49mpg possible from full size mechanical diesel?

[oil pan 4]

Originally Posted by ToddT58

That's it... a bit over my head but sounds familiar. Can the bottom end on an older engine handle the turbo?

The 7.3 is a medium to heavy duty pickup engine, quite a bit stronger than the GM 6.2 and 6.5 motors, which by comparison are light duty.

[bondvagabond]

Originally Posted by oil pan 4

The 7.3 is a medium to heavy duty pickup engine, quite a bit stronger than the GM 6.2 and 6.5 motors, which by comparison are light duty.

About the only problem I have heard of with the pre powerstroke 7.3 na idi's is popping head gaskets above 10psi boost, or 15psi boost with arp head studs or 20 psi boost with studs and girdle.

One thing I always loved about the 6.2's was the cooling system burp valve, talk about something every friggin motor should have.

[Isaac Zackary]

Originally Posted by oil pan 4

I saw a 2 to 2.5mpg improvement when I installed a turbocharger.
I put the turbocharger on my engine and changed nothing else beyond the intake and exhaust plumbing. I was also running hot boost.

You have a big high compression IDI kind of like my diesel with the same family of injectors and injector pump as my diesel.

Specific model of turbo for your application?
Big. The biggest cheapest turbo I can think of off the top of my head for your application would be a P-trim T76.
Do not use the OE turbo.

That is what everyone who has a big non turbo diesel says.
I was just like you 5 years ago. I thought my non turbo diesel had plenty of power and didn't think I had any needed for a turbo.
Then when I put the turbo on, I wish I would have done it in 2006 as my first mod.

Read the MPG improvement wiki, I put all my links about studies about turbo chargers increasing fuel mileage in there.

I've got a 1.6L VW diesel 1985 Golf. Do you think it would get better fuel mileage if I added a turbo? Right now I'm pushing 60mpg, and that's just driving, no mods except turning back the max injection so I don't cause an accident from the black cloud it used to cause as I climbed 12,000ft high passes.

[bondvagabond]

Originally Posted by Isaac Zackary

I've got a 1.6L VW diesel 1985 Golf. Do you think it would get better fuel mileage if I added a turbo? Right now I'm pushing 60mpg, and that's just driving, no mods except turning back the max injection so I don't cause an accident from the black cloud it used to cause as I climbed 12,000ft high passes.

This is one area I totally drink the turbo diesel cool aid. If you are routinely going over high passes or towing, the turbo is the way to go. All that black smoke is unburned fuel from not enough air for complete combustion. The alternative would be to turn your fuel screw way down till the smoke is reasonable, diesels don't have the same lean=overheat issues that gas engines have. The 1.6 does not have much power to spare and will get even more gutless with a turned down fuel screw. I have heard it is not advised to ad a turbo to an na 1.6 vw, even though they have same compression, there are some internal differences, forged pistons maybe? I can't remember.

[oil pan 4]

Originally Posted by Isaac Zackary

I've got a 1.6L VW diesel 1985 Golf. Do you think it would get better fuel mileage if I added a turbo? Right now I'm pushing 60mpg, and that's just driving, no mods except turning back the max injection so I don't cause an accident from the black cloud it used to cause as I climbed 12,000ft high passes.

Yes, but do not use the turbo the factory used.
The 1.9L tdi guys seem to like the K04.
I would use at least the KKK made K03 or K04 turbo. I say go big.
If you are at high elevation, go big for sure.
Oh and with the slightly oversized turbo, turn the fuel back up.

[oil pan 4]

Originally Posted by bondvagabond

About the only problem I have heard of with the pre powerstroke 7.3 na idi's is popping head gaskets above 10psi boost, or 15psi boost with arp head studs or 20 psi boost with studs and girdle.

That is not caused by boost pressure alone. When these engines are said to die from ____ level of boost, this largely due to people using too small of a turbo, running high drive pressure, scorching intake air temperatures and no intercooler.

I see up to 20psi of boost when I go back down to sea level. I have a 6.5L block and OE style torque to yield head bolts.
But I run 2 grossly over sized turbos and the boost is intercooled. So drive pressures are much lower than someone trying to force 15psi through a GMx series turbo, and running drive pressure to boost pressure ratios of up to almost 4:1 (40 to 50 psi of drive pressure to make 10 psi of boost pressure).

[oil pan 4]

Originally Posted by bondvagabond

forged pistons maybe?

The original non turbo 6.2L diesel pistons were standard cast aluminum and the turbo pistons were cast hypereutectic alloy.
Both have done very well under boost.
In a 6.5L chevy diesel the forged steel connecting rods will bend before the pistons cause any problem.
Most turbo diesels use cast hypereutectic alloy, some of the newest ones might be using forged since the new pickup truck diesels make 600 to 800 horses under 40 pounds of boost.

For the KKK made K03 and K04 they are both waste gated to limit boost to between 6 and 8 PSI.
If you intercool the boost and limit boost to that level you should be fine.
I would put the waste gate boost line right off the turbo compressor.

[Isaac Zackary]

Originally Posted by bondvagabond

All that black smoke is unburned fuel from not enough air for complete combustion. The alternative would be to turn your fuel screw way down till the smoke is reasonable, diesels don't have the same lean=overheat issues that gas engines have. The 1.6 does not have much power to spare and will get even more gutless with a turned down fuel screw.

That's what I did! With the screw turned back there's no more (or very little) smoke. But I have to keep it floored to maintain 70mph on a straight flat highway.

Originally Posted by bondvagabond

I have heard it is not advised to ad a turbo to an na 1.6 vw, even though they have same compression, there are some internal differences, forged pistons maybe? I can't remember.

The differences that I know of are: 1 the injection pump has a diaphragm that allows more injection only when the manifold has boost pressure, 2 the pistons are different, forged I do believe, and I think have more compression rings, 3 the turbo diesels have oil sprayers under the pistons and, 4 they also have an oil cooler that the N/A diesels don't have.

So would a turbo or a supercharger give better fuel mileage? I don't mind it being gutless without one though. What about making it a miller cycle?

[Isaac Zackary]

Originally Posted by oil pan 4

Yes, but do not use the turbo the factory used.
The 1.9L tdi guys seem to like the K04.
I would use at least the KKK made K03 or K04 turbo. I say go big.
If you are at high elevation, go big for sure.
Oh and with the slightly oversized turbo, turn the fuel back up.

Thanks! Now with the stock injection pump that means the engine will be running lean. Right? Or do you mean turn the fuel up even more? What is my objective here using a turbo? I would guess it would be best to use an intercooler. Right?

[oil pan 4]

I still use the stock non turbo injection pump from my original 6.2L engine on the twin turbo 6.5L, its turned up a little but not all the way. The old 6.2L would smoke some, now with the same injector pump setting with 2 turbochargers force feeding tons of extra air into the engine it only smokes a little if I stab the petal with my foot, with the vehicle in neutral or park. The non turbo injection pump will work perfectly fine.
Don't worry about running lean, diesels always run lean.
If there are any doubts about how well the 1.6L engine can handle a turbo, use an intercooler for sure.