When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Is there a piston ring on the compressor side? The part in your hand is too big to rotate with the shaft and it looks like it may contact what looks to be a rubber type circular seal in the housing in the picture. That may be an axial seal but it should have a radial seal on the shaft, no?
Is there a piston ring on the compressor side? The part in your hand is too big to rotate with the shaft and it looks like it may contact what looks to be a rubber type circular seal in the housing in the picture. That may be an axial seal but it should have a radial seal on the shaft, no?
The part on my fingers mounts on the shaft and rotates on the carbon seal under my hand. The turbine side has no replaceable seal. Just the 4 grooves on the shaft that rotate on a reverse groove in the housing to keep the oil in.
Is there a piston ring on the compressor side? The part in your hand is too big to rotate with the shaft and it looks like it may contact what looks to be a rubber type circular seal in the housing in the picture. That may be an axial seal but it should have a radial seal on the shaft, no?
Here are more pictures of some Jetfire turbo parts. The turbine side has these 4 grooves on the shaft and just spin in a reversed groove in the housing. No rings or replaceable seal. There is a service bulletin saying that if you have a vacuum exhaust vent in the shop and hook it up to the tail pipe of these cars it will suck oil from the turbo exhaust side. I actually experienced this one time. I had my girls turning the oil pump of the engine with a drill and I had a shop vac on the outlet side of the turbo trying to spin it. It was a junk setup, I was just goofing around. It ended up sucking a ton of oil into the vacuum.
Wow, that is very unique. I can honestly say no modern turbo is made like that. It also explains why you find it difficult to remove the heat shields! I'm guessing a significant amount of oil gets passed through to the downpipe (depending on operating condition). I'm also really surprised that large disc rotates on the shaft. All kinds of reasons why you wouldn't want to do that but, hey, I guess it worked.
You're doing a great job. Very nice.
Wow, that is very unique. I can honestly say no modern turbo is made like that. It also explains why you find it difficult to remove the heat shields! I'm guessing a significant amount of oil gets passed through to the downpipe (depending on operating condition). I'm also really surprised that large disc rotates on the shaft. All kinds of reasons why you wouldn't want to do that but, hey, I guess it worked.
You're doing a great job. Very nice.
They actually don't use any oil as long as the compressor side seal is good. I think there is a greater issue of exhaust coming back into the oil cavity than oil out. I am not an expert so not sure that is happening? There is a void between the pressurized bearing cavity and reversed groove so the oil is not pressurized in this area.
Not ready to bolt on the car yet but getting close.
Now that is some serious resto work. You remind me of a watchmaker with that amount of detail and knowledge. Well done. That turbo set up is like art work. It would go nice on a coffee table and I could look and talk about that for a time or maybe Im just weird?
Two steps forward and one step back. I had tested the water jacket of the throttle body last year when I built it and all was good. I had forgot to test the turbo's water jacket before I bolted the carburetor on. I decided to test the throttle body and turbo water jacket all at once after it was together and sure enough, I am leaking. I pressurized it to 15 lbs and no leak. I have a turbo blueprint I got from Jim and it shows it needs to hold 25 psi. I bumped it to 25 psi and started leaking. After that it would not even hold 15 psi. I pulled it back apart and decided to use a really small amount of RTV on it with a new gasket. I also used a torque wrench and tightened the screws to 40 inch lbs where before I just tightened them with a screwdriver as tight as I could by hand. I will test it again tomorrow
All depends on operating point as your turbine inlet pressure will, obviously, change - along with compressor pressure, thrust load, etc. Depending on where you're operating on your compressor map, all kinds of things can happen - especially when it comes to oil leaking past the end seals (very dependent on turbo speed, oil pressure and compressor pressure) or air/exhaust pushing into the oil cavity (blow-by).
Too bad your compressor water jacket leaked. I'm guessing the compressor side castings are all aluminum. Did you check to make sure the sealing surfaces were flat and had no gouges when you reassembled? Compressor outlet temps can get very high. If this unit saw any time in its life with no cooling water there may have been some warpage on the flat surfaces.
All depends on operating point as your turbine inlet pressure will, obviously, change - along with compressor pressure, thrust load, etc. Depending on where you're operating on your compressor map, all kinds of things can happen - especially when it comes to oil leaking past the end seals (very dependent on turbo speed, oil pressure and compressor pressure) or air/exhaust pushing into the oil cavity (blow-by).
Too bad your compressor water jacket leaked. I'm guessing the compressor side castings are all aluminum. Did you check to make sure the sealing surfaces were flat and had no gouges when you reassembled? Compressor outlet temps can get very high. If this unit saw any time in its life with no cooling water there may have been some warpage on the flat surfaces.
The surfaces were really good and flat. I only used air and not water the first time. Tonight I used water to start off with and it held 20 PSI. I did not push it past that. The car has a 15 lb cap so it should never get that high. I had some literature from the Heritage center that said they added the water cooling to the throttle body to prevent it from icing but it did not say why they added it to the turbo. The prototypes had no cooling jackets. they added that a very short time before they went into production.
