Twin Charged Corrado by Dylan

31 minute(s) of a 63 minute read

Twin Charged Corrado

Courtesy of Dylan @ michiganvw.org

So parts have been coming in last week and fedex just dropped off a bunch of parts today. Project started yesterday will the tear down. 

1990 G60 Corrado Lysholm 53mm pulley currently boosting 20 psi at 6000 RPM, 12 psi at 2K. Going to try and help that a little with this. 

.60/.63 T3 Turbo will be compounding the boost and hopefully bring up the bottom end boost numbers and maintaining the pressure all the way to redline without sacrificing lag. 

Day 1 

(or night1) one damn intake bolt stripped on me and I was fitting it for over 2 hours. Needed a break and to collect my self so a late night Taco Bell run with the girlfriend and came back with a new game plan. Got the bolt out, I guess all I needed was a little food in me and she is sitting with the intake, exhaust manifold, and down pipe all on the floor next to her. Hopefully tonight I can test fit the turbo manifold and bolt up the turbo.

Day 2

Jake came over to play a bit. We bolted up the turbo manifold. Its just an 8v manifold so nothing special. Fit was dead on so I thought we were doing good. Well, that thought didn't last long. After clocking the turbo and wastage there is just about no clearance on the cold side to the firewall. Jake started taking apart the interior and became spiderman and crawled under the dash to see how much inside clearance we had to "move" the firewall. After a hour or so of figuring we wouldn't hurt anything, we broke out the 5 lb and a 2x2. Some persuasion and the firewall was a lot further back than we thought we could move it. 

So next was bolting the turbo up again. Perfect!!!! (so we though). There is now enough room to stick your entire hand behind the turbo. Next was to test fit the intake manifold. We cut off a tab that was not needed (what really is needed on the corrado intake manifold anyways). Surprising a cutoff wheel is slower than a cheep wood hand saw lol. Set it in and ... crap the .60 A/R cold side it hitting the intake manifold. After countless ties to take the turbo out, reclock it, put it back loose and clock it, there is no way to get it to clear. I was just going to get a smaller turbo  but Jake wouldn't have it lol. 

We decided that we can space the turbo back (towards the clearance firewall we just made). So this morning I'm having a 1/2" spacer cut and if anyone has a t3 inlet gasket for sale, let me know. I clearance some firewall some more so hopefully, we will still have room with the spacer. 

Here she is though in there. Looks like the intake/charge pipe and down pipe should be relatively easy to route. Crossing my fingers

Day 3

Well I didn't do too much on the car today. The mower broke last weekend and I was able to find a new motor for that so mower motor swap comes before corrado. Tabby was able to make me the spacer that I needed to hopefully clear the intake manifold. I'll try and test fit it tomorrow night. Here is the flange.

Here is the old mower motor. Single cyl 5.5 tecumseh.

Here is the replacement. 20 HP B&S opposed twin. Figured some of you guys may like this swap.

Boog, yes its turbo feeding super. The turbo has a lot more volume than the super does. There will be no bypass for the supercharger because I'm going to try this as a compound setup. 

How it "should" work is that the supercharger alone can make 20+ psi at the top end (about 6k). Pressure ratio is (14.5+20)/14.5 = 2.379 at redline. At about 3k I make 8psi of boost so (8+14.5)/14.5 = 1.55

These are all numbers at the manifold. Now add in the turbo. It will full spool at about 4500 and make (wastage set to) 8 PSI. In theory, it will make max boot at 4500 (which i believe with my turbo to be about 35 psi) so it should start making boost at about 2-3k rpm. 

The wastage will take its signal from the intake, so after supercharger. This should (and I REALLY hope it does) keep the wastage open most of the time because the supercharger makes 8 psi at such low RPM. The turbo will be nothing more than to create atmosphere at the inlet of the supercharger instead of vacuum. 

The compound effect take into place when I start to manually increase what the wastage is set at. Say I set the wastage to be 20 PSI (my max at the top end now). The wastage will stay closed at the bottom end and the supercharger will be making about 8psi. The turbo should be able to boost 2-4 psi at this slow speed. Lets say it makes 2psi. 2psi of boost is actually 16.5 psi absolute pressure (2 + atm 14.5). so 16.5 psi x the pressure ratio of the supercharger at the bottom end, 1.55 will be 25.60 psi absolute pressure or 11.1 PSI. If the turbo makes 4 psi at the same 2k. The formula would be ((14.5+4) x 1.55)-14.5 = 14.17 psi boost at 2k. 

