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PMD

Well-Known Member
Joined
Apr 11, 2015
Messages
242
Location
Martensville SK
You’ve gotta admit it was a real POS.
If you had a good one, it was a not-bad engine at all. Once the GM head bolts were replaced with a set of studs, it was then a pretty decent engine. I only had one, never had any grief from it but didn't have it more than a year. Mine was in a C10, and everyone said they were so gutless...so I did a little matchup with my buddy's Wagoneer 360 CID gasser - and the "gutless" C10 walked away - not ran, but DID walk. I have a 6.5 K15 now as a chore truck, but compared with my wife's Q7, it really is gutless by today's standards. BUT: the real advantage is that I can throw just about any hydrocarbon into the fuel tank and it will run just fine.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,678
Location
Memphis, TN
They were pretty bad engines as engines go. My experience was all friends cars. ‘80 Cutlass, replaced with gas engine, a Olds wagon, last seen with original engine, and two Caddies 79 and 80, each had two engines under warranty before being converted to gas. I did help one of the Caddies throw a rod in a small part. These were all only about five year old cars at the time. I do know someone with another wagon but I never have seen it. Right now it has a broken head bolt. Probably one of the last around. He has a 6.5 truck too.
Gas wise, a friends mom had a gas olds wagon with a 403 and she had it regeared to pull a trailer. Magic sleeper with wood sides. Even she would race a Trans Am for a giggle.
 

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
413
Location
San Rafael, California
I had a C10 and a Cutlass with the diesels. The C10 would not pull itself and the airstream out of Monterey so it was traded in on a 3/4T Suburban. Bought the cutlass used as it was mint but had the diesel for $500.00. Gave it away a week later as it was a dog.
 

hangarrat101

Member
Joined
Aug 4, 2010
Messages
22
Location
Kent, South-East England
I haven't read each post exhaustively but I haven't seen Wilksch mentioned. 125hp and the factory quote 290lbs wet installed weight with a C/s prop. This is a ground-up aero engine. 2-stroke inverted 3 cyl with piston-ported inlet and poppet exhaust valves. Everything mechanical on this engine, there are no electronics or FADEC. I'm not sure what the current status is or if you can currently buy them but there are a few of them flying in the UK in RVs and such. There's also been one flying in a Pietenpol and one in a Thorpe 211. They had a 165hp 4-cyl which came in at just under 350lb too, although I'm not sure if that ever made it into production. Both engines are direct drive.
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,152
Location
Saline Michigan
No one is talking Gemini. Opposed piston two-stroke. Wish they would go forward with the 200 hp.
 

Grelly

Well-Known Member
Joined
Aug 27, 2010
Messages
256
Location
Surrey, UK
There are others too in the opposed piston diesel arena. Mostly with no updates for years. Dair, and Weslake for a start. I have been particularly disappointed that Superior Airparts haven't made more progress with the Gemini.
 

Geraldc

Well-Known Member
Joined
Nov 12, 2011
Messages
375
Location
nz
Another opposed piston diesel is Achates Power who Cummins are working with.
 

jsharp

Member
Joined
Feb 28, 2019
Messages
7
Location
Augusta, GA / USA
Don't you think it's more a market thing than a technological thing ? I.e, boating (like aviation...) is small numbers and high end, so everything is expensive (like aviation...)
There is obviously engineering in these engines, but not 2-3x more?
Multiple boat owner and former airplane owner/pilot since 1988 (Mooney M20 with an 0-360 A1A). The 5.7l (350 ci) Mercruiser inboard engine starts out as a factory block. The cam is not the auto version. The Mercruiser cam makes peak power much closer to WOT. The exhaust valves were chrome plated in the older days and now stainless exhaust valves are more common. The pistons on many of the Mercruisers were not auto spec. Head gaskets were not auto but marine for corrosion resistance. The carburetor for the earlier engines was a marine rochester unit. Both the starter and alternator have special spark shielding to prevent ignition of gasses in the bilge (didn't always prevent an explosion). The oil pan on the 5.7 is larger with more oil capacity than the auto version. There are other differences that mainly take corrosion and water operations into consideration. Whereas the auto versions of the engine are designed to perform well at 2500rpm, the marine version like its aircraft cousins, are designed to run all day long at @ 80% of WOT and components bearings etc, need to support those loads and run times. All the special exhaust manifolds and other supporting systems like cooling heat ex-changer's if you are using fresh water cooling and not direct sea water or fresh water, can get pretty expensive as well.
A freshly rebuilt mercruiser 5.7 long block from a reputable shop (not the very best reputation shops but still rebuild with new parts and to spec) can be had for less than $1000 in the southeastern US. There are so many of these engines that have been in service and are still in service.
There are many differences with the stock auto engines and the marine variants. Whether this warrants the extra cost, I believe it does as it specifically supports marine applications and environment, and although there are many marine engines that have been manufactured over the last decades, those custom components such as the cam shaft etc, are made in staggeringly low quantities compared to their automotive counterparts. This drives up per unit costs significantly. Also the designer/manufacturer has to recoup development and tooling costs, extra personnel to support a marine division, and other costs that drive up the costs significantly. These costs never seem to ever decline even though the designs have paid for themselves many times (my humble opinion only). Its like a new tax that politicians say will only last for 20 years and yet 50 years later we are still paying that same tax....
When a boat engine breaks down on the river, lake or ocean, you call seatow. When an aircraft engine breaks down at 9000' there is no seatow, just that lump in your throat when it happens, and it happens to many of us, and thank god I had great training and was in a great aircraft. Even though factory aircraft engines are 30k plus, and have just about the same amount of metal as a 3k car engine, they are vastly different in the areas of safety margin utilizing time proven manufacturing techniques such as less constrictive tolerances, limited complexity and moving parts, more torque at lower rpm's, etc...
Safety is the most important operating consideration for an aircraft engine (my humble opinion again). I do believe however that great strides have been made in some auto engine manufactures design, quality, and durability. I also believe that many of these engines could be candidates for very safe aircraft engines. Problems with each engine design, and each aircraft you want to put one in, are challenges for sure but we are a problem solving community, that more than appreciates a good challenge. Were would aviation be today without that spirit of conquest that is so innate and prevalent with experimental aircraft designers and builders.
With great respect... Joe
 

