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Re: Gas Prices- At What Point Do You Park It? [message #116512 is a reply to message #116338]

Fri, 25 February 2011 13:36

Craig Lechowicz

Messages: 541
Registered: October 2006
Location: Waterford, MI

Karma:

Senior Member

Gord,
Didn't mean to imply that I was against change, but remember it wants to be change for the better. Not unlike suspensions, I'm no engine expert either, but between a little racing long ago, several years as a mechanic (still master certified) and a long time with a big 3 automaker, a little rubs off. Matt Colie is probably the most knowledgable person I know as far as dyno results, as he was involved in a lot of development programs in his career.

Rob got part of good comment in there about not confusing hp with torque. But on a more fundamental level, at the scale of a GMC, specific output (horsepower per litre) is almost always opposed to fuel economy (at the engine level called BSFC, brake specific fuel consumption, often measured in lbs. per hp/hour). The reason, as you allude is friction. You get lots of hp per litre by spinning smaller engines faster, and friction losses go up with the cube of the speed. Additionally, higher rpms require stiffer valve springs, which drives more friction. So, don't underestimate the ability of a big slow turning engine to generate good fuel economy. Cars can get good fuel economy with small engines run at high speeds as they are not required to run there very often, and at cruise, most of those engines are running 2,000 rpm or less, not much different than the GMC. The difference is, if you put the same engine in the GMC it would have to turn a lot faster to move it, and some of those small engine fuel economy improvements are lost. To make a long story short, there is a reason big over the road trucks typically are over 10 litres, and sometimes way over that.

Couple of trivia bits for you on fuel injection. As cars and trucks at GM moved from carbs to fuel injection the conventional wisdom was that port systems helped torque a lot (maybe 40 or 50 ft. lb on a midsize V8), and didn't do as much for either hp or fuel economy. (maybe 10 hp and 3%) Their biggest gain was in emissions control, which was and is a huge part of engine design. There may be some incremental improvements since then, but it's not night and day. Carburetors don't do well in transient conditions, cold starting and on coast where injection can be controlled much more precisely, but at steady speeds and loads, if tuned properly can be surprisingly good.

My next door neighbor retired from GM Powertrain, and he tells the story of the "Cross Fire Injection" which was a sort of dual TBI system used for only one year on 1982 Corvettes because a certain executive who's son is now the president of GM North America was in love with it. Powertrain struggled to get the expected hp with it on the dyno despite a lot of development. Just for yucks one day, they bolted what he described as a beat up 5+ year old Holley and aluminum manifold on it, and instantly got 40hp more power. Admittedly not the world's best fuel injection system, but some credit to archaic carburetor technology as well.

No question you can spend $20 or $30k on an engine swap and pick up 20% if you don't mind living with a development project and don't mind driving it 300,000 miles to achieve some payback.

Craig Lechowicz
'77 Kingsley, Waterford, MI

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[Message index]

