Race rads and the existing thermostat valve.

When fitting larger race rads and oil cooler, is there really any benefit in dumping the thermostat valve from an overall running temp perspective? As I see it, the thermostat will allow water to short circuit in the motor until it is up to temp, after which it diverts it out through the rads?? Therefore all that removing it will do, is mean the bike engine will take a few mins longer to warm up as the rads will be permanently in circuit.

I am not worried about needing the extra minutes of warm up time if I am stuck in the grid etc as I have managed to maintain a fan with the new rads.

Only asking as some rad kits do not seem to supply the thermostat replacement pipe, and the one that has come with my kit is rough as a badger's arse and I reckon I am asking for leak issues if fitted.

Anyone have any experiences to offer?

990Glen said:

When fitting larger race rads and oil cooler, is there really any benefit in dumping the thermostat valve from an overall running temp perspective? As I see it, the thermostat will allow water to short circuit in the motor until it is up to temp, after which it diverts it out through the rads?? Therefore all that removing it will do, is mean the bike engine will take a few mins longer to warm up as the rads will be permanently in circuit.

I am not worried about needing the extra minutes of warm up time if I am stuck in the grid etc as I have managed to maintain a fan with the new rads.

Only asking as some rad kits do not seem to supply the thermostat replacement pipe, and the one that has come with my kit is rough as a badger's arse and I reckon I am asking for leak issues if fitted.

Click to expand...

You are basically correct. However, a thermostat "could" technically fail. During a race, you could have a failure and not realize it, due to being focused on the race, and since you are really pushing the engine, bam. Dead.

There is another factor to consider as well. The flow of coolant in the system. A thermostat slightly restricts the flow of coolant. This isn't a bad thing necessarily. If your coolant is flowing faster, it spends less time in the radiator, and thus has less time to cool. A slower flow (and/or larger radiator) can provide added time for coolant temperature to decrease.

What I've seen in the past on race teams is either they 1.)Remove it completely to eliminate a potential failure point 2.)Remove it, but add a restrictor plate of some kind to maintain the same flow rate or 3.)Just leave it in.

There are options for low-temp thermostats, but really they don't do a whole lot for track use.. sometimes you can use them to chase a cooling issue on track between high load and low load sections, but that is a bit of a band-aid honestly. I'd personally go for a higher pressure radiator cap to improve the boiling point, especially if you are going with a strict distilled water/water wetter mix and sans any anti-freeze.

Thanks for the response.

The oversize top radiator came with a new cap, but its 2.2b which is 1b over standard,
obviously raising other possible failure issues. Might try and find an item somewhere in between.

Am only racing endurance this season, so expect that average pace and subsequent peak engine
stressing will be lower than shorter sprint races. Between the oversize rad package,
a Mocool+water charge and the moderate scandinavian climate, I am hoping that I won't need
the last few degrees of cooling provided by junking the thermostat assembly or the 2.2b cap.
(I have never had temp issues during any track time previously).

990Glen said:

Thanks for the response.

The oversize top radiator came with a new cap, but its 2.2b which is 1b over standard,
obviously raising other possible failure issues. Might try and find an item somewhere in between.

Am only racing endurance this season, so expect that average pace and subsequent peak engine
stressing will be lower than shorter sprint races. Between the oversize rad package,
a Mocool+water charge and the moderate scandinavian climate, I am hoping that I won't need
the last few degrees of cooling provided by junking the thermostat assembly or the 2.2b cap.
(I have never had temp issues during any track time previously).

Click to expand...

Yep, sounds like it won't really be an issue for you. If your in a typically colder climate and not pushing the motor to or beyond it's limits regularly, it's likely not a big concern.

The higher pressure cap can be quite helpful in some situations (typically in summer months with higher ambient temps) and can be a good insurance policy. As the coolant heats up, the pressure rises and as the pressure rises, so does the boiling point. At least that's what I recall from physics/sciences classes, lol. There can sometimes be hotspots within the motor, and if the coolant is able to boil, it can actually act as an insulator (via the bubbles/steam) and cause temps to rise even higher or prevent lubrication of the water pump. Many refer to it as cavitation.

The problem is, water is awesome at heat transfer but kinda weak with a 212F boiling point. Anti-freeze can increase the boiling point quite a bit, but isn't the greatest at heat transfer. If you go with water/water wetter combo, the boiling point also drops, thus the addition of the higher pressure cap can help off-set the difference. Just don't let it get below freezing!