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Most GA ICE powered a/c still use a wet sump. Unless you are planning aerobatics, a dry sump is mainly a complication you really don't need, along with an air/oil separator.
The LS7 issues relate more with valve guides and block/head castings themselves. The valvetrain itself isn't the issue with LS7s.
I'm (and others here) glad you think so highly of us, though many here (not me) have engine knowledge that has been shown here to far surpass yours.
Yes, like the SOHC concept, it’s EASIER to just do what is already available. I think that everybody understands that, including me.
The wet sumps takes up room on the bottom of the engine that I’d prefer it didn’t. In addition, we probably need a scavenge pump for the turbocharger oil. I can assure that it’s lowest on the list of things that I’d like to do. Wet sumps work, and rarely fail. Things that aren’t on the engine NEVER FAIL !!!
There may be a BSFC advantage with a dry sumps at the 250-325 hp / 3800 RPM +/- 500 RPM value that this engine will run for HOURS every day. All the tuning is maximum benefit to BSFC at cruise power settings.
Maybe somebody would like to talk about SOHCs???? Did you know that both SOHC and DOHC have been done? Heck, I recently checked out a shop here in San Diego that has one set, running on an LS engine.
I think Bruce Crower also built a set (another San Diego company).
The best reason LS engines do well with wet sumps is the windage tray that comes on every one.
Oil frothing by the crank is not an issue at all.
I'm not sure why you feel the need for OHC's. It adds weight and complication, especially since this engine will not be revving high enough to make valvetrain instability an issue.
Even though there are excellent aftermarket rocker arms, pushrods, and roller lifters, even the OEM pieces do well past 6000 RPM for extended periods of time, The LS valvetrain is up to the job for aircraft duty. The oil system, once any extra cooling burdens are addressed is also very suitable.
The best reason LS engines do well with wet sumps is the windage tray that comes on every one.
Oil frothing by the crank is not an issue at all.
That sounds great!
I'm not sure why you feel the need for OHC's. It adds weight and complication, especially since this engine will not be revving high enough to make valvetrain instability an issue.
It’s always odd to me how anybody sees an OHC as “complicated”. They are bone *** simple. There are less parts. Sure, folks use OHCs because they can rev higher, but that’s not a criteria for this design.
Simplicity and less parts.
Even though there are excellent aftermarket rocker arms, pushrods, and roller lifters, even the OEM pieces do well past 6000 RPM for extended periods of time, The LS valvetrain is up to the job for aircraft duty. The oil system, once any extra cooling burdens are addressed is also very suitable.
Again, we aren’t building an engine for “past 6000 RPM”. Maximum RPM is likely 5252.
It’s always odd to me how anybody sees an OHC as “complicated”. They are bone *** simple. There are less parts. Sure, folks use OHCs because they can rev higher, but that’s not a criteria for this design.
Simplicity and less parts.
Again, we aren’t building an engine for “past 6000 RPM”. Maximum RPM is likely 5252.
OHC gets complicated when converting an engine initially without it, to it. That increases the part content.
If 5252 is max RPM, the OEM LS valvetrain will do that all day every day.
"Dead Man builds a OHC LS"
My friend Bruce Crower was DEAD when the first LS engine was assembled !
I did work with Dave Crower introducing my camless actuators with little interest as Crower manufactured camshafts.
I helped my customer, Dave, run a LS engine (turbo) that made 500HP @ 2600 RPM.
This could work well for your needs ?
For a constant load engine, marine, fan boat, airplane you would be be better off with the longest stroke possible and decrease the bore size to limit HP. Torque turns a propellor not HP. Bias your torque curve lower in RPM and you will not need as much gear reduction or engine RPM to make the torque you need to drive the propellor. Mercruiser has DOHC engines that are based off the LS and the big block. The big block is an absolute unit and was available with twin turbos. It will run WOT at maximum rated power as long as you want to pay for the fuel going into it. As for a crank sensor causing issues, simple, add a 2nd one for backup. Jaguar V12s used what amounted to two 6 cylinder ECMs. You could run dual ECMs each running half the engine and still have engine power in the event one failed. Treat the V8 as two 4 cylinders electronically. You could even run the systems off seperate power busses to gain redundancy which is what an airplane engine requires. Personally mechanical timed injection and magnetos ditching the electronics entirely would be my approach along with designing the cylinder heads to use dual spark plugs from the start.
Yes, like the SOHC concept, it’s EASIER to just do what is already available. I think that everybody understands that, including me.
The wet sumps takes up room on the bottom of the engine that I’d prefer it didn’t. In addition, we probably need a scavenge pump for the turbocharger oil. I can assure that it’s lowest on the list of things that I’d like to do. Wet sumps work, and rarely fail. Things that aren’t on the engine NEVER FAIL !!!