Interesting. Any late addition prior to production launch only happens when absolutely necessary due to cost. Even then, manufacturers do their best to keep the changes as low cost as possible. To introduce something like that compressor water jacket so late would lead me to think they still couldn't control the high compressor temperatures with just the throttle body cooling. Chances are the turbo manufacturer knew the risk and was working on incorporating it for some time and then a collective decision was made at GM to add it prior to launch.
Do you know what pressure ratio it's making? Some (certainly not all) modern systems go 5+. When you pressurize air you naturally increase its temperature so compressor out temps can easily approach 250C (not F). This is why after stage coolers are often used to bring the temps down prior to entering the throttle body. Adding another heat exchanger after the turbo would have been $$$ so they probably decided to try and make everything work with water cooling the throttle body. When that proved insufficient, they probably added the next cheapest option - water cooling the comp cover.
I'm sure everyone else following your build is sick and tired of hearing us talk about turbos but this is really interesting. It's fascinating to see how they did things back then. I may work with turbos every day but I'm in no way a 'turbo guy'. I'm obviously into the older muscle cars so this is a very rare opportunity where two worlds are colliding!
Do you know what pressure ratio it's making? Some (certainly not all) modern systems go 5+. !
I can't say I even know what that means. I am sure others enjoy reading what you have to say also. Feel free to comment anytime. Thanks for taking the time on this. I enjoy hearing from someone that know something about turbos. I am a restorer, not a fabricator or designer of any kind.
Atmospheric air is 14.7psi. This is also 'zero gauge pressure'. Turbos are really nothing more than glorified air pumps so boost pressure can be categorized by how much of a multiplier it is (e.g. 2x, 3x, etc.) over atmospheric. So, 2x would be a pressure ratio of 2. Seems like you have a fair amount of factory and aftermarket information on the production turbo. It should tell you somewhere how much boost (measured in psi) it's capable of. I think I've even seen a pretty cool looking factory boost gauge on some of these cars (mounted on the console?).
The more boost you're making, the hotter your compressor outlet temps will be (and the more heat you'll be putting into that water jacket). It's also interesting to consider what GM may have considered a typical 'duty cycle' for these applications. If they assumed the average buyer was going to be a 70 year old woman (no offense to anyone!) who only drove the car to church on Sunday, those comp outlet temps weren't going to be too high and they would've decided against the added cost of the comp water jacket. Conversely, if they assumed the average buyer was going to be a 20-something guy who was going to peg the boost meter pretty often, they needed that water jacket to avoid warranty in the way of failures as a result of those high compressor temps. Since they decided in the 11th hour to add the cooler, it may give us an indication of how conservative they were in their market projections for the turbo cars.
Most of the factory turbos were around 5 to 6 PSI of boost. Factory claimed 6 but most were closer to 5 from what I understand. I hope to be getting roughly 6.5 from mine when I am done with it. Before I took it apart, the bypass valve was stuck and I did not know it. I boosted and hit 10 to 11 psi. That popped the safety release on the fluid tank and quit injecting the water. 11 PSI is really bad and even more so with no water injecting. It is supposed to limit the boost if the water is out or not working but the valve that limits the boost in the throttle body was also bad, lol. It was the perfect storm of nothing working proper other than the turbo. It pulled really hard though and the engine survived. I will rarely push it that hard after it is back together. I will a couple times for sure because I want to make a really nice video of it.
You may have already seen this video but if you fast forward to the 2 minute mark I drive it and boost with it.
Thanks for all the extraordinary details on your build Eric!! Just like your W30 build, it's so interesting to follow along! The great length you've gone to in showing all the turbo parts & how they work is quite an education! I've always had a soft spot for the '61-'63s. My first car(went halves with a buddy when I was 13) was a '63 Cutlass convertible that didn't run. We paid a whopping $50 for it! It wasn't a Jetfire but It did have the 4bbl carb. I learned allot about cars working on it.
Thanks for all the extraordinary details on your build Eric!! Just like your W30 build, it's so interesting to follow along! The great length you've gone to in showing all the turbo parts & how they work is quite an education! I've always had a soft spot for the '61-'63s. My first car(went halves with a buddy when I was 13) was a '63 Cutlass convertible that didn't run. We paid a whopping $50 for it! It wasn't a Jetfire but It did have the 4bbl carb. I learned allot about cars working on it.
Thanks. You don't happen to have any old pictures of the car do you? I love seeing older pictures of these cars.
That really looks nice. All of the contrasting colors and finishes really make everything stand out. One thing that occurred to me seeing the installation - as a rule of thumb, OE turbo applications are typically mounted with their shaft parallel to the engine crankshaft to avoid engine firing related vibration that could cause poor shaft motion behavior. It's very rare to mount one with the shaft perpendicular to the crank.
Good luck firing it up.