I can't remember my turbo efficiency map for a 63 trim but let just say the turbo somehow is able to make the full 8 psi set by the wastage at 2k rpm. I will then have 20.37 psi of boost at 2k rpm. Obviously this can't happen because once the wastage sees manifold pressure above 8 psi, it will open and be nothing more than a bypass air restrictor. What I would then do is add a manual boost controller to set the wastage to 20 psi. Now the turbo will make boost until the compound pressure = 20 psi. Turbo pressure and supercharger pressure will always be inverse of each other but hopefully always totaling 20. This will also give me the option to increase pressure over the 20 with the manual boost controller on the turbo's waste gate. 

I was worried about the smaller turbo not having enough volume at the top end to maintain the volume that the supercharger needed. This also lets me increase the boost up to almost 30 psi if I were going to in the future (which forged pistons and probably alcohol). 

There is a fairly large front mount now that will stay between the charger and intake. IF needed I will do an air to water later.

If this works like I hope, I was going to get a smaller pulley for the supercharger to help slow it down. This should reduce heat and extend the life of the charger. The turbo will make up the difference. 

Day 4

More work on the mower and less on the Corrado. I test fit with the spacer and it just clears. Should work well though. Now time to fab the piping. 

This is all I have for photos for now. 

and this is what taking up my corrado time. Yes its dual open headers lol

Day 5

Well the mower is done, cut the front yard and it works well. Then did some needed work around the house and built a few things that I have been putting off. Needless to say, not much car time. 

What I have been able to do in the last few days of updating this:

Cut 5/16" flange for down pipe to cat delete pipe,

Did some heat protection on the fire wall, brake lines, and some wires that will be behind the turbo. 

Then Jake stopped by last night to help out with building the down pipe. took us nearly 3 hours to build this damn thing. 

Next on the list is to do the intake piping, charge tubes from turbo to supercharger, oil feed and return lines. Then take it all apart again and put it back together with gaskets and hope it all works. 

Day 6

Update for tonight:

So last night while test fitting the intake I came across a problem. anyone that has worked on an 8V counterflow head knows the intake bolts are a bitch to get at. Well, now the turbo is blocking 2 of the damn bolts. F ME!!!!!

So some brain storming today and I figured it would try and use studs instead of bolts to secure the turbo to the manifold. This should give me an inch or so to push the turbo away from the intake and bolt that first, then tighten down the turbo. Well finding studs was not easy (unless I wanted to buy a pack of like 25 or so). Finally found a set that would work but had to cut them down a bit. Test fired the turbo with the studs in place and I just squeeze the turbo on the studs with it pushed on the firewall. So worst case, I drop the turbo down under the manifold first, then bolt on the intake, then wiggle the turbo up. Either way, it should work (cross fingers). 

So with that problem solved, I moved on to the intake tube. 3" intake to the turbo. Basic, just cut some mandrel and weld it up. Then comes the charge pipe from the turbo to the supercharger. Again basic and easy (really glad something is easy with this project). 2.5" tube from turbo to super. Here are the pics of the tubing. 

Next is the boost bypass tube from the TB back to the pre-turbo intake. I was able to get some 1.5" radiator hose with bends that I hope to be able to make work. 

Thats all for now. 

Day 7

Well for future reference with anyone trying to use the CXracing 8v turbo manifold with a corrado 8v intake. It don't quite fit. There will some grinding to either the intake or the turbo manifold that needs to be done. I didn't get any pics because I was trying to hurry before work this morning. Basically the three long bolt holes on the intake are too thick and will contact the turbo manifold. Guess when I was test fitting, I was just looking to see if it was flat agents the head, not if the holes lines up (can't see from the front). An extra head would probable have been helpful at this time but oh well. Took off about 1/32" on each of the three bolt hole casting on the intake manifold and it clears well. Still plenty of material for the Manifold. I'll snap some pics when I pull it off again. 

Was also able to make some 1.5" radiator hose work as a boost return hose. about $15 each for some pre-bent sections of reinforced high temp hose. I just went back to the back where they had all their hoses and picked two of the longest with the most funky bends LOL. Will get pics up later for these too. Hopefully if all goes well, I'll be able to have this on a final assembly by this weekend. Still have one more hose coupler coming Monday so not drivable until maybe next week. I'm sure there will be some tweaking for a while after that as well. 

