Advance cam?
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The computer on our trucks governs the engine to about 3600rpm to protect the driveline. Getting a chip can eliminate this ; but please don't sling your driveshaft while I'm behind you. If the cam is advanced 20 degrees ahead of stock , it should provide better cylinder filling at low rpm's= more power. Shouldn't lose any top end because of the governor / driveline limitations already mentioned. I started this thread to see if anyone had tried this before and encountered any problems, such as needing valve cuts in the piston or such.
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Oops. my mistake. I was thinking of where my engine peters out in fifth to protect the driveline. I actually got to 95 mph at 3600 when it was on stock tires with the 4.10's. Milage, with the 4.10's and 32's was pretty damn good, about 24 to 26 mpg. with the e-fan and underdrive pulley. The 32's are on the stock rim and I just let enough air out to make the tread lay flat. That was with the 4.10's. They dropped the gearing to about 3.68. I have changed gears this weekend, in my search for the best highway fuel milage to 2.73's and the 32's will have to go , in favor of the stock tire size, 235/75/15. The gears aren't as tough to change as I thought they would be. Worst comes to worst I can put the 4.10's back in.
Last edited by BOB; 03-12-2006 at 10:45 AM.
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I just changed to the 273's, this weekend. I forgive you for not believing me, although I don't tkink you need it. I would be sceptical too. I can get over 450 miles to a tank of gas if I baby it, NEVER exceeding 2300 rpm's and no more than 50 miles of the 450 are city driving and not running the a/c. I live in a rural area and do very little town or city driving. I do have to drive to the Dallas/Ft.Worth metroplex to work, but my jobsites are usually within five miles of a highway or interstate, many, less than a mile.
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I don't figure my milage by tanks. I figure milage by miles divided by gallons. I do correct for tire size, the 32's being [31.5] a bit larger than stock. I also checked against a known distance, and found that I was going only 10% farther per tire revolution instead of the 11.15% I was expecting. Ok , I know I will have to do this, so grab your calculators! 31.5 [which the 32's actually are] x pi [ 3.14]=98.91 inches, divided by 12=8.2425 ft. X 2300[rpm]= 18957.75 ft. divided by 3.28=5779.8018 divided by 5280[ mile]=1.0946594 X 60 =65.67 actual miles and actual mph. I have a manual tranny so it is a mechanical lock, [ an auto can slip inflating figures] [ 4.10 X .80 = od final drive=3.28]. Tell me where I'm wrong.
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About the tires; I'd guess you'd have to see them. They don't look low and the and the sidewalls don't get hot at 18 psi. I guess the ranger isn't heavy enough to flex the sidewalls. I will remove the 18 psi from my sig since it bothers so many people, and I am going back to stock size tires for the new gear change. They were the quick gearing fix of the moment, the 4.10's were killing me. Fuel milage in the 70 mph range was 18. The tires helped alot , being about 10% bigger they droped my gearing to about 3.70 allowing me to drive 70 at a more fuel efficient rpm. E-fan gave me another 2 mpg and the underdrive pulley did the same, 2 mpg. My truck might have been a little better on gas than most to begin with. Purely stock, and with a new air filter, I got 23mpg once, but that was all highway100% and never going over 55
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Silverlude, do you have a tach? What rpm are you doing at 98? Mightyedge, the X2 will advance your spark timing, which in itself is a good power producer if not taken too far ; but I am talking, or trying to talk, about better cylinder filling, at lower rpms to create more low end power. Some engines have a ho-hum advance of 18 degrees and a hot corvette motor might have more than 60 degrees of cam advance ( valve opens 60 degrees before piston arrives at top dead center TDC). The more open the intake valve at the start of the intake stroke, the better the cylinder is filled. By the way , where did the squirrel dropping quote come from?
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BOB, I think the problem you'll have is, the stock cam doesn't have enough lift and duration to work any better any more advanced. If you advance it much, your going to be filling too early, closing off the intake side too soon, and end up with a weak, terrible running engine.
If you wanted to do the heads (have you seen stockers? WEAK) and slap a mildly aggressive cam in it, I think it would run ALOT better, but thats alot of money too.
If you wanted to do the heads (have you seen stockers? WEAK) and slap a mildly aggressive cam in it, I think it would run ALOT better, but thats alot of money too.
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Could very well be , but I was thinking I could sacrifice 1000 rpms off the top end ( that I never use ) to get better cylinder filling at lower rpms. I might try it anyway. I need to look into the engine myself, check valve clearances, and see what is possible. Mabey little can be done. And maybe a couple of forged 4 degree offset woodruff keys can turn up enough advance to get it to the factory freak stage.I'll try to find one partially disassembled , to sneak a peek at. I was hoping to find an engine mod that wouldn't be too pricy, for myself and others. Also if you could change your own timing chain and gears, you would have enough skill to do the mod.
Last edited by BOB; 03-13-2006 at 06:05 PM.
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