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Cooling system changes for high rpm use.

mine are hella stiff. gm poly tranny mounts at all 3 locations. if you look in the dyno video.....my motor does not move. i was thinkin of all the vibration could be dampened a little by softer mounts the problem might lessen. but your already runnin em. and im going to switch to them.
 
I had a single poly motor mount in mine when it cut loose (both times), I'm back to OE rubber now, at least for the moment.

Like I said in my first post.. in my case I'm not ruling out installation issues as well as other mitigating factors.. i.e. the blown headgasket on the dyno. and if fool up there wants to argue about sudden pressure increases and what "should give" and what "should not give", and cannot understand why shucking a hg at high rpms would cause sudden exit of ajacent freeze plugs, then fool above should not be allowed to continue in this discourse... I can promise that the 'instantaneous' pressure at the back of the engine when this occurred was substantially higher than 11 psi (closer to 30 + cylinder pressure), and nothing came out of the radiator cap. Think about compressibility and time frames for events like this:

you blow the gasket into the jacket and instantly that part of the cooling system is over-pressurized some 200psi +-. Water as most know, does *not* compress much at all, and you've just added half a liter of compressed air right there.. it will immediately start pushing and trying to get out/go where ever and at that point the closest pressure release points are the rear two freeze plugs as well as the freeze plug at the back of the cylinder head. All of which exited stage left in a terrific display of coolant and steam. the pressure wave from the back of the engine never made it to the coolant reservoir, never popped the "11 psi safety valve".

I have a spare 2.5 bar pressure sensor, maybe I'll hook it up to the proefi and datalog some pressures at various points in the cooling system, and see what's up.
 
I tend to think freze plug problems(if they are correctly installed) are most likely due block flex/vibes.Are not most of you guys having these problems running turbo boost pressures(& HP) way above what Volvo probably intended for these engines/blocks to stand? Especially when they get to be 18+ years old?

DO not most hi-perf V8 engine builders go to brass threaded freeze plugs for engines intended to run way above OEM intended HP engine blocks, figuring they will add a bit of rigidity in the freeze plug area, above the OEM press ins?

Actually, no. My dad built a couple of high performance v8s, and the last one he did was quite extreme....actually put out as much horsepower as some of these turbo brickers....500 at the crank.... No brass threaded freeze plugs. However, the first step was always the machine shop. They take the freeze plugs out, clean the block, get all the old paint and grase out, magna flux the block, and put brand new freeze plugs in.

Also, he was running a 190 degree thermostat. Never had a problem except once when he forgot to turn the water pump on....heheheh....always wondered why he didnt hook that into the ignition switch. Now, that particular engine was never ran on the street except a couple of times, drag track engine only. However, his smaller ones, which are more similar to a turbo brick in power, were ran extensively on the street..NEVER had a problem with freeze plugs. Never ran cooler thermostats either.

Anyway, boost itself is not going to increase the pressures in the cooling system. The boost does not get there...
 
as i said before, i dont run a thermostat in my 7mgte, however it reaches operating temp just fine. i use electric fans. the fan switch kicks on at 185deg and off at 170. when on the interstate the fans never run. in traffic, they cycle on/off on a reg basis. i guess it depends on the engine. in the volvo case, you guys have some sort of bleed back port i wasnt aware of. my engine doesnt have this and runs fine except it takes alot longer to warm up when cold outside. but its cold here so rarely that it isnt an issue. i just wait till the temp gauge reads at least a 1/4 of the way before i drive anywhere, cold or hot outside.
 
Alot of this conversation seems to go towards reducing the waterpumps effectiveness to reduce pressure at high rpm. If this is localized boiling causing a pressure spike, the only solution to this is Increased flow to the area of localized boiling. If you look at this photo of the group A head closer, they have drilled several smaller holes next to the cylinders. presumably to balance flow and coolant temps across the head.
gra-topp.jpg

http://www.240grupp-a.se/eng_site/motor.htm
It appears the coolant flows all the way from one end of the head to the other without these holes in a factory head, correct me if Im wrong.
It makes me think of the water manifold used in houses to balance pressure.
waltzm01.jpg


By adding pathways you add flow capacity, and prevent pressure spikes by having a balanced flow, resulting in no hot water scalds in the shower from a toilet flushing...... I imagine, the increased coolant turbulance in the head due to these holes might force stagnant overheated coolent out of the nooks and crannys of the head better, helping eliminate any hot spots there are.
 
Note on using pure propylene glycol, such as Evans.

http://www.uponone.com/howtos/15.pdf

If you are able to keep the water temp below boiling point of water, pure deionized water with some kind of additive with corrosion inhibitor effect like Water wetter would be the best (If your climate allow for this). If you engine have the tendency to boil, Evans coolant is an option or a mixture of anti freeze and water.
 
I do know that Smokey Yunick slowed the flow on water in the block on his NASCAR BBC engines. Said it was pumping too fast. But now they same the opposite.
Nobody is overdriving water pumps in a race app. NASCAR engines run 2:1, or on the big tracks, 3:1 underdrive ratio. They also run a high pressure system.

Actually, no. My dad built a couple of high performance v8s, and the last one he did was quite extreme....actually put out as much horsepower as some of these turbo brickers....500 at the crank.... No brass threaded freeze plugs.

