So I swapped in my LS1 last night out of my 99 Z28 donor car. Would the easiest way to get around that coolant crossover line be to use the 4th gen radiator and fan setup? I haven't tried to test fit it yet, figured I'd ask before attempting to install it.

 

I am using a 4th gen radiator and dual fans.
Here are some pics

 

I am running a 3rd gen rad with the ls1 fans.

I bought an adapter from amazon that allowed me to tee in the coolant line into the upper rad hose.

It had a bonus effect of making it really easy to fill and burp the coolant system

I will dig around for a pic of it, as I know I posted it here

Edit, found the post with the pics.... plus other options if mine is too expensive

https://www.thirdgen.org/forums/ltx-...team-line.html

 

nhra-trans-am - I REALLY like that hold down you made for that... I might steal that idea one of these days.

Im running 4th gen rad, fans, hoses and a/c condenser using the stock 3rd gen hold down. You have to cut the "nub" off the bottom of the 4th gen rad, or drill a locating hole in your rad crossmember. I would just cut the nub....

First swap...really messy still.


Fans get a little close to the steering box, but I was able to shift things and clear. I might have trimmed some of the fan shroud ribs a tiny bit.


I used the 4th gen, mostly because i had it sitting there. But, hooking the steam line up is all figured out for you, and I like the fan set up. Plus the modular mounting of the fans and a/c condenser is nice. Hoses off the 99 z28 donor car worked perfect for me. Still running them today. I think the actual radiator is pretty much the same between 3rd gen and 4th gen. As in I dont think one cools better than the other. IMO...advantage goes to the 4th gen, as Ide rather figure out small fitment problems then figure out coolant lines. Thats just me though.

J.

 

I'm planning to use the 3rd gen radiator and fans. My Z already had the dual fan set up and for simplicity will stay with what I have. From what I've read the third gen radiator is more than adequate for the LS swap.

 

I've read up a bit on it too. "LS" swap fans and fan shroud are what you want. 3rd gen radiator is fine. The fan motors plug right up, but spin faster, and the shroud is formed a bit better, helping to pull more air through whatever radiator you have. Minimal fab work required, although I haven't actually done it yet. It's on my list. ...along with a long list of other things!

 

I picked up an aluminum 2-core radiator off of Ebay meant for LS swaps for mine. 2 1" cores. Running an Ebay dual fan setup that I had bought for my 79 several years ago and rewired for this car. Keeps it right at about 185, even under load on the hot highways here.

 

Man thanks for the info! So your running all the 4th gen A/C lines? And they hook up to the third gen evaporator core?

 

Nooooo haha. Im running the entire 4th gen a/c system exactly as it came on the 99 Z28 donor car.

It requires one of two courses of action.
1) Mold the front half of a 4th gen hvac box to the rear half of your 3rd gen to accommodate the 4th gen evap. This is what I did...mostly because I had both sitting there.

2) Go hunting for an evap that will fit in the 3rd gen box, but has the newer style flange connection. You MIGHT get lucky and find something that fits and hooks up. The other thing you can do is have someone braze the 4th gen evap hook up to the 3rd gen evap. It will take a little work, but might be less than all the fiber glassing and fitting of option 1.

As for the fab work to fit the LS radiator, you have to trim off the nub, and relocate the rubber insulators that hold the rad in place. I chose to move the driver side rubber mounts towards the passenger side. If you look at my first picture, you can see the little nub of the driver side radiator isolator sticking up. You can see the original hole towards the driver side of the hold down. I think I moved it like 1-1/2 to 2". Bottom mount I just used a little adhesive to stick it to the bottom of the rad, and trimmed it so it fit in its new spot. After that, just do a little fiddling with the plastic hold down to clearance it and fit how you want. Piece of cake really.

J.

 

You can always drill and tap the steam line into the water pump. That is what I did and it works great! and only costs $2-5.00. I am running a turbo 5.3 in my car with the 3rd gen z28 radiator. no issues at all.

 

Thats what i did also.Drill and tapped the waterpump and ran hose to the steamline.Im using stock rad and dual fans and stock ls1 t-stat.With my turbo 6.0 hits 160* to maybe 195* when I beat on it.The secondary fan hardly Ever comes on even in heavy traffic. Do whatever method you can afford to do..there is no wrong answer from all the above.just be sure to burb the system..a few times lol.The air pockets can be a pain to get out at times.

 

Used the 3rd gen rad with the stock single fan, works just fine and I'm not nice to this thing.
Steam line, I made my own T-fitting in to the upper rad hose.

 

Instead of drilling and tapping the water pump, and having to do it again if/when the pump goes out... just use the port on the radiator and run a line to it. I used a 1/8 NPT nipple fitting and just ran a hose to it.

 

Drilling and tapping isnt that bad. The water pumps dont seem to fail that often.

But what port on the radiator are you talking about using an 1/8" Npt barb on? if you have a 4th gen rad, the port is already there. If you have a thirdgen rad, there are no ports that I know of. Just curious...

Justin

 

Ah, sorry. I forgot the stock radiator doesn't have a threaded hole. It should have a port under the overflow port, though, that I know people use. Believe it was the heater return port.

My aftermarket radiator has a threaded hole that I just screwed a nipple in.

 

I drilled & taped the waterpump and am running the Mishimoto rad.
It's a very tight fit but does fit in the stock location with a little trimming of the rubber rad holders.

 

My Modine replacement radiator heater return port is threaded and accepted a 1/4 - 13 NPT barb fitting, that is what I'm using.

 

My sizing of the barb is probably the 1/4-13 as well.. I thought I had it written down as being 1/8, but I can't find any of the info on it for some reason.