| MIATA BUILD |
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 | |  | March 4, 2008 - The moment of truth for the header.
Did all that work actually get me anything? In short, yes! I saw a gain of 15 lb-ft at 3500 rpm and around 10 hp at 5200 rpm. Cue the happy dance.
The car sure sounded different, as you could hear some strong resonances and beats coming from underhood. That's good, the header is all about resonant frequencies.
On the dyno run, you can see the Racing Beat header in blue and the new one in red. Other than a minor loss between 4000-4500 rpm, the new one is a winner right across the board. It didn't unplug the engine above 6000 rpm as I'd hoped, but a big slug of torque across the range is a lot more useful on the Targa.
Dyno chart
Now, the engine still isn't anywhere near its potential. Keep that in mind when looking at the dyno chart. I don't know if my 200 hp at the wheels goal is attainable, but 170 should be possible. The cams are under suspicion, as sister engines to this one have held power a bit longer without giving up the bottom end. I have another couple of options to try and there hasn't been any experimentation with the cam gears yet. Since they typically trade off low end for high end and vice versa, I don't think they're going to solve things overall. Still, it's worth trying.
Jeremy Ferber from Flyin' Miata was the tuning meister, working in temporary conditions as FM is in the middle of a move.
It wasn't all good news, though. It turns out the car has a problem with the wideband O2 sensor, so we couldn't do a whole lot with tuning. Normally, Jeremy has enough experience to tune via injector pulse width against horsepower, but the 2001 injectors I'm using aren't in his mental program. So I'll be doing a little diagnosis to sort that out - we suspect the heater circuit isn't working. The car was also running hotter than it should, so I'll take a look to make sure the thermostat is working properly.
entry 426 - tags: header, engine, dyno | | |  | March 4, 2008 - Despite the problems, we did get a chance for some comparative testing on the dyno.
My temporary intake pulled hot air from behind the radiator. That's one reason it was temporary, and why it was mounted upside down in the previous picture of the car on the dyno.
For interest's sake, we pulled out a stock 1994 intake tract that includes a resonating Heimholtz chamber. It's not perfectly sized for my engine - I believe the theory says it should be equivalent to 1.5 cylinders worth of displacement - but it was worth trying. And whaddya know, it did something! Nothing major, but 4 lb-ft at 4000 rpm for free is nothing to complain about. The red graph is the stock setup.
Dyno chart
Using the stock crossover tube will also let me put the filter in a cooler place than right behind the rad, which will reap benefits in the real world where having a filter sticking through the hood is awkward to arrange.
In the picture, you can see the filter from my original intake resting inside the engine bay. Don't be fooled, we don't have some sort of bizarre dual-filter setup going here.
entry 427 - tags: engine, dyno, intake | | | March 12, 2008 - Back on the dyno.
I took the long (loooong) way in to work this morning to make sure the wideband was working well. Other than a really slow warm-up time, it seemed to be. But when we strapped the car to the dyno, it was misbehaving by the third run. This is really frustrating. Time to do some more diagnosis - the guys at Hydra want me to try a different ECU.
I didn't do any cam testing as I'd hoped, so instead we basically just repeated what we'd done before - but we pulled out a bit of the excess fuel and put in a degree of timing. Nothing to make any difference to the curves.
Instead, I'll probably end up swapping cams at home, then using the autotune feature of the ECU to see if it wants to add fuel. Crude, but it'll give me a rough idea of what's happening. Then it'll go back on the dyno in a few weeks.
entry 434 - tags: engine, dyno | | | August 27, 2008 - Dyno run!
The car spent some time on the dyno yesterday, making sure that it was safe and ready to go. Jeremy at Flyin' Miata managed to pick up a bit of top-end power but more importantly he was able to confirm that everything was in good shape and ready to go.
The chart is interesting. There's a big dip in the curve at around 4000 rpm. I don't feel it when driving, but the car would be faster without it of course! Jeremy spent some time trying to tune it out but didn't have much luck. If I was building the car now, I'd probably use a VVT head from a 2001-05 Miata instead of the 1999-00 one I used. They have much better torque curves down low. But if you don't learn something over the course of a project, you're not trying hard enough.
