TR2/3/3A 89mm pistons in TR-3A

[deadair]

Has anyone installed 89mm pistons in their TR-3? If so, have you encountered any overheating problems? Other comments/observations?

 

[Tinkerman]

Hi, welcome to the forum. I installed new 89mm pistons and liners in my engine no problems with the installation. Still don't have it running yet so can't answer your performance questions. Someone else will ring in on that, I feel certain.

Tinkerman

 

[Dale]

Welcome to the Forum. Can't answer your specific question, but there are many here that can. Keep us posted.

 

[Perrymip]

I've had 89mm piston/sleeves for a very long time and without any unhappy consequences.

The topic of TRs potential for overheating has, however, had countless iterations . . . with almost as many candidate causes. Many people have gone to electric fans or some combination of electric and mechanical. Almost everyone who doesn't choose to use a skirted thermostat, has done something to restrict the bypass return hose. Many have converted to the TR6 8 blade fan. 6 blade water pumps. Water wetter. Not to mention a clean system and a well tuned engine.

 

[deadair]

Yeah, I'm completely revamping my cooling system:

* Alloy Radiator
* Electric Fan
* New alloy water pump housing (my cast iron one has pits,
which might be a factor)
* High performance water pump
* Bellows Thermostat

My car heats up so quickly when sitting still, I don't have time to do any tuning, like balance the carbs. It runs at a normal temp on the highway, but I can't run fast enough to keep up (particularly running sideways and stooped over with tools in my hand). So I'm hoping the electric fan and hole-less radiator will make a difference.

For the longest time, I resisted doing anything that wasn't original. Now I'm happy making whatever modifications are necessary in order to be able to drive the ?!%$*&$@ thing.

 

[glemon]

My brother stuck a radiator from an older Volvo on his TR3, it had to be angled a bit to fit, I beleive he can now pull the radiator without pulling the shroud, he say it helps cooling greatly, not a great cost but some fettling and sourcing of parts to get it done.

 

[deadair]

My brother stuck a radiator from an older Volvo on his TR3, it had to be angled a bit to fit, I beleive he can now pull the radiator without pulling the shroud, he say it helps cooling greatly, not a great cost but some fettling and sourcing of parts to get it done.

At this point, I'd consider such an alternative. I'm hoping to be a little more subtle with my mods, though. If I mount the electric fan in front of the radiator, I can keep the original look of the engine compartment. I can always paint the radiator and water pump housing black to maintain the orignal look. But I suspect I'll like the look of the alloy parts in their native color.

Anyway, if I can beat the heating problems, I'll probably refit the engine with 89mm pistons.

 

[trfourtune]

I was told by an expert tr engine builder/tuner that the larger bore sizes cause heating/cooling issues. I am guessing here, but i would suppose that is only with an original, unmodified cooling system.
When i wrote back to him about my particular build with a 20"X20" aluminum cross flow radiator and a 3200 cfm fan with a stewart electric water pump, he did not repond.
I am guessing that i have my bases covered.(hot- extensively modified street engine)
Rob

 

[deadair]

When I did my original rebuild, the sleeves were scored and I had them bored out and fit oversize pistons (I don't recall the size, but I think they were the maximum you could go). I've long suspected that too-thin liners were the source of my overheating problems. I'm going to approach the overheating problem as described above. If the car continues to overheat, I'll rebuild the engine with standard size pistons/liners or fit the 89mm set that has thicker liners.

 

[trfourtune]

thin liners will transfer heat faster than thicker ones so overheating is not caused by this. Water flow, temperature, and pressure, is what the cooling system requires as well as the engine cooling system need to be CLEAN. Overheating is caused by one or more of the above being inadequate. You need a thermostat to create resitance to flow, to cause pressure in the block. The whole system will increase pressure with the temperature rise but you still need that resistance. Triumphs operate at low pressure so an increase in flow or cooling is required. An electric fan is the best, cheapest, and first place to start unless your system is plugged up. IMHO
Rob

 

[deadair]

I was very meticulous during the rebuild: block and head boiled out at the shop and magnafluxed; radiator boiled and tested at a radiator shop. So I'm growing more confident that the new radiator, electric fan, and water pump will fix the problem.

 

[swift6]

Just because a radiator is boiled out and tested doesn't mean that it will operate at peak efficiency. It could still have sediment blocking or impeding some of the tubes. The testing just shows that it will hold pressure. Sometimes the only way to make sure that an "old" radiator is operating at peak efficiency is to have a new core installed.

 

[TR3driver]

Just because a radiator is boiled out and tested doesn't mean that it will operate at peak efficiency.

Indeed, that is true. Had exactly that problem with my 59 TR3A : the tubes were no longer in good thermal contact with the fins so even though the radiator flowed fine and held pressure (as tested by a radiator shop), it's thermal efficiency was lousy. A new core made all my overheating problems disappear.

 

[TR3driver]

thin liners will transfer heat faster than thicker ones so overheating is not caused by this.

A non-sequitor ... the inside of the cylinders is normally much hotter than the water jacket, so better heat conduction between the two WILL increase the heat transmitted to the coolant and hence overheating (since coolant overheating is what we measure/care about).

Our engines operate mostly on thermal expansion ... if the combustion chamber was held at coolant temperature (perfect heat conduction) they wouldn't run at all.

 

[deadair]

thin liners will transfer heat faster than thicker ones so overheating is not caused by this.

A non-sequitor ... the inside of the cylinders is normally much hotter than the water jacket, so better heat conduction between the two WILL increase the heat transmitted to the coolant and hence overheating (since coolant overheating is what we measure/care about).

Our engines operate mostly on thermal expansion ... if the combustion chamber was held at coolant temperature (perfect heat conduction) they wouldn't run at all.

That was my fear. Now the question is how much of this is a factor in my overheating problem? I'll be doing the mods and keeping you all posted on the progress.

 

[MDCanaday]

The real issue with the 89 mm liners has to be the distortion that can happen under stress of hard use.I once saw a motor with 87mm new sleeves that, as the head was torqued down, got harder to turn till at 75lbs it was locked up solid. It was found to be the result of a small burr on the lip of one sleeve.This was enough to cause the cylinder wall to pinch the piston in a death grip!!at only 75lbs of torque.!!!
I would not be surprised if they were just fine for most street use,if properly used.
MD(mad dog)