build diary
<< | show individual entries | >>September 9, 2005:
I've just had a bit of a chat with Larry at Carbotech.
He had a lot of complimentary things to say about the Porterfield R4S pads I've been using and was surprised to hear that I had complaints about the braking. His theory? I've glazed the pads over in one of my early track days due to overheating. That could be related to the blued rotors in the rear. I'll try scuffing up the pads a bit based on his recommendations but I've also ordered a set of Carbotech XP8 pads. It's similar to what Formula Ford cars run and much better suited to track use. I'm a little heavier (200 lbs) but I have a bigger pad, so hopefully it'll work out.
There is a large group of Se7ens driving across the US from Houston to San Francisco. They'll be circling around my area for a few days. I'll buzz out to visit them in Durango in a couple of weeks, then run down to Moab a few days later. It's going to be very interesting to see my car surrounded by the "real thing". Of course I have a list of things I want to do to the car before then so it's in good shape. I'd like to have a lower windscreen done but that's a matter of will on my part. I also need to sort out my bouncy headlights and possibly put in a muffler that actually, you know, muffles. First job is to get the car on the dyno with the throttle bodies and see if these bloody things are worth sorting out. They look and sound very cool but they still require a bit of attention. I've also had the tires pulled off another set of 1990 Miata wheels so I'll refinish those in black and silver like the others. These will get the Azenis tires remounted although the Seven will likely stay on the RA1 tires. Janel wants the Azenis tires for track use. Hey, I'm not going to discourage this behaviour!
entry 985
September 11, 2005:
Horsepower!
Finally, I put the Seven on the dyno. The car was not happy about the idea and did its best to convince me to rip the throttle bodies off the car and throw them away. But I'm either stubborn or a slow learned, so I did it anyway. My first run was underwhelming - 109 hp with lots of black smoke. About this time, Bill dropped by the shop to help out. So the car decided not to restart.
We eventually figured out a couple of things. One, something had been scrambled in the ECU during one of my program saves. And two, we eventually realised that in order to start, the car wanted a throttle position sensor plugged in and set so that it was off idle - but only if it wasn't hot. I can't explain that one but it got us to the point where we could consistently test the car. Bill sat down with the laptop at the dyno and started plugging away. The new injectors have a different response time than the stock ones, so while he was able to quickly able to dial in the lower load ranges by leaning out the overall fuel settings. It took a while to stuff in enough fuel to make the high power ranges work. Eventually he managed to get it rich enough (the injector response was radically different, not just a little) and the car made 146 hp at the wheels. See the dyno chart. That's the most this engine has ever produced by a fair margin, and I suspect I'll be very happy when I get the car back on its wheels. As an added bonus, the throttle bodies will (once the hood is cut for clearance) give a colder intake charge instead of the hot underhood air it's been breathing. It's quite possible that I'll find I have 20% more power on the track. Well, I'd like to think so anyhow. I'm still planning on testing the car with the long trumpets to see what difference that makes.
So what was I doing while Bill worked on my car? Helping of course. But I was distracted. Janel was also at the shop and we were stripping down two sets of wheels to be repainted. Apparently you lead an exciting life if you're a friend of mine.
Oh, and one more cool thing. Because the ECU doesn't cut fuel on closed-throttle deceleration (no throttle position sensor, it doesn't know what's going on), the Seven now shoots flame out the exhaust. Hee hee!
entry 986
September 12, 2005:
More horsepower.
Well, just a little bit. It's hard to say what the peak power is because it jitters around at the top end (mostly due to the way the dyno works) but it's definitely in the high 140's. Not bad for a 1.6! This evening I spent a bit of time comparing the short vs long runners once the fuel was dialed in a bit more. How did it do? Well, you can see the chart here. Red is the long runners, blue is the short. The long runners idle better and make a definite difference in the midrange. Right at 5000 rpm it sucked up a bunch of fuel and had to be fattened up. Above 7000 it got rich with the long pipes and was probably not flowing as much air, but it's a bit tough to tell from the charts how much less. I'll take 4 lb/ft in the midrange over a couple of hp above 7000 rpm though. This means I need to hunt down a new air filter. ITG makes one, hopefully I can find one somewhere.
So, almost time to put the beast together and drive it! Well, I'd like a hood before it goes too far. I'll build some solid motor mounts for the car tomorrow before cutting any sheetmetal. This will keep the intake from moving around as well as the exhaust. The car already has everything else bolted up solidly including the transmission so it's not a big deal.
entry 987
It seems that one of my tires has been chewing on the emergency brake cable.
Maybe I should tie that back.
entry 988
The Seven strapped to the dyno to see how the throttle bodies.
How did it do? See the dyno chart.
entry 989
A new music video starring the Seven.
Hey, I needed to spend some time exploring Premiere. It's a big file.
entry 990
Still on the dyno, testing different length runners for the intake.
entry 991
Short vs long runners.
entry 992
September 14, 2005:
If you're looking for online gambling just let me know.
