Your donations help keep this valuable resource free and growing. Thank you.
|
AMC 258 w/4.0 head & EFI |
Post Reply | Page 123> |
Author | |
amcguru
Supporter of TheAMCForum Joined: Jul/24/2007 Location: Maryland Status: Offline Points: 410 |
Post Options
Thanks(0)
Posted: Jul/22/2011 at 8:58pm |
Very true. My Benz has a .25 Cd and ambient temp/humidity plays a greater role in fuel economy than cruising speed. The truck on the other hand is a whole different story...20.5mpg @ 65 and 17mpg @ 75.
|
|
NAMDRA #3646 "I believe the best social program is a job" ~ Ronald Reagan |
|
tyrodtom
AMC Addicted Joined: Sep/14/2007 Location: Virginia Status: Offline Points: 6213 |
Post Options
Thanks(0)
|
Air resistance squares with speed. Go twice as fast, resistance increases 4 times, 3 times as fast 9 times more resistance.
Ever notice in the late 80 when NASCAR was still running somewhat stock appearing cars , with some aerodynamic improvements. The cars had about 4 times the hp of the stock car but wasn't quite twice as fast, even at Taladega and Daytona.
|
|
66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.
|
|
farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
Post Options
Thanks(0)
|
Are there any pull-a-part type yards in the are? Plenty of XJs in them now! If you find a Renix powered one the wiring is even pretty easy as the ECU/engine wiring is totally separate from the body wiring. The wiring is similar to the later H.O. engine, main changes are some of the sensor types. Shouldn't be too hard to convert a Renix harness to an H.O. ECU, but I haven't looked into that in detail.
|
|
Frank Swygert
|
|
billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
Post Options
Thanks(0)
|
>>Seems like more people are complaining about gas prices, but many of the
loudest complainers are also driving big vehicles at 75-80 and won't
slow down.<<
Ain't it the truth! I have done tests with my new truck. 55-60 I can do 22 mpg highway. 60-65, she drops 2 to 4 mpg with no other changes. 65-70, forget it, might as well be driving through KC during rush hour as far as mpg. But if you can stand to be 2 minutes later when driving from here to Ankeny, keep it at 60-65 and you'll do very well. OK, so that's a truck, right - brick through the wind........ but I've found it to be similar for many vehicles i've owned, including the javelin. When I can keep it under 80, it's a lot better for mpg. The Javelin is hardly brick-shaped. I do have to admit - if I could afford it, I'd be putting some form of fi on the 258 in the '80 Eagle wagon for my wife. She's been so long away from carb'd cars - it would just make sense. She's not mechanical and gets frustrated if something doesn't start quickly and allow her to simply drive off. (frustrated is a nice word for the effect) |
|
farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
Post Options
Thanks(0)
|
I've heard 60-65 is about the limit for most cars and more modern light trucks that are a little more aerodynamic than in the 70s. Most of out AMC cars are about the same aerodynamically as 90s-00s light trucks. Just a bit better than pushing a brick through the air (I'm NOT including an XJ Cherokee as a bit more aero...). The more frontal area the lower that speed. Some of the more streamlined cars don't hit that wall until 70-75 though. Seems like more people are complaining about gas prices, but many of the loudest complainers are also driving big vehicles at 75-80 and won't slow down.
Nali, I was referring more to a ready built system that a racer could use. You can assemble and piece together a Mega Squirt system for under $800. The MSIII assembled with daughterboard for sequential injection and wiring harness (which still doesn't have connectors) is just over $700. Then you need a laptop. I should have specified when I mentioned MS though -- I was considering the premium system, not the basic. An assembled MS1 unit with everything you need still runs around $500. The Micro Squirt would be the base level of EFI, and can be used on cars though it was designed for smaller engines. You're still looking at $400 (+connectors). The Micro and MSI are both batch injection with two injector drivers. |
|
Frank Swygert
|
|
poormansMACHINE
AMC Addicted Charter Member Joined: Jun/28/2007 Location: Shoemaker-Levy9 Status: Offline Points: 12302 |
Post Options
Thanks(0)
|
Double the speed and resistance goes up by a factor of 4.
|
|
billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
Post Options
Thanks(0)
|
70 mph ain't gonna get you MPG in any case........... you drop off seriously above about 60 or so, no matter how much you tweak, EFI or carb.
The smaller the engine, the bigger the drop in many cases. |
|
nali
Supporter of TheAMCForum Joined: Oct/30/2008 Location: Montreal , Can. Status: Offline Points: 984 |
Post Options
Thanks(0)
|
Farna , a Megasquirt doesn t cost 800 $ ... The controller is about 260 $ .
For this price , assembly is required , of course :P http://www.diyautotune.com/catalog/megasquirt-ii-kits-c-30.html?osCsid=a9b390422824ef8a7fdf45beff572c4c Edited by nali - Jul/19/2011 at 2:14pm |
|
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one. |
|
farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
Post Options
Thanks(0)
|
EFI is expensive for drag racing. The guys with big bucks ARE running EFI with computers. Instead of breaking out the jets and screw drivers they pop open a laptop. For an easily adjustable EFI system you have to start with at least $800 (Megasquirt), but that only gets you a controller and wiring. You have to come up with sensors and half the wiring harness. Figure more like $1200. I'm not sure the MS system is all that great for racing, but then I don't see why not. Carbs are way cheaper and easier to learn than an EFI system for most.
Most people (self included!) simply don't know HOW to set carbs up right. But I say even then they are only "right" within a certain set of parameters. They simply can't adjust for as great a driving condition range as EFI. I think we are all describing our "worst scenario" conditions. My truck didn't act up all the time, only on the colder days. Most other times it ran fine... except when the secondary float stuck, TWICE... mainly because the poor old thing hardly ever pulled in the secondaries. I don't think it was creating enough vacuum due to worn rings. I had a screw in the slot so at 3/4 throttle it would crack open the secondaries anyway. |
|
Frank Swygert
|
|
7Xpacemaker
AMC Apprentice Joined: Jul/23/2009 Location: Bentonville,Va Status: Offline Points: 96 |
Post Options
Thanks(0)
|
TWO new cars were taken to my friends Chevrolet dealership in northwestern Pennsylvania because one would barely run and the other would not run at all. Long story short- the gas was drained out and a sample was sent out from each vehicle. It turned out that there was 21% ethanol in the gasoline. You can take or leave my information or call it "hearsay", it matters not to me. No matter what I say it is all hearsay to anyone else. I have also gotten good mileage from carb'd vehicles as well. My daily driver (84 miles per day) was an '81 Concord/ auto with a two bbl carter. The best I could get out of it was 22 mpg at 70 mph. I had the car tweaked as close to stoich as I could without detonation. I am an aircraft mechanic by trade and definately have the skills to properly set up a carb. My intention when adding to this thread was not to stir up other people's emotions. I apologize if I have. I sometimes come across wrong, I guess. |
|
C.J.
1981 AMC Concord 1977 AMC Hornet AMX 2001 Firebird Convertible LS1 1978 AMC Concord 1982 AMC Spirit GT 1974 AMC Hornet |
|
Post Reply | Page 123> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |