the y8s one-car dyno day. - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 07-16-2007, 09:33 AM   #21
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Nice results, y8s!

So, the previous pull that was 13rwhp less was also done after you'd installed the new BEGi intercooler and tossed the A/W setup, right?
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Old 07-16-2007, 09:36 AM   #22
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I think you had another 10hp by 7k given the path your curve was on.
Post up a graph with AIT, rpm, IGN and boost....pleeeeeze.
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Old 07-16-2007, 11:32 AM   #23
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ok ok.
http://y8spec.com/nemesis/maps/?C=M;O=A scroll down to the bottom where the date is 7/16 and check out the CSV files. Those are the datalogs from the before and after runs. The dyno data dump is in there too (xls) as well as the maps.

Rob, what do you mean I had another 10hp by 7k? I dont get what you mean...

The two graphs are same day both with the BEGi setup. I'll work on posting the graphs of the datalogs from before and after. they're very similar though.

M
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Old 07-16-2007, 11:41 AM   #24
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Quote:
Originally Posted by y8s View Post
Yeah that's bizzare. we're within like 25 ft-lbs/hp in the spool-up zone.

course you're running 14 psi to my 9, but it's interesting none the less.

you're on the stock greddy turbo?
Yeah, if you look at power at any given rpm, it's pretty comparable. I'm running less displacement and a smaller turbo with more boost. You hit your torque peak before I do, but I'd bet that has to do with your nice 3" turbo-back exhaust vs my 2.5" dp going to 2" (or was it 2.25?) cat back with crush bends before and after my 1 in, 2 out muffler. I'm also running a Jim-B style under the rad and Saab FMIC, and I bet I'll gain a psi or so when I get my new IC in. You also have more capable EM in your Hydra, but I think my MS is doing a pretty good job.

Turbo is the standard Greddy/Mitsu 15g
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Old 07-16-2007, 11:43 AM   #25
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I screwed up and was looking at ben's power graph
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Old 07-16-2007, 11:43 AM   #26
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Mmmm, makes me want to get out there and really start tuning!
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Old 07-16-2007, 11:50 AM   #27
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I remember a post where you said your Hydra timing reporting and the actual timing was 6 degrees off (as shown in your .csv file where you're idling at 16 degrees). Right?

Thanks,
Frank
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Old 07-16-2007, 12:11 PM   #28
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I fixed the value in the hydra triggers menu so it's correct. I am idling at a true 16 degrees.
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Old 07-16-2007, 12:55 PM   #29
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wow you are running some nice timming almost as much as stock. the ramp up is way quicker though thanks for the info.
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Old 07-16-2007, 03:52 PM   #30
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You are getting 76 ft-lbs per liter per atmosphere. That is very good. F1 motors are at around 82 IIRC, and BMW M motors are at around 75.
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Old 07-16-2007, 09:47 PM   #31
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Very very nice.

Looking at 20070714_final002.csv:

1) Why the lean spot around 7150-7200rpm?

2) That's without knock? Wow. In your datalog your knock ramp goes up to 1.18. For my MSM I consider anything over 0.4V to be knock...I may be a bit conservative. I know the FM defaults are over 1V but I just assumed they were being aggressive or had a very noisy car. I went very fast down a hill while not in boost to determine my knock threshold. I also found I could squelch the knock spike after throttle let-off by making my high rpm vacuum load cells richer...which led me to believe I was getting rid of knock.
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Old 07-16-2007, 10:28 PM   #32
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1) I believe that lean spot is rev limiter. note the spark there is ~14 degrees. Not sure why it's cutting fuel--i didn't think the hydra did that. It could be the backing off the throttle triggered the enleanment there.

2) I didn't think much of it. Everything is so noisy at 7 grand I can't be sure it's knock (or NOT knock?). I was always under the impression that true knock resembles an outlier in the sensor readings. like 2-3x the "noise" level.

Or my engine will die soon.

In any case, FM is not known to be anything but conservative with tuning. So who knows?