There may be a BSFC advantage with a dry sumps at the 250-325 hp / 3800 RPM +/- 500 RPM value that this engine will run for HOURS every day. All the tuning is maximum benefit to BSFC at cruise power settings.
Maybe somebody would like to talk about SOHCs???? Did you know that both SOHC and DOHC have been done? Heck, I recently checked out a shop here in San Diego that has one set, running on an LS engine.
I think Bruce Crower also built a set (another San Diego company).
Or, we can keep comparing our d*cks.
As interesting as the idea is to me, your not going to get a lot of conversation here…on LS1Tech…about a SOHC LS simply because it doesn’t exist….so there’s nothing to talk about. NOW…I’m more than interested in you telling us how your going to do this and I’d love to see it come to fruition. As mentioned by Fast355, mercuiser put a set of DOHC heads on an LS and marketed it, but it’s not SOHC, so that’s off topic also.
Without a doubt, the guy here you want to talk to is Lance…IGN-1A. He’s the smartest guy here, with many, many patents on designs he’s built. If anyone here could pull this off, Lance could, as clean sheet design is his specialty. IIRC the Diesel engine design came from someone in his family. He’s literally a genius.
The discussion here is great, and your in the correct sub-forum…I just have nothing to offer as OHC tech is simply not in my wheelhouse. I’ll do my best to keep the roasting away, and keep everybody’s pants zipped up, so no measuring is involved.
I do have a thought about this endeavor that I’m curious about, which is timing belt, vs timing chain. The chain requires oiling, and must be sealed. The belt can be out front…or out back I suppose. Which do you prefer, chain or belt? They both have reliability issues in their own way.
As interesting as the idea is to me, your not going to get a lot of conversation here…on LS1Tech…about a SOHC LS simply because it doesn’t exist….so there’s nothing to talk about. NOW…I’m more than interested in you telling us how your going to do this and I’d love to see it come to fruition. As mentioned by Fast355, mercuiser put a set of DOHC heads on an LS and marketed it, but it’s not SOHC, so that’s off topic also.
Yes, I have found a number of OHC projects. Because we have to build the cylinder heads, and modify them from the LS design to handle two plugs per cylinder (it’s an FAA requirement), there’s always “feature creep” to want to do something else “that makes sense”.
Truly, the entire SOHC concept is PARTS REDUCTION… parts that aren’t there cost nothing, and never break.
So, I don’t really want lifters, pushrods and rocker arms. It’s a legacy of antiques. It’s only used in things like NASCAR, because the rules require it.
Yes, I’m fully aware that an LS-3 type engine would probably get the job done, even with pushrods.
Without a doubt, the guy here you want to talk to is Lance…IGN-1A. He’s the smartest guy here, with many, many patents on designs he’s built. If anyone here could pull this off, Lance could, as clean sheet design is his specialty. IIRC the Diesel engine design came from someone in his family. He’s literally a genius.
That sounds great.
The discussion here is great, and your in the correct sub-forum…I just have nothing to offer as OHC tech is simply not in my wheelhouse. I’ll do my best to keep the roasting away, and keep everybody’s pants zipped up, so no measuring is involved.
I do have a thought about this endeavor that I’m curious about, which is timing belt, vs timing chain. The chain requires oiling, and must be sealed. The belt can be out front…or out back I suppose. Which do you prefer, chain or belt? They both have reliability issues in their own way.
My thought all along has been a gear driven OHC. Obviously, the camshaft drive CANNOT FAIL. If we used a belt drive, it would require some periodic maintenance. That’s not the end of the world, but I would prefer something without maintenance… like gears.
Another inspiration, besides the LS series of engines, is the Toyota FV4000-2TC engine that was FAA certified in 1995. I believe is has DOHCs and chain drive, because that’s what Toyota designed for their cars.
For a constant load engine, marine, fan boat, airplane you would be be better off with the longest stroke possible and decrease the bore size to limit HP. Torque turns a propellor not HP. Bias your torque curve lower in RPM and you will not need as much gear reduction or engine RPM to make the torque you need to drive the propellor.
Toyota got this done with a 3.25” stroke, in an 8 cylinder engine that produced 360 hp at 5200 RPM. I plan to test 3.25” through 4” stroke, with the goal of 0.38 BSFC.
We are limited to about 2700 RPM on the (geared) output shaft, but I’d like to be in the 1600-1800 RPM range for the 250-325 hp cruise power setting.
Mercruiser has DOHC engines that are based off the LS and the big block. The big block is an absolute unit and was available with twin turbos. It will run WOT at maximum rated power as long as you want to pay for the fuel going into it.
We are definitely NOT going to use a Big Block. There is an FAA certified one, Orenda, that weighed a ton (well, not quite a ton), and was rated for 600 hp. Too much power, too much weight.
