I have no idea if this is a step in the right direction, but I like this type of troubleshooting process :icon_tup:

Does anyone know if he was able to find a solution? I am curious because I am close to purchase this setup, and before I pull the trigger I wanted to see.

Rx7aholic
Does anyone know if he was able to find a solution? I am curious because I am close to purchase this setup, and before I pull the trigger I wanted to see.

You might have to run an exhaust restriction in the form of a high flow cat or gasket with a smaller hole in it.

That is the solution!

I've been saying this......

a restrictor plate at the back of the DP causes zero negative effects, and has proven to limit my brother's BNR 3s to 13 psi vs the 19 psi it was seeing without. Sometimes you build an FD to flow, optimize everything---- and it freakin' flows :rofl:

Spoke to Brian at BNR at length about this and he gives it two thumbs up as the easiest, most cost effective solution. I'm talking 2.75 metal gasket in a 3 inch pipe.

We just had our first 8374 IWG turbo system with the new cast manifold street tuned by another big name shop. We were told its holding 10 psi... I will update when they dyno tune. I was told they were extremely happy with it.

If all goes to plan I am tuning the same combo in another week pending snowfall..

So, update.

I managed to secure some of Ray Wilson' time on a friend's dyno late last night. Bottom line, the wastegate just isn't big enough to bypass enough exhaust energy for MY car.

There's nothing wrong with the car. timing/Ignition/fuel check out. The car actually had older 10/10 plugs in it (my mistake) but replacing them with brand new ones made zero difference. We wired the wastegate door open. Zero difference. The car is running on spring pressure only with the boost solonoid bypassed. The power is there, and is excellent, it layed down 405 @15psi with the tires slipping quite a bit on an older dynojet, so it verifies the 430@15 that Speed1 registered.

Ray should be emailing me the logs/dynos and the map, but you can see on the logs where the wastegate opens, holds for a while, and then just starts to creep in the upper RPMs when the car starts to really make power. Some runs it's closer to 16 psi (1.10 on the PFC). It was about 45 degrees last night.

Unfortunately, for me, this car isn't usable. It's really pushing it on pump gas for the street, and it would absolutely necessitate race gas on the track as I've no doubt in really world conditions this could easily be 17-18 psi, and at these power levels will be creating a lot of heat and breaking transmissions.

So it's soul searching time for me. This was a shit load of work, and a shit load of money on a car I can't drive. Options include:

1. Obtaining an extra housing and porting the wastegate (likely removing the divider, which shouldn't matter much, the spool up is ridiculous as is.

2. Returning the car to TT's. I've got all the old stuff still. Just need a new OE engine harness.

3. Swapping to a different turbo/kit

4. Selling the car, and doing something else.

I'll post up the logs and such when I get them from Ray.

... Or

5. Do what everyone has told you and just put a small restriction after your downpipe. 10 minute job doesn't hurt spool and limits boost. Exactly what you want.

Seriously. ^^^This +1

You are completely ignoring the easy fix.

But you are the first to not be able to hold lower boost levels, so I would also look to see what is different about your setup.

I'm not looking for pity here or to blame anybody, I started the thread for the specific purpose of sharing details of different set ups with this turbo, and so far not many have shared specifics, just offered advice (which I appreciate nonetheless).

While exhaust restriction is an "easy" option, it isn't a very good one.

When we (Ray, PFS) finished this motor and put it on the dyno with '99 turbos in late 2012, it over boosted then too—worse, they just kept climbing past 16psi. Nothing else had changed with the setup, stuff was just new. We took the GReddy Ti off. Same. We started putting restrictors in the exhaust. We got down to the point where it was a 2" hole, and it finally held boost, but the power DID suffer. That's why open exhaust mods all come with a rough horsepower rating, i.e.: "adds 10hp". You can't expect to restrict your exhaust and not loose power or not create back pressure which creates heat, which was a primary reason I went single turbo.

We then took the turbos apart, ported the wastegate, and it held 12psi even at the top end of 4th/5th gear on the track in any weather. Fritz and I tracked two Thanksgivings ago and it was FRIGID, like in the 30's in the morning session. My car made over 390@15psi with sequential '99 turbos. I believe that's some kind of record, but at very least indicative of the fact that the overall set up is very efficient.

That's just the reality here. If you read the lit on this turbo, it says "42mm wastegate", well that's the size of the DOOR. The actual opening is more like 38mm, minus the divider, so that's pretty borderline for a very efficient setup. The EWG versions are running TWO 44mm gates.