Day 8

Tonight we ran the boost return line back to the 3" inlet pipe. The heater hose works great.

Ran the oil feed line. Will be chaining one of the fittings that came in the kit. It don't quite look like 1/8" npt like the rest of them and I worry it will strip over time. I'm sure it will work but better to make it fit right for my piece of mind. 

Started to mock up the oil return line. Removed the oil pan to weld on a -10an fitting. Looks like we have to clock the center of the turbo once again. Thats about it for tonight. 

Charge pipe from turbo to supercharger beaded and painted. 

Here are the pics of the intake that shows the grinding needed to fit the turbo manifold. 

Day 9

Got a lot done tonight. Started a bit late but Jake came over to help again. Thanks again. This was defiantly a 2 person job at least. There were a lot of dropping tools into the engine bay and a few hours trying to find them. 

Anyways. Turn out to get at the intake bolts, we needed to remove a motor mount, jack the back drivers side of the motor up, remove the turbo completely and drop it down, then get at the bolts. We tried every which way with the turbo in place but nothing worked (thus the dropping tools and bolts all the time). After about an hour of fighting it, we did the above steps and got the intake bolted on in like 20 min. The turbo was defiantly a 2 person fight to get on with the intake installed. IT finally bolted together and all the pre-fab work is paying off as its fitting together well.

Made the oil return line today and got that all hooked up. Ordered a wideband o2 so that should be here Sat. We plan on starting it tomorrow and seeing how it goes (and if we forgot anything)

here are some photos. 

Day 10

Anyways with the update. It runs. With any major fab there were some issues here and there on startup. Oil leak on the oil feed line, some odd and ends that needed to be done still that I forgot. Oh ya and Jake, the band clamp was NOT tight enough LOL. Major exhaust leak (tick). 

here is a video of it idling. 

http://s202.photobucket.com/albums/a...t=9d457fe8.mp4

Wideband o2 is installed and setup. Things are starting to come together so I can drive it. Still waiting on one silicon elbow to get in. Flared the over lysholm tube to make sure the boost tubes don't slide off. 

here are some pics.

And last of all a new euro plate on order

Day 11

Well, SHE RUNS. Other than two new tubes, there is really no visual difference. Kinda sucks cus that was a butt load of work to not show off anything lol. Oh well, its all about the go anyways. So its all back together (other than the cv guard I forgot to put back on that I found after cleaning the garage LOL). 

Here are some pics

http://s202.photobucket.com/albums/a...t=c5da3950.mp4

Here is the wideband installed in the custom gauge pod I made last year. 

And a color change on the gauges

Day 12

First drive to work today. Well, it was an interesting ride. Nothing broke so thats good. 

Seems like fueling is not a problem. With the injectors and standalone, I have way more fuel than I need. The compound setup still seems a smooth as before the turbo (well as smooth as a standalone runs a car).

all I can say is compound charging works, and works well. I'm trying not to boost too much with the system until I can make sure everything is working like it should. So low RPM high gear pulls to watch boost and fuel climb as slow as possible. 

What I have noticed is that now under 2k I get 10-12 psi of boost indicated where I used to only get 8-10. So I'm guessing the turbo is working and moving something at lower RPM like I figured it would. At about 2,500 RPM is where it gets interesting. The turbo will start to spool and really push air though. The boost gauge will now climb very quickly. Easily passing the original 14 psi indicated and continue to climb. I stopped at an indicated 20 psi on the gauge because it showed no signs of slowing. And all these pulls are in 5th gear. I can't imagine how the boost will get out of control in 1-3rd. 

right now I have to find out why the boost won't stop. I need to pressure test the wastegate to make sure it is opening correctly and is fully open at 8psi (or less). Really trying not to blow this motor up. 

Let the tuning begin

Day 13

So I found a small problem. The wastegate is an 8psi gate but it starts to open at 10 psi and doesn't open fully till 15 psi. I guess this isn't too much of a problem but I can't test the system at wot because I worry about the compound effect. It's too gradual of an opening and I can see some serious boost spikes. 

Its an internal gate so I can't really just change the spring. Looking into adding a spring the the actuator arm to help open the gate and reduce the pressure. My next thought was to use and electro magnet that can close a gate that is opened by a spring. I can use a cob switch to energies the magnet on any set boost I want and it will be instant fully open and fully closed. 

