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Cooling system changes for high rpm use.

When the blocks are at the machine shops, the freeze plug holes can be tapped for threaded pipe plugs, which will never come out.
On a related note- are racers running without the thermostat?
 
I didn't see any pictures. Are these holes in the head? or in the block...

There is interesting stuff always happening on Savarturbo. I wish I could understand it better.

The holes need to be drilled in the cylinder head deck. There are already holes in the gasket and the block in this area.

One interesting system would be to run a dry block. With just water in the cylinder head. Feeding the head with water parallel in four places from the exhaust port with outlets across on the inlet side. Would give an more even temperature in the cylinder head and the block could be filled completely with block filler.

http://www.topplocksverkstan.se/volvo16vrc.html
http://www.topplocksverkstan.se/volvo16v Turbotopp.html

http://www.polymoog.se/blog
 
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I think its pretty easy and realistic to spin the water pump at 6/7 the stock speed... so I don't think the pump speed is the problem.

If i were to guess, I would think the problem is local boiling of slow-moving coolant creating very high pressure steam pockets with nowhere to go.

So I see a few solutions:

1. coolant with higher boiling point

2. basically porting the cooling system, maping the path of coolant, and improving flow through engine.

good luck to all.
 
Freeze Plugs being pushed out at high RPM:
Its a pressure issue. So by lowering the rotational speed of the pump would help. If there are cooling issues at idle, then possibly an electric fan with a variable or lower cut in speed may help to remedy that.

Burping coolant at high RPM blasts:
Higher quality/boiling point yada yada yada yeah, may fix it. But i think the problem can be fixed by utilising the BMW Map thermostat idea. IF it could be computer controlled, that would be awsome, but a simple swtich in the cabin may be the go.

Temperature rise at high RPM even though there is sufficient cooling capacity:
That may just come down to the design of the cooling system. If it can be re-routed, it could help.......

The end result may be to install a cocker Davies Craig electric pump & controller system. Even if doesnt fix the actual issue/s, the control it allows you to have, may be sufficient to cover them up.....for a while atleast.....

Also, IMO, running a higher pressure cap is just making it worse. Because the whelch plugs popping out is caused by excessive pressure..... so your really, just fixing one issue and pushing another to the limits. You may be able to just run a lower pump speed and get away with it for a while....... Hope i was of some help.......
 
So as a fellow TB'er that has blown his freeze plugs twice....im going to ramble a bit.

3 stages to this problem.

1....bought 91 940 with 17x,xxx miles. stock balancer and stock "small" wp pulley. 15g turbo, IPD cam, AW71, blah, blah, blah. Mikes chips with 7200 revlimit. Car was fun, made 206whp and could rev wot throttle with noproblems. Safe to mention here that the tall gears of the aw71 limits how quickly the stock setup will rev imho. Also, found out later that the water pump had been replaced with an IPD unit that has the 6 stamped steel impeller blades like a chevy pump.

2...start the build of the 16v monster. I had a dales pulley, but wanted to keep the stock harmonic balancer as the dales pulley is just an alum pulley. I end up (by accident) with the larger early model wp pulley from the yard, have the block at the machine shop where they install some Dorman freeze plugs.
Get the whole thing together and about 50 miles on the motor, Im headed to lunch...motor is at 140* with 13lb radiator cap. (at this point during the build I had done a large 2 core alum radiator with standard american cap). I was having the to small of turbo syndrome and could not control boost....the motor would rev RFN and spike to 21psi (I also installed a gm 5 speed). At the 50 mile mark I blew 3 freeze plugs out of the block.
Start the fixing and wondering WTF!
I was able to put some retaining plates over the exhaust side, but since the intake side has the pcv box, I could only plate the forward 2. Drive car for a while and all is better. Didnt really do anything to fix the issue.

3...install better clutch and get a 57trim on there. To this point there have been no problems....now remember Im still tuning and keep the boost low at wg pressure for a while and slowly turn it up to 18psi, but all my runs are made in 3rd gear so the motor is loaded and does not rev out fast from a 20mph takeoff.....which gets us to the Dyno.
I was having boost control issues and could not build anymore than 15psi.....car gets taken off Dyno to do some street time.....get the boost issue solved and end up running the car with no lines to the WG.......pretty much revs out in first RFN, even more RFN than before and spikes to 30psi....wow! Got that fixed and was hitting 25psi on setting the Truboost was on......I make 2 more launches and blow them freeze plugs out that I could not plate on.

Go home and fix the problem...redo the pcv box and plate the final plugs in. Each time Im using loctite #1 for sealant and actually switched to a brass plug the second time around.

Now my remedies that have worked so far...plenty of pulls with no issues.

Kept the stock Harmonic Balancer......made a larger wp pulley. went from 5.375 to a 6.125. Its driven 1-1 now. Got rid of the heater conrol valve that the 9xx cars have thats pre-heater core. Now it flows like an old chevy does. And I install a 3/8 bypass from mid head to the forward side of the thermostat housing.

I should state now that when the motor was rebuilt i bought a Hepu pump that is a brass cast unit with built in cav plate, unlike the jap replacement which had bent impellers.

My findings to this point.

Car has trouble cooling at an idle now, so installed a larger electric fan on the radiator, and since the install is not "ideal", meaning the rad is not completly seal from the engine bay I was getting some hot air recircing to the front side with the hood down. So i installed fan infront the IC to feed the radiator with cool air. WORKS awsome. Tho i never had a problem cooling while driving, and none of my logs show any major coolant rises or splikes under any conditions.

If the 3/8 bypass is open, about takes forever for it to warm up.....................and if you open it up after its warm and drive at highway speeds, I got it to cool down to 160* before I closed it off again!

