Cars and Turbochargers

[Obi Heed Kenobi]

Georgetown Loop Railroad still running? That was a fun excursion, but it was about 25 years ago.

You bet it is - I hear the whistle every hour or so. It just opened back up for the summer about two weeks ago. It is amazing how many people love that thing. Actually, I'm one of them!

 

[kgruber]

I bought a Corvair Spyder in 1963. It was a turbo charged air cooled flat six, 144 CU IN 150 Hp.

The only real problem I had was with the fuel pump location. It was right above the air intake for the heating system. They weren't very good pumps and would start to leak about every 10,000 miles. Little drops of gas would get into the heating system.

I also was skiing at Mt Hood, and the drive up to Timberline got the old turbo Corvair pretty hot. So hot that the gasses in the heater would ignite.

Flames would shoot out the defrost. That's when I knew it was time to change the fuel pump.

 

[Obi Heed Kenobi]

I bought a Corvair Spyder in 1963. It was a turbo charged air cooled flat six, 144 CU IN 150 Hp.

The only real problem I had was with the fuel pump location. It was right above the air intake for the heating system. They weren't very good pumps and would start to leak about every 10,000 miles. Little drops of gas would get into the heating system.

I also was skiing at Mt Hood, and the drive up to Timberline got the old turbo Corvair pretty hot. So hot that the gasses in the heater would ignite.

Flames would shoot out the defrost. That's when I knew it was time to change the fuel pump.

I suppose that took care of the fog on the windshield.

 

[Witmo]

Really they tow gliders with them? What type of altitude do you get with a turbo VW?

Totally depends on the length of the tow cable

 

[Henning]

Ah, Henning? That's 114 years of continuous operation. That be some good oil.


James Dean

Oooop, Bad math...100,000hrs They were in operation for 12 years, no oil changes. Linehaul tugs don't sit around much. Considering those engines hold around 120 gallons each, figuring oil at $4 a gallon at 200 hr oil change intervals (which is were we'd change filters), I think that comes to $720,000 in 12 years. That paid for the overhauls.

 

[Dave Krall CFII]

Synthetic based oil definitely stands up to turbo temps better than mineral oil AFaIK, and that's what I've been using in my cars for years. It's also less prone to shearing and thus maintains it's viscosity longer.

I've been driving nothing but turbocharged cars since my first one bought new in 1978,

I've used synthetics for years but no turbos so this will be my first.

The engine guy tweaking my engine out says the turbo he ordered is NOT water cooled and in his extensive aircraft experience it will be fine with a short cool down during taxi and is about 4 pounds less weight up FWF on an already heavy engine application for this airframe. He says he will gladly plumb in the water cooled turbo model if I wish.

Question:
Regardless of cooling type, if I manage to somehow burn up any turbo after landing out on the ocean or out in the sticks, what kind of takeoff power can I expect to then be still available, if any, without working on the engine?

 

[kevin47881]

I've used synthetics for years but no turbos so this will be my first.

The engine guy tweaking my engine out says the turbo he ordered is NOT water cooled and in his extensive aircraft experience it will be fine with a short cool down during taxi and is about 4 pounds less weight up FWF on an already heavy engine application for this airframe. He says he will gladly plumb in the water cooled turbo model if I wish.

Question:
Regardless of cooling type, if I manage to somehow burn up any turbo after landing out on the ocean or out in the sticks, what kind of takeoff power can I expect to then be still available, if any, without working on the engine?

Disregard, I didn't notice we were discussing turbos in aircraft when I initially responded to this post.

 

[Dave Krall CFII]

Disregard, I didn't notice we were discussing turbos in aircraft when I initially responded to this post.

No sweat.
If my engine/turbo/intercooler don't work in the plane, they'll be going right back into a car!
Thanks for the dino/syn link, too.

 

[gismo]

Also, I'm curious about performance at altitude. Obviously, the turbo provides better performance than a NA engine can. Regardless, I haven't been able to find any information regarding the critical altitude (to borrow an aviation term) of auto engines. If anyone has experience or knowledge, what is the general elevation where turbo'd car engines start to lose power (I'm sure it varies from car to car, I'm just looking for a rough idea)?

The "critical altitude" of an automotive turbo isn't usually a hard limit like in an airplane because the automotive turbos are often capable of producing far more boost at full power than is required at almost any plausible (road) altitude. This is done so that the turbo can produce significant boost at fairly low RPM. The more important issue for automotive turbos at altitude is that they would run too fast (turbo RPM too high) if allowed to and actually "explode". To prevent this, the engine controllers open the wastegate (all production automotive turbo installations have variable wastegates) at lower MP when the air density goes below a set limit which could be as low as a few thousand ft at high engine RPM.

BTW, turbo overspeed can also occur if there's a leak in the intake downstream of the turbo compressor so it's a good idea to check the condition of that plumbing occasionally and stay off the gas until you get it checked out if you sense a drop in available power.

 

[Obi Heed Kenobi]

...
BTW, turbo overspeed can also occur if there's a leak in the intake downstream of the turbo compressor so it's a good idea to check the condition of that plumbing occasionally and stay off the gas until you get it checked out if you sense a drop in available power.

What causes that - is it because there is less exhaust "backpressure" fighting against the turbine? If so, I'm assuming it's not a good idea to do any modification to the post-compressor exhaust system (i.e., a more open exhaust)?

 

[gismo]

What causes that - is it because there is less exhaust "backpressure" fighting against the turbine? If so, I'm assuming it's not a good idea to do any modification to the post-compressor exhaust system (i.e., a more open exhaust)?

The cause of the overspeed is the wastegate controller trying to make full boost which requires more compressor RPM than it's designed to cope with when some of the compressor output is lost through a leak. Ironically, if the leak is really big, there usually won't be enough exhaust output from the engine to overspeed the turbo because the exhaust volume is diminished by the lack of boost. IOW, only a small leak will hurt the turbo. Some of the more elaborate engine control computers will actually sense that the boost is sub par, open the wastegate, and turn on the "check engine" indicator.

WRT the exhaust downstream of the turbo, it's common to improve the flow of that if you modify the ECU to provide more boost (manifold pressure).

 

[tonycondon]

saw a Jetta TDI driving down the road today. it didnt have a hitch on it but I was definitely wishing it was mine.

 

[Obi Heed Kenobi]

The cause of the overspeed is the wastegate controller trying to make full boost which requires more compressor RPM than it's designed to cope with when some of the compressor output is lost through a leak. Ironically, if the leak is really big, there usually won't be enough exhaust output from the engine to overspeed the turbo because the exhaust volume is diminished by the lack of boost. IOW, only a small leak will hurt the turbo. Some of the more elaborate engine control computers will actually sense that the boost is sub par, open the wastegate, and turn on the "check engine" indicator.

WRT the exhaust downstream of the turbo, it's common to improve the flow of that if you modify the ECU to provide more boost (manifold pressure).

Gotcha - you meant a leak in the boost system...not the exhaust system. Derrrrr.....

 

[2002 Harv]

Last summer my wife and I drove our 04 TDi Jetta wagon 5sp from Ohio to Boulder Co. Then up to Loveland, over the pass and down into ass pain and back to Boulder. I can honestly say that I didn't notice any difference in performance from Ohio to the pass. I do think it idled a little higher up there but that was it. Now I'm sure that if there was a chasis dyno laying around, we could measure some sort of difference but it wasn't noticeable to me, and I'm a dyed in the wool car guy.

John