The cooler weather is obviously not helping, but the goal here was to build an all weather track car. I had to take the HOT months off with the TTs due to IATs, now it's the opposite scenario. Porting the wastegate is the only REAL solution with this setup, given the fact that there's no E85 or race gas available here (race gas is available at the track).

I'll beat the dead horse:

quickest, easiest, cheapest (reversible) solution is to run a 2.75 inch restrictor, which is not a huge step down from 3 inch, and see how the boost holds along with what kind of reduction in power you see.

You can then make an informed educated decision about whether or not to move to the next steps.

Just trying to help Pete ;)

Sorry, I edited my post.

I wonder if a dual external gate stup would be more ideal for your situation. I wonder what it is about your engine that ends up moving so much more volume.

This is a mental block you have dude, this refusal to give up power. Why not put in a quieter exhaust that's a bit more restrictive if you want to be cat less? Put an RB cat back in there. Then you can enjoy not waking up the neighbors.

You want almost everything but with no trade off: the packaging convenience of internal gate, the power of open exhaust, the boost control of a complicated dual gate setup, the street ability of not just trailering the car and always running E85/race fuel with so much boost that waste gate size doesn't matter.

Reminds me of a project I was working on for an OEM, a boosted gasoline engine. They wanted peak torque starting at 1600rpm and but were having trouble accepting that would hurt their top end power without some inconvenient and expensive solution.

If this was me, I'd put a water meth kit on it and be done and live with the small creep. However, I understand paying good money for shit that should just "work" and then have to modify it for yourself. But this is just part of the "fun" with modifying anything.

Lowering the boost sacrifices power so I don't understand the idea of adding a restriction and losing power as a result as an unacceptable solution to control boost.

Don't let the idea of a properly engineered boost control solution (properly sized wastegate) cause you to struggle with it so much in the interim.

I don't really see where this a problem with me, or a "mental block".

Since this setup is supposed to be able to hold 10-11 lbs of boost, I really don't think it was an unreasonable expectation that it might hold 12 or 13, but given that 15 is the reliable limit on the only fuel available here, 15-17 really isn't acceptable. Borg Warner recommends you put at LEAST two turns of pre-load on it for longevity of the canister. I'm at zero. With no margin of error left, that canister fails it's kaboom. I can't even turn on the electronic boost control.

Likewise, the goal is obviously to be able to make as much power as possible with as little boost as possible. My personal experience is that putting enough restriction in the exhaust to lose 4psi is going to hurt power at a GIVEN BOOST LEVEL. So, yes, I think I'll be rightly disappointed if the car makes 390hp @15psi because I stuck a banana in the tailpipe after I paid for an expensive turbo/kit. I could have slapped a much cheaper turbo or left it Twin Turbo and made that power. What was the point a year and $6k (or more) later?

On that same note, restricting an exhaust with some combination of a restrictive muffler and cat also builds up heat—that's why most track cars are open exhaust. I want to be able to run 13psi on the track to keep it cool and save mechanicals and run 15psi on the street and make over 400rwhp. Not actually a big ask—easily done with a 35R and a single 44mm wastegate. I would have liked to avoid the unreliability of external gates and multiple exhaust connections, which was the promise of this setup, but that didn't happen without an unexpected trade-off. I researched every aspect of this setup pretty thoroughly, and it should have worked. This was no pie-in-the-sky mega complicated build that you see shitting the bed all the time on the forum. My car is simple and done right.

This isn't anyone's fault. Elliot in particular has been very helpful at every step, as have many others including Fritz, Rich, Ray, Dave, Tom, and others. But it's also not my fault, so stop blaming me, I had very reasonable expectations, and did everything right.

THAT all said, I'm likely to try exhaust restriction as it's relatively easy and I'm curious as to how much it would take. If it's really minor, maybe I'll live with it. I'm also quite likely to just put it back to TTs. I could have that done in a couple weekends and be guaranteed ready to hit the track in March.

In the mean time, if others would like to share details on their set-up, so that perhaps something can actually be learned from this, that's why I started the thread.

I would turn the boost controller on down low, and taper the curve down as RPMS come up. This will help with response down low and help flatten the torque curve. It also makes tuning a little bit easier in my experience. Then just set the ECU boost cut.

I have an easier solution that does not require any exhaust restriction and goes hand in hand with your idea of track longevity( assuming the creep is high RPM based, I am assuming past 6500?); just shift earlier.
One does not need to string out the RPMs on these turbo systems, most of these cars make a ton of power from 3 to 6500rpms.