I waffled a little bit about whether I should put this chart online as it will invariably get held up on various forums for ridicule and taken out of context, but what the heck. Here goes.
This is Janel's little blue car vs the race car. She has a Flyin' Miata Voodoo II turbo installed on a stock 110,000 mile 1.6 engine. The turbocharger itself is the smaller 2554 unit, chosen for response instead of ultimate power. Since her power level is limited by the injectors in the car regardless of altitude, I used an uncorrected chart for her. Since I'll be able to make more power at sea level (close to 20% more), I used the SAE standard correction. This chart should be accurate for the relative behaviors of the two cars at sea level. The biggest change will be that the turbo will spool up a bit quicker.
What's interesting about the chart is how similar the power curves are, once you hit 3700 rpm. Two very different ways of making power but with surprisingly consistent results. Below 3700, the big displacement of the naturally aspirated car really helps. It's no wonder people comment on how quickly it squirts out of corners, with almost full torque available at 3200 rpm. That's more important than some sort of headline horsepower number. The dip that bothers me (intellectually, I've never noticed it driving) in the race car is there in the turbo car as well, but it's not as noticeable because it doesn't have the big torque swell earlier in the range.
I've always known that I chose a more difficult way of making power. If I was using that little turbo 1.6 in the Targa, I'd be running in the Unlimited class and would have to drive much faster to avoid penalties. But really, it was an excuse to build a cool engine. I love the response of a good naturally aspirated motor. I'll do more development on the engine when I return from the race, trying to open up the breathing on the intake side and maybe swapping a VVT head on. For the race, reliability and tractability are more important and I didn't want to have to babysit a fussy mill. Focusing on the handling and suspension of the car will pay greater dividends, so that's why I spent my time there.
I'm looking forward to feeling how the race engine feels at sea level with a 20% power boost. I think it's going to be a very good tool for the job at hand - dealing with unknown roads as expeditiously as possible.
Dyno chart
entry 520 - tags: engine, dyno | | | October 28, 2009 - Time to see if the fuel pressure changes did anything!
Background: there's a big dip in the car's torque curve between 3500 and 4500 rpm. Massive, actually. It's about a 10% drop. The theory was presented to me that the B (1999-05) injectors are designed to run at a higher pressure, so they weren't atomizing properly. Thus my work of late to raise the pressure.
Unfortunately, it did nothing. Nothing at all. After a bit of tuning to deal with the different fuel curve that's a result of the fixed fuel pressure, the car didn't change a bit. I spent some time playing with timing and fuel, just to prove that naturally aspirated cars have a pretty big sweet spot. Adding an extra 3 degrees of ignition advance didn't do anything, so I took it out again.
Dyno chart
Okay, so that didn't do anything. While the car was on the dyno, I decided to mess with the intake cam timing because that's quick and easy. I advanced the cam by 5°. This should theoretically help the bottom end while hurting the top. And it did. Kinda. The bottom end got stronger and there was a bit of a taper above 6700 rpm. Pretty good tradeoff. The weird thing is that the dip was unaffected. All the gains were on each side of it. It's obvious that there's something that's just not working in that rpm range, but what is it?
Dyno chart
Next, I retarded the intake cam 5° from my original setting. More overlap, should be a bad idle, a weaker low end and more up top. These are fairly big changes, but I was trying to see trends. Oddly, the car purred at idle. It's always had a very grouchy idle, lumpy and a bit tricky to launch. Not any more. But the car really didn't like the cam settings, losing a huge amount of power down low and only gaining a little bit way up top.
Dyno chart
So, not a terribly successful day really. Although it was educational. The cams in the car are Stage 2 cams from Integral Camshafts, and they say that for some reason their 1.8 hydraulic lifter cams just don't work well. The 1.6 ones do, as do the 1.8 solid lifter cams. Just not these. So the next step is to play with a few different cams. It's the second set I've tried, but I have at least three other options to stick in there and see what happens. Once that's done, I'm going to play with a couple of intake manifold options that are available to me. What I'd really like is a VVT head, as I've seen a very similar engine to mine make big torque right where I have my dip. That engine is in the FM shop, not far from where the Targa car is parked. And the boss is going on vacation...
