So...TurboSmart E Boost Street boost controller set on 0%, which should be wastegate, (6# spring, usually making 5 ish psi post intercooler). Made over 18#. on 3rd and last pass, Saturday.

Open cutout, made 3 passes...1 time run, and 2 rounds of eliminations
1st pass: Should have ran 11.0's at 132ish, with a no boost idle launch, but went 10.00@147, I knew it was on a pass, and wideband glance showed good, so wasn't about to let off, LOL
2nd pass: Blew the tires off, just beyond 60' lights, let off and easily ran down a car that ran what I USUALLY run, which is low, low 11's.
Last pass let off between 660' and 1000' and hard on the brakes, to run a 10.74@93

Wastegate is not binding, works and moves freely on bench, using minimal air pressure.
MAC valve removed and bench tested, works as it should.
I use a 3/8" boost reference line off of my charge pipe, as I always have.
Then, from vacuum tree to MAC, MAC to lower port of wastegate...all plumbed as it's always been.

Only "change" since last month's shootout, was ditching the 3" On3 intercooler, for a 4.5" Treadstone one. It seemed to control boost fine the last couple times I drove it, but that was also with my cutout (on downpipe), closed, running through full exhaust...

Is it possible that the open 3" downpipe is causing/letting exhaust just bypass the wastegate entirely? Any ideas? I'm stumped...

Even with open cutout, the car's setup has ALWAYS been able to control boost

FWIW, Car's a 4060# race weight Trans Am, and has been [email protected] on 16# a few weeks back, at a no-time test & tune.

On3 A/C Delete hot and cold sides
On3 44mm wastegate
On3 50mm blow-off
VSR 78/75 Next Gen Billet turbo (.96 AR, open T4)
Treadstone 4.5" intercooler

 

All my Turbo stuff is still in the box, but I think with 0% you should be on the top to get gate. You want 100% on the bottom to help open it.

 

Turbosmart says Boost Controller Set Point of 0% = it not doing anything, just allows boost pressure to bottom of gate (run on wastegate spring), so "should" in my case, be 6#, not almost 19.

Normally, car goes 11.0 or so, at 132-133 MPH with EBC set like this. I actually bracket race the car.

 

Hopefully some one with real experience will chime in, all I have at this point is OEM and keyboard knowledge. I understand wanting to be able to control it but it sounds like 18 is more fun than 6!

 

Oh it definitely is FUN...but trapping 147mph without so much as a rollBAR, is frowned upon at my local track, lol

 

The only thing I can think of is that the air isn't venting out of the WG dome. Maybe the solenoid isn't working or isn't plumed correctly or the exhaust port is plugged. Does the solenoid have a little brass muffler on it for venting? If so It could be plugged.

A quick way to tell would be to unplugged both hoses from the WG completely to let the WG breath then make a run to see of the WG opens from exhaust pressure.

ks

 

That is definitely what it seems like.
Plumbing is the same as it's been since turbo install, back in December 2019
The exhaust port on the MAC valve has no brass filter, just a nipple with open hose

Yesterday, I removed both the wastegate and the MAC valve/solenoid. Using shop air, and a small jump box, both functioned as they should, no binding or anything.

I tested the vacuum/boost hose everywhere between the charge pipe source, to the vacuum tree, to the solenoid, to the w/g.

Only change to anything at all, was an intercooler swap...from a On3 3", to a Treadstone 4.5".

I've always gotten boost "creep", if cutout is open, since swapping on this EBC.
It actually works out great for me, making it harder for the car chasing, to judge my speed...since it's normally 15-20+ mph faster than the ET would suggest...

But...With EBC set the same as last month's race, open cutout at end of 3" downpipe, it made over 18# in 2.5 seconds, from a barely off idle, no boost, footbrake launch...
NORMALLY, (and according to datalogs from last race), it takes 10 seconds or so, on a same type run, to "creep" from no boost, to 12 or 13ish#

 

If you had boost creep before, and the car is making more power due to the intercooler change, it may be just more flow than the gate config can handle.

Is it creeping to 18 or going up quickly then flattening off?

 

It is SPRINTING to 18+...within 2.5 seconds, footbraked, launched just off idle, boost controller at 0%.

For comparison, with boost controller set at 70%, and using transbrake, it took roughly 5 seconds to make 16#, from the 4# it had on the transbrake. That was PRIOR to intercooler swap...and when it ran it's current best: 9.76@142

 

UPDATE:
Was able to take a couple short drives w/datalogging after work today...

Totally disconnected the wastegate from anything...no hoses going to it anywhere, both ports open to atmosphere
Made consistent 16# boost with cutout open OR closed

Spliced the two hoses that connect to the MAC valve, to totally bypass boost controller, and so that it SHOULD only make wastegate boost (6# spring)
Cutout OPEN = 12-13# boost
Cutout CLOSED = 6# boost

Boost Controller/MAC valve plumbed back in, exactly how it's always been, to lower W/G port ONLY...
Cutout OPEN = 16#
Cutout CLOSED = 10# peak, one rolling higher speed "hit", but under a few other lighter throttled "hits", only made 4-5#

So, now I still don't get, what is happening...Is the wastegate just not able to bleed off, if cutout is open?

