Just come back from running my banger roadster on the rolling road or chassis dyno as you stateside guys call it. Not much to report in regards to changes as the only change was slightly bigger power valves. Fuel and ignition was un-changed so it ended up with a few power runs. Heres the 'perts setting p all the sensor and strapping the car to the road. Strapped down and ready to go... More stuff connected to the car to read all the vitals. Clash of era's! The screen is showing two power runs lapped over each over to compare various points in the curves. How the car sits on the rollers. Heres the vids. First vid is pretty slow and boring. Basically getting the road and car in sync with each other. Second vid shows a power run that went wrong! I had turned the fuel tap off for changing the power valves and forgot to turn it back on again! Final vid and power run. Vid was taken from a different position obviously! Final outcome.... 114.3 BHP (At wheels) @ 3910 rpm (98 mph) 188.8 lBft @ 2450 rpm
congratulations enbloc . it takes a lot of time and money to get these little buggers up to that level not to mention a lot of dogged determination when things go wrong. i salute you.(should give the early v8 flattie guys a bit of a scare as they did in the early days) dave
Is this your "good" motor? The one you were having all the problems with? It sounds healthy and has good numbers to support it! A local guy just put one of those "dyno's" in his shop....I might have to go try mine out this summer.....
How reliable are these at that state of tune? I have an A speedster in the planning stage, I wouldn't expect to put that much power out of the A plant, but I figure some 'tuning' is mandatory. So how hot can you recommend in something that you want to survive?
Yes, this is the "good" motor, the one with all the problems! Like with anything the rolling road/chassis dyno is only as good as its operator. I've had a lot of problems but not necessarily because of the engine state of tune. I've work through them problems and it has so far been very reliable clocking up several hundred miles over the last month alone.
I forgot to post this yesterday. This is the print out from the afternoons activities. The lines of interest here are the blue, green and yellow. Blue shows the torque produce over the rev range and the green is power at wheels (bhp). Both are nice, straight, uninterrupted lines. You can't ask for more than that. The yellow line is the air/fuel ratio over the rev range. Things get interesting here particulary if your running Stromberg 97's. The ratio is fairly constant over the rev range until the top of the rev range then the carbs run lean. There are several possibilities suggested for this: Lack of decent air filters/ no air filters. Most carbs are designed to run with a filter, even the antique "97". Bigger power valves. The power valves supply fuel enrichment on full throttle. It could be a basic design flaw of the carb. A problem more common than you'd think even with much newer carbs. Correcting this problem involves modifying the carb with an auxiliary "main jet" that serves the same purpose as the power valve and only becomes functional at full throttle/high revs.
How much does the whole lot weigh full of fluids? That torque curve must make that thing scoot outta the hole if it's a light as it looks.
I don't know the weight. Its not a stripped out race car but its certainly not a heavy weight. As you've spotted the engine is about torque! Theres too much to go into here, but the full build up was documented in the Banger threads late '06/early '07 http://www.jalopyjournal.com/forum/showthread.php?t=161498
So you are talking about a 'power jet' like the Mikuni's and other 'bike' and 'sled' carbs use? I know it might not look quite right for your type of build, but would the re pop 'Scot' injection tops build enough velocity at those engine speeds to draw from a set of those? I figure 1 ea per carb (centered between the booster venturris upstream so it won't screw up the airflow through the boosters) and draw the fuel from a modified plug at the bottom of the float bowl (just a plug with a hose nipple on it for the main or power valve well). But there i go brainstorming out loud again, hijacking people's threads sorry.
Awesome. Sounds smooth all the way through, too. Well done! As you mention to John, torque is king here. You've got enough to pull a house along behind you there. Just looking at your print-out, are we saying that the 114bhp (purple curve) figure is at the flyweel and the green curve is the bhp at the wheels? About 90bhp? Or am I reading the chart wrong. I'm looking on a crappy old laptop at the moment...
I agree that the quoted horsepower figure is on the flywheel. Still very impressive. Interesting to compare the dyno test with the numbers for a blown V8 flatty. (159hp @wheels, 233hp @ flywheel). Both very cool cars. www.thecheatersgang.com/dynotest.htm
Your right. My mistake. I took the detailed figures from another sheet and didn't check which it was referring to.
Doesn't make any difference, the figures are still excellent. A genuine 100+bhp banger. Quite an achievement. I'm more impressed with the torque figure though....