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Just got a turbo back from being rebuilt and balanced.
Have left a message with the tech who rebuilt it and got it balanced to check when the damage occurred (i sent it without the damage), to see if it happened pre-balancing or after.
Anyone have experience with running a turbo with this sort of damage .. is it going to grenade itself?
Was thinking if it was damaged in transit and balanced with the damage, then it should be ok, but if after, then at 100,000+rpm it *could* cause issues?
Not sure how much luck I'll have with the turbo tech, runs his work out of his shed etc. not a store.
it is a td05HRA with the titanium aluminide wheel mated to a stock 16g6
Do not run that turbo until you have 100% confirmation that those blades were damaged BEFORE balancing. That thing will vibrate so badly and most likely come apart at higher rpms.
And don't let him just say he didn't do it to get out of it, it's going to be a lot easier to buy a $50-100 turbine wheel and re-balance than buy a new turbo+motor cause you ejected a turbine blade into your block lol.
It could be that he uses a file on the blade tips to balance them, but that is a terrible way of doing it IMO, it would take away from the efficiency of the blades by increasing the gap between airfoil tip and the housing. Most people use an ink marker or a little paint to balance the blades/shaft.
Source: Bachelor's in Aircraft Engineering (big turbines lol)
my bet is the damage was there and it was covered by carbon buildup. the glass beading done before balancing just makes it more noticeable. I have run way way more damaged turbine tips turbos without issue. you wont notice a thing. that turbo is ready to run. that type of damage couldnt possible have happened after being build.
Do not run that turbo until you have 100% confirmation that those blades were damaged BEFORE balancing. That thing will vibrate so badly and most likely come apart at higher rpms.
And don't let him just say he didn't do it to get out of it, it's going to be a lot easier to buy a $50-100 turbine wheel and re-balance than buy a new turbo+motor cause you ejected a turbine blade into your block lol.
It could be that he uses a file on the blade tips to balance them, but that is a terrible way of doing it IMO, it would take away from the efficiency of the blades by increasing the gap between airfoil tip and the housing. Most people use an ink marker or a little paint to balance the blades/shaft.
Source: Bachelor's in Aircraft Engineering (big turbines lol)
Thanks for the reply!
They do look like tooled marks instead of damage.
Damage caused by impact wouldnt remove material. impact damage on a ductile material will show bulging and extended deformation to the entire fin. if it is to a brittle material, it would show signs of crack induction and be a lot less consistent.
I've never heard of trimming individual turbine fins to balance .. but I guess it would do the job?
I have a BE in Mechanical Engineering .. and have worked with aircraft repair, AOG support but only with fuse damage from lighting strikes etc, never in powerplant!
my bet is the damage was there and it was covered by carbon buildup. the glass beading done before balancing just makes it more noticeable. I have run way way more damaged turbine tips turbos without issue. you wont notice a thing. that turbo is ready to run. that type of damage couldnt possible have happened after being build.
The tech mentioned he used electrolysis to clean up the parts.
Sorry, not familiar of the process performed pre-balancing etc, I would assume parts would be cleaned before balancing given the rotational speeds and the effect carbon build up would have.
here is one of many images I took of the turbine prior to shipping, rebuild and balancing .. as you can see, its very dirty, but can't see any indication of that sort of damage .. as I mentioned before .. the damage seems very uniform
here is another closeup of the turbo now.
of course it would be good to just get a new wheel, but this wheel is a little hard to find where I am, and I've spent a lot of time trying to get the TiAl wheel to work.
I did a google search of turbine damage and this doesn't really fit with anything i saw, (granted it was all pretty catastrophic failure images!!)
wow thats an interesting video! Thanks for sharing it
This turbo is going into a 1997 Evolution 5.
I just got confirmation that when the tech cleaned the turbo, the nicks were there already (just hidden by carbon buildup).
The turbo went back to him because of a faulty bearing, i had it re-balanced it just to check that the bearing issue didnt throw anything off, the balancing was done at a proper shop, they said the balance was pretty good, not much adjustment required .. so it will hold up to the rpm stress loading (albeit just temporarily on the balancing machine), but how it holds up when pressure and heat are applied on a cyclic basis .. no idea.