Niels

Well-Known Member
Joined
Aug 15, 2019
Messages
61
With an engine like that, are the cranks far enough apart that you could mount intermeshing props with one on either crank?
25 years ago I was trying to interest companies in something like that.
All declined and quite a lot went bankrupt later anyway without my help.
To keep the two cranks in step I dreamt of two bevel-gears and a carbon shaft.
Torsional vibration calculations anyone?
The new possibility is to omit the gears and use modern electric motors as desribed on an electric thread heretwo months ago




https://emrax.com/wp-content/uploads/2020/03/manual_for_emrax_motors_version_5.4.pdf

For inspiration please look at some very old stuf



Junkers for everything
 
Last edited:

AdrianS

Well-Known Member
Joined
Jul 5, 2014
Messages
562
Location
Australia
Multiple boat owner and former airplane owner/pilot since 1988 (Mooney M20 with an 0-360 A1A). The 5.7l (350 ci) Mercruiser inboard engine starts out as a factory block. The cam is not the auto version. The Mercruiser cam makes peak power much closer to WOT. The exhaust valves were chrome plated in the older days and now stainless exhaust valves are more common. The pistons on many of the Mercruisers were not auto spec. Head gaskets were not auto but marine for corrosion resistance. The carburetor for the earlier engines was a marine rochester unit. Both the starter and alternator have special spark shielding to prevent ignition of gasses in the bilge (didn't always prevent an explosion). The oil pan on the 5.7 is larger with more oil capacity than the auto version. There are other differences that mainly take corrosion and water operations into consideration. Whereas the auto versions of the engine are designed to perform well at 2500rpm, the marine version like its aircraft cousins, are designed to run all day long at @ 80% of WOT and components bearings etc, need to support those loads and run times. All the special exhaust manifolds and other supporting systems like cooling heat ex-changer's if you are using fresh water cooling and not direct sea water or fresh water, can get pretty expensive as well.
A freshly rebuilt mercruiser 5.7 long block from a reputable shop (not the very best reputation shops but still rebuild with new parts and to spec) can be had for less than $1000 in the southeastern US. There are so many of these engines that have been in service and are still in service.
There are many differences with the stock auto engines and the marine variants. Whether this warrants the extra cost, I believe it does as it specifically supports marine applications and environment, and although there are many marine engines that have been manufactured over the last decades, those custom components such as the cam shaft etc, are made in staggeringly low quantities compared to their automotive counterparts. This drives up per unit costs significantly. Also the designer/manufacturer has to recoup development and tooling costs, extra personnel to support a marine division, and other costs that drive up the costs significantly. These costs never seem to ever decline even though the designs have paid for themselves many times (my humble opinion only). Its like a new tax that politicians say will only last for 20 years and yet 50 years later we are still paying that same tax....
When a boat engine breaks down on the river, lake or ocean, you call seatow. When an aircraft engine breaks down at 9000' there is no seatow, just that lump in your throat when it happens, and it happens to many of us, and thank god I had great training and was in a great aircraft. Even though factory aircraft engines are 30k plus, and have just about the same amount of metal as a 3k car engine, they are vastly different in the areas of safety margin utilizing time proven manufacturing techniques such as less constrictive tolerances, limited complexity and moving parts, more torque at lower rpm's, etc...
Safety is the most important operating consideration for an aircraft engine (my humble opinion again). I do believe however that great strides have been made in some auto engine manufactures design, quality, and durability. I also believe that many of these engines could be candidates for very safe aircraft engines. Problems with each engine design, and each aircraft you want to put one in, are challenges for sure but we are a problem solving community, that more than appreciates a good challenge. Were would aviation be today without that spirit of conquest that is so innate and prevalent with experimental aircraft designers and builders.
With great respect... Joe
As far as I know, Yanmar marine diesels take a similar approach, but starting with Toyota engines.
 
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