Is it worth refurbing my turbo?

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Re: Is it worth refurbing my turbo?

Postby esprit888 » Sun 08.03.2009, 21:18

The compressor wheel does exactly that. It compresses the air going into the motor. There are 2 major measurements on this wheel. The inducer and the exducer. The inducer is the smaller diameter measurement (exactly where yours is damaged) measured from the top of the wheel (the chipped edges). This is where the air comes into the compressor housing from your intake pipe via the air filter. The exducer measurement is the larger one, or at the base of the vanes, and this is where the air is driven out of the housing into the engine and creates that wonderful thing called ‘boost’. This is what is known as turbo ‘trim’, it’s just a mathematical equation based on the comparison of inducer and exducer sizes. The trim measurement is (inducer/exducer)^2x100.

The number one cause of turbo failure is lubrication, be it not enough, dirty, too hot or the wrong type. There are also several others such as ‘scrub’, FOI (foreign object ingestion), carbonization, turbine failure (typically crap going out the exhaust I.E a piece of a ring or piston) excessive axial or radial play, etc etc. Without question your ‘damage’ was caused by F.O.I, but don’t think that’s solely through your air intake (although that’s the most common) Many vehicles, including the Elan, vent crankcase vapors into the intake and over time, as I am sure you know, these hoses deteriorate due to heat and oil. Carbon can be a turbos enemy in more ways than one and a hardened piece, or chunk of rubber, that finally comes loose from the inside of the breather hose will cause exactly the kind of inducer tip damage you have. Heat is the big enemy and the warm up/cool down cycles, along with nice clean oil, will increase your turbos life exponentially. Again, for me that wheel should be replaced (attached is a minor nick that warranted replacing the wheel, and this is towards the center, along with how the wheel should look, remember the further out the more critical to the balance as the area you have damage is precisely the point at which the compressor wheel, spinning along happily at over 90,000rpm, slices through the air (saw one cut a guys finger off at the first knuckle once , cut so clean it didn’t bleed for the first 30 seconds!) Just because you didn’t notice a problem does not mean there wasn’t one there! If you had no problems with your rear wheel bearings, but during a service to grease them you noticed chipped rollers, would you stick them back in anyway ? Now ,imagine they were an absolute bugger to get at and you wouldn’t want to do it again………….
Just my 10 cents worth (worth even less now :roll: )


vi11ain wrote:
GeoffSmith wrote:What would worry me is what caused the damage as it should be clean air downstream of the filter, whereas some big lumps have obvoiusly been injested. Is there any way you could have got crap in from outside or is something coming apart in the plumbing?


The only other point I can make is that the turbo was working perfectly and making no funny noises etc prior to removal - in fact it was easily producing 1 bar boost as the point of removing it was to port the wastegate to eliminate boost creep after installing a Peco 2 1/4" exhaust.

So calling all you turbo experts (and amateurs) out there with a camera - please post your compressor wheel photos, failed or otherwise, for the sake of comparison!

Ben
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Re: Is it worth refurbing my turbo?

Postby muley » Sun 08.03.2009, 22:26

dapinky wrote:
muley wrote:It's not far from me, either :)


Distance doesn't really matter when their website states that they offer free collection & delivery :D :D


:oops: D'oh!
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Re: Is it worth refurbing my turbo?

Postby vi11ain » Sun 08.03.2009, 22:53

No worries Colin, I am with you on this - I am taking the turbo in for a refurb and I'm fully expecting them to replace the compressor as it is clearly damaged - I'd be very surprised if anyone would provide a warranty reusing a part like that.

My question was more to see what level of pitting/wear/damage is normal on a turbo compressor of this sort of age. If the blades are usually spotless, then I've clearly got a problem to investigate, but if a few pits are normal, then I'm not going to stress too much.

Having said that, I will be taking a close look at the breather hoses and possibly replacing them next - I certainly want to eliminate any possible sources of future FOD.

Anyone else got photos of their used compressor?
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Re: Is it worth refurbing my turbo?

Postby vi11ain » Wed 11.03.2009, 19:47

I finally(!) managed to get over to Brentford to drop off my turbo. When I asked the guy what he thought of what he saw, he said "Well, that's got hardly any wear at all - that amount of pitting's nothing to worry about and is just due to some dirt getting past the filter at some point - we'll be able to dress that back like new."

When I asked him about the cost of a new compressor, he just said "That won't be needing a new compressor".

He also told me to bring in the actuator when I came to collect the finished unit, so he could check that as well (I'd taken off all the "extras").

So, happy days - it should be done within a week (I told him not to hurry, as I'm not able to work on the car this weekend anyway) - peace of mind (and a 12 month warranty) will be mine!

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Re: Is it worth refurbing my turbo?

