Harmonic balancer question
Thread Starter
Teching In
Joined: Nov 2024
Posts: 4
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From: Greater Vancouver, BC
Harmonic balancer question Hello, looking for advice with my swap.
The L9H that I purchased will go into a vehicle that is very space-limited under the hood, especially front to back. For that reason I have been looking into how to reduce the overall length of the engine.
If I replaced the harmonic balancer with one from an LS4, by how much would that shorten the engine at the front compared to say a Corvette balancer?
I am not looking to machine the crankshaft to get the balancer to sit where it would sit on an actual LS4, or even replace the crankshaft with one from an LS4. All accessory brackets would have to be custom.
I searched this topic and could not find the answer to this.
Thanks very much!
The L9H that I purchased will go into a vehicle that is very space-limited under the hood, especially front to back. For that reason I have been looking into how to reduce the overall length of the engine.
If I replaced the harmonic balancer with one from an LS4, by how much would that shorten the engine at the front compared to say a Corvette balancer?
I am not looking to machine the crankshaft to get the balancer to sit where it would sit on an actual LS4, or even replace the crankshaft with one from an LS4. All accessory brackets would have to be custom.
I searched this topic and could not find the answer to this.
Thanks very much!
Last edited by Bremer; Nov 15, 2024 at 05:43 PM.
TECH Enthusiast
Joined: Sep 2019
Posts: 532
Likes: 630
You really cant get a shorter engine in overall length than the older LS1 / LS6 "High Mount" accessory drive, but even it doesn't get you much.
the LS4 accessory drive is weird.
If the LS engine doesn't fit, there are plenty of other options, including the new 4.3 LV3 V6 that is literally a LT1 engine with two cylinders chopped off, like the old 1990s 4.3, but unlike the old 4.3 it's actually good.
the LS4 accessory drive is weird.
If the LS engine doesn't fit, there are plenty of other options, including the new 4.3 LV3 V6 that is literally a LT1 engine with two cylinders chopped off, like the old 1990s 4.3, but unlike the old 4.3 it's actually good.
The face of the LS4 harmonic balancer is 2 3/4" from the face of the block and is the most compact.
Here is a truck water pump for comparison:
However, it isn't compatible with any of the non-LS4 water pumps and accessory brackets due to the shorter offset.
So you either have to use the LS4 water manifold monstrosity, or go custom.
Stock LS4 accessory drive:
Here is a truck water pump for comparison:
However, it isn't compatible with any of the non-LS4 water pumps and accessory brackets due to the shorter offset.
So you either have to use the LS4 water manifold monstrosity, or go custom.
Stock LS4 accessory drive:
Keep in mind the LS4 Crankshaft snout is shorter than a standard LS crankshaft.
I posted some measurements in this thread https://ls1tech.com/forums/forced-in...l#post20270246
I posted some measurements in this thread https://ls1tech.com/forums/forced-in...l#post20270246
The published length differences between the LS4 crank vs. the standard (not the early longer ones) are:
- 10mm shorter on the accessory end
- 3mm shorter on the flywheel end
Thread Starter
Teching In
Joined: Nov 2024
Posts: 4
Likes: 0
From: Greater Vancouver, BC
Thanks FastBrick and Fieroguru, great information.
With the current truck balancer the engine measures about 26.125'' long (front face of balancer to rear of block). Using the LS4 balancer, that reduces to about 23.225'' (not counting the protruding bolt head). Using the Corvette balancer, this dimension would be 24.55''.
Since I have 24.5'' available before the balancer hits the steering rack, I'll be using the LS4 balancer. That gives me some clearance to play with when positioning the engine. I accept that the accessory brackets will have to be custom and that I may need a spacer between crank bolt and balancer.
It also leads me down the path of a remote electric water pump since there's no way I'm using that monster LS4 pump... but one thing at a time.
Thanks again, appreciate it!
With the current truck balancer the engine measures about 26.125'' long (front face of balancer to rear of block). Using the LS4 balancer, that reduces to about 23.225'' (not counting the protruding bolt head). Using the Corvette balancer, this dimension would be 24.55''.
Since I have 24.5'' available before the balancer hits the steering rack, I'll be using the LS4 balancer. That gives me some clearance to play with when positioning the engine. I accept that the accessory brackets will have to be custom and that I may need a spacer between crank bolt and balancer.
It also leads me down the path of a remote electric water pump since there's no way I'm using that monster LS4 pump... but one thing at a time.
Thanks again, appreciate it!
Here is the accessory drive I built for my original LS4 swap back in 2013. I cut up the stock water pump housing and relocated the coolant entrance/exit and thermostat to make room for the alternator and AC down low.
There is another swap with a LS4 that basically cut the LS4 housing down to just the runners connecting the 4 coolant ports on the engine and welded in some hose connections for an electric pump.
When I redid the swap from 2019-2023, I reworked that area. The clearance to the side frame rail was also tight, but it is angled giving me just enough room for a fabricated water pump setup to fit. I put all the accessories on the front of the engine to keep them hidden and help with weight bias. The Fieros have manual steering, so that was 1 less accessory I needed to fit.
There is another swap with a LS4 that basically cut the LS4 housing down to just the runners connecting the 4 coolant ports on the engine and welded in some hose connections for an electric pump.
When I redid the swap from 2019-2023, I reworked that area. The clearance to the side frame rail was also tight, but it is angled giving me just enough room for a fabricated water pump setup to fit. I put all the accessories on the front of the engine to keep them hidden and help with weight bias. The Fieros have manual steering, so that was 1 less accessory I needed to fit.
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Thread Starter
Teching In
Joined: Nov 2024
Posts: 4
Likes: 0
From: Greater Vancouver, BC
Thanks Fieroguru. Your new setup looks very slick. What is that water pump you are using?
I found your original build thread. Is there another one where the rework of the accessory drive is described?
I found your original build thread. Is there another one where the rework of the accessory drive is described?
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