XR Build Thread

John, any update on getting XR lights?

Haven't posted in a while. Its been a cold winter and working in a cramped mildly heated garage is not that appealing. Have been busy with rallycross events though.

Supra Diff since I havent posted a picture of it in yet.


December


Early January


Stock powersteering line rusted threw and blew during this event.


Decent time to upgrade the powersteering cooling anyway and get it out of harms way. There is almost never a moment in rallycross when the wheel isn't moving


Then came the ice events in February.

Course was very icey




Took a look at the rear tires and it seems im missing most of the studs.


Latest event


Car hasn't had one mechanical DNF yet but there are some things that still need to get figured out and fixed.

Photo credit for most pictures go to DaggerSlade media. Great guy who comes to pretty much every event to take photos.

Quote
MarkHille
Ditch the stock "oil cooler". It puts more heat in than it takes out.

For some reason, this is a very common misconception with coolant to oil heat exchangers.

You may be able to argue that the stock oil cooler is not very effective, but it is a violation of the laws of thermodynamics to state that "it puts more heat in than it takes out".

Heat ALWAYS flows from a warmer source to a cooler source. When the engine is warming up, the coolant will heat up much faster than the oil. So, in this case, the heat exchanger is flowing heat from the warm coolant to the cold oil. But, this is actually a good thing - you want the oil to warm up as fast as possible to maximize lubricity. Later on, once the engine is up to operating temp, and you have your right foot deeply planted on the floorboard, the oil temp will exceed the coolant temp. Now the hotter oil will ALWAYS flow heat to the cooler engine coolant. In other words, the stock heat exchanger will never "cause" your oil to get too hot. But, at some point in modifying the engine to put out monster power, you will exceed the heat flux capabilities of the stock heat exchanger, and will have to add an additional cooler. I would recommend putting an additional cooler inline, instead of removing the stock one, so that you retain the oil warmup feature.

Quote
JonArmstrong

Quote
MarkHille
Ditch the stock "oil cooler". It puts more heat in than it takes out.

For some reason, this is a very common misconception with coolant to oil heat exchangers.

You may be able to argue that the stock oil cooler is not very effective, but it is a violation of the laws of thermodynamics to state that "it puts more heat in than it takes out".

Heat ALWAYS flows from a warmer source to a cooler source. When the engine is warming up, the coolant will heat up much faster than the oil. So, in this case, the heat exchanger is flowing heat from the warm coolant to the cold oil. But, this is actually a good thing - you want the oil to warm up as fast as possible to maximize lubricity. Later on, once the engine is up to operating temp, and you have your right foot deeply planted on the floorboard, the oil temp will exceed the coolant temp. Now the hotter oil will ALWAYS flow heat to the cooler engine coolant. In other words, the stock heat exchanger will never "cause" your oil to get too hot. But, at some point in modifying the engine to put out monster power, you will exceed the heat flux capabilities of the stock heat exchanger, and will have to add an additional cooler. I would recommend putting an additional cooler inline, instead of removing the stock one, so that you retain the oil warmup feature.

First I should say that I agree with the laws of thermodynamics.

Maybe my statement was not as precise as you would have liked but I don't think it is wrong especially when put in context. This is a rally forum and I assumed we were talking about rally purposes. At full boost, high rpm, sustained driving the stock cooling system quickly becomes overwhelmed and the temp of the coolant rises to numbers you don't want them. At that point your oil is even hotter (partially because of the turbo oil returning to the block) and adding more heat to your already burdened system. Hence adding more heat than it takes out. You could leave it in and cool the oil somewhere else.....but when you remove it it leaves a perfect little place to put an oil temp valve. Then you plug your oil cooler too it and life is good. You might still be saying it is worth it to leave it in but that would also require leaving all of the unnecessary coolant lines that run to it. To each their own but I prefer not having unnecessary lines of anything, never mind coolant lines, running around the engine compartment. Less things to go wrong and ruin your fun time. And as far as heating up the oil quicker, I've personally never had to worry about my oil temp being too cold especially when you usually have a transit to get to the first stage. (the turbo does a pretty good job at heating up the oil) I'd take it out every time with out thinking twice and recommend everyone else rallying a merkur to do so also, but that is just me.

Yeah I am definitely removing the heat exchanger when the oil cooler goes on. Less coolant lines to fail, less plumbing in the way. Should be fine as long as the motor is warm when you start to race.

Quote
MarkHille
Ditch the stock "oil cooler". It puts more heat in than it takes out.

Quote

For some reason, this is a very common misconception with coolant to oil heat exchangers.

You may be able to argue that the stock oil cooler is not very effective, but it is a violation of the laws of thermodynamics to state that "it puts more heat in than it takes out".

Heat ALWAYS flows from a warmer source to a cooler source.

--->When the engine is warming up, the coolant will heat up much faster than the oil.

Oh.
Really?

That is how people make errors.
The bolded bit is only an assertion.
It like all else is actually a case of "in actual practice a number of significant thing effects which warms sooner including but not limited to size of water rad, size of water rad fan, thermo fan swith on/off temp, thermostat temp, oil cooler thermo stat temp, oil cooler itself.blah blah blah"

This is not for arguing---don't get butt-hurt..

What you are doing is what 90% do: take an idealized truth : water heats up faster than oil heats up...and applying it to a real world situation where there are heaps of variables....

Quote

So, in this case, the heat exchanger is flowing heat from the warm coolant to the cold oil. But, this is actually a good thing - you want the oil to warm up as fast as possible to maximize lubricity.

