REVERSING an LS1
09-30-2014, 11:49 AM
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REVERSING an LS1 Here's one that i'll bet doesn't get asked every day on this forum.
I'm wondering exactly what would have to be done to REVERSE the operational direction of an LS engine... We will say an LS1 from a 98-02 camaro simply for the sake of argument and to put a face to the name.
THERE ARE practical applications to this, and i am asking for a specific reason, namely research for a potential project. This is step one of what will be an incredibly expensive undertaking, that will involve engineers, hours of cad development etc. hopefully for the greater good of people in an industry who don't know nearly enough about the incredible potential of the engine you and i love so dearly. They can greatly benefit from something like what i am explaining. (That's all you get for now.)
for reference, general operational RPM will be around 50 to 75% throttle the majority of the time. i'm not looking for a reverse rotational 8000RPM drag monster. the horsepower will be right around STOCK.. 327 to 350, MAYBE as much as 400 (we're talking flywheel) but nothing too serious. low-mid RPM torque is helpful. i.e. a cam profile similar to a truck cam would be ideal. hopefully that helps with what i'm about to explain.
Here's what i can say with relatively definitively. I haven't been able to find anyone who has done this with my last few days worth of research. (lol... days...) If i could? it would help greatly, because i could more than likely purchase the parts i need from them and continue development be done with it, rather than playing god.
SO... this is what i have come up with for things that would need to be done to make an LS1 spin in reverse and operate normally. i.e. exhaust goes through headers not through the intake.
Please add anything else i am not thinking about, and DISCUSS.
Starting from the most obvious.
1. a custom ground cam will have to be made. hopefully the reasons are obvious. (will be touched upon later.)
2. the water pump will have to be omitted and replaced with an electric pump. all of the accessories will be omitted anyway, and the alternator relocated etc.
3. i'm not sure if the oil pump will work? i'm wondering how the engine direction will affect oil pumping through the journals the way it was designed to flow? Would it create too much oil pressure? would it matter at all? would an entirely new mirror image block need to be developed?
.......
firing order, ignition, injection...
I feel that it would be possible to use the STOCK crank, STOCK ecu and STOCK injectors IF the physical plugs that go into them were re-ordered in such a way that top dead center were on a completely different cylinder. (you'd ignore this fact when assembling the engine and align everything to natural TDC) the injector plug and coil plug would have to match whatever NEW cylinder were cylinder 1, etc. does this make sense? 8 may be 1, 2 may be 4, 3 and 4 may switch, etc etc. any problems with that theory?
IF this is possible, what would the NEW firing order be?
(cam shaft note mentioned above) if the stock crank were used, the custom ground cam would not be a mirror image, it would have to be set for the new firing order in accordance to the stock crank.
The other alternative is to grind a custom "mirror image" crank shaft as well as the "mirror image" cam shaft, that means it would be a mirror image in operation. WITH THE EXCEPTION that it wouldn't be a true mirror image, because the cylinders are staggered.
O 1
O 2
O 3
O 4
O 5
O6
O7
O8
so it would basically be
O 2
O 1
O 4
O 3
etc..
and that would have to be accounted for in the cam grind obviously.
OR...... would it make more sense if:
-balancer
O 8
O 7
O 6
O 5
O 4
O 3
O 2
O 1
- flywheel
(i just noticed that the spacing didn't work above... it's not an inline 8.. but.. use your imagination)
someone else proposed a question to me about the oil journals for the crank and cam bearings. He seems to think that they would have to be machined for the rotation, however, i seem to remember the oil ports being at a direct 90 to the bottom, and the bearings themselves being flat to the journal. ??
In other words, NOT slanted towards the direction of rotation.
--
The goal is to be able to use the STOCK ecu, and just switch wires around to make it fire in the right order. (injectors, coils etc). It would take too long and way too much money to have someone program a custom ECU, and... i don't know if i would trust one over a factory ecu as far as bulletproof reliability.
with THAT said.. sensors? what else is there?
How much of what i said, will or won't work in your opinions?
Remember, this is a serious inquiry, but i'm still in the very beginning stages and trying to get opinions from other people who know these motors inside and out.
Thanks guys, have fun with this one!
I'm wondering exactly what would have to be done to REVERSE the operational direction of an LS engine... We will say an LS1 from a 98-02 camaro simply for the sake of argument and to put a face to the name.
THERE ARE practical applications to this, and i am asking for a specific reason, namely research for a potential project. This is step one of what will be an incredibly expensive undertaking, that will involve engineers, hours of cad development etc. hopefully for the greater good of people in an industry who don't know nearly enough about the incredible potential of the engine you and i love so dearly. They can greatly benefit from something like what i am explaining. (That's all you get for now.)
for reference, general operational RPM will be around 50 to 75% throttle the majority of the time. i'm not looking for a reverse rotational 8000RPM drag monster. the horsepower will be right around STOCK.. 327 to 350, MAYBE as much as 400 (we're talking flywheel) but nothing too serious. low-mid RPM torque is helpful. i.e. a cam profile similar to a truck cam would be ideal. hopefully that helps with what i'm about to explain.
Here's what i can say with relatively definitively. I haven't been able to find anyone who has done this with my last few days worth of research. (lol... days...) If i could? it would help greatly, because i could more than likely purchase the parts i need from them and continue development be done with it, rather than playing god.
SO... this is what i have come up with for things that would need to be done to make an LS1 spin in reverse and operate normally. i.e. exhaust goes through headers not through the intake.
Please add anything else i am not thinking about, and DISCUSS.
