47-55.1 GMC LS Swap Radiator question

[JDarby]

Have been checking out my options for a radiator for my 55.1 GMC 6.0 swap,
and have learned most all the differences between GMC and Chevy radiators for the 47-55.1' year span.
My question for you GMC LS swap owners is have you ever bought a LS swap radiator from Turbo Nasty and how did that work out for you?

[Hcb3200]

what is your plan with your truck and what type of LS are you dropping in there? daily driver, low and slow, dragging that thing on weekends? where do you live? what is the cooling needs southeast where 100+ and humidity or mountains. etc.

Little more info.

[Hcb3200]

I currently run a stock 6.0 in my 1956 with the stock or close to stock brass radiator. Unless I am stuck in bumper to bumper traffic and its over 90 i rarely turn on the fan. (electric when I want to run them) That LS runs at 200 if I am lucky half the time its at (188) and never over 210 which is really cooler than GM runs them in Tahoe's and Suburbans. Unless you are in the need for a radiator see how it goes with what you got first.

[JDarby]

I could try what I have but its very old.
It gets very hot here is Texas and I will be running an automatic and AC!
My question really is Turbo Nasty related because they claim that there is no difference
between a Chevy / GMC radiator 47'-54' which I know is simply not true!
At least the web site shows the same radiator for both trucks!
When I questioned them they said they have sold many with no issue.
Puzzling to me?

[leegreen]

I agree, stock LS do not seem to be hard to cool. There is a lot more radiator in my original '52 than in front of either of two LS in our fleet right now. So if you have a good radiator in the truck now that will support a 15lb cap give it a shot.

the turbonasty rad looks right, hose sizes, steam port etc. Maybe ask them for specific radiator hose part numbers to see if they have actually supported the install before.

I'd also get them to confirm there is clearance between the rad hose outlet on the block and the water pump pully to that electric fan they sell. Looks to me those three are all going to be in the same spot. If they give you a vague answer you know you are on your own to make it fit.

[Hcb3200]

I run AC, Power brakes and steering, and automatic(6l90) cooler in radiator here in georgia where humidity rules during the summer.

I think you should run with what you got and determine if you need more.

A electric fan does wonders even with stock radiator when sitting in traffic. Fan means nothing when driving as forced air does its job.

But if you do need to upgrade then you definitely want to make sure your own measurements matches to what your vendors says it it. Don't just trust yea they are all the same it will fit.

[jweb]

I have never heard of Turbo Nasty but it looks like they do have a GMC specific radiator.
https://turbonasty.com/1947-1954-gmc...ruck-1950-5183

If you're buying a new radiator, you want GMC specifically. The mounting tab on the sides of the radiator are located very different than a Chevy.

Also the filler neck is correct for your truck.
First pic is GMC
Second is Chevy

[Hcb3200]

that would look good in front of that LS

[leegreen]

No steam port shown on the GMC variant pictured. If I was buying aftermarket rad for LS swap I'd want one. Less hassle fitting upper rad hose into available space if you don't have to include a coupler with steam port in the middle of it.

[dsraven]

if you check the bellavista site, or pirate 4x4 site, there is a write up on LS stuff, including their cooling systems and requirements. they are not like the old sall blocks where a simple rad will suffice. no steam ports will yield problems down the road I think.

http://billavista.com/tech/index.html

[jweb]

I just noticed their GMC LS swap radiator is just a Chevy. I wouldn't recommend this for a GMC but I can't say if it would work.

The Chevy radiator would be closer to the engine. Even with the Chevy radiator in a Chevy I had to cut my core support to move the radiator forward. I have about 1/2" from my fan to my intake.


The LS swap radiator has the upper hose offset to the right side and has an added steam port which is nice but neither of those is necessary.

I ran a stock style radiator in my Chevy for a few years and the hose location wasn't a problem. Actually wonder if it looked better with the upper hose centered.

The steam port I have running into my water pump. so it wasn't needed on the old radiator or the new LS swap radiator.

Basically what I'm saying is the GMC radiator I showed in my other post would likely be a better option.

[leegreen]

Nice clean install jweb!.

Tapped water pump is a common solution with swaps.
I may be overly cautious, but GM did go to the extra expense of routing steam port to rad for a reason. My thoughts on why: With tapped water pump it would be best practice to crack that fitting open with every radiator fill to make sure the air bleeds from high point of engine. And any coolant boil event will cascade if steam cannot escape from high point of engine.

Both our DD LS swaps use a steam port tapped coupler in upper rad hose. And stock Camaro / S10 rads with no steam port provision.

[jweb]

Originally Posted by leegreen

Nice clean install jweb!.

Tapped water pump is a common solution with swaps.
I may be overly cautious, but GM did go to the extra expense of routing steam port to rad for a reason. My thoughts on why: With tapped water pump it would be best practice to crack that fitting open with every radiator fill to make sure the air bleeds from high point of engine. And any coolant boil event will cascade if steam cannot escape from high point of engine.

Both our DD LS swaps use a steam port tapped coupler in upper rad hose. And stock Camaro / S10 rads with no steam port provision.

