak, or your boost control method isn't bleeding off enough air.

What boost control are you using?

1slowhatch · Jul 5, 2016

doubleclutch said:
I completed a E316g (same as B16g i believe) this winter and with running on wstegate spring pressure alone I get 8-9 psi. That being said with the controller working correctly the thing builds boost like a mother after about 3200 RPM. No reason you shouldn't be building boost before 4500. Either the wastegate is too weak, or your boost control method isn't bleeding off enough air.

What boost control are you using?

Just a manual boost controller (NXS ebay). Seemed to work ok.

Does it build boost at 3200 RPM on the wg alone??

ErikTande · Jul 5, 2016

pauleyman said:
Did you use the fire ring between the manifold and turbo? Ive seen those get in the way as they dont fit ported units.

Isn't that what happened in this Jarfro vid? The compression ring / fire ring is the same thing, right?

Skip to 8:16 to see it.

You must be logged in to view this image or video.

1slowhatch · Jul 5, 2016

I just ordered one of the $75 15 PSI 16g actuators. I'll report back with hopefully good news (I'll be sad if the $75 is a waste).

doubleclutch · Jul 5, 2016

1slowhatch said:
Just a manual boost controller (NXS ebay). Seemed to work ok.

Does it build boost at 3200 RPM on the wg alone??

i want to say it did. no reason it shouldn't. it might be alittle bit slower because the wastegate is opening up a bit, but it seemed to spool like normal just not any power well, cause 8 lbs isn't that much.

On the way home from work I was commanding an open BCS (100% duty cycle) at 3500 rpm and it would spike to 20lbs before about 3800, then the rest of my tune brought it down to something safe for 450cc injectors.

The boost control system is very sensitive. I had a 0.035 restrictor in and couldn't make more than 15 lbs of boost with BCS wide open. I put a 0.025 restrictor in and the thing will build boost like no other. Is you manual BC wide open?

1slowhatch · Aug 23, 2016

Just an update for you guys... put a new aftermarket wastegate on it with supposedly a higher set point. Basically no change. Same spool characteristics. I have also since installed a VRSF style FMIC.

How many lb per minute should I be seeing with this B16g? It seems like I picked up a little airflow from the FMIC. I'm now getting a max of 27.5 lb/min at about 19 lbs (would see a max of 27 lb min on 22 psi with stock SMIC) on a cool night. I fuel cut on anything higher.

doubleclutch · Aug 24, 2016

You are getting air at a lower temperature, which means more air for a given PSI. Naturally this means that you will see more flow post vs. pre intercooler install for the same psi.

Probably should stop installing parts that may affect your troubleshooting.

Back to your issue, if a new waste gate makes no difference, it must be something with your wastegate control, or something with the performance of the turbo. If the thing is as solid as you have said, then it shouldn't be the turbo. Please post a diagram and/or pictures of how you are controlling boost (where your lines come from and what they go to). I understand the frustration of a turbo swap that nets the same psi. Let's get it fixed.

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