Postby esprit888 » Thu 12.03.2009, 07:15

Ben,
There are opposing views on the refurbishment of turbo’s and ‘dressing’ is one alternative. It’s typically done on more expensive turbine and compressor wheels, in particular on the larger diesel engines. After numerous failures GM advised their north American Detroit Diesel Allison dealers to replace damaged wheels as it was deemed not cost effective to attempt to repair them (plus a significant number ‘let go’ and guess where all the bits fly when a compressor wheels disintegrates ! :( ) Not to say your guy is wrong, as he has the parts in hand for closer inspection and we are peering at a picture, but the nick at approx 8 o’clock will take quite a bit of dressing and without seeing it first hand I don’t see how its going to be done without altering the trim and require balancing. From the pic it appears yours was individually balanced as I don’t see any removal of material on the compressor nut (when balanced as a rotating assembly-turbine and compressor bolted together- material is removed as close to the center as possible) Yours looks to have had material removed from the wheel itself indicating it was balanced individually. Don’t forget to show him which blade you bent back into shape (see below in red) and ask him again the cost of a new compressor wheel as they are really not as expensive as you may think (if it is shop around) I assume you will be charged extra for the ‘dressing’ and re-balancing of the old compressor wheel? What’s the cost of a new one in comparison? Pasted below is a quote from a turbo rebuilder:

“Dirty turbo wheels can be cleaned with solvent and a wire brush. Avoid using abrasives and don't sand blast. Do not attempt to straighten a bent wheel blade. Doing so will only weaken it further, causing the wheel to explode when the turbo hits high rpm. A bent blade upsets the aerodynamics of the wheel, reducing pumping efficiency, so always replace any wheel that doesn't have perfect blades.”

There is also a very good Garrett site (start with Tech 101 and work your way up)

http://www.turbobygarrett.com/turbobyga ... ch103.html

Again your decision but the risks in trying to save a few dollars on such a critical engine component can sometimes come back and bite you in the A** (I know !) A crappy analogy would be that I have nicks and a dent on the top of one of my pistons, I could get it dressed down until it’s nice a smooth again, and it will only slightly affect my performance and balance. Refurbish or replace, it’s a tough call.

My 10 cents worth (now 11 as it went up :D )



vi11ain wrote: When I asked the guy what he thought of what he saw, he said "Well, that's got hardly any wear at all - that amount of pitting's nothing to worry about and is just due to some dirt getting past the filter at some point - we'll be able to dress that back like new."

When I asked him about the cost of a new compressor, he just said "That won't be needing a new compressor".



So, happy days - it should be done within a week (I told him not to hurry, as I'm not able to work on the car this weekend anyway) - peace of mind (and a 12 month warranty) will be mine!

Ben
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Re: Is it worth refurbing my turbo?

Postby Monty » Thu 12.03.2009, 12:25

I would say that most M100 owners turbo compressor wheels are in a very similar condition, on the two Elans i`ve had both had pitted wheels and even the spare turbo i bought was in the same condition.

But whilst it`s being seviced and the turbo will be in bits you might as well ask how much it would cost for a new compressor wheel. Might only be another £50 but well worth doing.
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Re: Is it worth refurbing my turbo?

Postby esprit888 » Thu 12.03.2009, 17:49

Hi Monty,
I Guess that speaks volumes to the importance of frequent replacement of the air filter AND the seals around it. I wonder too if aftermarket filters do not perform as well as the coffee can ? Just to be clear i am not talking about pitting, which as you say is common where microscopic dirt or carbon particles hit a compressor wheel rotating at a zillion RPM, more about the chunk missing on the one inducer tip and the bent blade that was straightened. I am a conservative pessamist and change a lot of things that would probably (but not guaranteed :lol: ) outlast me.

Monty wrote:I would say that most M100 owners turbo compressor wheels are in a very similar condition, on the two Elans i`ve had both had pitted wheels and even the spare turbo i bought was in the same condition.

But whilst it`s being seviced and the turbo will be in bits you might as well ask how much it would cost for a new compressor wheel. Might only be another £50 but well worth doing.
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Re: Is it worth refurbing my turbo?

Postby GeoffSmith » Fri 13.03.2009, 00:06

Don't forget that the outer part of the turbo is travelling close to the speed of sound when it running at ~100,000 RPM. I've always been aware of the importance of balancing and I don't think you can underestimate it - I think I correctly calculated that the radial force due to a cubic millimetre at the periphery is ~5kN at these speed, i.e. it's like hanging 20 x 25kg bags of cement on the turbo shaft! :shock:

I didn't take any photos but my turbo was lightly pitted and certainly didn't have any chunks gouged out of it.
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Re: Is it worth refurbing my turbo?

Postby vi11ain » Sun 15.03.2009, 20:26

Well, thanks for all the advice guys, but as I said earlier, the turbo's now in the hands of a professional. I'm going to call him to find out what the final verdict is on the compressor.

Geoff, you need to check your maths, as I think it might be a little rusty: Assuming that a 1 cubic mm piece is missing at the end of a blade, the blade has a radius of 2cm and it's spinning at 100,000rpm, that would give a somewhat less impressive force of 5.9N - just over half a 1kg bag of sugar. :roll:

The turbo is going to be completely disassembled, bearings repalaced, any other faulty components also replaced, reassembled and balanced by a company that only does this kind of work and provides a warranty - I think I'm going to trust their opinion. I'll be sure to let you know what happens with it and provide photos for you to gawp at once I've got it back next week.

