Project Miatabusa part 15

As we inch ever closer to getting Project Miatabusa on a dyno, more and more unfinished business keeps revealing itself. Ok, the car starts and runs now, but it still has lots of disconnected hoses, gauges not working, and untested changes waiting to blow things up.

Neel Vasaveda of Apex Speed Technology is on board to tune the engine. I keep mentioning Neel as some guy who knows more about Hayabusa engines than we do, but his tuning expertise goes much deeper than that. Neel does engine management, wiring, and race support for a staggering variety of serious race teams, like the Jordan Suzuki AMA superbike team, The Porsches of Magnus Racing and The Racers Group (between them, 24 Hours of Daytona winners in 2009, 20011 and 2012), and Leslie Porterfield's Bonneville bikes. But this pro-racing stuff is a total snore compared to the oddball special projects he's always entangling himself with. Like replacing the pathetic '80s Italian dual ECUs on a Lamborghini LM002 with a Pectel SQ6, or making sure there's enough electronic wizardry in this V10 E30 M3 to match its mechanical awesometude, or cleaning up the mess that is a certain Hayabusa-powered Miata. Yeah, we're in good company here...

Experienced as he is, we're not gonna ask Neel to tune this thing by ear. Good tuning requires data. Most dynos have widebands you can stick up the tailpipe but that data is always suspect. You have no idea of the quality or history of the sensor, and the exhaust in the tailpipe took some non-negligible amount of time to get to the tailpipe. If the engine is revving quickly, you could be reading data that is a few hundred rpm out of date.

More importantly, the Hayabusa has different air/fuel trims for each cylinder, partially in an attempt to adjust for the inconsistent airflow caused by the unusual pairing of its 4-2-1 header. Since we replaced that header with a 4-into-1 header custom made by SPD, there's a really good chance fuelling is going to be wrong on at least two of those cylinders. The only way to know is to simultaneously sample the air/fuel ratio directly at each exhaust port.

To make this happen, we grabbed an AEM 4-Channel Wideband UEGO Controller. Wideband O2 sensors aren't just a simple self-contained sensor that spits out a voltage corresponding to air/fuel ratio. The sensor works in a feedback loop with some complex controller electronics. If you want the full scoop on how this works, dig way back in the MotoIQ archives to Mike Kojima's story on how widebands work, which was one of the first stories published on this site. Otherwise, just understand that the electronics are complex and expensive, and having one box that simultaneously controls four sensors is quite handy.

One cool feature of the AEM 4-Channel Controller we're not using yet is the backpressure compensation. If you read Kojima's story, you'll understand that accurate sensor readings rely on the sensor being near ambient pressure. if you have a lot of backpressure, the readings will drift. This is why you should never put a wideband before a turbo. But if you want individual cylinder data on a turbo car (and isn't that why you have a 4-channel?), you can install an exhaust pressure sensor and the UEGO controller will automatically compensate the readings. The box comes pre-wired for this feature, but doesn't come with the pressure sensor, since not everyone has a turbo (yet).

Project Miatabusa Mazda Miata Suzuki Hayabusa engine

Even though the AEM 4-Channel UEGO controller can control up to 4 sensors, the box only comes with one. This way you're not paying extra for unnecessary sensors if you're tuning a Geo Metro. Keep this in mind when ordering!

The sensor comes with AEM's Stainless Tall Manifold Bung, shown above. The bung is extra-tall to hold the sensor farther out of the exhaust stream. The sensing element is still in the stinky stuff, but the recessed position is less disruptive to exhaust flow. The bung is also finned to help keep the sensor from overheating with high EGTs. Both these features are hugely important when installing sensors on the small, hot, flow-sensitive header primaries!

Project Miatabusa Mazda Miata Suzuki Hayabusa engine

Before drilling big holes in the sexy SPD header, I wanted to test fit  the bungs to make sure they were in positions that didn't block bolt access to the header flanges or air injection fittings, and left wrench room for installing the sensors themselves. I did this mockup with cyanocrylate glue (a.k.a. Super Glue). Just go to any hobby shop that deals with model airplanes and ask for CA glue. The Zip Kicker activator makes the glue cure instantly, so there's no need to sit and wait. Just put two drops of glue on the bung, put it where you want it, and spray the activator on it. There will be a little crackling sound, a toxic plume of stink, and sometimes even a little plume of smoke, and BAM, the sensor is locked in place. The glue is still weak enough to break off by hand, but the bung is held on well enough to confirm wrench clearances.

Project Miatabusa Mazda Miata Suzuki Hayabusa engine

These sensor locations were deemed wrench safe, so I took the header, with bungs glued in place, to Mario Lozano at TSR Fabrication in Gardena, CA. Having the bungs glued in place annoyed Mario slightly, since he had to clean the glue residue, but there was no question where the bungs had to be.

(By the way, the air injection fittings shown here will cause some minor complication. If the air injection system is operating during tuning, the extra oxygen will throw off the air/fuel readings, so we'll have to be careful to plug the air injection's inlet every time we test.)


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Monday, April 16, 2012 4:38 AM
Great article again! I'm wondering, with all of the other AEM components, why aren't you going to use the EMS 4 to control the engine rather than using a piggyback on the stock ECU that only has fuel control (correct me if I am wrong about that one).
Monday, April 16, 2012 6:33 AM
Love the in-plenum filter and individual cylinder trim monitoring. Any idea what effect the filter might have on helmholtz tuning in the plenum? I imagine it changes the effective plenum volume for one, so if you wanted a 2 liter plenum you would have to subtract the filter volume?