Starting from the most obvious.
1. a custom ground cam will have to be made. hopefully the reasons are obvious. (will be touched upon later.)
2. the water pump will have to be omitted and replaced with an electric pump. all of the accessories will be omitted anyway, and the alternator relocated etc.
3. i'm not sure if the oil pump will work? i'm wondering how the engine direction will affect oil pumping through the journals the way it was designed to flow? Would it create too much oil pressure? would it matter at all? would an entirely new mirror image block need to be developed?
.......
firing order, ignition, injection...
I feel that it would be possible to use the STOCK crank, STOCK ecu and STOCK injectors IF the physical plugs that go into them were re-ordered in such a way that top dead center were on a completely different cylinder. (you'd ignore this fact when assembling the engine and align everything to natural TDC) the injector plug and coil plug would have to match whatever NEW cylinder were cylinder 1, etc. does this make sense? 8 may be 1, 2 may be 4, 3 and 4 may switch, etc etc. any problems with that theory?
IF this is possible, what would the NEW firing order be?
(cam shaft note mentioned above) if the stock crank were used, the custom ground cam would not be a mirror image, it would have to be set for the new firing order in accordance to the stock crank.
The other alternative is to grind a custom "mirror image" crank shaft as well as the "mirror image" cam shaft, that means it would be a mirror image in operation. WITH THE EXCEPTION that it wouldn't be a true mirror image, because the cylinders are staggered.
O 1
O 2
O 3
O 4
O 5
O6
O7
O8
so it would basically be
O 2
O 1
O 4
O 3
etc..
and that would have to be accounted for in the cam grind obviously.
OR...... would it make more sense if:
-balancer
O 8
O 7
O 6
O 5
O 4
O 3
O 2
O 1
- flywheel
(i just noticed that the spacing didn't work above... it's not an inline 8.. but.. use your imagination)
someone else proposed a question to me about the oil journals for the crank and cam bearings. He seems to think that they would have to be machined for the rotation, however, i seem to remember the oil ports being at a direct 90 to the bottom, and the bearings themselves being flat to the journal. ??
In other words, NOT slanted towards the direction of rotation.
--
The goal is to be able to use the STOCK ecu, and just switch wires around to make it fire in the right order. (injectors, coils etc). It would take too long and way too much money to have someone program a custom ECU, and... i don't know if i would trust one over a factory ecu as far as bulletproof reliability.
with THAT said.. sensors? what else is there?
How much of what i said, will or won't work in your opinions?
Remember, this is a serious inquiry, but i'm still in the very beginning stages and trying to get opinions from other people who know these motors inside and out.
Thanks guys, have fun with this one!
10-01-2014, 07:50 AM
#5
With earlier gen motors, there are a couple ways to reverse rotation but most common is a gear drive on the front that results in crank reversed with cam, distributor, and oil pump going in standard direction. That way only custom reverse rotation cam and rear seal are needed in addition to the gears.
The biggest issue with LS motors is the oil pump. It's run off the front of the crank. I suspect only an oil pump made from scratch would work, if that was even possible. An external dry sump oil pump might be easier.
Not sure if rear seal of LS motors is directional.
I'm not sure how the injection and spark is timed and don't recall any reverse rotation efi marine motors. But this may be beyond the scope of an average tuner. So yeah, switching wires might be an option. But even then, whether you go with gear drive or chain driven cam, I'm not sure how the ecu would respond to one or both reluctors going in reverse.
Internally, the earlier motors didn't care about directionality, same crank, rods, pistons. Not sure about LS.
Alternators spin either way, even the later versions of water pumps were omni-directional. I've had the back off the LS pump but don't recall if the impeller vanes were directional.
Crusader, Indmar, Raymarine all offer Marine LS motors. Although non reversed, I suspect someone in their engineering might be familiar with reverse rotation.
Btw, if this is a boat application, the availability of full power reverse capability marine trans makes it economically unrealistic.
The biggest issue with LS motors is the oil pump. It's run off the front of the crank. I suspect only an oil pump made from scratch would work, if that was even possible. An external dry sump oil pump might be easier.
Not sure if rear seal of LS motors is directional.
I'm not sure how the injection and spark is timed and don't recall any reverse rotation efi marine motors. But this may be beyond the scope of an average tuner. So yeah, switching wires might be an option. But even then, whether you go with gear drive or chain driven cam, I'm not sure how the ecu would respond to one or both reluctors going in reverse.
Internally, the earlier motors didn't care about directionality, same crank, rods, pistons. Not sure about LS.
Alternators spin either way, even the later versions of water pumps were omni-directional. I've had the back off the LS pump but don't recall if the impeller vanes were directional.
Crusader, Indmar, Raymarine all offer Marine LS motors. Although non reversed, I suspect someone in their engineering might be familiar with reverse rotation.
Btw, if this is a boat application, the availability of full power reverse capability marine trans makes it economically unrealistic.
Last edited by garys 68; 10-01-2014 at 08:11 AM.
10-01-2014, 08:48 AM
#6
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10-01-2014, 09:42 AM
#7
Yes, the oil pump only works in the normal direction.
On small and big block reverse engines, the cam is driven by two gears so it turns in the "normal" direction so the oil pump and distributor function as normal.
You could install an external belt driven oil pump.
http://petersonfluidsys.com/pump_wet.html
On small and big block reverse engines, the cam is driven by two gears so it turns in the "normal" direction so the oil pump and distributor function as normal.
You could install an external belt driven oil pump.
http://petersonfluidsys.com/pump_wet.html