begi s3 / gt2860rs crew: what AR turbine did they send you?
 

I was talking to someone about how my car was making only 5psi at 4k rpm, then 7psi at 5500, and he thinks the turbine housing is too large.

What AR do you have, and at what RPM does it make 10psi? I think I have the .86 and want to change that.

Thanks.



pics for the hell of it:
http://i26.tinypic.com/4gry9k.jpg
http://i19.tinypic.com/66wp3sx.jpg
http://i36.tinypic.com/aebebn.jpg

The big housing is not suitable for <300 whp methinks. The 0.64 housing will have far better spoolup.

could having the wastegate adjusted pretty far out have that dramatic of an affect on spool? With the wastegate disconnected, the motor is stronger than the 1.6 ever was, even with the lowered compression.

pain:
http://www.turbobygarrett.com/turbob..._1_turbo_e.gif

I bet you have no idea how to read that too :)

you never happened to look at your turbine housing to see what it actually is did you? Any chance BEGi might have documentation?

What is with the inconsistency at BEGi? a friend ordered an S2 or 3 with a 2560 and the intake on the turbo is 3" funneling down to about 2. That thing looks like 2-2.5". What gives?

basically, my target pressure ration (2) will be achieved with roughly 25% less airflow through the turbine.

I don't know what's up with the #'s, I'll have a friend go look at it. Any chance a "tuned" spark map will give me 1000rpm better spoolage? What about having the wastegate backed way off? I guess I need to go home, unplug the hose, and see how early it makes target boost. I think with the 1.9l, 3" exhuast, and standard DIY spark map I should be spooling sooner.

If I have to get a smaller turbine housing...then whatever, but I'm getting tired of hemorrhaging money.

do you know how many lb/min you displace through your exhaust at a given rpm?

no, but considering that 25% shift in flow correlated to RPM would put me at roughly 3500rpm, that would be nice. I think that's a fairly accurate assumption because 3500rpm or so is in the neighborhood of peak-torque output.

Is this unreasonable? There are other variables I must address first though...like snugging up the wastegate actuator and pulling the vac hose to the spring, then adjusting spark. I'm about to go get the car and just leave it at BEGi. Time > money.

is that what the chart is saying? (and fwiw, it's a 16% shift)

you have a 1.9L motor correct?

The same volume of air is always getting ingested regardless of RPM and boost pressure.

The Corrected Gas Turbine Flow is the amount of this air that moves through the motor during a specific time period. (lb/min)

if you calculate the amount of Volume Air Flow or Gas Turbine Flow in this case, it would be easier to read the turbine efficiency plot based on the demands of your motor.


VAF = (CI/1728) x (RPM/2) x VE

116/1728 x 7000/2 = 235 CFM (16.2 lb/min)

so maybe you want to draw a line up from 2PR and over from 16 lb/min and see where you end up. Then say, hmmmm the max efficiency of the turbine in a .63 A/R housing is just above the volume I displace...so the .86 may be too large for what I need.

The smaller housing is 74.4% the size of the larger one. I'm apparently talking out of my ass, so correct me. I read till 1:30 last night trying to figure out how much work I have to do when I get back home in January.

Why don't you just do it for me since I'm your bitch. Let me know if you need help with flood insurance, lol.

So, wtf do I need to do since you are an engineer and I'm a beuracrat? Switch to a 2560, or get a smaller turbine housing? I'd still like to get an answer from the DP owners here. I just want to drive my fucking car, not the rental G6.

I have the same turbo and turbine size. I have full spool by 4400 or so?

all i was saying is that you posted the turbine efficiency plot without knowing how to read it. And im not an engineer, just an artist.


Was this just with a line from the turbo to the wastegate can?

on a 1.6L no less.

you have the .86 turbine housing? My motor is something like 1871cc now, but lower compression, but considering the motor is stronger than the 1.6 off-boost, even with the turbo on the side, I think it should get the turbo spinning.

If yes, then my pants are getting tight and I can rest easy with less work to do on my car. :hustler:

yes, he has a 2860 .86 on a stock 1.6L.


http://i295.photobucket.com/albums/m...otta-dyno1.jpg


this was with his chewed up wheel too.

I have the Gt2860Rs .86AR and I'm at 12 psi by a tick after 3,500rpm. S4 manifold through.

The spark map will help out tremendously.

thanks brain. I guess I need to get the car tuned, then cry like a ------. I'm going to snug up the wastegate.

Is there any chance that adding a little 3psi wastegate would help spool, and not overboost?

cool. This motor should be blowing the tires off then.


Time to get the miata and drop it off at the dyno. Damn business travel job, lol.

We use the 0.86 AR turbos. If you are not getting full boost, you might want to check the actuator. It could be you have a 7 psi one. Send me the #'s on the side of the can and I can find out what it is.

Paul-The inlets on the S4 kits have changed to 2.5" due to fitment issues around the PWS pump. However, most GT2554's and GT2560's have 2.25" inlet and the GT2860's and larger turbos have a 3" inlet. The only recent change was the S4 inlet sizing.
Stephanie

Thanks Stephanie. I can't get to the car for a week or two, but I'll just bring it to you and let you "call me when its done." It hurt to put that car together after waiting 2-years, put 200 miles on it, then get in the rental car and leave it sitting for a month.