Also one can run much more than 15psi on pump gas safely, you just need to fatten up the AFR curve. I have done 21+ psi on pump only, and 29psi on pump and meth( this car never blew an engine and we did 30k miles like this, blew every drivetrain part 4x times).

Getting rid of the divider is really the only thing I can think of that would help with increasing WG flow. I am not sure if you were quoting one of my blog posts, but you are right the WG runners are smaller than the actual WG door.

One could if they REALLY wanted to, add a 50+mm wastegate to the turbine housing, and eliminate the IWG( I would just weld the door shut). One would be welding the EWG runner/flange to the turbine housing itself.

You mention you. Checked timing in the dyno and it was "OK" ... Did you try advancing timing?

Things that reduce efficiency of the engine will create more exhaust energ. If the charge is burning late (retarded timing) it will still be expanding while the exhaust port is open and can have a huge effect on the turbo.

Ultimately if fitting a 2.75" gasket sorts the boost creep and you lose 10-15hp, so what?

You're reducing the exhaust diameter by 6 whole millimetres! You still have a car making 390odd at the wheels....

I really cannot see that much heat being generated by restricting the exhaust by 6mm, certainly not an amount that would be excessive compared to the exhaust temps on a modified twins setup with an open exhaust and the brick manifold that comes with the twins... in fact I reckon the EGTs seen from your current setup with a small restricting gasket would still be lower than a modded twins setup.

Yup,
We advanced the timing, adjusted the split, leaned it out, and changed the plugs. No real affect. The power and smoothness are also pretty good indicators that everything is functioning correctly and the tuning is right. And like I said, previous experience tells me that a 2.75" restriction isn't going to do it, and I've stated my reasons for not wanting to restrict it to the point where it's below 400rwhp. Remember, I already switched from a GReddy Ti, which is one of the least restrictive exhausts available (Fritz has sometimes seen a 2psi gain on cars after putting it on) to a PFS which is probably closer to a Racing Beat, with zero affect.

I understand that Twin Turbos have their shortcomings as well, I ran them for years, but they also weren't many thousands of additional dollars and a years work. It was an extremely well sorted setup.

It's all pretty baffling—I got a note from Dan Chadwick this AM indicating that he runs the HIGH boost canister and gets 13psi, and the boost actually droops if the use the medium canister. I'll see if I can get details on his setup, as that was the purpose of this thread.

This is good advice.

I get that you may not need the redline RPM's to make power on this setup as much as other setups, but just shifting early isn't the way I'd call this or anything, fixed.

Hoping you can find a solution that keeps your setup nice and simple. Twin gates are awesome, but I see why you'd not want to do it in your application.

A $400.00 water/meth setup should resolve your issue of worry about boost creep and give you more security. You guys that don't run it Ill never understand why. It helps in multiple ways, especially on track. I know it would make me personally feel a ton better when doing 4th gear pulls after multiple laps.

With the above said, if you wanted 10-11 psi power levels you could install a restrictor and run 12-13psi and achieve the same power without creep. Just saying.

So it's soul searching time for me. This was a shit load of work, and a shit load of money on a car I can't drive. Options include:

1. Obtaining an extra housing and porting the wastegate (likely removing the divider, which shouldn't matter much, the spool up is ridiculous as is.

2. Returning the car to TT's. I've got all the old stuff still. Just need a new OE engine harness.

3. Swapping to a different turbo/kit

4. Selling the car, and doing something else.

I'll post up the logs and such when I get them from Ray.

I know exactly where you are coming from in not wanting to run a "restriction" to limit boost creep as that is where I was with my old set-up that I worked so hard to extract every once of flow on and then had to work so hard on to stop boost creep without using a "restriciton".

So I offer another alternative-

5. Trade someone manifolds with an older Turblown kit with the tubular shorty manifold and adapt it to external wastegates. You can search out a non-wg exhaust housing if you want or run IWG and EWG together.

I was super paranoid about boost creep when I made my EFR 7670 kit so I used dual TiAl MVR (44mm) with high WG priority.

I put the wrong spring combo initially (from friend looking up old TiAl spring chart) and my set-up was able to hold 6psi running the same tune I had to use to overspin my old turbo set up to 18psi (it would drop boost over 16psi so I tuned it richer than 9AFRs and pulled timing on the top end- made 5hp peak over leaner and 16psi LOL).

I guess I am saying I think you could get away with the much cheaper dual MVS 38mm wastegates as long as they are high priority- especially if you keep the IWG.

Edit- don't use the other brand WSs they fail, check the forums for yourself.