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"6. Cooling System
The inlet and outlet locations on radiators for
traditional Small-Block and Big-Block engines do not
match the flow patterns of LS and LT engines. The
builder will need a new radiator to accommodate
a double-pass design that features the inlet and
outlet on the same side."
anyone running a single pass radiator with their LS3 Swap.
I have a direct FIT dewitts / Dual spal fans I used for my ZZ383 do I need to replace with a double pass design.
Without some sort of schematic of the coolant flow within the system I am at a loss to understand the concern. Have had no cooling issues with my deWitts with inlet and outlet in the conventional positions. I did have to piece together custom hoses. There is also a "steam line" running to the radiator.
You have to be a bit careful not to get air trapped in the heads when you fill with the coolant. A vacuum fill worked well for me.
For some reason my laptop is refusing to upload multiple pictures. This sort of shows both hoses. You can see the lower hose under the spreader bar.
Without some sort of schematic of the coolant flow within the system I am at a loss to understand the concern. Have had no cooling issues with my deWitts with inlet and outlet in the conventional positions. I did have to piece together custom hoses. There is also a "steam line" running to the radiator.
You have to be a bit careful not to get air trapped in the heads when you fill with the coolant. A vacuum fill worked well for me.
For some reason my laptop is refusing to upload multiple pictures. This sort of shows both hoses. You can see the lower hose under the spreader bar.
I originally ran my old dewitts direct fit/replacement radiator and ford focus fans with my ls3 (originally cooled my 383 just fine). I was fighting the ls3 engine running hot at idle w/ac for 25 minutes in 95* temps. While trying to diagnose the problem, i switched to a dual pass (dewitts ls swap radiator) with the spal fans (recommended by others that it'd be more efficient) and the "LS" radiator/fan swap didn't solve my problem of running hot while idling for a prolonged period of time.
All that to say I don't think you need the LS swap radiator. Just route the steam line to a high spot in the upper hose or radiator.
I also used a vacum system to fill both setups with coolant to keep from getting air pockets.
If you splice hoses look at getting the gates power grip hose clamps. Basically heat shrink clamps, they look nice and you won't see regular hose clamps everywhere.
Without some sort of schematic of the coolant flow within the system I am at a loss to understand the concern. Have had no cooling issues with my deWitts with inlet and outlet in the conventional positions. I did have to piece together custom hoses. There is also a "steam line" running to the radiator.
You have to be a bit careful not to get air trapped in the heads when you fill with the coolant. A vacuum fill worked well for me.
For some reason my laptop is refusing to upload multiple pictures. This sort of shows both hoses. You can see the lower hose under the spreader bar.
Where did you connect the steam line from the engine to ?
I've done the steam line three different ways on my LS swaps.
Drill and tap the water pump for a 1/8" pipe and plumb the steam line. Couple of down sides to that is if the water pump fails you have to drill the the new pump. Also steam likes to go up not down. But my 98 Wrangler LS swapped has been like that 12 years and no issues.
If you have to splice the upper radiator you can buy a tubing splice with a pipe fitting welded in and you plumb the steam line into that.
Last but the one I like the best is have a pipe bung welded into your radiator and plumb the steam line into the that.
As for the steam line its self I use -4 SS braided line. -4 fittings. On the metal steam line that bolts to the engine block has a nipple that you can put a rubber hose on. I cut that off and drill and tap the hole for 1/8" pipe thread. Then you can use -4 fittings all around.
In regards to the radiator hoses I was able find a upper hose that didn't need a splice. I've found Oreill'y has the best selection.
I never found a lower hose that fits without a splice but you can't really see it down low.
I've done the steam line three different ways on my LS swaps.
Drill and tap the water pump for a 1/8" pipe and plumb the steam line. Couple of down sides to that is if the water pump fails you have to drill the the new pump. Also steam likes to go up not down. But my 98 Wrangler LS swapped has been like that 12 years and no issues.
If you have to splice the upper radiator you can buy a tubing splice with a pipe fitting welded in and you plumb the steam line into that.
Last but the one I like the best is have a pipe bung welded into your radiator and plumb the steam line into the that.
As for the steam line its self I use -4 SS braided line. -4 fittings. On the metal steam line that bolts to the engine block has a nipple that you can put a rubber hose on. I cut that off and drill and tap the hole for 1/8" pipe thread. Then you can use -4 fittings all around.
In regards to the radiator hoses I was able find a upper hose that didn't need a splice. I've found Oreill'y has the best selection.
I never found a lower hose that fits without a splice but you can't really see it down low.
All good suggestions. My radiator was advertised as for LS motors so it came with a bung in the driver's side tank.
When I was doing this install 8 years ago, I found a site 'jagsthatrun' that had lots of odd fittings for this and that application. Here is a steam vent that you can add to a hose splice.
Myself I never found a top hose that worked so had to build one up. The bottom hose was quite a challenge to duck under the spreader bar. I took the angled inlet, carefully sawed its spout off and had a guy weld it to point pretty much directly down.
I halfway remember that deWitts had a regular New Year sale so if you elect to buy one (sounds like you won't) it may pay to wait.
As to how the coolant flows in mine, I really can't say but I don't think it is crossflow as when I flushed it, to drain, I inserted a hose that reached all the way to the bottom of the tank. Better of course to have a stopcock fitted but pumping the old fluid out the way I did was no big deal.
I found a few hoses i thought i could make work at the parts store. See below what used in the upper hose for the steam tee and idea for splicing 2 hoses together cleanly. I'm using the straight (cbm?) Tstat housing . Yeqh it's fun trying to get it to clear the spreader bar if you have one
LS3 radiator requirements.