 

Correct. Evidently there is enough flow resistance through the turbo when your exhaust is restricting flow to divert through the gate instead. When you open the cutout you reduce the flow resistance past the turbo, the exhaust gas takes the path of least resistance.

I think Backpressure on the turbo is multiplied by pressure ratio, so a change in post turbo resistance is more dramatic. I can't site that as fact, hazy memory.

You need to improve your gate location, go to a bigger gate, or add another gate. Essentially you want it to be easier to flow through the gate. Are you running a hater pipe or does your gate recirc to exhaust?

 

Wastegate has small pipe directed at ground.

I'm debating whether to add one, on the passenger side, as looking at the pics, or just welding up the area where the existing one is, and install a pair on the locations marked "1", in the pics

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Your current wg location is not good. I would install 2 at the #1 locations you have in the picture.

 

Yeah, it's the On3 F body A/C Delete "kit", sans turbo, and looking back through older datalogs and such, it has never controlled the boost as it should...unless my cutout (at end of downpipe) is CLOSED. That, unfortunately, also chokes off a ton of power, so not an option, lol. I only close it when I am just cruising around, or in and out of my neighborhood.

I guess I have my winter project...Thanks for replies guys.

Should I just buy another matching w/g (On3 44mm), or go smaller, like a pair of 36-38's?
Can you run 2 different sizes? I doubt I would, but just curious.

Any suggestions where, or best cost effectiveness, please chime in.

Thanks.

 

That's a tough one. I don't want to spend your money, but if it's my car, I sell the one WG you have and buy two Tial 38mm or 44mm gates and install them in location #1 posted above.

I theory you could run mismatches sizes. In practice I doubt it's a good idea.

 

2 38's gives you the area of a 53mm single, and they'll be in a very good spot.

 

I went ahead and bought 2 new VS Racing 44mm ones. They come with 3 different springs, gate and pipe flanges, and two v bands. Going to put them in "Position 1" on my awesome mspaint above, lol.

The "matching" On3 version was $144 + shipping, but their customer service sucks, and hasnt/doesnt exist for me. The VSR 44s are 99 bucks a piece, and I havent really heard or read any bad about them. My son grabbed me a 4 port MAC valve, so I have a little winter project now.

 

Wow and you wonder why you can’t control boost lol. On 3 has some piss poor WG location. At least the problem is figured out and it’s getting fixed before something expensive got destroyed

 

Well, here's the story, as short as possible...
Ironically, the end goal (which we all KNOW, is BS, lol), started out being 500RWHP, which is a realistically healthy runner, and a goal easily attained.
Last year, the car made little 500rwhp with a shot of nitrous, but I wanted the car faster, without depending on bottles being filled.

I bought the On3 kit, because it was actually cheaper ($1850), and was much less wrenching for me, than new headers, new cam, new (or restalled) converter, and a gear swap in the 9", to optimize the nitrous setup.
The included manual boost controller, controlled boost with zero issues.
Swapped the 70mm turbo out within 2 months, for a cast 78/75 VSR turbo, and added a Turbosmart E-Boost Street EBC, and that's when issues of boost control, for me, started.
On 16# of boost, my portly TransAm ran a 9.92@138, so I was happy.....for a day, lol.

Ordered a new billet Next Gen 78/75 shortly thereafter....

The E Boost Street has 2 easily sourced boost levels.
At my lower boost setting (0% mac duty cycle), it steadily creeped, from gate pressure of 6#, up to as high as 13-14, on a footbraked, off idle pass. This actually worked GREAT for me bracket racing, as it is hard to judge a car dialed in at 11.0 or so, running low 10 second MPH. I actually used my higher boost setting, 18#, as a scramble button, if needed, through the traps.

Month or so ago, went to a Test & Tune, intent on running better than the 9.92, and did....running a 9.76@142, then a [email protected] with the 3" On3 intercooler.

Bracket race 2 weeks later, me trying to stay 11.50 or slower, since I have no rollbar or rollcage, I ran with my cutout closed, (which is ONLY way my boost does what the controller says to do), and on gate spring, ran 11.51@124

Swapped on a Treadstone 4.5" intercooler, a few days later, and nothing else...car felt MUCH better seat of the pants.

Hadn't ran it until this past weekend, where 1st time run, footbraked, idle launch, but OPEN CUTOUT, went the 10.00@147....

Hence the thread question started above...

Hope I didn't bore too many of you, lol.

I do have one last test & tune, which is a no time/no clock event, so will run it out the back door, as they say, as is, to finish off the effed up 2020 season.

 

i have had similar chineese wategates, all of which need a complete disassembly, deburring, cleaning, making sure it has the right fasteners and polishing of the valve stem. then they work fine.