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Interesting observations... Not sure if anyone mentioned or factored the CVT in the Civic Hybrid, or if it was the older 5-speed used to compare (it probably doesn't change the final ratio at cruise, but holds another advantage up the speed range). Finally, I think the only way we can get the cars we want, is to design them ourselves. To the mass public, Automakers don't have an incentive to make small, inexpensive, FE-oriented vehicles -- the profit margin is paper-thin compared to the truck-based SUVs. It'll take a paradigm shift of customer education and demand through outlets such as these. First people have to care -- that generally translates to the wallet. Sigh, I'm preaching to the choir here...and in the wrong thread :o RH77 EDIT: Based on the ideal piston travel speed, would there be interest in a custom calculator for ideal cruise (like a set of input questions in a web-based form or something? |
Did the calcs
OK -- so for 1000-1200 ft/min piston speed, with a 3.5 inch stroke in my auto,
Then (accounting for some slight tire wear) ...I'd have to drive in 3rd gear at 60, since that translates to: 1000 ft/min @ 3428 RPM = 55 mph in 3rd, 85 mph in 4th (wind resistance starts to hit). only went up to 4000 RPM for engine longevity... 1283 ft/min @ 4000 RPM = 64 in 3rd, 98 mph in 4th Should I be driving around in 3rd? What else is at play here? RH77 |
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Now I throw in a few simple aero mods -- grill block, rear wheel skirts, etc. and maybe I've got my 50 mpg at 70 mph. Any ideas? |
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Ideal kind of car...
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Even more sense, around 45 is the perfect speed for FE in this car. My best segments are on a road with slight hills while using P&G/DWL between 40 and 50 mph. OK, designing cars. Take something like the Pruis and ditch the drivetrain/batts. Now you have 4-doors + the use of a hatch + a slick Cd. Throw-in a 1.3L like the Yaris' x-US version: 2NZ-FE, VVT-i 10.5:1 Compression. 88 hp @ 6000, 89 ft-lbs @ 4400. There's also a 1.0L, but with a larger platform, it may not be efficient on the highway. Gearing -- dunno. 6-speeds. You'll have some torque with the VVT and compression. To sell it to the U.S., it would have to be manual only in this version, then have a bigger engine and automatic for everyone else (or sport version with the big engine and 6-speed). One could argue all day about the auto being CVT or traditional, I suppose... My ideal new car is a CNG 4-door Civic, using the older 1.6L variety with the unavailable standard shift -- maybe a 6-speed -- only one I can think of is from the Si, but the top gear might not be efficient, so a swap of sorts is appropriate, or throw in a 5-speed. Same for the Toyota example. A CNG-Hybrid needs more research, but sounds pretty cool. RH77 |
According to specs I got from metrompg's site and the team swift site, a 1.0L metro engine coupled to the 1.3L suzuki tranny (metrompg did this swap, and it's documented on his site) with 13" wheels would yield piston speeds of 1,192, 1,291, and 1,391 ft/min at 60, 65, and 70 mph respectively. This is the only non-hybrid gearing that I've so far found that could put you in the ideal-piston-speed ballpark at highway cruising speeds (still need to check out the CRX HF gearing).
By the way, the stock XFI trannies give piston speeds of 1,282, 1,389, and 1,496 while the regular non-XFI trannies from '89-'94 give piston speeds of 1,389, 1,505, and 1,621. The '95 and up trannies have a shorter R & P gear, so the piston speeds are even higher. |
I think you're making a bit too much out of it. Just think in terms of load and yer set. This holds true for small and large, diesel and gas, AFAIK. The only notable difference comes from friction reduction in hybrid engines, which allows 'em to rev higher w/o the usual drop in efficiency. Every other BSFC map is pretty consistent in terms of efficiency. Something less than peak load at ~2-3k rpm.
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