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Engine Specific Info and Questions => IDI Engine => Topic started by: starrd on March 21, 2008, 04:11:52 pm
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Thought this might help some people - I rebuilt Jake's rebuild post.
Original is here, but images are no longer working, but I had saved a copy just in case:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1841
Here is where I started today:
(http://members.shaw.ca/dcstarr/images/K24/Pic2.jpg)
The wastegate was stuck...
(http://members.shaw.ca/dcstarr/images/K24/Pic3.jpg)
So following Andy2's advice, I slide hammered those heat shields out of there! Here is what it looked like when they came out... lots of carbon built up:
(http://members.shaw.ca/dcstarr/images/K24/Pic4.jpg)
The wastegate passages are kind of interesting. The gasses flow in toward the wastegate. Could the wastegate really get a good seal on this valve seat???
(http://members.shaw.ca/dcstarr/images/K24/Pic5.jpg)
Some wastegate measurements:
wastegate valve seat ID: 24mm
wastegate valve head diameter: 31mm
wastegate installed travel/pre-load: 2mm
pressure to reach 2mm travel: 10 psi (approximate. Note: it is very "sticky" when completely closed.)
max travel: 10mm (8mm travel from touching the valve seat)
pressure to reach max travel: approx 14 psi
These wastegate pressure measurements pretty closely match what is published in the SAE paper:
(http://members.shaw.ca/dcstarr/images/K24/Pic6.jpg)
Some detail of the turbine wheel. The vanes look pretty aerodynamic. I am impressed overall with the quality of this KKK turbo...
(http://members.shaw.ca/dcstarr/images/K24/Pic7.jpg)
Turbine wheel specs:
OD: 59mm
exducer bore diameter: 49.5mm
thickness of fin section: 21mm
Compressor section "GW" before disassembly:
(http://members.shaw.ca/dcstarr/images/K24/Pic8.jpg)
Here is what the inside of the compressor housing looks like:
(http://members.shaw.ca/dcstarr/images/K24/Pic9.jpg)
Diffuser style is like most modern turbos, a parallel wall diffuser. The outer wall looks like a separate piece of metal that is pressed into the main housing.
Compressor wheel is a backward curved impeller type. This allows for more efficiency although less pressure ratio capability. Detailed shot:
(http://members.shaw.ca/dcstarr/images/K24/Pic10.JPG)
The measurements of the compressor wheel are:
inducer bore: 37.5mm
OD: 60.5mm
And here is what the cartridge looks like (AKA the "guts" of the turbo...) A large colored o-ring seals the compressor housing to the cartridge.
(http://members.shaw.ca/dcstarr/images/K24/Pic11.JPG)
I also tried to get some measurements necessary to calculate the turbine housing A/R ratio...
(http://members.shaw.ca/dcstarr/images/K24/Pic12.JPG)
This thickness of 8mm was measured at a 59mm diameter.
I made some more progress with the turbo disassembly today...
To get the compressor wheel off, I first removed the nut, then I played some heat onto the compressor wheel with an oxy-acetylene torch. At about the point where the wheel got hot enough that the oil residue started smoking, I tapped it into a coffee can lined with some paper towel cushioning. The compressor wheel fell right off.
(http://members.shaw.ca/dcstarr/images/K24/Pic13.JPG)
Behind the compressor wheel, I found four T-30 bolts holding on the compressor backing plate:
(New) I checked the torque and I got 70 in-lbs
(http://members.shaw.ca/dcstarr/images/K24/Pic14.JPG)
After removing those bolts, the backing plate came off without trouble.
Here is what it looks like behind the backing plate:
(http://members.shaw.ca/dcstarr/images/K24/Pic15.JPG)
Anyone have a good source on a rebuild kit for one of these? I'd like to continue taking everything apart, and freshen it up with new bushings, seals, etc as I put it back together
I got the turbine wheel out yesterday...
Here is the thrust bearing exposed. It is resting on two dowel pins in the center section:
(http://members.shaw.ca/dcstarr/images/K24/Pic16.JPG)
This shot shows the back of the throwout bearing and the oil supply passage in the center section. You can see the channel machined into the back of the thrust bearing, (shaped like a "C"), which routes oil from the center section supply hole to the thrust bearing surfaces through two tiny oil galleys that are drilled in the thrust bearing:
(http://members.shaw.ca/dcstarr/images/K24/Pic17.JPG)
To get the turbine wheel/shaft out from here you just have to pound it out squarely on the end of the shaft, to overcome the tension from the piston-ring type oil seal which is holding it in. The seals on both turbine and compressor side are two little piston rings with their gaps offset 180 degrees. Here is how coked-up mine looked just after it came out. There are some really hard, nasty carbon deposits around the turbine seal:
(http://members.shaw.ca/dcstarr/images/K24/Pic18.JPG)
kkk compressor:
blades: 6 major, 6 minor (12 total)
wheel diameter: 60.5mm
inducer bore: 37.5mm
tip height: 4mm
findings: nearly identical compressor wheel OD means pressure ratio capability of the two are about equal. However, ~6% larger inducer bore of the KKK means it can flow a bit more air. There is also a very significantly greater tip height with the KKK turbo (33% greater on the KKK).
garrett turbine:
blades: 11
wheel diameter: 59.00 mm
exducer bore diameter: 49.00mm
kkk turbine:
blades: 12
wheel diameter: 59mm
exducer bore diameter: 49.5mm
findings: except for one additional blade on the kkk turbine, the turbine sections have nearly identical specs.
The trim of the compressor and turbine wheels can be calculated from the major and minor wheel diameters using this formula:
trim = (minor_diameter ^2 / major_diameter^2) x 100
I'd love to measure the A/R of the K24 turbine housing, but to do so requires the accurate measurement of the cross-sectional area of the turbine housing and also of the radius to the "centroid" of the area. I don't know how to do these measurements... got any ideas?
Here is a pic of the turbine housing where it has numbers on it:
(http://members.shaw.ca/dcstarr/images/K24/Pic19.JPG)
Best I can make sense of these numbers is:
"NI CR 202" - the alloy of the metal in the casting. Nickel - Chromium 202, an austenitic grade stainless steel.
"/03 05 83" - looks a lot like a build date. 1983 Jibes.
"5324 101 7097 [1?]" The 5324... number sequence of 11 digits indicates a KKK part number. The 1 at the end might be a casting mistake.
"[1 ...] 39" - unidentified number. Could the "39" be the A/R ratio of the turbine housing - .39? That would be right in the ballpark of what we might expect.
I leakdown tested my wastegate:
(http://members.shaw.ca/dcstarr/images/K24/Pic20.JPG)
I found a steel plate that I drilled and tapped for an air fitting and bolted it sealed to the turbine inlet.
Here's how I sealed the turine inlet area. I jammed a couple thick rubber wedge-shaped pieces deep into it and sealed the cracks with grease. The only route left for pressurized air to go was to to the wastegate valve, though the side port.
(http://members.shaw.ca/dcstarr/images/K24/Pic21.JPG)
Results: Sure enough, the wastegate valve was leaky. At 30psi pressure, it only held 25.5 psi (so it had a 15% leakdown.) For engine cylinder head valve standard, that would be a very poor valve seal. But I am not sure about what is expected for wastegate standards. What do you guys think? Would that much wastegate leakage cause a noticeably added lag in turbo spool-up?
To make sure all the leakage was through the wastegate valve, after the test I remove the wastegate, sealed it's valve, re-assembled, and re-tested. It had 0% leakdown (held the full 30psi.)
Thanks for the info, and also an update: I am having good results with restoring my wastegate valve seal! ( I will be including detailed instructions with my K24 turbocharger rebuild kit. )
original:
(http://members.shaw.ca/dcstarr/images/K24/Pic22.JPG)
restored:
(http://members.shaw.ca/dcstarr/images/K24/Pic23.JPG)
I think I've finally figured out the A/R ratio for this turbo, and it's .3. This comes from the KKK catalog. I also heard that the A/R for KKK turbos are sometimes cast inside the turbine inlet. Well I took a look at mine, and sure enough, was able to locate a "3" right there!
