| MIATA BUILD |
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 | |  | March 28, 2010 - Time for some more dyno testing!
One nice thing about the individual throttle body setups is that I can change out the air horns and alter the intake runner length. In theory, a short runner should trade off low rpm torque to gain high rpm power - and a long one should do the opposite. But if they're way off, then you just plain lose. Since I have a collection of horns, I'll simply do some back-to-back testing and see what happens. It's always interesting to simply install a pipe that's 1" longer and see a power bump.
I had the chance a while back to talk with Bill Schenker, a national-level CSP autocross competitor about his engine. It makes very good horsepower - similar peak power to my engine, but with less torque - and it's all come from hundreds of dyno runs, testing one slight change against another. One thing he told me was that the length of the intake tube running from the stock intake manifold to the filter had a big effect. Again, a 1" change made a notable difference. Of course, he was talking about naturally aspirated power so it wasn't a 15 hp difference, but if you can find 10 places to gain 1.5 hp, there's your 15 hp gain.
So, bring on the air horns!
entry 736 - tags: testing, intake, air horns, IRTB | | |  | 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 29, 2010 - Another new video.
This is a run up the Targa Simulation Road to test both the springs and the video camera. I'm pretty happy with both. We'll see how the springs do on-track this weekend.
Video
entry 739 - tags: video, testing, suspension, video | | | 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 | | | April 1, 2010 - Spent a long day working on the intake.
And of course, I didn't take any pictures. The Pipercross plenum showed up. These are made in either left-hand or right-hand configurations, with my application being the right-hand version. Naturally, I was only able to obtain the opposite.
No worries, all I had to do was to fit the base plate on upside down. But that interfered with my fuel rail. After some poking and prodding, I figured out that the plenum was made in a couple of pieces. I separated the two, flipped one over and voila, my left-hand plenum was now the right-hand version! I had to epoxy everything back together, so that meant I wasn't going to be finishing today.
In the meantime, I cut the base plate to match my runners and installed the short air horns. Due to the shape of the plenum, I also had to relocate the idle speed control valve and reroute some wiring. The latter needed to be done anyhow, it was kind of rough looking. Since I knew I wouldn't have time to test the car any more before the track day on Saturday, I unshackled the car from the dyno.
Over to a lift, I swapped out the current exhaust midpipe (with an empty cat) for anther one that we'd been using for testing. I also needed to find a place to fit an air filter. One of the problems I'd found with the IRTBs on the road was that my intake air temperatures were quite high. The new plenum will not only hush the car (important for Laguna Seca on Friday!) but will give me the opportunity to pipe in fresh, cool air. I decided to try a filter mounted behind the front bumper. It's not the best place if I decide to ford a river, of course, but for normal use it should do just fine. After a bit of thinking, I decided to bolt the top of the filter to a handy flange. Three bolts with big backing washers going through a top that's about 3/4" thick (really, I was amazed at it!) and it's solidly mounted. I'll run the air hose in it tomorrow and the car will be ready. I'll also take some photos.
Is it going to be quieter? Oh man, I hope so.
entry 741 - tags: ITRB, plenum | | | April 4, 2010 - No pictures of the new intake yet, but I have track videos!
Fastest lap
Smoother fast lap
The track day went pretty well. It was a fairly cold one and I only got about three sessions in the Targa car (along with the chance to drive a 350Z, a BMW M Coupe and a couple of FM Miatas), but my best time was a 1:04.959. That's about 0.2 seconds off my best in the car, nothing to be ashamed of. There was a time when simply dropping below 1:06 in any car was unusual!
The dual spring setup does allow for some body roll, but the lap times would indicate the car isn't suffering too badly. It absorbed the berms well and was very stable under braking. I'm trying to decide if I want to keep this setup for Laguna Seca or if I want to pull the secondary springs so the car corners flatter and has quicker reflexes. Tough call. If it can still hustle around our little autocross track here this quickly, I'm thinking the dual setup is working.
The engine felt good. For the first time, I noticed a lack of pick-up coming out of one of the hairpins at 4000 rpm - that's the dip in the torque curve. The heavier throttle pedal (due to a stiffer spring) took a little getting used to in order to be smooth, but I adapted pretty quickly. Nobody noticed that the car was particularly loud, so I'm hoping that's good for Laguna Seca sound levels. Hoping hoping hoping. I did have one person ask me if it was a V8 because it didn't sound like a four-cylinder!
Pictures of the intake are at work, I'll put them up tomorrow.
entry 742 - tags: video, GJMS, testing, track, IRTB | | |  | April 5, 2010 - Time for some pictures of the new plenum!
