117 vs 124 TC
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Outstanding HDF Member
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From: Minnesota
117 vs 124 TC
I know everyone always goes for the biggest cubes but does the shorter stroke of a 117 offer any benefit? Mainly at lower rpm range? This would be on a twin cam.
Road Master
Joined: Oct 2017
Posts: 815
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From: Uptown Bay Area, Cali
If you are starting from scratch, there is no reason not to go bigger. You will have more torque at lower rpms.
Saying that, the more power your motor pumps out, the less mellow it becomes. I cant ride my 124 easy just putting around anymore. It begs you just to go fast. Power does corrupt, lol.
Dave
Saying that, the more power your motor pumps out, the less mellow it becomes. I cant ride my 124 easy just putting around anymore. It begs you just to go fast. Power does corrupt, lol.
Dave
Thread Starter
|
Outstanding HDF Member
Joined: Jan 2014
Posts: 2,482
Likes: 239
From: Minnesota
If you are starting from scratch, there is no reason not to go bigger. You will have more torque at lower rpms.
Saying that, the more power your motor pumps out, the less mellow it becomes. I cant ride my 124 easy just putting around anymore. It begs you just to go fast. Power does corrupt, lol.
Dave
Saying that, the more power your motor pumps out, the less mellow it becomes. I cant ride my 124 easy just putting around anymore. It begs you just to go fast. Power does corrupt, lol.
Dave
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Road Master
Joined: Oct 2017
Posts: 815
Likes: 292
From: Uptown Bay Area, Cali
This is sort of what I was thinking. I know cam choice changes things but I have heard from a few that you cant lug a 124. S&S claims not to run theirs below 3K. I know lugging is bad but I want to build a good touring motor that has torque where I use it and not just chase numbers.
You can cam a 124" to run no problem at 2,000 rpm. It will run out of breath at the top end, but you can still get 130 hp with great torque at the bottom with a good combo.
Dave
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Road Master
Joined: Oct 2017
Posts: 815
Likes: 292
From: Uptown Bay Area, Cali
For reference, when I picked up my Dyna LRS, it had the stage 4 117" kit installed. It had a theoretical 9.9 compression.
For the first performance rebuild, I had the stock rotating assembly welded and balanced, timken conversion, heads and manifold ported, heads shaved to get 10.5 compression, S&S lifters, and Thunderheader. This motor definitely ran smoother than before.
For the 2nd rebuild, the 124" kit was installed, new TB, new cam, Fab28 exhaust, and the compression was now around 11 to 1. If there was a change in vibration, it was very slight to none at all.
For the 3rd rebuilt, the heads where ported some more for the added cubes, the compression was increased slightly, and the muffler was changed from the Fab28 to a Thunderheader. The vibration increased a little due to the compression, but the muffler made the engine run smoother from 2,500 rpm to 3,000 rpm.
I would say compression has a much bigger effect on vibration than 7 cubes going from a 117" to 124". A 124" with 10 to 1 is going to be smoother than a 117" with 11.5 to 1 compression.
But hey, it's a tractor motor. It was never designed to be smooth from the get-go, lol.
Dave
For the first performance rebuild, I had the stock rotating assembly welded and balanced, timken conversion, heads and manifold ported, heads shaved to get 10.5 compression, S&S lifters, and Thunderheader. This motor definitely ran smoother than before.
For the 2nd rebuild, the 124" kit was installed, new TB, new cam, Fab28 exhaust, and the compression was now around 11 to 1. If there was a change in vibration, it was very slight to none at all.
For the 3rd rebuilt, the heads where ported some more for the added cubes, the compression was increased slightly, and the muffler was changed from the Fab28 to a Thunderheader. The vibration increased a little due to the compression, but the muffler made the engine run smoother from 2,500 rpm to 3,000 rpm.
I would say compression has a much bigger effect on vibration than 7 cubes going from a 117" to 124". A 124" with 10 to 1 is going to be smoother than a 117" with 11.5 to 1 compression.
But hey, it's a tractor motor. It was never designed to be smooth from the get-go, lol.
Dave