(http://members.shaw.ca/dcstarr/images/K24/Pic24.JPG)
Here is a comparison of my Dieselicious 360 degree thrust bearing upgrade versus the stock 1.6lTD K24 thrust bearing:
(http://members.shaw.ca/dcstarr/images/K24/Pic25.JPG)
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Very imformative post. I'll mark this for future use for sure.
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Jake,
My dieing turbo thanks you...
I buy from Jim & Gerry, G-Pop ShopSpecializing in rebuilt and new turbos,turbo upgrades, turbo rebuild kits, and turbo partswww.gpopshop.com(479)-751-7966
Now whered you get that Dieselicious thrust washer?
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I'm still dying to see the lapping procedure detailed... I cant see how you'd spin the entire waste gate around at high enough speed to get it that clean..
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I did mine last night while watching TV - took about 1/2 hour. That is exactly how I did it. Valve grinding compound and I rotated the whole waste gate. I would rotate about a 1/2 a rotation for a while and then I would index a 1/2 a rotation and just kept doing it, adding compound as required. I did glass bead mine first to clean it up. Here's what it looks like now.
(http://members.shaw.ca/dcstarr/images/K24/Pic28.JPG)
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Good breakdown! Great pics! And from Merrit too! :D
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Excellent!!
I figured just spinning it wouldn't do dick!
but man, what a difference..
Ok, I'm a believer!
8)
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Got my rebuild finished finally. I bought a used K24 and got a kit from Jake. I had problems getting things apart which seems to be an issue with these old turbos. I'm happy with the final result. I borrowed the first 2 pictures, but they look almost exactly like what I started with.
Start
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-1.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-2.JPG)
The good old hot section bolts and clamp plates - can't believe i got these bolts out!
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-3.JPG)
Center section
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-4.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-5.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-6.JPG)
spacer orientation behind thrust bearing
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-7.JPG)
Boost line prior to glass beading and painting
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-8.JPG)
Home made replacement hot section clamp plates
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-9.JPG)
Glass beading results - the NI CR 202 Stainless comes out nice!
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-10.JPG)
Compressor end
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-11.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-12.JPG)
Center section - quite a difference if you look at the before picture
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-13.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-14.JPG)
One of the 4 snap ring retainers for the 2 center bearings - had to modify some snap ring plier tips with the dremel to fit
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-15.JPG)
Wastegate seat re-lapped
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-16.JPG)
Just prior to assembly
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-17.JPG)
Close up of the hot section end of shaft after cleaning - the sealing rings go in the wider groove and are staggered 180 deg
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-23.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-18.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-19.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-20.JPG)
Finished result - looks like Brand new
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-21.JPG)
(http://members.shaw.ca/dcstarr/images/K24/Mine/k24-22.JPG)
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That's impressive work ^^^
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awsome pics and info, just one question, will the exhaust turbine fit out of the casing, or does the turbine casing have to be removed?
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Good work! It really does look just like new. What size beads did you use?
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ahhh you guyd kill me with this perfect turbo re-build stuff?
jake still sells this turbo re-build kits? Can i still get the 360 thrust washer off him?
Beautiful re-build dude, Perfectly clean
good work!
Nice to have a bead blast every now and then
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How do you get the center section off? I have all the bolts off and have pulled and tried heating up and knocking off with a rubber mallet and all that. Any tricks from the guys who have done it?
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Soak the joint with PB Blaster for a few days or more. Then, re-install the clamp plates/bolts so the center section isn't able to cock too much. Then try and get the center section to rotate relative to the hot section. Clamp one side in a vice and use a block of wood and a large hammer to break the joint free, by rotating. Once free, then remove the clamp plates and lift the center section straight up so the impeller doesn't contact the hot section housing.
Another possibility is try and use 2 of the clamp bolts and a spacer to the oil inlet/outlet flanges on the center section and use the bolts to jack the center section off, but I think the above method is a better bet.
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Sweet I will give that a try. Hopefully I can get it out so I can get this rebuilt and start putting the engine together again. It has had some stuff soaking it the last couple days so maybe I will add a bit more and try again tomorrow.
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this thread is damn good and should be saved forsure
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hey all very good right up
does anyone know where these rebuild kits can be purchased from?
thanks craig
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they sell the on ebay, here is the item # 380013005387
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Sorry to bump up an old thread.