Why did my turbo get the little inlet welded on?

Are you tired of me yet? I promise to drop my car off soon, shut up, and just drive the car.

Throw your map up if you have it :)

I could really use a spark table for a gt2860rs on a 1.8. I'm at 8.8:1 compression, running 93 octane, so its probably a good bet.

If you feel like installing the Xede software, I'll certainly post it.

Downloading it now.

It can at least provide reference points vs actual useable map for my MS of course :p

480009-6


Looks like I have the 12-14psi spring. I wonder if that is going to be too much boost?

I'll post the map tonight. Keep in mind, Xede's map is relative to the ECU's timing values, not absolute like MS.

If you can translate it to MS talk, send me a copy. I'm dropping the Xede here shortly.

I'll take a swat at it. I'm interested in the range of values themselves more so than the specific tune.

I've heard that the stock ecm uses either 32 or 34* advance across the entire rpm range at full throttle from a reliable source. I don't know about off-boost #'s.

sounds like someone is having the same kind of bullshit problems I did....

I'm guessing slow spool likely has more to do with the WG/ wg actuator/ flapper than conservative timing.

Take a look at this thread. There's several guys MS spark maps here. Look for one that's middle of the road. Should be a good place to start. Of course you should post up all your MS settings to let everyone pick apart and help. https://www.miataturbo.net/forum/t18648/

Please note: anything I say could cause your car to spontaneously combust, implode, explode or otherwise fail in spectacular fashion!

Stephanie said that everything will be OK, so I'm going to let them take care of it. I'm sure they'll make it right.

Awwww....it looks so cute:).

PTS_Leaned2_cruise_more_timing.BAK:
Invalid File

Looks like I can't attach the file here. If you have an email address I can send this to, PM it to me and I'll send the map.

zip it, then upload.

splitime@gmail.com and i'll play with it at work tomorrow.

I'm with the adjust the arm crew. When we installed my cousins greedy on the Del Sol, we had the same problem. We adjusted the arm and presto, it hit boost properly.

Too much work after a 16 hour workday :)

Here are all the maps I have. I'm pretty sure the map I use is in the folder 7-15-08; I will verify during the day. More timing after dyno or something like that.Attachment 9204

I have to get a softer spring. I don't know that this motor is ready for 1BAR yet.

Built motor with all those high dollar parts years of planning and no EBC? No need for that heavy spring in the 1st place if you are using EBC. Something in a 7-9lb spring should be plenty with EBC and the power levels you are shooting for.

By the way. With my lack of any real knowledge that was my ass talking just now.

My only add in on that is... use the highest spring you are willing to have as your "low" boost. It just makes everything a little easier in the system. Allows you to use a MBC for higher boost later if you are unhappy with EBC results too.

I'm running a 10.x spring on my stock 1.6l.

Personal opinion though.

Split - Thanks for the save. I didn't think it made sense for him to be using a 12-14lb spring when he isn't running that high. You said it much better. Spring should be equal to your low boost settings. Well said.

unless you have some butterz flow going on.

My 6psi spring (with a ported wastegate outlet) creeps me up to 12psi currently.

http://www.boostedmiata.com/dynos/wastegate_spool.jpg

the ebc is not hooked up yet because the motor has a whopping 140 miles on it. I want a 3psi spring so I can go ultra-low boost with baby throttle inputs. Think "4th gear, closing radius, off-camber, over a crest" or turn 4 at hallett. I didn't request a spring that heavy. I ran a 3psi spring with a profec b on my last turbo car and it was flawless.

If your car turns out anything like mine you are going to be shocked at how driveable it is with all that power. I was afraid it would be too on/off or would have that turbo lag kick like my Saab had. It really is very linear and easy to control.

There is some controversy regarding engine break in out there. There is the baby it for 1k vs. the hammer it right off the bat crowd. Both sides can point to plenty of support data. I'm leaning a little toward the hammer it crowd. I wouldn't put full boost into it but I wouldn't be afraid of 6-8psi, unless your engine builder/guru/sensei told you otherwise.

the car is seeing 7psi after 5k rpm...I'm just not ready to hang it in the red at 14psi in 4th gear yet. I wanted good ring seal, so it saw a very small amount of boost and lots of vacuum on break-in...then enough boost at 5psi to go through a tank of fuel in 120 miles. lol I want to put 1000 miles on it before the track or dyno.

He he he. Big injectors and boost sure don't help the mileage do they?
I'm not much different freeway cruising but around town it's pretty bad. At the track it's unreal. Only good for 3 - 20 minute sessions. Gotta gas up again for the later sessions!

Driving fast sucks gas. I get 6mpg on track. 16mpg around town. 28-30 on the highway at 70mph.

Once that motor has about 100 miles of solid break-in (high vacuum, a little boost, varying revs) it's good to go. You think race motors get 1000 miles of break-in?