But still, the engine's getting stronger. Here's a comparison between what it looked like when it first hit the dyno and now. Since then, I've altered the intake pre-throttle, built the header and changed cams.
entry 714 - tags: dyno, fuel pressure, cams | | | October 29, 2009 - A quick engine comparison.
Before Elvis - a 2002 Miata at Flyin' Miata that should be fitted with velcro motor mounts - was fitted with a V8, it had a naturally aspirated motor that was broadly similar to mine. The car had a set of roller barrel throttle bodies and a Racing Beat header but more importantly, it had a VVT head. The dip is missing!
Dyno chart
entry 715 - tags: dyno | | | February 27, 2010 - That was worthwhile.
Overall the throttle body setup shows gains over most of the range with no real losses anywhere. The peak gain is probably around 15 hp at 6000 rpm. Based on some post-dyno tuning, I know I'll be able to pick up a bit more in the 3500-4000 range as well.
Dyno chart
The dip is persisting, though. I've seen it with both headers, two sets of cams, three intake variations and some cam timing changes. I've looked at a number of other cars with similar engines, and while they don't have as big a dip, they also have less torque on each side so the change in output is downplayed. They never actually make more torque than my setup.
The two exceptions were a well-tuned 1.8 CSP engine and another high-compression 2.0. What did they have in common? Variable valve timing. In the case of the 2.0, there's a massive difference. I'm trying to get my hands on a 2001-05 head, preferably one that has some work done to it so it's equivalent to my current one.
Before I go that far, however, I'm going to try some different cams. Why? Because it's easy and I have them!
When I compare this dyno chart to the first time this car hit the dyno, it's come a long way.
entry 729 - tags: dyno, intake | | |  | March 28, 2010 - Here are the air horns I have to work with.
The silver one is what came with the throttle bodies, the others are some Titan units that I found in the shop. At least, I think that's where they're from. I have some TWM units around as well.
The first dyno runs were with the silver, "stock" horns. I followed that up with the longest of the black ones, just to see if they'd actually fit. The answer is yes, but the filters I was using won't fit over the end of them.
Dyno chart - the red trace is the medium-length silver horn, the black is the long one.
Overall, it looks like a big win for the long tube, with a solid gain from 4200 to redline and no real loss anywhere else. Unfortunately, it's not an apples-to-apples result. The biggest change is that the long tubes had no filters. Now, these are some pretty open filters with a large surface area, so I don't expect they have much effect. But I do need to test them back-to-back to confirm.
There's also a difference in the design of the bell mouth on the air horns. Note how the silver one has a simple horn shape, while the black ones have a more complete radius. This entry is fairly important, and it could be that the black ones have a better design.
The internal diameter of the horns is also a bit different. The black ones actually match the diameter of the throttles, while the silver one is a bit oversize. Interesting, given that it's the one supplied with the kit. The lip of the throttle bodies has a small chamfer in it that steps the diameter down, but basically there's a step change in the size.
Luckily, I have a black air horn that's almost exactly the same length as the silver one, so I can do comparative unfiltered tests between them to see which is the better design.
I only had the chance to do two different runner lengths today. I'll spend more time on the dyno this week and test all four options in the same session. Hopefully.
entry 737 - tags: dyno, IRTB, intake, engine, air horn | | |  | March 28, 2010 - Dyno run video.
It's not exciting, I know. Really, this was just an excuse to practice uploading video off the new camera and make the changes in the website code to use YouTube instead of the no-longer-accepting-uploads Google Video. But if you want to hear how the engine sounds with the new intake, well, it might be worth your time. Video
entry 738 - tags: video, dyno, IRTB, noise | | | March 30, 2010 - Results for the intake runner length testing.
This was interesting. Not because of what happened, but because of what didn't.