Now that is some serious resto work. You remind me of a watchmaker with that amount of detail and knowledge. Well done. That turbo set up is like art work. It would go nice on a coffee table and I could look and talk about that for a time or maybe Im just weird?
I missed your post till now. Thanks. I feel the same way about using the turbo for display. I took the car and an extra display engine to MCACN and I had a long line of people waiting to get a chance to look at the engine and turbo syatem more than the car.
as a rule of thumb, OE turbo applications are typically mounted with their shaft parallel to the engine crankshaft to avoid engine firing related vibration that could cause poor shaft motion behavior. It's very rare to mount one with the shaft perpendicular to the crank.
Good luck firing it up.
I sure didn't know that. Maybe that is one of the things they learned from these cars?
One other thing I noticed in the mounting picture - the passenger side exhaust manifold feeds the turbine inlet. Where does the driver's side manifold dump? Does it have a typical downpipe or does it wrap around and somehow join the passenger side to also feed the turbine?
Obviously a turbo increases exhaust backpressure so you don't ever want to 'block' one bank and not the other. I'm NOT trying to pick the car apart - it's a great piece of engineering from the early '60's and you're doing a fantastic job bringing it back. It's just really something to see what they did back then before a lot of application lessons got learned.
One other thing I noticed in the mounting picture - the passenger side exhaust manifold feeds the turbine inlet. Where does the driver's side manifold dump? Does it have a typical downpipe or does it wrap around and somehow join the passenger side to also feed the turbine?
Obviously a turbo increases exhaust backpressure so you don't ever want to 'block' one bank and not the other. I'm NOT trying to pick the car apart - it's a great piece of engineering from the early '60's and you're doing a fantastic job bringing it back. It's just really something to see what they did back then before a lot of application lessons got learned.
They used a crossover pipe and all the exhaust from both sides go to the front and to the turbo. I have a magazine article from the early 60's that showed to wrap the crossover pipe with heat tape to help hold the heat in to get it to the turbo.
Thanks for the details. That makes a lot more sense. It'd be interesting to see what the exhaust gas temperature (T3) going into the turbine would be with the wrapped x-over vs. not wrapped. The more heat you retain in the turbine, the better your efficiency and shaft power. This is one of the reasons aftermarket turbo applications that mount a turbo under the body or even at the rear of the car when there's no under-hood real estate are very poor investments and are way more trouble than their worth.
For anyone interested in more turbo application theory, there's an older book that you can still find around called "Maximum Boost" by a guy named Corky Bell. I think it was published sometime in the '80's but the basic application guides still apply for aftermarket enthusiasts. Being older, it goes into detail about turbocharging cars with carbs. That's almost unheard of today since everything is FI but you may find it interesting since it's applicable to this car.
No pictures but I took it back to the body guys house today. He is going to repaint inside the trunk area. I had originally had him not paint the bottom side of the trunk lid and was going to keep the majority of in the trunk untouched. Well, now it just don't look right at all. With the original paint against the base clear I decided I want it done also. He said he would have it done in a few days but I hope to not pick it up till next weekend. With the car gone I am going to clean out the garage again and stage some more of the parts in the garage that I have stored in the basement. I will not be doing to much with it till after the first of the year but when I do, it should really start coming together.
...I have a magazine article from the early 60's that showed to wrap the crossover pipe with heat tape to help hold the heat in to get it to the turbo...
Wrapping pipes and headers is done so that the exhaust gas moves more rapidly
No pictures but I took it back to the body guys house today. He is going to repaint inside the trunk area. I had originally had him not paint the bottom side of the trunk lid and was going to keep the majority of in the trunk untouched. Well, now it just don't look right at all. With the original paint against the base clear I decided I want it done also. He said he would have it done in a few days but I hope to not pick it up till next weekend. With the car gone I am going to clean out the garage again and stage some more of the parts in the garage that I have stored in the basement. I will not be doing to much with it till after the first of the year but when I do, it should really start coming together.
Your painter is so familiar with these cars now, I almost want to ship my car to him. With labor rates what they are here, it might be worth it.
Yeah, it's holidays now, so getting project stuff done is way tougher. Come the 2nd of January though, nothing to do but build!
Your painter is so familiar with these cars now, I almost want to ship my car to him. With labor rates what they are here, it might be worth it.
Yeah, it's holidays now, so getting project stuff done is way tougher. Come the 2nd of January though, nothing to do but build!
he only does this stuff in the winter and installs pools in the Summer. He just told me yesterday that he is taking this winter off from major car projects and doing a major house remodel job for someone, lol. He does fantastic work on pools, construction, and cars but is hard to get in to have a car done. When he starts on a car it don't take him long though. If you happen to decide to do that you would want to arrange it nearly a year in advance.
Got the car back from the body guy. I decided to work on the back end of the car today. Installed lots of NOS stuff and repainted the center of the rear molding. I painted it just a little to thick but it is ok. I located an NOS one and not sure if I will use it or this one.