Where'd you get the .4V number?
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Old 07-16-2007, 11:58 PM   #33
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So how fast do you reach full boost?

How big of a roll does the size of your compressor play when making so much power at 9psi vs someone else's making the same power at 14psi?
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Old 07-17-2007, 12:24 AM   #34
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right around 4200 is where I hit max boost. it depends on the gear of course.

compressor size has a lot to do with top end. boost pressure is a small part. imagine a 10 foot pipe with 2 psi vs. a garden hose with 2 psi flowing into a pool. which supplies more water?

Matt
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Old 07-17-2007, 03:39 AM   #35
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Quote:
Originally Posted by y8s View Post
1) I believe that lean spot is rev limiter. note the spark there is ~14 degrees. Not sure why it's cutting fuel--i didn't think the hydra did that. It could be the backing off the throttle triggered the enleanment there.

2) I didn't think much of it. Everything is so noisy at 7 grand I can't be sure it's knock (or NOT knock?). I was always under the impression that true knock resembles an outlier in the sensor readings. like 2-3x the "noise" level.

Or my engine will die soon.

In any case, FM is not known to be anything but conservative with tuning. So who knows?

Where'd you get the .4V number?
1) Page 28 of the Hydra 2.5 manual indicates that hitting the soft rev limiter retards timing and cuts 60% of sequential fuel events. Strange that it's already doing something at only ~7200rpm. But the Hydra seems to do some interesting interpolations...another being the coolant spark trim (if you pull 1 degree at 100C it'll start pulling timing if you break 90C).

Letting off the throttle should actually cause a rich event due to the slight lag in pulling fuel after the throttle closes...I think.

2) Now you've got me wondering. I don't have any experience with detecting knock so I guess I'm being overly careful. I believe some professional tuners actually use something like a stethoscope on the engine block to listen for sub-audible knock.

The 0.4V is just from watching my datalogs when I had things very rich. It also came from loggin while running very high rpms without being in boost. Though I probably don't get above 6500rpm that often...which is where yours really starts getting noisy.

Last edited by VanMSM; 07-17-2007 at 03:40 AM. Reason: typo
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Old 07-17-2007, 04:27 AM   #36
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Quote:
Originally Posted by JasonC SBB View Post
BTW I think Al Gore sucks greenie dick with his global warming propaganda, but letting blowby out your cam cover dumps filth in the air!


Yeah, why does it smoke so much in the video?
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Old 07-17-2007, 09:20 AM   #37
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Quote:
Originally Posted by VanMSM View Post
Letting off the throttle should actually cause a rich event due to the slight lag in pulling fuel after the throttle closes...I think.
That's right, and getting back on the throttle causes a lean event (drop in pressure causes fuel vapor to momentarially change back to liquid form and vice versa). Hence fuel acceleration and fuel deceleration trim maps based on either delta TPS or delta MAP calculations (in the AEM EMS at least) If these aren't set right you may get knock when you snap your throttle open after a shift on the road even though you may never get knock on a dyno run.
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Old 07-17-2007, 09:20 AM   #38
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Quote:
Yeah, why does it smoke so much in the video?
holding boost in high rpms.
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Old 07-17-2007, 10:13 AM   #39
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Quote:
Originally Posted by VanMSM View Post
1) ...I believe some professional tuners actually use something like a stethoscope on the engine block to listen for sub-audible knock...
Knock detectors are stoopid- easily fooled by other noises. I'm seriously considering something like below:
http://www.homemadeturbo.com/forum/i...?topic=78720.0
http://autospeed.drive.com.au/cms/article.html?&A=0353

I get the same rise in my knock curve as the rpm goes up. Then a large step up and have assumed it's all mechanical noise. When I see something that's a spike over 50%, then I examine the other parameters and determine if conditions suit knock.
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Old 07-17-2007, 10:26 AM   #40
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I dont want to clutter your thread with more quesitons, so my next one I will take to my thread. If you can please take a look, I would really appreciate it.
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