I plan to use this as a reference in the next few months but have a question. I was telling a local VW turbo guru friend of mine about my desire to rebuild my own turbo and he says I should leave it to a pro b/c they need to be rebalanced once taken apart and reassembled. Any thoughts? Also where is the best place currently to get a good rebuild kit with that 360 deg thrust bearing? I'm not sure if I'll be picking up the KKK or the Garrett version though.
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gpopshop has kits. call for the k24 kit. If you mark everything well, you can do it with out rebalance. If you want, you can just send in the wheels and shaft for rebalance. New machines will get it better than one from 20+ years ago. CHeck out all the costs. There might not be that much difference between having them do a performance rebuild(includes balance) and you buying the kit and paying for a balance. You will still save by doing t your self, just figure out how much.
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Ok, thanks for the reply.
How do I get ahold of this company?
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Ok, thanks for the reply.
How do I get ahold of this company?
http://www.gpopshop.com/
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Thanks for the save, maybe worth a sticky or a place in the FAQ
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Thanks for the save, maybe worth a sticky or a place in the FAQ
already there :wink:
tyler made an impressive sticky thread with links to all sorts of good relevant topics! its very clean and tidy, so the FAQ doesn't have a bunch of sticky's clogging everything up.
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Anybody know how exactly turbos are balanced? Is there some sort of electromagnetic superconductor that the shaft is placed on for zero friction or what? :wink:
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Little google action turned this up:
TURBOCHARGER BALANCING
FACTS AND MISCONCEPTIONS
One of the most important parts of building a turbocharger that will operate quietly and efficiently for a long time is being sure that the rotating components are properly balanced. The problem is that many people do not know what “properly balanced” really means.
Unbalance is usually expressed as the product of weight and radius. If a one gram weight is placed at a one inch radius on a balanced part, the part is said to be unbalanced by one gram-inch. Modern turbocharger tolerances are typically expressed in milligram-inches, or thousandths of a gram-inch. For example, the Garrett T-3 and T-4 frame turbos generally have component balance tolerances around .010 gram-inches (10 milligram inches).
One area of confusion about balancing is component versus assembly balance. Turbocharger rotating groups are made up of several component parts that are assembled to make up the rotating assembly. Of these components, only the turbine and compressor wheels are component balanced. Balancing of these components is critical, and must be done prior to assembly. The axial thrust spacers and compressor locknut are not balanced, and the mechanical fit of these components are subject to machining tolerance limits. When these pieces are mated a certain amount of “stackup” unbalance is introduced into the completed turbo.
Stackup unbalance is not a major concern with larger turbochargers. Typically, the turbine and compressor wheels in these turbos are balanced to a tolerance substantially closer than required by the assembled turbo. This way, when the components are assembled, the stackup unbalance is not large enough to cause a problem with the complete turbo.
With the increasing popularity of small turbos in automotive applications, stackup unbalance has become more of a factor. Due to the light mass and high rotational speeds of these small units, simply balancing the components to an overly close tolerance may not be enough. The typical symptoms of a slightly unbalanced small turbo are oil leakage from the ends of the bearing housing, and “screaming,” an unbalance induced vibration of the rotating assembly. The fastest, most effective method of eliminating the stackup unbalance that causes these problems is to trim balance the moving parts of the assembled turbo CHRA (center housing rotating assembly).
It is possible to build turbos that are well balanced without CHRA balancing. The turbo builder must be very critical during the inspection and assembly portions of the rebuild to assure the quality of all the components, and their fit with each other. Many of the best “custom” turbo builders do not CHRA balance due to a combination of critical inspection and careful assembly procedures. Higher volume builders of turbos, and shops desiring to have complete knowledge and control of the assembly process, perform some type of CHRA balancing.
There are basically two types of CHRA balancing, high speed (VSR) and low speed (balancing machine). The VSR (vibration sort rig) is a machine that uses compressed air to spin the assembled CHRA to a relatively high speed, while pressure oiling the bearings and sensing vibration of the unit. Small unbalance corrections are then made on the compressor nose or nut to fine or trim balance the unit.