Wrong you want it to heat up to minimize fuel puddling on cylinder walls and bore wash down, and consequent bore wear and oil dilution.

Quote

Later on, once the engine is up to operating temp, and you have your right foot deeply planted on the floorboard, the oil temp will exceed the coolant temp. Now the hotter oil will ALWAYS flow heat to the cooler engine coolant. In other words, the stock heat exchanger will never "cause" your oil to get too hot. But, at some point in modifying the engine to put out monster power, you will exceed the heat flux capabilities of the stock heat exchanger, and will have to add an additional cooler. I would recommend putting an additional cooler inline, instead of removing the stock one, so that you retain the oil warmup feature.

Once again in actual practice the little Modines are a pain in the ass... the water cooling sysytem has to shed addition heat. Also the execution is a pain--molded curvy hoses buried under the intake manifold, very annoying to get access to, very expensive.
And in the specific case of Xratties with cast iron head and block the Modines literally fill up with crud..nasty horrible crud..

No reasons in practice , today, to retain something so marginally effective when there are simpler and better solutions...

There is a big difference between "ideally" or "in a laboratory" and installed in reality and for our specific use.

Nothing happens in isolation, reality counts, theory or isolated "facts" are the way we make mistakes which later can be annoying at best, costly at worse case.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.



Edited 1 time(s). Last edit at 03/11/2015 11:15AM by john vanlandingham.

Quote
MarkHille

Quote
JonArmstrong

Quote
MarkHille
Ditch the stock "oil cooler". It puts more heat in than it takes out.

For some reason, this is a very common misconception with coolant to oil heat exchangers.

You may be able to argue that the stock oil cooler is not very effective, but it is a violation of the laws of thermodynamics to state that "it puts more heat in than it takes out".

Heat ALWAYS flows from a warmer source to a cooler source. When the engine is warming up, the coolant will heat up much faster than the oil. So, in this case, the heat exchanger is flowing heat from the warm coolant to the cold oil. But, this is actually a good thing - you want the oil to warm up as fast as possible to maximize lubricity. Later on, once the engine is up to operating temp, and you have your right foot deeply planted on the floorboard, the oil temp will exceed the coolant temp. Now the hotter oil will ALWAYS flow heat to the cooler engine coolant. In other words, the stock heat exchanger will never "cause" your oil to get too hot. But, at some point in modifying the engine to put out monster power, you will exceed the heat flux capabilities of the stock heat exchanger, and will have to add an additional cooler. I would recommend putting an additional cooler inline, instead of removing the stock one, so that you retain the oil warmup feature.

First I should say that I agree with the laws of thermodynamics.

Maybe my statement was not as precise as you would have liked but I don't think it is wrong especially when put in context. This is a rally forum and I assumed we were talking about rally purposes. At full boost, high rpm, sustained driving the stock cooling system quickly becomes overwhelmed and the temp of the coolant rises to numbers you don't want them. At that point your oil is even hotter (partially because of the turbo oil returning to the block) and adding more heat to your already burdened system. Hence adding more heat than it takes out. You could leave it in and cool the oil somewhere else.....but when you remove it it leaves a perfect little place to put an oil temp valve. Then you plug your oil cooler too it and life is good. You might still be saying it is worth it to leave it in but that would also require leaving all of the unnecessary coolant lines that run to it. To each their own but I prefer not having unnecessary lines of anything, never mind coolant lines, running around the engine compartment. Less things to go wrong and ruin your fun time.
And as far as heating up the oil quicker, I've personally never had to worry about my oil temp being too cold especially when you usually have a transit to get to the first stage. (the turbo does a pretty good job at heating up the oil) I'd take it out every time with out thinking twice and recommend everyone else rallying a merkur to do so also, but that is just me.

Beer for you Mark... just emphasizing a few things for the others...

Context is everything.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Hey John, you got that box of alternator and power steering brackets? Graham probably needs stuff sent east as well.

Anyone know of any exhaust paint worth putting on? My exhaust is only a year old and is rusting away.

Quote
Thomas Kimsey
Anyone know of any exhaust paint worth putting on? My exhaust is only a year old and is rusting away.

Dude, heat is the best. KILL THE RUST BY ROASTING IT OFF, keep it clean by spraying GRAVEL on it...

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
john vanlandingham

Quote
Thomas Kimsey
Anyone know of any exhaust paint worth putting on? My exhaust is only a year old and is rusting away.

Dude, heat is the best. KILL THE RUST BY ROASTING IT OFF, keep it clean by spraying GRAVEL on it...

So I should use reverse more?

most low speed accidents happen while in reverse.

practice practice practice.

Realize I should probably post an update so that people don't think this car is dead.

Finished off the 2015 Rallycross season with a overall win.



Did the John Buffum Winter Challenge TSD in Vermont. Unfortunately it was the coldest night of the year, below -16F and windy. Even more unfortunately the heat quit working in the car and with no interior things get pretty chilly. I had enough hand warmers and sleeping bags to make it through the night without loosing an appendage but damn was it cold.


Happy faces of everyone getting out of the cold and mobbing a McDonalds in the middle of the night.


Now its time to get serious about getting the car log booked. Pulled the engine on saturday to clean up since the valve cover and front main is leaking. Also makes it easy to stitch weld the engine bay as well as to put the cage in.

Almost forgot, got a puppy this winter and he has been taking up most of my free time.


Going to put him to work soon doing some filming.

On the square end cast VW jack is the normal procedure to cut the square end off and weld on a round bit or leave it square?