So as some of you know i recently pulled the MSM turbo off because it was making too much boost (17-19psi) for my 99 motor with stock internals. We figured it was due to the wastegate opening being too small and the 3" exhaust being so unrestricted.

Fastforward a month. I have the Garrett GT2560R with custom tubular manifold and 3" exhaust with that super smooth downpipe. Car is still making 17 lbs of boost. 17.8 on a datalog last night and that does correspond to what I saw on the autometer boost gauge too. Tim has a theory that the timing on my MSPNP base map is so retarded that the exhaust valves are opening before combustion is complete and its working to spool the turbo like a ************. The car has amazing spool and responsiveness and power. It throws you back in the seat in any gear and 1st or 2nd break the tires loose with ease at any speed.

Today I started playing with my timing map to more closely resemble Tim's(which he claims is a touch conservative too). I backed off 1-2 degrees from his since I run the slightly higher compression 99 motor vs his 94 motor. My intake temps are never of concern as they are only slightly above ambient. During logging today max boost was 17.2psi. Not much different but I believe it was colder this morning.

Below are screen shots of the PNP base timing map and my new one. Does anyone think my timing is way too aggressive? Do I have room for more advance? Short of getting it on a loading dyno to tune the timing what are some guidelines to follow?

Oh, and I'm supposed to be dynoing(not loading type) this thing Monday to see what kinda power it's making. Hopefully I won't be starting off the new year with a post about blowing the motor on the dyno.

 

forgot to mention:

I am running the stock wastegate actuator without a boost controller, manual or electronic.

with the wastegate arm disconnected the car was making 15 lbs of boost at 5500rpm yesterday.

 

i was running 17* at 200kPa for a while, 20* at 180kPa row, then the pistons melted (most likely unrelated) so I backed it up to be safe, I believe I'm at 13* at 200kPa row now. I'll be tuning the map on a dyno come spring.

 

Makes no sense to me.

Throw that guy's AEM on there with my full map and see if it makes a difference.

Or take off yoru turbo and try to hog out the wastegate.

Or save for an external Tial.

Or build an engine.

 

I've talked with Paul and here is what is pretty much ruled out for sure:

1) boost controller - Because there is nothing aside from the stock wastegate that came with the turbo. He also has visually confirmed that the actuator opens the wastegate by reving it in neutral and watching the arm push the wastegate open. Also, this has happened with three setups now (custom MSM turbo, Tim's twins, and new custom GT2560 setup) so unlikely to have a dead wastegate on three separate setups.

2) manifold/turbo/DP issue - As stated above, Paul has had boost creep with three different setups with three different manifolds/turbos/DPs so I think that pretty much rules out those as a problem.

3) wastegate binding - Paul said that with the wastegate actuator disconnected, the wastegate moves freely with no catching or limited movement. Plus, it happened with three different setups and all three DPs were bellmouth so nothing really to catch on.

So he's got boost creep which means not enough exhaust flow is exiting out an open wastegate so instead keeps the turbo spinning. (I am assuming that the wastegate is not binding, but as I write this, Paul should be wiring his wastegate open and taking it for a spin and a wastegate door that is not opening completely would be the easiest explaination.) I find it hard to believe that even with the cold/dense air + 99 head + GT2560 that there is so much exhaust flow as to overwhelm the wastegate hole or regular FMII/BEGi setups with the same turbo on 99 miatas should report similar issues.

The only thing that is really different on Paul's car is his Absurdflow exhaust, which IIRC, is basically an open 3" DP that extends to the back of the car. Considering that his backpressure is significantly less than even a typical turbo exhaust with high flow muffler, and that this minimal backpressure decreases the restriction thru the turbine much more than thru the wastegate hole, I'm guessing that is what is causing his boost creep because everything else is pretty much ruled out. Unless or course Paul bought his engine from the same guy who sold Jack his beanstalk beans...

 

I used to get 7psi wastegate pressure to redline, now trying to keep it as low and level as possible with my EBC I can't get less than 10psi at redline.

 

i noticed today that the swing arm on the wastegate can go a lot further than the actuator can push it. like another 15mm. i tested by putting a bicycle tire pump on it and seeing where it maxed out.

then i went for a drive with the swing arm maxed out used an aluminum bracket i fabricated just for that. boost level reaching 15psi max still but up in the 7000rpm range. thats an improvement over yesterdays test with wastegate arm just swinging in the wind. it was hitting 15psi at 5500rpm. at 5500 rpm today it was 8-10psi fully open wastegate

tomorrow tim and i a probably gonna take the turbo off and try to hog out the wastegate opening AND lengthen the actuator arm. hopefully that will make the difference i am looking for, 14 psi max. if that makes it open too early it'll give me something to do with this EBC function which right now is useless.

 

it can happen, if the wastgate is opening all the way then you'll need a larger wastegate, either get your turbo modified for a larger wategate hole and flapper, or weld it shut and go external

 

if today doesn't end with the desired results we'll be going external.

 

Wouldn't surprise me a bit if the wastegate flapper wasn't opening enough-- I don't have any boostcreep issues on my car, with a wide the heck open 3" exhaust, no cat. BUT-- that's on the 1.6, the 1.8 is likely flowing more and that could make the difference.

If it's not the shaft, then the porting you're doing will likely do the trick.

And if all else fails, external...

Heck-- I'm thinking about intentionally boosting 17psi . Gotta build myself a better ignitor first to charge the coils better-- I drew it out the other day, just gotta build it up.

 

Well we did the porting on the wastegate opening. Not only did Tim make it a lil wider he shaped the entry side of it to aid in flow. There was no room to make the actuator arm longer, it wouldn't have allowed the flapper door to close.

Of course it was ******* raining when we got done so i have to drive 45 miles north out of my way to some dry roads. With wastegate disconnected from actuator the car made only 5psi @ 5000rpm. at 6500rpm it was making 12psi. Thats a big improvement over the other day when it was making 15 at 5500 with it disconnected and even a lil warmer out.

I then pulled over to reattach the actuator arm but as I was doing it it started freezing raining so I left it off. That car accelerates way to violently to drive it in freezing rain. Even the wet is a challenge, especially with the EBC tuning i did this morning. Yeah i coulda set all the duty cycle cells to 0 but it's still to powerful for those low traction conditions.

I'll have to reattach the actuator arm before leaving for the dyno tomorrow and see what she does like that but I think it's safe to say in summation

 

excited to see the results!

 

me too and hoping those don't include some melted aluminum

 

If it pings, lift and retard.

or lift and be retarded and leave as is, then get upset later that day when you dont have your 250rwhp pull at only 13psi, because you didn't take it to redline, then you have to settle for only 230rwhp at 6K....

 

hopefull we will be able to hear ping if it's happening, that car is hella loud with the 3" exhaust no muffler. it should sound pretty evil in that shop. you guys should come just to hear it.

 

two hour drive to watch your car...or cut fenders, install cops, cut my hood, etc.

 

my bad, thought you were closer.

 

Not as loud as the Ford.

 

uhhh. i believe it's louder. and so do 100% of the people I surveyed.

 

Meant the one at the dyno last year. Something like 750HP