...edit...

Anyway, boost itself is not going to increase the pressures in the cooling system. The boost does not get there...
A V8 is not nearly as stressed as a 4cyl at that HP.
And if a head gasket leak allows cyl. pressure into the jacket, it becomes a high pressure problem.

are you guys making sure the system has no bubbles? via vacuuming down the system, and adding coolant under vacuum?
That is silly.
 
Nobody is overdriving water pumps in a race app. NASCAR engines run 2:1, or on the big tracks, 3:1 underdrive ratio. They also run a high pressure system.
Butthere are a lot of hi flow capacity WP on the market today.

Smokey restricked the hole in water neck/Tstat hsg to 3/4" IIRCC. to slow flow.
 
They do it at the factory for Porsche. ;-)


actually, its standard for a lot of shops... i've been a tech for a good number of years, and have run into this problem on many vehicles. air pockets can cause some serious issues. vacuuming it down and adding coolant take care of it, especially in such a poorly designed system like these are.


most shops have tools for this, and makes it far easier then regular fill anyway.
 
Alot of this conversation seems to go towards reducing the waterpumps effectiveness to reduce pressure at high rpm. If this is localized boiling causing a pressure spike, the only solution to this is Increased flow to the area of localized boiling. If you look at this photo of the group A head closer, they have drilled several smaller holes next to the cylinders. presumably to balance flow and coolant temps across the head.

Smokey's theory was that if the coolant flows too fast, it wouldn't absorb the heat as well. Seems it worked for him in NASCAR for many years.
 
Its really only a problem in cars with awkwardly designed engine and cooling system layouts. The long pipes between the engine and radiator in a Porsche make this necessary. Its just not that complicated in a Volvo engine compartment. Air goes up, water goes down.

actually, its standard for a lot of shops... i've been a tech for a good number of years, and have run into this problem on many vehicles. air pockets can cause some serious issues. vacuuming it down and adding coolant take care of it, especially in such a poorly designed system like these are.


most shops have tools for this, and makes it far easier then regular fill anyway.
 
Its really only a problem in cars with awkwardly designed engine and cooling system layouts. The long pipes between the engine and radiator in a Porsche make this necessary. Its just not that complicated in a Volvo engine compartment. Air goes up, water goes down.



air goes up, water goes down... except when water is being pushed by at a rapid rate. forcing large bubbles into smaller ones and carried around causing then to heat and expand in unexpected areas.
sure once the engine is off, they collect back where they normally would.
I've seen this happen many times, and have seen some a lot of over heating in a otherwise perfect cooling system, once pushed hard.its really nothing new.
 
This is a great thread to have as a sticky. Seems like lots of people are having cooling issues and this is one of the areas that does not have a cut and dry recipe for success yet.
 
When my head gos back on, Ill be going back to the larger of the volvo pulleys to help cooling at idle in traffic (its about an inch smaller than the one I have right now). Ill also be installed the solenoid vavle that is tied into the rearmost head port, and Im thinking about T'ing into the stbd side pipe plug behind number 2 exhaust...something smaller tho, like 1/4 tube which is smaller than 3/16 on the ID......just to eliviate some water from the front of the block too under boost/rpm.
 
Here is a picture of a new Volvo water pump, they have switched to a stamped impeller. Not sure if it is just a cost reduction thing though. Says made in UK, but no other maker markings.

large.jpg
 
We are still talking about this?

actually, its standard for a lot of shops... i've been a tech for a good number of years, and have run into this problem on many vehicles. air pockets can cause some serious issues. vacuuming it down and adding coolant take care of it, especially in such a poorly designed system like these are.


most shops have tools for this, and makes it far easier then regular fill anyway.
Generally, it only saves time on an initial fill when the system is completely drained. If coolant blocks an air pocket, it just expands the pocket, then allows it to contract again. unless you are filling your cooling system in space.
The best way is to use the bleed screw if so equipped, then take your time and allow all the bubbles to migrate to the top of the reservoir, tank, etc.

Smokey's theory was that if the coolant flows too fast, it wouldn't absorb the heat as well. Seems it worked for him in NASCAR for many years.
That silly theory (I never saw any proof that he believed it, but lots of car guys tell that tale)about the speed of coolant was wrong. He slowed the pump so he could make power. Everything he did was in the interest of making power. Power first, longevity second. That's why he was so good.

Toyota's current NASCAR engine does not even have a housing for a thermostat. Big pulley for most tracks, huge pulley for superspeedways, heat the hell out of the oil prior to qualifying but leave the coolant alone, only shut it off if it gets really hot, but about 20 deg. F cooler than the best teams.
 
I have driven multiple 'statless cars that ran cool around town, but would overheat on a spirited drive up the mountain.
This completely cured by installing a thermostat, even one with the pill clipped out.
 
Here is a picture of a new Volvo water pump, they have switched to a stamped impeller. Not sure if it is just a cost reduction thing though. Says made in UK, but no other maker markings.

large.jpg

I've been putting pumps with that impeller design on for years and they always seemed to work well. I picked up a new GMB a couple weeks ago for the 940T just to have on hand and now their new pumps have been internally redesigned/reshaped and are running this impeller:

picture.php
 
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