My guestbook is suffering an onslaught of spam.
I've ordered a new air filter for the longer runners. It wasn't cheap and if I'd thought about it, I might have been happy with the shorties. Oh well, at least this will idle better. The starting problems have been fixed and all that remains to make the car a little more liveable is to fit a 1.6 throttle position sensor so I can use the idle switch. That will let it idle a bit better but it's actually pretty happy once warm. I also have to cut the hood and I'll probably do that tonight. Then it can be driven!
I've decided against building new solid engine mounts to prevent stress on the frame (thanks for pointing that out, Ted!). Even Caterham uses small rubber bushings as it turns out. Instead, I've installed a set of Mazda Competition motor mounts that are 40% stiffer than the existing ones (or at least, than they were originally). I took the opportunity to lighten the steel portions of the motor mounts as well. They were big enough to handle a small block Chevy before. Finally, a change that doesn't add weight to the car!
entry 993
A view of the throttle bodies from below.
The black part is the throttle cable bracket I built.
entry 994
A short piece of metal and voila - no more bouncy headlights!
entry 995
While installing the stiffer engine mounts, I decided to take some weight out of the engine mount brackets.
They were overkill before.
entry 996
September 15, 2005:
First test drive!
I feel as if the Seven has been off the road for ages. I put the second motor mount in last night and the engine is much more solidly mounted than before. There's no real increase in vibration so I think that upgrade can be called a success! The new rod ends for the upper control arms arrived yesterday and they were installed as well. Then it was time to put the hood over top of the new throttle bodies. This involved a new hole. It hurts to take a saw to my hood but seeing the filter stick out is just too cool. It's cool for intake air as well so that's good. I'm still waiting for the other filter to arrive so I only approximated the shape for now. The headlights were aligned and then it was time to roll the car out of the garage.
How did it drive? I didn't go far due to a little wiring problem with the headlights, but it seems strong. The air intake temperatures stayed low and on closed throttle I could see flashes from the flames coming out the exhaust. Tee hee hee! I still have a bit of work to do before the Se7ens USA trip comes through. A lower windshield so my car doesn't look TOO huge as well as the final hood trip. Who knows, maybe even a grille...
entry 997
A rough cutout in the hood and it fits over the air filter.
I'll refine the shape once my other air filter is here - it's straight sided and not sausage shaped. The wrinkle at the front is some aluminum tape that I put on to protect the filter.
entry 998
I needed a 5/8 x 3" bolt for the upper control arm.
But a standard SAE bolt of that length has too much thread and I wanted to avoid putting a load on the threads. A 5/8" x 4" bolt had the right length shank so I cut it down.
entry 999
September 17, 2005:
The hood is on.
My new filter showed up on Friday. It's HUGE. Still, a bit of careful cutting and I managed to make the hood fit over top. The filter protrudes fairly far and looks like it really means business. Now I can drive the car more. I've also fitted an idle switch so the car will idle better - but more importantly, I can tune the car better. It's fine at wide open throttle but part-throttle needs a lot of tweaking to get it right. Fair enough, we didn't bother with that on the dyno.
The front fender stays are currently covered with wet paint so they'll be final shortly. Now it's just a matter of looking at the windscreen. Just like the first time, it's taking me some time to get started on this. I know it'll be a quick job. I just have to DO something.
entry 1000
The new filter compared to the old.
It's much larger.
entry 1001
Sevens always look cool with the engine bursting through the hood.
entry 1002
I'm pretty happy with the fit of the hole for the filter.
entry 1003
The idle switch for the throttle bodies.
The wiring is a total riot right now due to redundant bits and rerouting compared to the original design. I'll clean it up shortly and replace these temporary connectors with the proper one.
entry 1004
September 19, 2005:
More driving!
The car's pretty happy. The throttle response is fantastic and the car pulls hard. I spent some time tuning the computer and even managed to get rid of most of the flames on overrun. There are still some little problems though. The throttles don't always close fully unless I snap them closed but that's only obvious driving in traffic - I'll find I have an 1100 rpm idle at a light. I'll have a close look at the linkage. It seems to be related to heat. The car also seems much more eager to turn left than right. It could be my weight or it could be a toe problem in the rear. Eyeballing things, it appears the right rear is toed out but I don't trust the rear fenders to be straight. I'll check it today with tools instead of eyeballs.
Polishing the spare wheels yesterday revealed that the perfect tool for the job is seveal grades of Scotchbrite (or a reasonable facsimilie thereof) because it's fast and easy to use. The new wheels look good and are being painted now. I also cut up plywood for the new, lower windshield and discovered that the aluminum channel I use for the frame is no longer available in 8' lengths. All I can get is 4' but that's not enough to go around the windshield. Argh. I'll have to find a solution to that.
entry 1005