		Gas Prices- At What Point Do You Park It? By: philipswanson on Thu, 24 February 2011 09:16
		Re: Gas Prices- At What Point Do You Park It? By: Dennis S on Thu, 24 February 2011 09:26
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Thu, 24 February 2011 09:45
		Re: Gas Prices- At What Point Do You Park It? By: gordh1 on Thu, 24 February 2011 10:03
		Re: Gas Prices- At What Point Do You Park It? By: jhb1 on Thu, 24 February 2011 10:19
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Thu, 24 February 2011 17:46
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Craig Lechowicz on Thu, 24 February 2011 18:28
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gordh1 on Thu, 24 February 2011 18:31
		Re: Gas Prices- At What Point Do You Park It? By: cbwoodsr on Fri, 25 February 2011 08:39
		Re: Gas Prices- At What Point Do You Park It? By: Jim Galbavy on Fri, 25 February 2011 15:13
		Re: Gas Prices- At What Point Do You Park It? By: Luvn737s on Thu, 24 February 2011 10:18
		Re: Gas Prices- At What Point Do You Park It? By: Larry C on Thu, 24 February 2011 11:06
		Re: Gas Prices- At What Point Do You Park It? By: philipswanson on Thu, 24 February 2011 11:27
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Thu, 24 February 2011 11:48
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Fri, 25 February 2011 14:46
		Re: Gas Prices- At What Point Do You Park It? By: mike miller on Thu, 24 February 2011 11:51
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Thu, 24 February 2011 11:58
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Thu, 24 February 2011 12:30
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Keith V on Thu, 24 February 2011 12:49
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: philipswanson on Wed, 02 March 2011 12:15
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: philipswanson on Wed, 02 March 2011 12:21
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Thu, 24 February 2011 18:12
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Thu, 24 February 2011 23:15
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 01:16
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Fri, 25 February 2011 08:53
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: ejuk8em on Thu, 24 February 2011 12:15
		Re: Gas Prices- At What Point Do You Park It? By: lqqkatjon on Thu, 24 February 2011 14:09
		Re: Gas Prices- At What Point Do You Park It? By: carguy on Thu, 24 February 2011 15:41
		Re: Gas Prices- At What Point Do You Park It? By: cbwoodsr on Thu, 24 February 2011 15:43
		Re: Gas Prices- At What Point Do You Park It? By: gordh1 on Thu, 24 February 2011 17:01
		Re: Gas Prices- At What Point Do You Park It? By: Carl S. on Thu, 24 February 2011 19:54
		Re: Gas Prices- At What Point Do You Park It? By: rwbmitiopt@comcast.net on Thu, 24 February 2011 19:56
		Re: Gas Prices- At What Point Do You Park It? By: Carl S. on Thu, 24 February 2011 20:21
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Tim Conway on Thu, 24 February 2011 21:51
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: hnielsen2 on Thu, 24 February 2011 22:13
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Tim Conway on Thu, 24 February 2011 22:22
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Mike Teets on Thu, 24 February 2011 18:10
		Re: Gas Prices- At What Point Do You Park It? By: John Ruff on Thu, 24 February 2011 18:49
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Tim Conway on Thu, 24 February 2011 19:00
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Carl S. on Thu, 24 February 2011 19:46
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Tim Conway on Thu, 24 February 2011 21:56
		Re: Gas Prices- At What Point Do You Park It? By: Carl S. on Thu, 24 February 2011 20:19
		Re: Gas Prices- At What Point Do You Park It? By: gordh1 on Thu, 24 February 2011 21:00
		Re: Gas Prices- At What Point Do You Park It? By: Craig Lechowicz on Thu, 24 February 2011 23:09
		Re: Gas Prices- At What Point Do You Park It? By: gordh1 on Fri, 25 February 2011 10:59
		Re: Gas Prices- At What Point Do You Park It? By: WD0AFQ on Fri, 25 February 2011 11:48
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 12:52
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Bob de Kruyff on Wed, 02 March 2011 15:37
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 13:19
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gordh1 on Fri, 25 February 2011 14:04
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 15:14
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 15:27
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gordh1 on Fri, 25 February 2011 15:45
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 16:17
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 17:43
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 17:59
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 18:04
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 18:19
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 18:33
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 19:10
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jhb1 on Fri, 25 February 2011 19:44
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 19:55
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Byron Songer on Fri, 25 February 2011 22:24
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: UziYaH on Fri, 25 February 2011 23:24
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Little Yimmy on Sat, 26 February 2011 08:16
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: mike miller on Fri, 25 February 2011 20:38
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: WayneB on Sat, 26 February 2011 10:43
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Dennis S on Fri, 25 February 2011 15:34
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gordh1 on Fri, 25 February 2011 15:48
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Dennis S on Fri, 25 February 2011 15:59
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Wed, 02 March 2011 17:55
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: jimk on Thu, 24 February 2011 23:13
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: shawnee on Fri, 25 February 2011 07:46
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Wed, 02 March 2011 17:58
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Steven Ferguson on Sat, 05 March 2011 09:04
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Sat, 05 March 2011 15:05
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Sat, 05 March 2011 17:08
		Re: Gas Prices- At What Point Do You Park It? By: Craig Lechowicz on Fri, 25 February 2011 13:36
		Re: Gas Prices- At What Point Do You Park It? By: gordh1 on Fri, 25 February 2011 14:26
		Re: Gas Prices- At What Point Do You Park It? By: Larry on Fri, 25 February 2011 16:08
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Fri, 25 February 2011 16:16
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: UziYaH on Fri, 25 February 2011 22:34
		Re: Gas Prices- At What Point Do You Park It? By: mschultz on Sat, 26 February 2011 08:52
		Re: Gas Prices- At What Point Do You Park It? By: Larry C on Wed, 02 March 2011 18:06
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: gmcrv1 on Thu, 03 March 2011 09:28
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: UziYaH on Thu, 03 March 2011 15:27
		Re: Gas Prices- At What Point Do You Park It? By: Hardie Johnson on Sat, 26 February 2011 10:27
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: UziYaH on Sat, 26 February 2011 11:36
		Re: Gas Prices- At What Point Do You Park It? By: Larry C on Sat, 05 March 2011 08:54
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: comcast on Sat, 05 March 2011 08:59
		Re: Gas Prices- At What Point Do You Park It? By: Bob de Kruyff on Wed, 02 March 2011 12:52
		Re: Gas Prices- At What Point Do You Park It? By: philipswanson on Mon, 07 March 2011 21:13
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Mr ERFisher on Mon, 07 March 2011 21:48
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Tue, 08 March 2011 07:27
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Mr ERFisher on Tue, 08 March 2011 07:42
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Ray Erspamer on Tue, 08 March 2011 08:04
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Tue, 08 March 2011 08:34
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: midlf on Sat, 12 March 2011 16:43
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Tue, 08 March 2011 08:33
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: philipswanson on Tue, 08 March 2011 08:47
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: James Hupy on Tue, 08 March 2011 10:58
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Bob de Kruyff on Tue, 08 March 2011 11:10
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Tim Conway on Tue, 08 March 2011 11:18
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Carl S. on Tue, 08 March 2011 11:34
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Dennis S on Tue, 08 March 2011 11:30
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Ray Erspamer on Tue, 08 March 2011 12:28
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: hal kading on Tue, 08 March 2011 14:34
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry C on Tue, 08 March 2011 15:43
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Ken Henderson on Tue, 08 March 2011 20:37
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: Larry on Sat, 12 March 2011 18:52
		Re: Gas Prices- At What Point Do You Park It? By: PETEinLongBeach on Tue, 08 March 2011 01:00
		Re: [GMCnet] Gas Prices- At What Point Do You Park It? By: USAussie on Tue, 08 March 2011 03:24
		Re: Gas Prices- At What Point Do You Park It? By: Keith V on Tue, 08 March 2011 07:39
		Re: Gas Prices- At What Point Do You Park It? By: PETEinLongBeach on Wed, 09 March 2011 06:22
		Re: Gas Prices- At What Point Do You Park It? By: cbwoodsr on Tue, 08 March 2011 08:07

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