How do I...Reverse the coolant flow?

What is involved in making the coolant flow backwards...I forget what they call it...reverse flow, or something...

You know, so it cools the heads first...?

 

I'm not sure about this at all... But i think you would need either a serpentine system(one that specifies it will reverse coolant flow), or an electric water pump, that specifies the reverse rotation...

 

change to a late model 5.0 water pump and belt setup.

 

My understanding is the coolant still flows the same direction. The difference is the impeller is made to work with the belt rotating in a reverse direction. The coolant still flows through the block as it always has.

Any reason you are looking to do this? Not many cars are reverse cooled a couple Honda's and a the vettes I think. They were engineered to do this though

 

It's a waste of time. Tried it a while back on my '74 when it was turbocharged and noticed nothing but the fact that it ran warmer than normal and the heater took FOREVER to get warm enough to be comfy...not that I was too worried about that, but it did take a WHILE.

It is a marketing gimmick from GM that was used on the LT1 engines, possibly more, but for sure the LT1s. They were designed around the reverse cooling.

Our engines were designed to run the water in one direction. If you think about how the water flows through it, you'll see that the water will get heated by the heads, and then the hot water flows through the block...which will tend to heat the cylinders hotter than normal. The heads are where approx. 70% of the heat is (exhaust ports, combustion chambers, etc).

Can it be done? Probably...if you're willing to reinvent the wheel so to speak. Is there a benefit? I seriously doubt it.

 

If you keep the heads too cool, there will probably be carbon build up. I don't see a reason for trying to reverese what 75 years of engine design taught the engineers at Ford.

 

OK, forget I asked.

I just read that some of the higher performing, higher compression engines use reverse flow so the heads stay cooler and the compression can be higher without pinging.

I currently have 8:1 compression...pinging is not an issue, but if I put a blower on it, it might be. So, just thinking out loud, a little ahead of time

 

The trick is to run the coolant at 190 without getting hot spots in the heads.

This is more of an issue of the chevy engine because the middle two exhaust ports got really hot and would pre-ignite under hard running.

The way the coolant flows, the rear cylinders and the front of the head are the hot spots. By reversing the coolant flow and adding additional ins and outs you can get a much more uniform engine temperature. This works best on high performance engines that are driven like high perf engines at the race track for extended periods of time.

Check out the tech articles at www.grapeaperacing.com

They're chevy guys, but they're really smart chevy guys so it's ok.

The 2.3 turbo benefits a LOT from reverse flow, even on street engines. Almost every 2.3 turbo head I've seen has cracked exhaust seats. The other fix for that head is to put a coolant outlet line above each exhaust port, but that gets real messy real quick. I've only seen that done on race engines.

The 4.6 has dual inlets for each head and also a dual outlets on the back of the heads to try and get uniform coolant flow across the engine. So, ford is trying to get better heat transfer in the V8s now.

 

Sounds way too difficult for me. I just want to eventually do a medium low compression 347 stroker with a Rotrex or similar supercharger with a moderate 6-8psi boost. Something I can drive around all day on, without killing my MPGs, yet can get 400-450 HP at the track without refilling bottles.

I may change my mind on some of the details, depending on what the "experts" suggest, but after driving my wife's supercharged v6 bonneville around (238 hp, I think), I can't think of anything but doing the same with the mav, but with about twice the HP...

 

Actually, in our cars, the water goes from the radiator into the bottom of the water pump, the pump pushes it into the block (the two water ports in each side of the timing cover) from the front to the rear. Then the water travels up into the heads at the rear and comes front again to the intake manifold water passages where the thermostat is. When the t-stat opens, the water is allowed to be cooled in the radiator and the process starts all over again.

You're right, most of the heat is in the heads. The purpose of reverse cooling is to cool the heads first, then the block. Back in the 60s and 70s chevy racers would sometimes externally plumb their engines to do this. Don't know that it really helps anything. If you have a good pump and radiator and the water jacket is clean you don't need to get fancy.

 

I remember the Engine Masters challenge. Jon Kaase won with a Ford small block without reverse flow. He was asked and diddnt seem to think too highly of it. It was only worth like 3 degrees or something once the engine reached operating temperature. It's not the reason GM gets away with high (11:1) Compression ratios in street motors eather. Its mostly due to their all aluminum engine and advanced engine control computers. They all have knock sensors now too.