I will just have to take things easy for now I guess.

Day 14

MBC comes in tomorrow. My experience with MBC is that it only can go above the lowest wastegate setting (set by the spring). I am not sure if there is a way to lower the boost pressure without replacing the WG all together on this internal WG. 

I ended up adjusting the WG arm to remove all of the preload on the WG. It seems to help out. Still can't fine a "peak" boost in low gears. In 5th gear WOT at about 2,000-2,500 I can get 20 psi data logged, and man can you feel it. 

In all the other gears you can just about control boost with the throttle. So far the highest I went is about 22-25 psi. Air fuel is right around 12-12.5. I am developing some spark knock at about 20 psi that I'm worried about. Going to try and pull some timing and see if that helps. Gotta tune with going boom. 

Day 14

Well, bad news already. I guess I was bound to find the weak spots in this motor. Well, short story. Air fuel is great, went one plug colder and spark knock seems gone, boost to 20 psi indicated on gauge in 4th=lots of white smoke from the tailpipe. Not your typical white smoke though. It's not coolant. Its oil . Well get her home. No oil when driving it. back off throttle to shift and lots of oil. A little bit of oil at idle.

Get it home and pull the plugs. All are dry and fine. No oil burning (probably why it was not blue smoke). You can see the white smoke (looks like crank case gasses) coming form one plug. OH NO. Compression test. Well all cyl were what they were before. 120+. So not a blown ring or piston....sigh of relief. Well where the hell is the oil coming from?

Pulled intake tubes between turbo and super. No excessive oil there. Pull tube from front mount at throttle body, no excessive there either. Each time revving it a bit to see if oil blows out. Nope, but oil is dense out back at the tailpipe. 

My thought goes to oil blowing by the turbo into the exhaust. Well, that makes sense but that would blow more oil as the revs go up and pressure builds. This is opposite. More oil when compression brake/ off throttle. 

Next thought is valve seals. They are original 90K on this motor. Never saw exhaust pressure till now with the addition of the turbo. Before with the supercharger, it was only the intake that saw boost pressure. Now with the turbo, the exhaust ports should have pressure as well. Figured it just blew the exhaust valve seal open. Thats the only thing that makes sense to me. When off throttle and the supercharger is still spinning, its spinning the cold side of the turbo, thus spinning the hot side as well. This will act as a scavenging effect and pull vacuum on the exhaust side. I think this is whats pulling in the oil though the valve seals. 

Well, getting the seals are easy, $20 and they will be here sat. Now the tools to do it and not have to pull the head. Did a google search and found the perfect tool. CTA 2235. This lets you leverage agents the head and pull the retainer. You keep the valve closed with air pressure. Perfect!!!! Also found tool valve stem seal pliers that will fit down the opening of the 8v head to pull the seal with the valve in place. CAT 2205. 

Best thing is amazon sells them for a bit more than ebay (knock offs) and its a prime item. $9 more and they will be here Sat as well. 

Hope this fixes it.

Oh and the car runs fine other than the smoke.

Day 15

well, new valve seals and it still smokes. Guess those were not the problem. Did notice that when I was using air to hold the valve closed I would get lots of blow by on 3 of the 4 cyl. I'm guess the oil rings are blown or the cyl are cracked below the first compression ring. The oil is helping the compression numbers but when closed throttle and cyl are at high vacuum, its pulling oil into the cyl though the rings/crack. Only thing I don't get is the plugs look fine. 

Guess I'll just pull the pistons and see whats wrong. Valves are closing and there are no leaks on any of them. I guess thats one good thing. 

If I have to put pistons in it again, I'm going forged this time

Day 16

So a bit more update on the oil issue.

I installed a crankcase evacuation setup that pulls it into the exhaust instead of the intake tubes. This gave me a chance to check the turbo for oil leaks because there is no longer anything but filtered air that should be going in there. 

Well pulled the charge pipe off and still have oil. Clean it out and give it a few revs and there is oil. Turbo is blown. Not sure what caused this but crap!. I can't even imagine how much oil is going into the exhaust. Pulled the plugs and they look fantastic. Look into the plug holes and the piston heads look dry. I'm guessing the turbo is leaking a bit on the charge side and a lot on the exhaust side. 

