Worst GM engine ever made?
Postmaster
Joined: Feb 2003
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From: Las Vegas
Thanks,
It's difficult to compare power output between the two because of variables but there are a couple of manufacturers that make EXACT heads in each material.
The results may surprise many. In a DART test the Iron heads made a few more ponies due to the EXACT reasons you stated............heat retention in the chamber. BUT!!!!(we all knew there'd be a butt er I mean but.) the 60-80 pound weight savings, the ease of machining/porting and the repairability all make the aluminum head the choice when building a motor.
It's difficult to compare power output between the two because of variables but there are a couple of manufacturers that make EXACT heads in each material.
The results may surprise many. In a DART test the Iron heads made a few more ponies due to the EXACT reasons you stated............heat retention in the chamber. BUT!!!!(we all knew there'd be a butt er I mean but.) the 60-80 pound weight savings, the ease of machining/porting and the repairability all make the aluminum head the choice when building a motor.
Hotshot
Joined: Feb 2004
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From: Marengo, Iowa
There is such a long list of legendary motors that had aluminum heads... All manufacturers have used them, with varying success, but certainly not bad enough results to say it is a failure, by any means. Many of the current production vehicles are using aluminum due to the weight reduction if nothing more, and the aftermarket is thriving on them.
Hotshot
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From: iowa
you forgot one advantage to the alum heads, the detonation resistance is a lot higher in an alum headed engine, most people agree you can run a full point of compression higher with alum heads on the same fuel, and same combustion chamber design which makes up for the loss of HP do to the heat loss.
Yeah I know about the exact heads in iron, vs alum Blue thunder is a prime example of that with the SCJ ford heads bu tthe iron heads weigh 110lbs each. vs the 41lbs each for the alum version.
Yeah I know about the exact heads in iron, vs alum Blue thunder is a prime example of that with the SCJ ford heads bu tthe iron heads weigh 110lbs each. vs the 41lbs each for the alum version.
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From: Las Vegas
Originally Posted by fellro86
Just to let you know, they did install the olds style motor in trucks for a few years, before they made the 6.2. They started putting them in as far back as 78, but according to Autozone's website, only about 5% had them. I have worked on some, but it has been a while. The 6.2 came out in 82. Ford didn't start with the 6.9 until 83
Thanks, good info............but in order to compare the 6.9/7.3 to the GM diesels you'd have to compare the 6.2 vs the 6.9 due to the years available.
From what I've heard/read, the 6.2 vs 6.9 N/A there wasn't that much of a difference.
They were both mutts.
Just recently, my bubble was burst by Cletus12 and Logical Heretic when I learned the 6.9 was a converted gas motor!!!!
Last edited by DOHCmarauder; Aug 20, 2005 at 01:23 AM.
Postmaster
Joined: Feb 2003
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From: Las Vegas
Originally Posted by monsterbaby
you forgot one advantage to the alum heads, the detonation resistance is a lot higher in an alum headed engine, most people agree you can run a full point of compression higher with alum heads on the same fuel, and same combustion chamber design which makes up for the loss of HP do to the heat loss.
Yeah I know about the exact heads in iron, vs alum Blue thunder is a prime example of that with the SCJ ford heads bu tthe iron heads weigh 110lbs each. vs the 41lbs each for the alum version.
Yeah I know about the exact heads in iron, vs alum Blue thunder is a prime example of that with the SCJ ford heads bu tthe iron heads weigh 110lbs each. vs the 41lbs each for the alum version.
100% agreed..........I've had to R&R my BBC heads in my boat a few times.....Thank goodness there has been no ill effects from the turn and cough test................so far!!
Hotshot
Joined: Feb 2004
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From: Marengo, Iowa
If the 6.9 is a converted gas motor, it is an awful big one... Mine runs just fine, will run circles around my sister's 6.5 N/A... the 7.3 IDI is the update of the 6.9, uses the same block and all, just "upgraded" a bit... It is built by IH/Navistar, who hasn't been in the gassers since the 70's. I'd like to see the info that shows it was based off a gasser... they sure did their homework if they did base it on a gas motor. The 5.7 and 6.2/6.5 motors do not have oil coolers, nor are built nearly as heavy duty as the 6.9/7.3. IH even installs the 6.8/7.3 in medium duty trucks, GM didn't do such with their light duty diesels...