As for a crank sensor causing issues, simple, add a 2nd one for backup. Jaguar V12s used what amounted to two 6 cylinder ECMs. You could run dual ECMs each running half the engine and still have engine power in the event one failed. Treat the V8 as two 4 cylinders electronically. You could even run the systems off seperate power busses to gain redundancy which is what an airplane engine requires. Personally mechanical timed injection and magnetos ditching the electronics entirely would be my approach along with designing the cylinder heads to use dual spark plugs from the start.
Yes, we intend to use two reluctor wheels, and three Hall effect sensors per wheel. Two of the sensors have to agree. One sensor can fail.
Each reluctor wheel runs an independent ECU. Each ECU runs all 8 cylinders (remember, two spark plugs per cylinder). The coils use “wasted spark”, so that any coil failure will stop firing two spark plugs from two different cylinders, yet all 8 cylinder have at least ONE spark plug firing. No loss of power.
There are dual fuel injection systems, too, each operated by its own ECU.
Unfortunately, none of this addresses the SOHC concept.
Toyota got this done with a 3.25” stroke, in an 8 cylinder engine that produced 360 hp at 5200 RPM. I plan to test 3.25” through 4” stroke, with the goal of 0.38 BSFC.
We are limited to about 2700 RPM on the (geared) output shaft, but I’d like to be in the 1600-1800 RPM range for the 250-325 hp cruise power setting.
We are definitely NOT going to use a Big Block. There is an FAA certified one, Orenda, that weighed a ton (well, not quite a ton), and was rated for 600 hp. Too much power, too much weight.
Yes, we intend to use two reluctor wheels, and three Hall effect sensors per wheel. Two of the sensors have to agree. One sensor can fail.
Each reluctor wheel runs an independent ECU. Each ECU runs all 8 cylinders (remember, two spark plugs per cylinder). The coils use “wasted spark”, so that any coil failure will stop firing two spark plugs from two different cylinders, yet all 8 cylinder have at least ONE spark plug firing. No loss of power.
There are dual fuel injection systems, too, each operated by its own ECU.
Unfortunately, none of this addresses the SOHC concept.
I would look at the 2008+ Dodge 4.7L cylinder head as an idea for the SOHC head design. It was 2 valves per cylinder, flowed exceptionally well and had 2 spark plugs per cylinder. Not saying it is a perfect head for the application but worth investigating for the layout of both ports and chambers. The chamber is designed similarly to the Hemi head except twisted 45*.
I actually wonder what your main focus is here.
Is it to develop the most durable aircraft engine you can conceive of, or just see an OHC engine come to fruition? Because one is not the other.
At the RPM scale you mention (about 5300 RPM) The stock LS mechanicals, even turbocharged to 500+ HP, will do the job without doubt, provided fluid temps are kept in check.
Where I do have doubt is your idea for all-gear OHC drive. The gear lash is going to be all over the map with the thermal expansion an all-aluminum long block will have. The gears will not expand in lock step with the block and heads due to different thermal coefficients.
And we already know the pitfalls of chain and belt drives.
I DO admire your ideas for electrical component redundancy in case something goes electrically wrong.
1930 Aircraft engine with two pistons on ONE Conn Rod.
The two pistons were on each end of the piston pin.
Thus an UNDER HEAD "centered" camshaft was required.
There are no rocker arms, direct action on the lifters, and one lobe for two valves, opposite each other.
Norman A. Nist (inventor)
1930 Aircraft engine with two pistons on ONE Conn Rod.
The two pistons were on each end of the piston pin.
Thus an UNDER HEAD "centered" camshaft was required.
There are no rocker arms, direct action on the lifters, and one lobe for two valves, opposite each other.
Norman A. Nist (inventor)
You never cease to amaze me Lance. Your gramps was a smart guy.
Tony Williams, this is why I mentioned you should talk to Lance…
Haven’t done much this week. Flew to Salt Lake City, and went skiing. Will return next week.
You’ll note picture below with cowling intended to house an LS inspired engine. Currently, there is a turbocharged, intercooled, 520 cubic inch, 6 cylinder, horizontally opposed, AIR COOLED antique, with constant flow fuel injection and fixed timing magnetos, not much different from that used in WW2 warbirds.
That engine produces 335 hp at 41 inches Hg MAP, and 2700 RPM, 35 GPH, with about 230 hp in cruise using 31-33 MAP, 2400 RPM, 15 GPH fuel flow (Lean of Peak Exhaust Gas Temperature) or 18-22 GPH while Rich Of Peak EGT.
The propeller is direct driven (no gear box).
Last edited by TonyWilliams; Jan 17, 2025 at 11:28 AM.
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