First, I had to drill a backing plate for my intake setup. In order to clear the fuel rail mounts, it has to sit a bit low.
entry 743 - tags: intake, plenum, IRTB | | |  | April 5, 2010 - The plenum clips on over the base plate.
I had to notch the edge of the plenum slightly to get clearance for the fuel rail, but here it is in place.
You can see the relocated IAC back by the fuel pressure regulator. It's a tight fit wiggling this on!
entry 744 - tags: intake, plenum, IRTB | | |  | April 5, 2010 - Now, I have to get cold filtered air into that plenum.
I have a conical filter that fits into the inlet, but I need to do some dyno testing to see how well that works. The ideal plumbing here would be to put the conical filter in, then run straight to a hole in the hood. But not today.
So instead, I used some flexible 4" hose and ran it down to the filter. It's a tight fit and I'm not excited about the tight radius bends from an airflow standpoint. But it's critical I get this car as quiet as possible.
entry 745 - tags: intake, plenum, IRTB | | |  | April 5, 2010 - The filter is a monster.
I needed one with a 4" inlet to match the inlet on the plenum, so I grabbed the same filter we use for our V8 Miatas. It's Honda sized! A 90 degree piece of silicone and a slightly-fudged adapter into a piece of 4" tube, and we're hooked up to the hose.
entry 746 - tags: plenum, IRTB, intake | | |  | April 5, 2010 - The filter is pretty exposed to road muck and goo thrown by the tire in this location.
And the weather forecast for the trackday on Saturday was looking sketchy. So I took this plastic cover from a 2005 Mazdaspeed and did a very quick and dirty installation. Very quick and dirty - note the use of tape! That's what happens when the track day is Saturday morning and you're still working on the car on Friday night. As it was, the day was dry so it wasn't a concern.
The first day at Laguna Seca has a 92 dB limit. I'm hoping to get past that. The next two days are 103 dB, so I might just pull the plenum off and stick the sock filters back on for maximum roar! Because I'm a child.
entry 747 - tags: intake, filter, IRTB | | |  | April 14, 2010 - Welcome to California!
Three days of track time with two drivers, mixing it up with faster cars. It's a good thing this little car is tough.
The first day was sunny and beautiful. The track day was run by the Checkered Flag Racing Association, which is basically a grown-up version of the Red Rock Racers I run in Grand Junction. Sessions were 30 minutes long and full of some very serious machinery. Even the novice group had a Porsche GT3, a fast little Caterham and a couple of Nissan GT-Rs. The Nissans were being driven extremely quickly, and were really in the wrong group. Overall, a very experienced bunch that were good to share the track with.
The goal for the Friday session was for it all to be about Janel. She's spent so long hanging around as I run around at the track it only seemed fair for her to have her own track day. So our friend Rick Weldon offered to give her personal instruction, and I was pit crew.
We started off doing a sound check. The limit was 92 dB, and we went by the meter at 93.3 dB. After a certain amount of chaos on the part of the organizers who all told us different things, we found that by holding 4th gear through turn 5 we tripped the meter at 88 dB. So there's that solved then.
Rick was running behind, so I went out with Janel for the first three sessions. We had a good time and everything seemed to be working fairly well other than a car that was very grouchy when cold. The biggest problem was dealing with the traffic.
Rick showed up just as we left for the third session, so he only got to ride with Janel for a couple of sessions. She was all warmed up and ready to go, though. He's a fantastic instructor and not only helped her with her lines, but also with how to deal with traffic. She's a great learner, and if you tell her to go full throttle through a certain corner without lifting, she'll do it!
I was running a stopwatch, and we saw her times drop by about 12 seconds per lap - partly due to the way that she dealt with faster cars passing her. The big grin is from her last session, when she spent two or three laps holding off a 911 GT3 (really!) before the monster power on the straight finally proved to be too much for the little Miata. She was putting down consistent 2:00 laps with only a few tenths of a second of variation, plus one solid 1:59.28. You can see her session on the video page. After seeing the times, Rick commented that she'd be a great endurance driver. On the way to dinner a couple of nights later, she asked me how you get involved in endurance racing...
Does she look happy to you?
entry 748 - tags: janel, laguna seca, track | | |  | April 14, 2010 - After Janel had so much fun on Friday, it was time to meet the hundreds of Miatas that had come for Miatas at MRLS.