Postmaster
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From: Las Vegas
Hold on, I'll look by searching Logical Heretic's posts........he found the link, I believe.
Now I did find how the newer 7.3 powerstroke was NOT a gas motor and isn't related to the 6.9/7.3.
I'll be back.
Now I did find how the newer 7.3 powerstroke was NOT a gas motor and isn't related to the 6.9/7.3.
I'll be back.
Post Fiend
Joined: Feb 2004
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From: Damascus-Boring, Ore
Yep- unfortunately GM did put a few of those 350 chuggers in 1/2T pickups. Oy vey- talk about the dark ages in the Chebbie biz. GM's biggest mistake was putting those motors primarily in Oldmobiles and Cadillacs. Some disgruntled owners might get a lawyer- but a good percentage of this upscale crowd probably were lawyers.
The Vega was a special piece too. Mine was on it's third engine at 26K miles when sanity prevailed and I dropped-kicked it in favor of a Jeep CJ5. The Vega had actually started to rust through by then- a two yr. old west coast car! It's a bloody miracle imports have only 30% of the market.
The Vega was a special piece too. Mine was on it's third engine at 26K miles when sanity prevailed and I dropped-kicked it in favor of a Jeep CJ5. The Vega had actually started to rust through by then- a two yr. old west coast car! It's a bloody miracle imports have only 30% of the market.
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Postmaster
Joined: Feb 2003
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From: Las Vegas
Originally Posted by fellro86
If the 6.9 is a converted gas motor, it is an awful big one... Mine runs just fine, will run circles around my sister's 6.5 N/A... the 7.3 IDI is the update of the 6.9, uses the same block and all, just "upgraded" a bit... It is built by IH/Navistar, who hasn't been in the gassers since the 70's. I'd like to see the info that shows it was based off a gasser... they sure did their homework if they did base it on a gas motor. The 5.7 and 6.2/6.5 motors do not have oil coolers, nor are built nearly as heavy duty as the 6.9/7.3. IH even installs the 6.8/7.3 in medium duty trucks, GM didn't do such with their light duty diesels...
It was Cleatus who posted this link originally;
http://www.oramagazine.com/archive/n...oldiron_01.asp
Hotshot
Joined: Feb 2004
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From: Marengo, Iowa
Originally Posted by DOHCmarauder
Hold on, I'll look by searching Logical Heretic's posts........he found the link, I believe.
Now I did find how the newer 7.3 powerstroke was NOT a gas motor and isn't related to the 6.9/7.3.
I'll be back.
Now I did find how the newer 7.3 powerstroke was NOT a gas motor and isn't related to the 6.9/7.3.
I'll be back.
The 7.3 powerstroke isn't really related very well, nothing really trades, I would likely believe it was drafted from the start as a diesel.
Postmaster
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From: Las Vegas
It just sorta bugged me with all the razzing that I/we have done toward the GM debacle.
To be honest, I don't remember what the problems were with the GM 5.7's.....I'm almost inclined to remember the internals were fairly decent (that Olds block had some thick webbing, 4 bolt mains and a lot of head bolts) I seem to remember a lot of pump/electronic/no power problems.
PB????
To be honest, I don't remember what the problems were with the GM 5.7's.....I'm almost inclined to remember the internals were fairly decent (that Olds block had some thick webbing, 4 bolt mains and a lot of head bolts) I seem to remember a lot of pump/electronic/no power problems.
PB????
Hotshot
Joined: Feb 2004
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From: Marengo, Iowa
the one big thing I noticed is the lack of return lines, what goes in is all there is, no excess, no way to recirculate, or clear out.... they weren't any too powerful and the EGR valve made things worse. Worst idea I ever saw was the egr on a diesel, recirculate the soot into the engine... they carried that over to the 1/2 ton 6.2's as well.
Hotshot
Joined: Dec 2003
Posts: 18,423
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From: iowa
the only mechanical problem I ever remember really on them was blowing head gaskets time to time (it wasn't a big problem but did happen more regularely than on a gas engine) the lack of power, smoked all the time. and lack of maint. cause the oil would get saturated with soot, and wear the bearings out fast.
Oh and on the strength side they had forged steel cranks too. plus the good "pink" rods
Oh and on the strength side they had forged steel cranks too. plus the good "pink" rods
