April 19, 2013 at 7:28 am #7698jensenracing77Participant
here is a link. Not much info that we don’t already know but still cool to see them do an article on them.April 19, 2013 at 11:30 am #7699jetfireguyModerator
Enjoyed the article. But left of the maroon ’69 Mustang, it says “….to generate boost (and thus lubricate the turbo’s compressor shaft).”
I know the alcohol and water mixture cooled the turbo and/or engine, but thought the seal and beaaring were lubricated with oil.
Cam someone show me the light? jimApril 19, 2013 at 4:37 pm #7700jensenracing77Participant
lol, I never noticed that. It is getting lubricated with engine oil at all times the engine is running.April 20, 2013 at 9:48 pm #7701JimNoelParticipant
First, it is good to see another article on our little gems! I have yet to see one that has all the facts correct and this one is no exception. Kurt starts out the article by stating the Jetfire was “The Oldsmobile Jetfire was based on the brand’s F-85 compact two-door hardtop”. The ONLY 2 door hardtop in the F-85 line up WAS the Jetfire. The statement implies that you could get a two door hard top in some other F-85 body style, Cutlass or ?…….nope!
He is correct that the turbo system was “over” safety controlled! Three different methods to shut down the boost would have to be all working correct to allow the driver to “feel” the boost. By-pass controller, boost limit baffle in the throttle body (controlled by the fluid metering valve) and pop off pressure cap on the Turbo Rocket Fluid tank.
The dealer mechanics were NOT informed/taught how to service the units when problems arose. Primary fix was replace the turbo unit with another or 4 bbl system conversion. Oldsmobile records, that I checked on back in the 1980’s, stated about 80% of the Jetfire systems were converted to 4 bbl’s by the late 1960’s! Removed turbo systems did not have to be returned to Oldsmobile so the dealers could dispose any way the wanted, scrap them out or the mechanic could take them home. I talked to one mechanic at a dealership in the Chicago area back in the 1990’s and he said he had 13 of them in his basement that were replaced in the late 1960’s.
As for the Turbo Rocket Fluid, it only cooled the combustion chamber, primarily the piston tops. Had NO interaction with the internal turbine side of the intake system. It is injected into the throttle body and goes directly into the intake manifold, only contacting the fined compressor wheel.
Cooling and lubrication to the main turbine shaft and bearings was accomplished with engine oil. The flow of engine oil continuously flooded the shaft and free floating bearings any time the engine was running. Supplied directly from the oil pump to the top of the turbo housing and returning to the right side valve cover…all the time. I have NOT found a single bearing “froze up” on the rotation shaft, ever! The only obstruction that I have found to stop the turbine shaft from rotating is “coking” of oil that has to be supplied with the exhaust gasses to the housing and turbine wheel.This side of the turbo will reach 1500+ degrees and will “coke” oil fast! Primary failure seems to be the rotating shaft seal on the compressor side of the turbo housing allowing the lubrication oil to be forced into the intake, partly burned in the engine and then going to the turbine housing and wheel for final degradation to coke/carbon within this housing.
The turbine shaft is turning whenever the engine is running. At idle and low RPM’s, not fast enough to produce boost greater than the vacuum created and present in the intake manifold.
This has been the Jetfire turbo operation and failure short version………………April 22, 2013 at 7:55 pm #7702jetfireguyModerator
Super explanation, Jim! Thanks a bunch!
- You must be logged in to reply to this topic.