There is an electronic 3/8 solenoid in the bypass and is controlled by the ECU to open under 1psi of boost or more....so really any conditons that will cause the motor to rev to quickly, the loop is open.

Looking at a 16v head and an 8v head, the 16v already has all the passages opened up, and its just a minor flow restriction in the head gasket....while the 8v has small ports and some are not even present.

Im still leary of it happening, or at least pushing a hose or something, but nothing so far....very happy.

So its stock Harmonic, matching diameter wp pulley, valve gone on heater line to heater core, and a bypass (that could be activated by a nitrous switch or something) and my issues seem to be gone.
 
Rember also the stock pump circulates water that bypasses the radiator, even when the thermostat is open. The inlet is in front of the impeller and there is a lower pressure there, the outlet of the head is the hump on the front. This is part of the higher pressure area after the pump, water will be bypassed the radiator going straight back into the engine. This hole is about half an inch. It's a very simple and crude solution for fixing the problem when the thermostat is closed, so that the pump can circulate water even then.

P1000045.JPG


http://www.daviescraig.com.au/Electric_Water_Pumps__EWP-content.aspx
 
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how about an electric thermostat.

aka an electrically actuated valve.

MS could control it, and when its open, you know its open.
 
No thermostat;
Unless you are drag only, you are bound for failure, and in drag you will only be adding another variable to the equation.

I've never understood this. Unless you can load the engine in such a way as to obtain some perfect temperature equilibrium, there's no way to accurately control operating temp without a thermostat (all other things being equal). Thermostats almost never fail, and if you're so worried about it, then replace it every few races. Removing it is like fixing a problem that doesn't exist.
 
I didn't see any pictures. Are these holes in the head? or in the block...

There is interesting stuff always happening on Savarturbo. I wish I could understand it better.
gra-topp.jpg


The 531 castings was modified with five new cooling canals, the so called "Group-A Canals". The three cooling holes on the farside of the cylinderhead was 4mm and the two ones the far side of the cylinderhead was 6mm. Note the red marked circles below on the pics.

http://www.240grupp-a.se/eng_site/motor.htm

On the same site they show a waterpump with some holes drilled and others welded up for better cooling.........

I know on production cars, part of the reason for the radiator bypass loop is to allow the engine to come up to temp faster. This greatly reduced startup emissions on non efi cars especially. I wonder if volvo eliminated/changed the bypass for racing, cause it works better at the expense of fuel economy at startup. The WP works fine in stock volvo's driven normally....might as well save the gas.
 
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I'm going to chime in a bit here.

1. In any motor we build we only use stock VOLVO freeze plugs. Early on I used dorman and other aftermarket stuff and they would seemingly push out. Started using volvo stuff and have yet to have one come out. All that to say we stock volvo factory freeze plugs now and its all we use.

2. The stamped steel waterpump has an odd number of fins on it, so merely cutting the fins makes it very difficult to achieve a balanced unit and we kept wearing out bearings.

3. If running a B21 or B23 by all means run the Dale or other underdrive pulley. If running a STOCK crank B230 I would be a little on the leary side. Volvo in high RPM testing of engines broke countless crankshafts when originally designing the B230. The design engineer in charge of the cranks as to retool for cranks with a larger radius on all of the rod and main journals as the radius was to small and lead to localized cracking at the number 1 journal. Instead of retooling they created a crankshaft damper to deal with the issue. I've spoken with the engineer and he says anything over 7500-7750 is at risk. Our billet cranks don't have this issue so feel free to run an Avalanche underdrive pulley.

4. DO NOT run without a thermostat. We support a few race cars at the track and in July the temps on the asphalt were around 110*. I showed up a little late and found that guys were gutting their thermostats....and the problem got worse. The coolant was moving through the radiator so fast it could not transfer the heat out of the system. Minor note, once I got him to install the Splash Pan..which helps keep airflow through the radiator as opposed to creating a dead zone behind it the cooling issues went away.

5. It is my personal belief that when these pumps spin up super high they create cavitation and the cavitation creates micro bubbles, when the shockload of head comes it is my belief that those micro air bubbles begin to expand exponentially and the system pressure rises quickly.

6. Internet lore for years has suggested that the cast impellor pumps cavitate less than their stamped counterparts. As such we have only used cast pumps for 6 years now..

7. For cars that our reving to the far reaches of the universe I think an electronic water pump is the best option. But I'm not convinced its the best thing or a street car.
 
I never had a freeze plug pop out ever with dales underdrive crank pulley and the bigger 93+ water pump pulley and I rapped it up to 7.5k and beyond on LH every day. The temp would go up 10 degrees at idle but would then go down once moving. This was with everything stock coolant and radiator wise with regular fan.

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Of course the thermostat should never be removed with the stock pump, only with an temperature controlled electric pump. When the coolant temperature is not up to working level, the pump will not circulate it and the heat will build up quickly leaving the thermostat obsolete. The stock cooling system was never designed to spend much time at the rev limiter and definitely on a raised limiter or on a "race car", so if you are driving very vigorously and are often on the track you should definitely consider an electric pump leaving you with a more balanced cooling system and extra power.
 
why? why not add a rear radiator connected to where the lines for the heater core would have it's feed lines? one could route it under the cowl. along with upping the thermostat temperature.
 
We'll at upper higher RPM's the problem isn't enough rad he ate her, it's the water cavitation from the water moving to fast from the motor spinning real fast. I might be explaining this a little to fast also. Also I did also run a mini little radiator in that spot, actually it was a heater core from a ford van....
 
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