Seems like the failure mechanism from TiAl is pretty catastrophic .. glad i stuck with the stock 16g6 comp wheel instead of mating the turbine to push a heavier 20g wheel.
so .. damage noted after cleaning.
balancing done with damage present
goes onto the car this weekend!
hoping it doesnt decide to throw itself into the engine
can't do an upgrade then? i mean i would rather buy a new turbo and save the engine instead of putting a turbo in with fingers crossed. some options to stay stock bolt on in case you change your mind:
can't do an upgrade then? i mean i would rather buy a new turbo and save the engine instead of putting a turbo in with fingers crossed. some options to stay stock bolt on in case you change your mind:
I could upgrade - I have the fuel, brakes, drivetrain to support running more
I drove a 1.8L lancer with a td04 (JDM Lancer GSR) for a few years .. and similar cars inbetween. with the driving style i prefer, due to the traffic, roads, speed limits etc around where I live, having 2nd gear being usable is ideal.
people have different opinions of what usable is of course .. but at the moment i'm running a stock td05hr 16g turbo at 12psi untuned. its running very rich and waiting for this turbo and a tune.
I had a road legal track skyline with a high comp 2.5L straight 6 and a giant garret t04e and in 4th gear over 3500rpm, it was a tonne of fun, but in 2nd when the load was lower, you'd need to wind it out a bit more before it would spool. by then, you're running over the speed limit and unless you pinned it in first, you shift right into the threshold in 2nd and things happen very unexpectedly and quickly esp when rwd.
here i'm hoping to be able to short shift first into 2nd and be well above the boost threshold so I just have to deal with any lag instead of dancing around the threshold line, then take it to 6k which is probably over the speed limit, but not by as much.
the other option would be to use the inconel turbine and drop the housing size to 9.0, with the TiAl wheel I can probably get the same response but with a 10.5t and prserve 'some' top end.
anyway the limiting factor is my stock block which will already be stressed from a tune which has more low rpm torque. id be happy with 300-320whp if the torque curve is right.
i see, dropping to the 9.0 will def spool that thing faster. heck on my stock 8 turbo 9.8, it spools very quick. i could only imagine how much quicker on 9.0. also, im sure the stock block can handle it, 320whp is fine on stock block.
i see, dropping to the 9.0 will def spool that thing faster. heck on my stock 8 turbo 9.8, it spools very quick. i could only imagine how much quicker on 9.0. also, im sure the stock block can handle it, 320whp is fine on stock block.
Yep will drop the size of the exhaust housing if I don't get the torque curve I want.
Will be adding timing to bring on boost as quickly as possible .. so will have to be careful, even at that power level
dang. from those pics it looks like he switched turbine wheels on you.
it does look like that from the pics. The photo of the turbine pre-rebuild as expected has a lot of carbon buildup. Not only from the fact it was a used turbo, but also because I had been troubleshooting some other issues with the car - boost leaks and also an untuned fuel pump upgrade meant I was running really rich from baseline and even richer at times.
The turbine was then sent back to the tech, where it was cleaned in an bath using electrolysis low voltage.
I guess there is some doubt as to the validity of some of the statements hes made .. its tough to tell really. if he did switch wheels, its at least with another TiAl wheel.
new stuff is great, but i have a budget to stick to ... try to stick to. I picked up the turbo from him as a rebuilt unit, sent it back because it wouldnt make any more than 5psi, he pulled it apart, found a faulty bearing, bought new bearings etc, rebuilt it again, and we split the cost of the rebalance (i think it ran me about 50usd) and he sent it back all cleaned and balanced. the guy foot the bill for the new rebuild kit, bearings, half the balancing cost, freight and time in cleaning and assembly.
the photos i have don't show conclusively that the wheel was swapped or anything dodgy happened .. and im not the type to go pointing fingers without proof. might end up biting me in the *** later, but I suppose that is the risk with used parts. He would have sent it back without balancing, I asked for it to be balanced, and I guess its a good thing I did. Apart from what could potentially happen from the now visible damage to the fins (trusting that it was there all along hidden under carbon) .. the balance of the rotating assembly is in check so if anything fails from here on in, its part and parcel of trying to make things go faster right
Carbon covering up those nicks is total BS. Think about that for a second, you've got a high pressure turbine wheel, spinning at 60k+ rpms on a regular basis, completely ignoring all the gases flowing through it at high speed, the centrifugal force alone would through the carbon sitting in those nicks out onto the turbine housing.