Each engine setup was dynoed three times in quick succession, because I found the first one tended to be erratic. The second and third would be almost exact copies of each other. When I was done, I went back to the beginning to test both the silver runners and the filtered option.
Here's the biggest difference: Short (blue) vs long (red). The shorties did indeed suffer in the midrange, with the biggest difference right around 4500. They didn't gain much up top though, which is a bit odd. Cam limitations? The medium and short runners were basically identical. The silver runners and the black ones of the same length were identical despite the difference in lip design.
But here's the really telling test: Filtered (blue) vs unfiltered (red). That's where my high-end gain came from last time. I'm a bit surprised by this, because the ITG filter I use on the Seven makes no difference at all. It's a big boy and apparently very free-flowing. Something will have to be done - read on for more.
So, the long runners were the winners. Everything else was the same. The short runners make the same power as the ones that came with the throttle bodies.
I need to quieten this car down for a 92 dB day at Laguna Seca in a bit less than two weeks. Ideally, I'd build a plenum to enclose those long runners and see what happens. But there's a way to cheat. A friend who runs a business selling parts for Titan race cars has a nice Pipercross 600 plenum I can use. I'll have to stick with the short runners to fit it, but it's a quick and easy way to quieten the car and bring in cold air. It should be here on Thursday and I'll fit it then.
entry 740 - tags: dyno, intake, IRTB, plenum | | |  | March 2, 2012 - Dyno time!
Before the Targa, our dyno was down for an extended period so all of my tuning was done on the road. And in a car with this sort of power/weight ratio, that's pretty difficult to do. It doesn't spend much time in a particular rev range before leaping on to the next. The car was running really rich which is safer than running lean, but definitely not ideal. So this visit was overdue.
My goal wasn't to determine the maximum power, it was to get the fuel delivery calibrated a bit more intelligently. So I set the dyno up to hold the car at a given RPM. By working the throttle, I could then move the car through all of the load ranges at that engine RPM with lots of time to let the computer zero in on a good mixture. Then I moved on to the next RPM band 400 rpm higher, and do it again. From 2800 to 6000 rpm, it was a long and noisy procedure. By the end, however, I had a tuning map that was a pretty big step up from the hacked-up one I'd started with.
Heat was a bit of a problem. Obviously, holding an engine at 5000 rpm at full throttle against its will does make a bit of heat. The coolant and intake temps would rise over the course of one of my runs, making the numbers a bit less accurate. But still, it helped.
Of course, I did a power run at the end, just to find out. With a very hot engine, the car pulled over 350 hp at the wheels. Not quite the 400 we'd been quoted for the engine, but still pretty darn healthy. There might be a bit more in it when tuned by someone with more experience with these engines.
Thanks to the inopportune arrival of a bunch of snow, I haven't had the chance to feel what it's like on the road. With the leaner mixture, it should have better throttle response. I'm really looking forward to getting the car back down to sea level again.
entry 1020 - tags: dyno, tuning | | |  | March 2, 2012 - I mentioned there was some heat involved.
This is what the hot exhaust did to a piece of stovepipe being used to extract the exhaust. In fact, the pipe blew some of the exhaust back out again and melted the bumper - despite having a big suction fan on the other end.
entry 1021 - tags: heat, dyno, testing | | |  | March 27, 2014 - Dyno time!
Was all that engine swap work worthwhile? Short version: yes. The car spun the rollers at 466 hp and 432 lb-ft. Even better, it was making 300 ft-lb at 1700 rpm and more than 400 from 2900 to 6100. That's one healthy little car.
Here's the dyno run - the whine is from the tires on the rollers.
In other words, yes. It was well worth the work. The old 5.3 made decent power, but didn't have that massive amount of torque. On the road, it's just ridiculously eager, ready to rip forward at any moment. The 6.2 with the ASA cam has the same light feel as the old high compression 2.0 that I used to run, but with approximately three times as much power.
Wow, that puts it in perspective. Nearly three times as much power as the 2008 Targa Newfoundland spec.
entry 1120 - tags: dyno, ls3, 6.2 | | |
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