 

Reverse flow coolant systems are really good on high output diesels and piston aircraft engines where cylinder head temps can go above 230 degrees. Reversing your water pump won't do it thogh. All that does is pump less water in the same direction as it is a centrifugal pump and the flow is from the center to the outside of the impeller. You have to place a pump that puts water from the bottom of the radiator into the headsand then let the coolant flow out the block into the top of the radiator.
To make it effective you have to use a coolant that doesn't boil below the highest average temp of the cylinder head. That insures that the coolant will boil at the hot spots in the head. There are a few rules:
1. No air in the system at all.
2. pressure in the system is kept high enough that coolant will not boil over.
3. the coolant is allowed to boil at the hot spots and then condense right back into a liquid as it is carried away (that removes the most heat from the hot spot and allows more coolant to flow over the hot spots.
4. Ethylene glycol is not a good coolant in reverse flow systems.
5. evaporators have to be fitted to the top of the cooling system path to trap and remove any air.

With all the strange stuff that reverse flow systems require and the temperatures that are required for it to work well it is not practical on automotive engines. It is not practical for aircraft engines because of the added weight and since it is not necessary to run diesels that hot to keep them efficient it is not cost effective for them. Basically it is not worth considering.

 

I want an engine that will run "easily" at 400+ HP. In my lo-tech imagination, it seems like a blower would help along a less powerful, but more sturdily built engine, as opposed to building the engine up that high and having something that is not really streetable, and will have a short life-span due to the specialized parts (I think mostly that I keep hearing about rings cut into the wrist pin and having poor oil seals, or something like that).

Also, Wouldn't the blower put my power band down around 4000-6000 (or widen it) whereas a 450 N/A motor would likely have to run higher RPMs for the same HP/Torque?

Again, This is just my non-tech mind making assumptions. The only blower motor I have driven is the V6Bonneville. It runs really nice when you drive it normally, and gets 30mpg. But when you need it, it really kicks in and gets you going, and I know that motor is not the strongest built on the market. But it IS fast! with only 6psi boost.

I could use some web or book sources to read into this and do some research. Any suggestions?

I have at least 3-5 years to think about it, so no big hurry with getting parts together and yanking the engine.

 

I was being modest. I admit I know little about blowers, other than theory, but I knew nothing about Ford motors in 2003 when I got this car, and if you check out my website, you will see how, and how much, I have learned. (sometimes the hard way)

I have no doubts that I can hook up and run a blower, I just need to work out what other parts will perform with it efficiently and effectively without passing my 450 HP limit (I want to stay in a safe range so I can keep my numbers matching block in one piece).

The website you linked to had good information, but was a teaser...it let you read pages 1 and 2, then makes you buy a subscription to read 4-6...

I really want a motor I can get 150,000 miles on without an overhaul. After I paint this thing and drop the engine back in, I don't plan on getting under the hood anymore.

 

PAW (performance automotive warehouse) used to sell complete blower motor longblocks with blowers. I would bet they still do - no core deposit and trucked to local area. That would give you a good starting point as you can pick the components from a selection and specify compression ratio, etc.
If you start with 7.5 or 8.0 compression and have it set up with a max pressure of 13 pounds of manifold pressure it would be a good starting point. If you feel the need to have some help then they have a tech line and you can get info right from them.
The blower can be set up to give posative boost from off idle to whatever RPM you want. They are typically set up to start out at a low boost and very quickly reach maximum boost. A roots type blower is a "posativedisplacement" pump but even they have a range for efficiency - that means the faster they turn the more air they pump per revolution - up to the RPM that they are at or near 100% - from then on it is all the boost you get - but the key is that it is always there. No sudden crankloads like most of the NOS systems (the throttlable are milder) and as long as you keep out the dirt and bugs it will run a long time - maybe not 150000 miles but longer than an equivilent HP normally aspirated engine. You don't have to turn a blower motor as fast as you would a NA motor to get the same HP out of it. Aproperly set up blower motor is capable of 2 HP per cubic inch at around 5500 RPM. The bearings take a lot of abuse but if they are selected and setup properly you won't have a problem with them. Tine-ups will come more often because the pressures in the combustion chamber are higher and the burn is more violent.
A good book for beginners is "Super Power" by either SA Design or Petersen. That will introduce you to the options that you have for turbos, centrifugal superchargers, Posative displacement blowers and nitrous. The easiest on the engine is the centrifugal supercharger (belt driven) but it is not the best for all out power. If you want to go high tech you can build a "gated" blower motor with a clutch drive that runs as a NA engine until you throw a switch which activates a series of solenoids that route the air through the blower (instead of by-passing it) and connect the blower pulley electrically to the engine via 4 or 5 V-belts (or the normal cog belt). Now you have a low output motor that with the flip of a switch becomes a 2 HP per cubic inch monster motor.
It would be easy to build a 5000 rpm blower 302 that gives over 400 HP and that motor could go 80000 miles between rebuilds - maybe longer with pressurized oil starts and 10 qt capacity oil pan.