The plan was for me to drive the car in the fastest A group and take people for rides, and Janel would drive in the C group. However, when I first jumped in the car, I discovered that it was very unhappy under part throttle. It was too late for me to do any more tuning on the car, but spending a single session with a laptop jammed under a seat would have made a big difference. Still, it was easy enough to drive around. I also discovered that while my spare rubber was up to pressure, I had the tires on the car about 7 psi low. Whoops. So the car should have been faster on Friday for Janel if I'd been able to take a quick test drive. Sorry!
For the rest of the weekend, the car pounded around and around the track. The other cars from Flyin' Miata were under orders not to run at 10/10ths to ensure they'd last, but that didn't apply to the Targa car. So I ran it pretty hard, and I know Janel did as well. This is one solid little critter, and so much fun.
The new suspension wasn't a big hit with Janel, and it certainly did allow a lot of lean. Still, it put down the power well and seemed friendly enough. I wanted just a bit less understeer but didn't want to mess with it after Janel had spent so long honing things with Rick.
I spent a lot of my time staying out of trouble with the A group, populated with winged beasts and drivers that were considerably faster than me.
Janel had a different problem. She was much faster than everyone in her group, and so she spent most of the time waiting for the slower driver to point her by. It was frustrating. She really should have been in the B group.
Sunday started off cold and looking like rain, and it started to sprinkle fairly early. Janel came into the Corkscrew with the back end of the car quite loose and almost looped it, and I found the grip level changing on every corner. So we parked the car, and shortly afterwards the skies opened. The track was closed early due to the deep water, and we packed up to go home.
A pretty good weekend.
entry 749 - tags: laguna seca, track | | |  | April 14, 2010 - New videos have been uploaded!
There's a video of Janel's fastest session on Friday as well as a couple with me driving in the middle of a fairly entertaining group. Videos
On Saturday, the event organizers gathered a few of us together for a video shoot. There was a hand-held camera in one of the cars, and the rest of us were basically tasked with putting on a good show. Two Spec Miata drivers and a couple of modified super Miatas - and my little rally toy. I was probably the least experienced track driver of the bunch, so I had to pedal pretty hard just to keep up! The extra horsepower of the Targa car let me reel in the Spec Miatas most of the time, but not always.
Still, it was like a little race. One of us would take the lead, then allow someone else to pass. Meanwhile, the camera car was zooming back and forth. I certainly wasn't the fastest driver or car in the group, but I consoled myself with the thought that if there was a speedbump in the middle of the front straight, I was the only person who could take it at full speed!
The Targa Miata is one solid little car. This picture was taken after Janel ran for a full day on Friday, and then she and I both drove the car on Saturday. On Saturday, the car was on the track for 20 minutes, then parked for 20 minutes before it went out again. And that's the state of one of the tires. A tire that we used in the Targa. A week long race, followed by a bunch of local track days, followed by two days at Laguna Seca last year, then repeat the local track days and two more days at Laguna. And it's only about half worn! Amazing.
entry 750 - tags: play, laguna seca, video | | |  | April 25, 2010 - Some pictures from the Laguna event.
More are coming. This is the first session on Saturday (it must be, I'm not wearing my driving suit) and that's John Anker coming down the Corkscrew behind me. He was never behind me for long!
Photo by Mark Booth.
entry 751 - tags: laguna seca | | |  | April 25, 2010 - Mark got a this great shot of Janel at speed.
I'm not sure where it was taken - it's a right hand turn, so I'm thinking it's either turn 4 or 10, and something it telling me it's 4 - but I really like it.
Photo by Mark Booth.
entry 752 - tags: laguna seca | | |  | April 25, 2010 - A shot of our video session from outside turn 2.
I'd just steamed by the whole group on the straight (with their acquiescence, as there's no way I could power by a couple of those cars), and was taking a wide line into 2 to let that Spec Miata run inside me for a cool pass. The camera is in the red car about halfway back. This was fun stuff. The photo was taken right at 2:00 in this video.
Photo by Mark Booth
entry 753 - tags: laguna seca | | |  | April 25, 2010 - Laguna Seca is a pretty track.
Quite a change from the dusty desert. Here's Janel about to dive over the edge into the Corkscrew. Photo by Got Blue Milk.
entry 754 - tags: laguna seca | | |  | May 1, 2010 - More magazine coverage!
The June 2010 issue of Grassroots Motorsports has a good article on our Targa adventure. Not just the story of the race, but also some sidebars on how to survive your first performance rally, details on the car and what it's like to run an event like this with your spouse. Thanks to Grassroots for the attention!
If you'd like a free copy, they're happy to send you one. It's a good magazine, even the issues that don't have a mention of the Targa Miata in them.
Get a free copy
entry 755 - tags: magazine, grassroots, publicity | | |
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