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Thermodyne Turbo Upgrade


Schmidt
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I have a 58 B-61 with a naturally aspirated 673 Thermodyne which I would like to upgrade with a turbo. I thought about swapping the engine but mine only has 90K origional miles on it,ie. no rebiuld and runs great. I have 2 later model turbo setups a 1973 and 1978 with an intercooler, both Macks. Do I need to strengthen the bottom end? Change pistons to lower compression ratio? And how much boost will she handle?

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If it is going to work for you then change engines because that engine there has no piston coolers and the pistons are a high ratio on conbustion and it may not have a oil cooler and if not that means it has not gfot a full flow oil filter.Find you a 237 engine and you will be happen that is if you get a larger air cleaner on it.

glenn akers

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This question comes up alot on this site -

If you are up in Durango, Colorado you probably need all of the extra power you can get from a turbocharger.

Unfortunately using the normally aspirated Thermodyne diesel as a base isn't the way to do it.

It's not designed for any boost at all, and it will self-destruct under the added stress.

There were several models of factory turbocharged 673's with the necessary modifications, the latest having piston oil coolers. They work pretty well.

Glenn is absolutely right - find a 237 Maxidyne for your use, and sell the 673 to finance it, if necessary. You'll be delighted with the difference.

If you are using an original Mack transmission you probably don't want any more torque than the 237 will give you, or you need to treat it pretty carefully. The transmission becomes the weak link when the power goes up.

Doug Fetterley says: "Drive it like you own it, and you'll be fine". He's probably right.

There will be some head scratching involved in getting the clutch linkage reversed from a push type to a pull type operation, but nothing that's that difficult.

237's are getting old, and a little hard to find, but they are out there. They make almost a perfect engine for our old trucks in that they are cheap, reliable and easy to operate.

Good luck with your project and keep us posted.

Paul Van Scott

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This question comes up alot on this site -

If you are up in Durango, Colorado you probably need all of the extra power you can get from a turbocharger.

Unfortunately using the normally aspirated Thermodyne diesel as a base isn't the way to do it.

It's not designed for any boost at all, and it will self-destruct under the added stress.

There were several models of factory turbocharged 673's with the necessary modifications, the latest having piston oil coolers. They work pretty well.

Glenn is absolutely right - find a 237 Maxidyne for your use, and sell the 673 to finance it, if necessary. You'll be delighted with the difference.

If you are using an original Mack transmission you probably don't want any more torque than the 237 will give you, or you need to treat it pretty carefully. The transmission becomes the weak link when the power goes up.

Doug Fetterley says: "Drive it like you own it, and you'll be fine". He's probably right.

There will be some head scratching involved in getting the clutch linkage reversed from a push type to a pull type operation, but nothing that's that difficult.

237's are getting old, and a little hard to find, but they are out there. They make almost a perfect engine for our old trucks in that they are cheap, reliable and easy to operate.

Good luck with your project and keep us posted.

Paul Van Scott

I put a 237 in front of a quad and drove it for years that way, used the push type clutch and flywheel. Had no trouble what so ever. terry
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I put a 237 in front of a quad and drove it for years that way, used the push type clutch and flywheel. Had no trouble what so ever. terry

I've done that too, and it works just fine as long as it's driven properly and shifted smoothly.

.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Hey guys, thanks for the advise and direction. I have been keeping to the back roads and looking forward to a little pavement. I'll get some pics downloaded and am happy to keep you all posted. She's a rough old girl but do hope to take her to the prom some day. "So to speak"

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