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Got my turbo back!

Postby vi11ain » Fri 27.03.2009, 01:34

Hey guys

I've got my turbo back from Turbo Developments now. After a terrifying few minutes when the guy behind the counter thought I was someone else who is due some very bad news regarding his Elan turbo (they very rarely have them in, but they happened to have three in just now!), he remembered my one which was on the shelf, complete and sealed up in a plastic bag. All I can say is that I'm very glad I got them to look at it - they replaced all the bearings, seals etc as well as thoroughly cleaned up everything. They didn't replace the compressor, just dressed it back a little as they suggested that they would. The turbo looks like it's brand new, as you can see from the photos.

While I was there I had a look at a few other compressor wheels from used turbos and they all looked about as pitted as my one was - some more so.

Enjoy the pics and thanks for all your advice. The next step is getting the rotter back into the car!

Ben

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Re: Is it worth refurbing my turbo?

Postby theelanman » Fri 27.03.2009, 02:36

very nice but did you find out what the 'bad news' was??....
if so what??...
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Re: Is it worth refurbing my turbo?

Postby theelanman » Fri 27.03.2009, 02:37

oh and how much was your work :)

:oops: :shock:
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Re: Is it worth refurbing my turbo?

Postby max and andy » Fri 27.03.2009, 06:02

When we first bought maxines car on the way home the wastegate stuck open. No boost. We didnt no that at the time. The local fitter who's main trade is turbo cars. Said it was going to have to be reconditioned. He said at the time it would cost £450 and a few days turn around. So off it went. Or so we thought. A couple of days later they rang to say the car was ready. When i asked about the bill. He said they managed to sort it out in house. The bill was still £450. He said he had trouble getting nuts loose and had to tap a few threds. But he had sorted it. Now thinking about it he probably just wiggled the wastegate and charged for a full recon. He charged more than a recon. Looking at the new turbo above i'm gutted. And i'm sure under the heat shield my turbo looks nothing like the one above. Plus less then 1000 miles later my wastegate is stuck again no boost. What should be the going rate to have your wastegate wiggled at a garage? Andy
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Re: Is it worth refurbing my turbo?

Postby Paul.P » Fri 27.03.2009, 08:30

max and andy wrote: What should be the going rate to have your wastegate wiggled at a garage? Andy


Sounds like you was ripped off big time Andy, there are a lot of unscrupulas places out there !. To anyone who knows what there doing, it should take minutes, not hours, to free the wastegate, so presuming they have a minimun charge, thats what it should be, but £450 is really taking the piss. This is the exact reason that i & many others on here use Gerald at GST Performance, you know what your gonna get !
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Re: Is it worth refurbing my turbo?

Postby vi11ain » Fri 27.03.2009, 09:42

theelanman wrote:very nice but did you find out what the 'bad news' was??....
if so what??...
ta


Ah yes - I saw the "bad news" turbo all right - he brought out a carboard box of parts that had clearly been eating into each other for some time - the turbine shaft had almost no bearing surfaces left on it, the back of the turbine wheel had been badly worn where it was moving back into the heatshield and the compressor wheel was knackered too. Basically the internals were scrap, but I think the housing parts were still usable - they were just being cleaned up while I was there.

The guys suggestion (as the shaft is pretty much unobtainable nowadays) was to fit a shaft from a different turbo to make a "hybrid", which they can do in house apparently.

The work on my turbo came to £175 +VAT, including a 12 month warranty, which I think is pretty reasonable, all told! :)

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Re: Is it worth refurbing my turbo?

Postby muley » Fri 27.03.2009, 10:45

Ben

Ah ha! You saw the insides of my broken turbo before I did. I'm having that one recored.

The other one checked out OK - just a retapped hole!

I'm off now to pick it up.

Max and Andy

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Re: Is it worth refurbing my turbo?

Postby vi11ain » Fri 27.03.2009, 17:44

Ah ha - so they were both your turbos - I think that having three elan turbos in at the same time really threw them!

I'm just glad that you didn't manage to get away with my turbo! :-D Glad to hear that your other unit was ok.

I'll be interested to hear how much recoring your knackered one comes to - it'll help deaden the blow if it ever comes to that in future....

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Re: Is it worth refurbing my turbo?

Postby muley » Fri 27.03.2009, 20:48

Ben

Quote over the phone was £380 plus the dreaded. Phoning around the cheapest I got quoted was £450

I'm not sure if the £380 is for a hybrid, though.

Your turbo looks lovely!

I'll keep you posted

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Re: Is it worth refurbing my turbo?

Postby G UK » Tue 05.05.2009, 11:02

Just dropped my turbo off at Midland Turbo for them to have a look at.

It had an Oil Leak and plenty of play when I wiggled the compressor, not to mention plenty of chips in the compressor wheel. At first glance they thought it may be buggered but they are going to get back to me later to see if its repairable for which they quoted me £480.
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Re: Is it worth refurbing my turbo?

Postby max and andy » Tue 05.05.2009, 11:20

Can you buy a recon turbo? Andy
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