I’m on the road this week, so I figured perhaps it’s time to post up some controversial stuff. Cooling system mods for a performance application. Here’s a summary:

1. Plug the inboard large coolant holes in the block. This is straight out of Smokey’s books, it strengthens a weak area of the block, reduces the maze of parallel paths for coolant to take, as parallel paths are very difficult to regulate for flow. Steam holes are drilled, as there’s no where for the air or steam to go. Pipe tap, NPT plugs, install with epoxy and machine when decking the block.







2. Use a NASCAR style water pump, this one is made by RCR and is plumbed for the required pressure and suction ports. The OEM Corvette pump is shown for contrast.





3. Tap an 8AN line into each side of the block at the midpoint, for the pressure side of the pump on each side.

4. Tap a 4AN line into each of the cylinder heads, between the 3/5 and 4/6 exhaust ports. This is a suction line plumbed to the top of the water pump previously shown.

5. Restrict pump outlets in the front of the block from a 1” diameter to 1/2” diameter. In my case, this was done at the motor plate, welded a plug, to be drilled and resurfaced.

(removed picture of the process as it seems to have people believe that the holes are blocked)

More later…

 

Cool stuff here.

 

Found a couple of more pictures on my phone, cylinder head modification to pull coolant up and out by the hotspot between 3/5 4/6




heres the head gasket configuration, its tricky to drill holes in the copper head gasket, ordered it without any cooling ports.

 

Few more pictures to illustrate the idea.

 

Nice Mill ... Are you endurance racing ? ... I'd think that these mods would be overkill for a street engine ... and I think the reduced water pump to block holes would just = kill on the street .

 

Thanks, and to clarify the cooling is more of a change in location for the water pump output to block input points. I don’t think it’s optimized 100% but it should be better.

Based on research on how currently dirt track cars and years ago NASCAR, figured out the importance of reallocating half of the cooling resources to the side of the block, providing the path of least resistance to the priority cooling between the pair of exhaust valves. AFR places a boss here to aid in achieving this. Don Terrell (speed talk founder) wrote a book detailing the need for this on the SBC and that the front entry needs to be restricted to 1/2” to bush more to the center of the block, some also to the rear of the block. And then some of them push coolant to the center of heads also, but consensus seems to be that it’s much more effective to pull.

The two 1/2” holes front block and then additional two entering the block in the middle, the goal is even heat distribution, and the OEM system creates two front cylinders relatively cooler, especially block/cylinder temps, with most of the other six cylinders hot or with hot spots. By the way the holes shown aren’t quite 1/2 diameter as the hole was enlarged with a reamer at an angle towards the center and down, to align the direction of flow.

I don’t see how this is not adequate for the street, should be a very streetable setup. The LT1 reverse cooling set up perhaps went too far in the other direction, and the aluminum block needs more priority for coolant entry than the heads, and upward flow path prioritizing exhaust side.

Intent is street use, open track, autocross.

 

FYI I have never pulled water from between the exhaust ports on the exhaust side of the casting. We always push water in there (-6AN line) and pull it out from the intake face across from there... That way water is flowing across the head between the paired exhaust seats.... you also will need to fabricate a tube on that -6AN fitting to get the water pressure closer to the exhaust seats as it's a good distance from where the fitting just dumps water in the jacket without it.

I'm not sure creating a negative pressure area there plumbing a -4AN line connected to the suction side of the waterpump is going to be benifitial and may be the opposite.

The water you are pushing in the block won't maintain enough pressure to do anything once it gets to the head there.
Will

 

You make some interesting points . Keep in mind that the dirt track/Nascar cooling system research and development was aimed at engines that are operated at high RPM levels for long periods of time where it is necessary to slow the water down enough to do its job . I just don't think that same R&D would apply to street driven vehicles with the same intended benefits , particularly on our C4 Corvettes with their marginal cooling systems .
I drag race and my engine sees idle speed for several minutes ... 4500rpm burnout ... then 2-step RPM for a second (2500-3000) ... then wide open throttle for 6 1/2 seconds Max 7200 ... then a short drive back to the pits . In the heat of Florida summers , this sees cooling temps never higher than 170 degrees from start to finish .

 

I get it about the “pushing coolant” to the center of the Siamese exhaust ports, it was published in a technical journal decades ago, and some of the top dirt track SBC builders have done it as you have described. I’ve been a student of the subject for about 30 years, and I used to think the same.

It was on the Speed Talk forums where this was discussed a long time ago with test results showing the significant benefit, and I was a little bit skeptical, how could you effectively pull coolant from this area, it seems like it only works well when the thermostat is closed, otherwise there’s such a huge draw from the radiator return that it wouldn’t be effective. Then I read the discussion where the following was stated, I think I understand it better now:

 

Great info, just note that I'm not trying to restrict the amount of coolant flowing through either the heads or the block. The dwell theory I think is flawed... Smokey was always looking for ways to increase volume, and back then the engines needed at least 100gpm in the operating RPM range (installed on the engine, not freeflow). That's a lot more flow requirement, and their radiators weren't so big either.

If the engine makes 2X-3X more power than stock, the cooling system needs to handle 2X-3X the heat to keep the engine happy.

I'm not directly aiming for better cooling efficiency, other than the type of water pump I'm using (pumps a lot more than the street setups). Pump will be 1:1 driven... most of the old Winston Cup cars were at a much lower ratio not to slow down the pumping volume but to place the pump RPM at the sweet spot for the engine RPM. That's where the street and race cars diverge, I will be closer to a street setup.

So the goal is proper heat management to reduce local hot spots and steam pockets, through prioritized pathways.
In other words, more priority/balance for rear cylinders, and more priority/balance for the center twin exhaust port areas. Better balance means the engine is expanding more evenly, and the minimizing of the hotspots causing steam and rapid temp rise in the area. Lot of people have burned headgaskets in between the 3/5 4/6 cylinders. These areas should be hot but avoiding overheating. It's common for the hot spots to be 300-350 degrees, I'd be much happier with 200-240.

The plugs in the block... they do restrict flow straight from the front block water inlets upwards, but that's partly because it really doesn't make sense to utilize the coolest water entry to go straight up to the intake sides of the front of the heads, and return quickly to the thermostat housing... I don't think anyone is suggesting that this is beneficial, my last set of cylinder heads weren't even drilled at all for the corresponding holes, and it was common practice to use gaskets with a very small hole. So I'm not doing much different, other than strengthening the block and head gasket grip/seal.

From the front of the block, the first upward flow is at the rear of the cylinders. From the side of the block (additional inlet to the side) the most direct upward flow is at the exhaust side of the heads and directly under the twin exhaust ports, then equally to the front and rear.

 

Was cruising our forum and found this excellent writeup...Very well put together, and informative. Thank you AZSP33D. I was wondering about a similar potential issue with my 93 . The difference is if I can bolt a Gen 1 SBC intake onto my LT1, and how to handle any water issues which may popup. The particular intake I want to use is for 8 IDF downdrafts, that does not have any water passages. My guess is that all water in the heads remain in the heads an circulates only between the heads and block counter clockwise. I have not found a diagram showing that, but identified only in text. Am I correct?