The problem with compression breaking has stopped. No longer do I get the puff of white after compression braking and back on it. I think the valve seals did help that. 

So I called CXracing up today (as they requested on email). First I wanna say SUPER nice people. Transferred me to Tech support right away, and the hold was less than a min. I talked to the guy there, he took my info (zip and name only. They pulled up everything else. I love companies that have their act together). Knew exactly the history of my problem. Asked me about restrictors and prime method I used to prime the turbo. 

After that he let me know that their turbos have no warranty (it says so on ebay also so I knew that it may be that way) but they are willing to send me a new turbo shipped for $100 or a free rebuild kit. I was surprised and very confused on what I should do lol. Part of me said get the new and just put it in and see how it works. Then part of me says just get the free rebuild, its not hard. 

Biggest kicker to this is I found a local new T3 (slightly smaller) turbo for sale that I'm getting tonight. I was going to put this in for the weekend and see if it took care of things. I opted for the rebuild kit. Figured I wouldn't need 3 turbos laying around lol. So I'll put this turbo I get tonight on and see if that has the same problem. If it does than its something motor/oil feed or return related. If not than its turbo related and I'll rebuild the turbo after the kit gets here and put that back in and move this one to the Jeep :D

Day 17

Ok, so I started to pull the turbo for swapping the new one in. Got all the parts on top taken off, went to the bottom to pull of the oil lines. Well, a crap load of oil came out in the lines and from the oil pan fitting. Not to mention the corrado was jacked up on one side.

Well thats a big problem. Took out about .5 qt of oil and cut down the return line to make it a bit straighter even. Looks like the corrado will need a deeper pan or just do more frequent oil changes. I welded the fitting as high up as possible so I don't think there is any way to go higher. Going to put it all back and see how it goes. 

Oh and the hot side is clean. Just dry carbon. So the smoke must be coming from the intake side or the crank case pressure.

Edit for update: So went for a drive this morning. Better but not gone. cursing on the highway or in town it does not blow oil (that I can see). Under boost or just cruising its fine. So the turbo is no longer "blowing" oil. I am getting oil when taking off though and low RPM. The charge pipe just after the turbo is still getting oil in it.

With less oil in the pan and the straighter return line, crank case pressure seems to be down a bit also. 

I tried revving it a few time with the boost tube from the turbo to the super unhooked to see if oil was accumulating or blowing and it was not. Perfectly clean air coming out of the turbo. So Now all I can think of is that the supercharger is sucking oil though the turbo charge side when I first take off. This would explain why when I'm higher on the RPM and the turbo is already spooling that I can get on it and no oil.

Thing that gets me is will this happen again with the new turbo or do you think its just a damaged turbo because of the oil backing up from before? It worked fine for about 20 miles or so after I first got it all put together. 

I guess I could just leave the turbo out of the system and let it dump and put the air filter on the super and see if my theory holds. Without the turbo there, there should be no oil on takeoffs and low RMP accel. 

Day 18

Update from last night:

Well pulled the old turbo. Wasn't too bad to get out. There was a lot of oil in the compressor side, intake pipe, and charge pipe. I cleaned it all out and went to transfer the waste gate over to the new turbo. problem.......

ya the turbo I have now just barely fits as is. There is no way i'm getting this new one in there. Not sure what brand this turbo is but I guess if anyone wants a brand new T3/T4 hybrid with .50 compressor and .63 hot, hit me up lol. 

So I guess back in with the old. I thought of taking the seals from the new turbo and putting them in the old, but Didn't want to have 2 f'ed turbos. Figured I know what is wrong with this one so i'll just run it. 

Here is the down pipe and exhaust side. Perfectly dry. The oil must be just burning but I don't get how clean it looks for as much oil as it's burning. 

Day 18

A few days late but still cool. We took 3rd place at Midwest Treffen. Was dog sick Friday and most of Saturday and in pain from a wicked tooth ache Saturday and Sunday. Someone tried to brake into the corrado at the hotel. Lucky only a small scratch between the window seal and door frame. Glad they stopped at that. 

Found that the exhaust driven crank case evac system works too well and sucks way too much oil from the breather. Need to install a catch can and see if that will remove the oil before it hits the exhaust. Also will be rebuilding the turbo soon to see if this stops the oil in the charge pipe. Add the diverter between the after turbo charge pipe, and port out the wastegate and see how she runs.