Also, watch out for someone overtightening the hose clamps onto the carbon runners on the intake- I've seen several carbon tubes crushed by hose clamps. We eventually bonded aluminum tubes over the carbon to take the load. The aluminum also allows for you to machine a lip onto the clamping surface so the hose doesn't slip off.
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 6:39 AM

We're running the piggyback as a learning experience. We want to see how little investment is needed to get a Miatabusa running. Its entirely possible the datalogger will tell us we can just slap this combination together and go play. Also, Neel says there is no need for timing control on a naturally-aspirated Hayabusa.

Once we go turbo, then we'll be doing stand-alone management. Very likely an EMS4, but we're not decided yet.
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 6:43 AM

You raise a good question about plenum volume, and we're not entirely sure what the answer is. We roughly copied the stock plenum volume when we made this, and the stock plenum has the same filter setup. We think the filter will be acoustically invisible, but we're not 100% sure. Once we're on the dyno, we can actually try running the filter inside and outside (different filters, so we don't suck the dirt off the dirty side when we flip it!) and see if anything changes.
Monday, April 16, 2012 8:26 AM
@ Dave: my SWAG is that you'll move the powerband up 300rpm with the filter outside the plenum.
Dusty Duster
Dusty Dusterlink
Monday, April 16, 2012 8:41 AM
Mr. Dave Sir:

So how close is this project to being running and track-capable?
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 8:46 AM

What does the "S" stand for?
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 8:47 AM

Let's find out together. You wanna use my time machine or yours?
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 8:51 AM
Oh, and Matt, great advice on bonding the aluminum into the plenum. I already suspect this will become necessary on the inlet runners, if not the filter.
Dusty Duster
Dusty Dusterlink
Monday, April 16, 2012 9:29 AM
My time machine operates on an old Big-block Ford 429 V8 converted to run on unicorn farts instead of petrol. I'm fresh out of unicorn farts, though.

In all seriousness, I figured you had a list of things needed to be fixed and were steadily checking them off one by one. But then again, if your experiences in engine swaps are like mine, 3 more items appear on said list for every one you check off.
Monday, April 16, 2012 10:41 AM
You can use my time machine of you want. Its very slow though. For example it takes a good sixty seconds to carry you one minute into the future.
Dave Coleman
Dave Colemanlink
Monday, April 16, 2012 12:35 PM

Based on my plan and checklist, the car runs already and was turbocharged last month! Reality has failed to comply with my checklist...
Monday, April 16, 2012 8:39 PM
Glad to see you used your time machine to get Mario to do some work for you. That guy is an artist with a welder and infamous in the Datsun world. It takes an alignment of the planets to get his full attention for work, but well worth it.
Can't wait to see some tuning on this thing.
Tuesday, April 17, 2012 7:03 AM
Dave: SWAG = Shitty Wild Ass Guess.
Tuesday, April 17, 2012 9:02 PM
For a vacuum bung, you could also look into a carbon fiber hunting arrow. They are available in many different diameters. Any sporting goods store should have a fairly wide selection. A single high quality arrow would run you alot less then $30, but you wouldn't have the pleasure of crashing anything.
Der Bruce
Der Brucelink
Tuesday, April 17, 2012 9:23 PM
If only Miatabusa could reach that 88mph mark you could see when you finish and then go back to correct mistakes. Thinking 4th dimensionally and seeing the paradox this would create has nullified higher brain functions!

On a serious note, are you hoping to create NA maps to help Alex and othe Hayabusa swappers to follow? I ask because of the effort that will be required to change things out for the probable and inevitable turbo addition. Any thoughts on reasonable HP hopes and expectations after the Turbo "boost" ? ;-)
Wednesday, April 18, 2012 3:52 PM
Dave you're killing me with this build. Update faster ;)
Thursday, April 26, 2012 2:43 PM
you never should use super glue for welding mock up, because certain types of super glue, when heated vaporize as cyanide gas. Which is no fun for your welder and anyone in the area of the welder
Friday, April 27, 2012 7:00 AM
read again they remembered to clean off all the glue residue. good tip in general though. cyanide definitely is a nasty gas!
Thursday, June 07, 2012 12:41 PM
As another source for carbon fiber bits our friends at McMaster-Carr now have a selection of rods, bars, sheets and u-channels. I am already busy conjuring up things for which I could use them.
Friday, June 29, 2012 11:36 AM
Best of luck with this project. I hope to read about it in the future. Thread deleted, blog deleted, motoiq website deleted. I think I started following this in 2010. I repeat what I said in earlier posts that fewer projects might allow for more progress.
Friday, July 13, 2012 8:22 AM
Im really enjoying this build. I have a British Leyand Mini Station wagon I wanted to do this with. It only weighs 1500 lbs. wet, and i wanted to put something a little less traditional in for a powerplant. Seen lots of Motorcycle builds in the minis, but no reverse! That wouldnt be fun around town. I'm a future customer when you get your kit ready to sell!
Wednesday, July 25, 2012 8:07 PM
I must have another update Dave!
Dave Coleman
Dave Colemanlink
Wednesday, July 25, 2012 8:22 PM
Working on it at this very moment...
Thursday, November 21, 2013 1:26 PM
what is the email address I want the extended shaft with the Miata fly wheel on it and how much is it
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