You need to ask him if he put those nicks in there for balancing or if he accidently sent you the wrong turbine. High pressure cycling is no joke, that turbine WILL fail. It's not a matter of IF, but WHEN.
If he had gotten a turbine with those damages, any tech worth their salt would have at least rounded out the bottoms to help reduce stress induced failure. A symmetrical notch increases stress factors by 7x, where as a rounded edge or circle increases stress by 3x.
Those will crack at some point and get worse.
Plus, it is highly unlikely that a piece of debris flew into your turbine wheel and took a chunk out of only 2 blades and nothing else, because it would've hit the compressor first, then your valves and pistons, then finally hit the turbine. If your compressor looks perfectly fine, this most likely wasn't caused by normal engine operation.
Carbon covering up those nicks is total BS. Think about that for a second, you've got a high pressure turbine wheel, spinning at 60k+ rpms on a regular basis, completely ignoring all the gases flowing through it at high speed, the centrifugal force alone would through the carbon sitting in those nicks out onto the turbine housing.
You need to ask him if he put those nicks in there for balancing or if he accidently sent you the wrong turbine. High pressure cycling is no joke, that turbine WILL fail. It's not a matter of IF, but WHEN.
If he had gotten a turbine with those damages, any tech worth their salt would have at least rounded out the bottoms to help reduce stress induced failure. A symmetrical notch increases stress factors by 7x, where as a rounded edge or circle increases stress by 3x.
Those will crack at some point and get worse.
Plus, it is highly unlikely that a piece of debris flew into your turbine wheel and took a chunk out of only 2 blades and nothing else, because it would've hit the compressor first, then your valves and pistons, then finally hit the turbine. If your compressor looks perfectly fine, this most likely wasn't caused by normal engine operation.
Hi! thanks for your response, its good to get peoples different opinions
I've asked the tech multiple times about when the damage was identified, and he has categorically said it was apparent when he had cleaned the turbine wheel. He used a low voltage electrolysis bath to clean the parts - I haven't done enough research into whether this should have been the method to clean carbon off titanium aluminide. usually it is used to remove oxidation from steel. perhaps someone here has more experience with what might happen with electrolysis and these alpha/gamma titanium aluminide materials.
I work with aircraft and so am aware of cyclic loading cycles, heat/thermal loading, crack induction/propagation and fatigue. I agree that the nicks to the fins are not ideal with regard to shape, in an ideal world, those damaged areas would have been finished/polished down to a curved profile to remove any stress risers (locations for crack propogation) and zero any micro cracks. then a liquid penetrant test at the least to check that there arent any inherent flaws which would grow (although liquid penetrant can only identify a certain size of crack .. i wouldnt expect to spend the sort of money on any more precise NDT.
quoting the tech, he thinks debris was not passed through the engine, but rather coming up through the exhaust, or debris from a cracked aftermarket manifold or the like.
obviously with gas flow going the opposite direction, it is a bit difficult to imagine debris coming the other way ..
the facts I know:
it was balanced with the damage by a proper tech - it does provide some confidence that the stress from rotation up to 100-200k rpm didnt induce an immediate failure.
it doesn't rule out ongoing cyclic loading and the addition of heat and pressure.
I guess I will keep a lookout for some more TiAl turbines in good condition - this is a toy car for now ..
I have plans on another project.. my daily is a a BMW e36 M3 Evo euro spec with the 3.2L s50b32 pushing 321hp in factory form behind a getrag 6spd. Its tipping over 300,000kms (200,000 miles-ish) and id love to rebuild it and hang two td05HRA-15gk turbos with 9.0t housings off the side
Mar 1, 2016, 01:02 PM