Balancing machine CHRA balancing consists of mounting an assembled turbo CHRA in a conventional two plane dynamic balancing machine. The rotating assembly is then driven at a relatively low speed by belt or air, and unbalance readings are taken on both the compressor and turbine ends of the rotating assembly. Oil is not pressure fed into the turbo, as the shaft is prelubricated before the balancing operation. The low speed and short cycle time preclude the need for pressurized lubrication.
Either type of CHRA balancing will generally eliminate stackup unbalance to an acceptable degree. Machine balancing has a slight advantage, in that the rotating components are dual plane balanced, as opposed to single plane balancing with the VSR. The main advantage of the VSR is that the turbo has actually spun at high speed, so the operator may be able to hear unusual noises from the turbo, and in some cases the oil flow can be checked (though this is not very reliable.)
Another common misconception about balancing is that balancing at higher speeds results in closer balancing. This is not inherently true. A rigid rotor that is out of balance by 10 milligram inches at 1000 RPM will be out of balance by 10 milligram inches at 100,000 RPM. The force created by a given amount of unbalance increases exponentially as speed increases, but the absolute amount of unbalance does not. It is critical that the balancing equipment being used has sufficient sensitivity to balance the rotor to the necessary tolerance at the desired balancing speed, but balancing at operational speed is rarely advantageous. The logistic and safety considerations of very high speed balancing rarely outweigh any accuracy gained.
In conclusion, the key to maximum life out of a turbocharger is proper selection of components, precision balancing of those components, and careful assembly of the turbo. An additional balancing operation performed on the completed turbo is not absolutely necessary in most cases, but it does provide a higher degree of confidence in the final product.
Article copyright 2002, Heins Balancing Systems, Inc., the TURBO-PAC balancing specialists.
The preceding article was written by Mark Bowman, President and CEO of Heins Balancing Systems, Inc. Heins is the world’s largest supplier of balancing equipment into the turbocharger aftermarket, and supplies both OEMs and aftermarket facilities worldwide. For more information, visit the Heins website at www.heins-balancing.com.
Mr. Bowman has been in the turbocharger balancing business since 1975, and regularly gives seminars and classes on turbo repair and failure analysis. Having built turbo systems and turbos, as well as owning turbocharged vehicles, Mr. Bowman has a good “hands on” view of turbos.
And this video:
http://www.youtube.com/watch?v=TMA5RFpGRbg
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starrd, what engine will you use this turbocharger on?
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Subsonic - in laymans terms does that mean if i disassemble a turbo of its moving parts and put it together again it will still be balanced as it is the components that are balanced and they would still be balcned unless i change something on them?
The added "spinning" balance is done more for piece of mind?
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If you mark everything well, and reassmeble it back on those marks, then it should be back to the original balance as it came from the factory. The side note would be--as long as there has not been any contact or damage to the wheels or the shaft.
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You can find Ti hardware form this site
METTEC.COM
GEE-BEE
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Hey I need to know the exact bolt size for the exhaust side bolts that connect the casting to the cartridge. I measured them and they were spot on to 8mm, I picked up some bolts that are under grade 8 strength.
I think I need to re-tap the holes, and try again but if anyone can confirm that they are 8 mm that would be great.
I will post picks of the Hybrid Turbo build.
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Hey I need to know the exact bolt size for the exhaust side bolts that connect the casting to the cartridge. I measured them and they were spot on to 8mm, I picked up some bolts that are under grade 8 strength.
I think I need to re-tap the holes, and try again but if anyone can confirm that they are 8 mm that would be great.
I will post picks of the Hybrid Turbo build.
I will measure a spare one tonight if you like and I will post the info back here.
OK - for K24 the 6 bolts are 8mm x 1.25 pitch x 16mm long
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Thank you sir, I needed that info as I cannot locate the original bolts. Had to re tap all the holes tonight, will take some pics, and build it tomorrow.
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great write up.. should be put in a FAQ or something..
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great write up.. should be put in a FAQ or something..
x2! Actually just mentioned and relinked to this in my build direction query thread.
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Jackpot. That is the link I was telling you about in the other thread, I used it for reference whenever I put my wastegate back on my turbo.
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Pics are down...any way to resurrect?