I am curious if anyone on ST has taken a step back and tested any LS engines utilizing different firing orders and intake configurations? I currently am building a EFI LS with a traditional singleplane 4 bbl configured intake. But with a 4 bbl efi throttle body and injectors positioned about 1.5" up the runner from the intake flange. Kinda traditional location. So the plenum and upper portion of the intake runner is basically dry. No fuel cloud. I am curious if the LS firing order is still a best choice when using an old school style intake. I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
LS "out of order"
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Re: LS "out of order"
The LS firing order is the best way to go.induction apprentice wrote: ↑Fri Nov 27, 2020 5:57 am I am curious if anyone on ST has taken a step back and tested any LS engines utilizing different firing orders and intake configurations? I currently am building a EFI LS with a traditional singleplane 4 bbl configured intake. But with a 4 bbl efi throttle body and injectors positioned about 1.5" up the runner from the intake flange. Kinda traditional location. So the plenum and upper portion of the intake runner is basically dry. No fuel cloud. I am curious if the LS firing order is still a best choice when using an old school style intake. I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
We have done many other engines using the LS or Ford firing order and seen gains and less vibrations and wear on bearings etc etc ect.
Correct the air flow through what ever induction system you have to the ports and you will be fine
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Re: LS "out of order"
This is an older post of mine. I was surprised no one had any thoughts regarding this. So I am taking another swing.
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Re: LS "out of order"
Comparatively, A Ford "Cleveland" and 351 engines have been using that firing order forever; the 302 HO switched to it.induction apprentice wrote: ↑Fri Nov 27, 2020 5:57 am I am curious if anyone on ST has taken a step back and tested any LS engines utilizing different firing orders and intake configurations? I currently am building a EFI LS with a traditional singleplane 4 bbl configured intake. But with a 4 bbl efi throttle body and injectors positioned about 1.5" up the runner from the intake flange. Kinda traditional location. So the plenum and upper portion of the intake runner is basically dry. No fuel cloud. I am curious if the LS firing order is still a best choice when using an old school style intake. I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
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Re: LS "out of order"
viewtopic.php?t=46463
lots of circle track cars switch from traditional to the new firing order and call it a 4/7 - 2/3 swap.
lots of circle track cars switch from traditional to the new firing order and call it a 4/7 - 2/3 swap.
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Re: LS "out of order"
YesProPower engines wrote: ↑Fri Nov 27, 2020 4:24 pmThe LS firing order is the best way to go.induction apprentice wrote: ↑Fri Nov 27, 2020 5:57 am I am curious if anyone on ST has taken a step back and tested any LS engines utilizing different firing orders and intake configurations? I currently am building a EFI LS with a traditional singleplane 4 bbl configured intake. But with a 4 bbl efi throttle body and injectors positioned about 1.5" up the runner from the intake flange. Kinda traditional location. So the plenum and upper portion of the intake runner is basically dry. No fuel cloud. I am curious if the LS firing order is still a best choice when using an old school style intake. I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
We have done many other engines using the LS or Ford firing order and seen gains and less vibrations and wear on bearings etc etc ect.
Correct the air flow through what ever induction system you have to the ports and you will be fine
again it works well but you need to taylor the intake system to suit.
There is other engines that use the same firing order and a carb with no distribution issues thats what you learn on the dyno and correct with a divider of cross jetting the carb or both. With a correct spacer combo they work fine depending on what intake you want to use.
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Re: LS "out of order"
All 3 common firing orders have the middle 4 cylinders firing in order.induction apprentice wrote: ↑Fri Nov 27, 2020 5:57 am I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
Std: 4-3-6-5
4/7: 3-6-5-4
LSx: 6-5-4-3
All 3 sequentially fire 2 cylinders next to each other
Std: 5-7
4/7: 4-2
LSx: 3-1
All 3 sequentially fire both cylinders on the same throw, on 3 of the 4 throws.
Std: Throws 1,2, and 3
4/7: Throws 1,3 and 4
LSx: Throws 2,3 and 4
This is the biggest advantage of the LS firing order. Firing back to back on the rear 3 throws reduces stress on the crank.
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Re: LS "out of order"
Thank you. That was a great answer. I can now let the idea RIP.CamKing wrote: ↑Tue Mar 02, 2021 12:53 pmAll 3 common firing orders have the middle 4 cylinders firing in order.induction apprentice wrote: ↑Fri Nov 27, 2020 5:57 am I believe the firing order finishes with the middle 4 cylinders in succession and in a circular pattern. I wonder how that effects pumping eficiency?
Are the middle 4 cylinders trying to compeat for air
Std: 4-3-6-5
4/7: 3-6-5-4
LSx: 6-5-4-3
All 3 sequentially fire 2 cylinders next to each other
Std: 5-7
4/7: 4-2
LSx: 3-1
All 3 sequentially fire both cylinders on the same throw, on 3 of the 4 throws.
Std: Throws 1,2, and 3
4/7: Throws 1,3 and 4
LSx: Throws 2,3 and 4
This is the biggest advantage of the LS firing order. Firing back to back on the rear 3 throws reduces stress on the crank.