Another good idea, tapping into the upper hose. I know it can be difficult to get all the air out of these systems. I've been lucky so far.

Either way I think the replacement GMC radiator is a better option than their LS swap Chevy radiator.

[JDarby]

I see now what my issue is with Turbo Nasty, its the web site and whoever I was texting with from there company.

Depending on what year GMC from 47-54 you input they show both chevy and GMC radiators. It's not sorted out correctly!!!

And I'm sorry but the person I texted with from Turbo Nasty was soooo F'ng aggrivating!!!

Thank you all for your input and jweb your LS swap under hood shot is very nice indeed!!

I am using a serpentine belt system from KWIK with mine.
My suspension is C4 IFS and IRS from Flatout.
I'm building a driver!!

One last thing about Turbo Nasty, they sell Champion LS swap radiators.
Like most vendors there are few suppliers to look too.

Again Thanks to this ever so helpful community!!!

[jwhotrod]

with all that frontal area why dont you use that space and put in a cross flow radiator? in my streetrods i am resricted to 17" of width by the grill shell, id kill for that wider space. the crossflows are much more efficient.

[leegreen]

Originally Posted by jwhotrod

with all that frontal area why dont you use that space and put in a cross flow radiator? in my streetrods i am resricted to 17" of width by the grill shell, id kill for that wider space. the crossflows are much more efficient.

about 19" core width in these trucks and the radiator support is integral to holding up front sheet metal. So there is room for a cross flow but you'd need to do major rebuild of core support.

[jweb]

Here is a GMC/ LS swap radiator. A little more money but no mods needed. Even has the nice curved top like a GMC should.

https://www.rndfabrication.com/ChevyGMC47-54.html

[mr48chev]

Originally Posted by jweb

Here is a GMC/ LS swap radiator. A little more money but no mods needed. Even has the nice curved top like a GMC should.

https://www.rndfabrication.com/ChevyGMC47-54.html

The side brackets on that one are at the Chevy bracket position rather than the GMC bracket position.

The 49 GMC radiator shows that factory GMC brackets give you over a free inch and by swapping to a GMC radiator and with a minor mod to the piece that runs across the top of the radiator support that is missing the piece that needs mods on a lot of them you can gain room on a Chevy.

I'm going to see if I can drag my buddy away from his gal friend long enough to help me move the brackets on my aluminum radiator. Even at 76 years old he is the guy who gets calls for critical welding when they need the best in the area.

[JDarby]

Here is Spreed Sheet with a few radiator manufactures related to LS swap or not:

General rule is if the Radiator comes with a steam port it is LS direct swap,
you even have the option sometimes to indicate where you want your port/s

If no Steam Port you can still use the radiator in a LS swap you just need to
add a steam port at the highest point in the motors water line.

There are many more manufacturers I am sure, please feel free to add
to the list! I'ts a rabbit hole if you let it be.

Thanks again to LeeGreen And DSRaven for all the technical support,
between the Mac ,Touch Pad, Mouse and general lack of abilities we
made this small spreadsheet happen.

[JDarby]

Thank you to LeeGreen and DSRaven for technical support!!
This Mac was driving me crazy between the touch pad , mouse and my lack of ability, ARG!!!

[leegreen]

big price difference to get the steam port!

here is the upper rad hose coupler with steam port I used on last LS swap:
https://www.amazon.ca/gp/product/B0BKRS2GPN/
1-1/4 inch Radiator Hose Barb Adapter with 1/8" NPT Port is description. Check dimensions as some listings use that description but the coupler is much smaller OD than 1 1/4

and the 1/8 NPT 1/4" hose barb :
https://www.amazon.ca/gp/product/B06XS164TV/

I do think a rad supplier for LS swap into a specific vehicle should be able to specify hoses that fit, but if you need to cobble rad hoses grab the hoses from your swap donner vehicle and some 1-1/4 and 1-1/2 hose couplers without the steam vent.

[JDarby]

Here is another option for a steam port or at least 1/2 of it.

Cost just under 40 buck's on Ebay.

[e015475]

A Chevrolet radiator support is braced with cross rods in front of the radiator - a GMC is not, and the radiator sits inside the support (the reason there's a gooseneck radiator fill on the GMC)

If you are fitting an LS engine with the truck accessories, you're going to need all the room you can find in front of the water pump. A GMC radiator will give you 1-1.5" more than a Chevy. This is the radiator in my 49 GMC and it is almost flush with the support.



I used a US Radiator -

https://usradiator.com/product/gmc-t...minum-radiator

It can be configured specifically for the LS with a steam port installed.

I built a fiberglass shroud for mine and installed a 17" high CFM SPAL fan. The fan is controlled by the ECU. Here's a photo of the assembled radiator and shroud (shroud isn't painted yet in this pic - still sanding it down. Note location of the inlet tube for the LS motor

[JDarby]

I was going to make a listing all of the LS radiator info we have
come up with on this thread but am having a hard time making rows
and columns look right.

Can anyone please tell me what tool I can use to accomplish this?

[dsraven]

excel from microsoft is what I usually use for spread sheet info