installing twin remote mount turbos on a class c motor home

[master53yoda]

I made the decision to install twin garret remote turbos and the turbos arrived today. I have ordered the inter-coolers, and a gear drive oil return pump. I've also ordered a triple multi-gauge pyro, boost and trans oil temp. The cost so far is $1150.00 the dual 2 1/2 turbo back exhaust was quoted at 600.00 by a local shop. So materials should total bout 1800.00 when I'm done. I also plan to install an Amsoil bypass dual filter kit.

The garret turbos are capable of feeding enough air for about 225 hp @ 15 psi. which is more then I can expect a stock 6.2 to handle without engine work. I intend to turn down the boost using a common signal from the intake manifold/s.

Questions:
1. What is the maximum boost that I can expect to be able to supply without having head gasket problems with 23-1 compression. My banks turbo on my 84 stock pickup seems to max out at about 8 to 9 psi.

2. A.) I will have 2 ea 2" charge air pipes coming up from the inter-coolers, should they be merged prior to the manifold or is it Ok to leave them separated and deliver separate air flow to the each bank as the J manifold separates the air streams if I use a flat adapter plate on the manifold. Would this generate a possible power imbalance on the crank.
b.) Would there be an advantage to installing a hummer intake with the large common air chamber.

3.Will there be any reason to NOT use a crankcase oil catch can prior to the turbo, and will a 1/2 Line be large enough to provide sufficient crankcase ventilation.

4. I am thinking about placing a bypass filter in the line feeding the oil to the turbos, my thought here is supper clean oil to the turbos.. I have been unable to find a pressure drop # on the Amsoil bypass filter at 3 gpm, and if it plugged, would i loss turbo oiling or would it bypass the filter....

Well that's all the questions for now, I'll probably have others is I go. Once I get started I'll put up progress pictures as i go .

[DmaxMaverick]

1. 8-10 PSI on a stock 6.2. With charge air cooling, perhaps 10-12. More importantly, is the EGT. Keep it in check, or all your efforts will be in vain. I recommend dual pyro's, especially with twin turbos.

2. Having the turbos charging air for only the same bank as the turbines will open it to serious imbalance issues. Either merge them before/at the plenum, or before a single intercooler. Another option, with 2 intercoolers, is a cross-feed system, where one compressor charges the opposite bank that feeds the turbine. This would be my choice, and would eliminate the balance issue.

3. The turbo needs full oil pressure to support the spindle bearing (which is an Oilite type bushing). No catch can necessary, nor desired.

4. Again, the oil supply to the turbos should be full, unobstructed oil flow/pressure. Too little pressure, and the spindle will burn up. The oil is the bearing, like for crank and rod bearings. Return flow should be unobstructed and unpressurized back to the sump, as well. Any return pressure will cause spindle seal leakage. A typical turbo oil system is gravity flow out of the turbo. The only restriction in the system should be the spindle bushing itself. If you are using a bypass filter system, install it as instructed, without consideration for the turbos. Turbos do not typically have issues with oil, unless the flow stops, or the return gets restricted. It is also to have sufficient airflow around the turbo, for after-run cooling.

[master53yoda]

1. 8-10 PSI on a stock 6.2. With charge air cooling, perhaps 10-12.

The intercoolers should help the Egt and I plan to limit it to 950, What i was realy concerned about was how much boost can i go without blowing head gaskets.

3. The turbo needs full oil pressure to support the spindle bearing (which is an Oilite type bushing). No catch can necessary, nor desired.

The Catch can would be in the crankcase ventilation line to keep the compressor side of the turbo and intercooler from getting oil logged over time.

4. Again, the oil supply to the turbos should be full, unobstructed oil flow/pressure. Too little pressure, and the spindle will burn up. The oil is the bearing, like for crank and rod bearings. Return flow should be unobstructed and unpressurized back to the sump, as well. Any return pressure will cause spindle seal leakage. A typical turbo oil system is gravity flow out of the turbo. The only restriction in the system should be the spindle bushing itself. If you are using a bypass filter system, install it as instructed, without consideration for the turbos. Turbos do not typically have issues with oil, unless the flow stops, or the return gets restricted. It is also to have sufficient airflow around the turbo, for after-run cooling.

The turbos will be to low for gravity oil return to the oil pan, I'm am using a gear drive scavenge pump to return the turbo drain oil back to the oil fill tube.

[DmaxMaverick]

Intercooler(s) or not, drive by EGT. Lowering EGT's does little to "allow" more boost. The pressures I stated were according to the temp. The head gaskets should hold this pressure. More will get you into trouble with the gaskets. Some get away with more. Others blow with less. It's hard to say, and much depends on the build, conditions and your driving habits.

Ah...You mean an oil vapor condenser (separator). Not a bad idea, in any case.

I understand the height/distance. You could/should have a remote sump (vented) near/below the turbos, and pump it back to the crankcase sump. Just using a pump to pull the oil will cause a vacuum on the return lines, and that's not good for the turbo spindles. The oil flow NEEDS to be pressure in, free-flow out. Ideally, the remote sump should have a float operated switch for an electric pump, so you aren't pumping air (foams the oil and causes molecular shearing).

[master53yoda]

just an update, I had to get a hummer intake manifold to give me about 1" more clearance and to provide a mixing chamber as the J manifold was divided, this resolves the concern i had that was confirmed on this site about power balance problems.
I also bought a Gear vendors off Ebay and paid way to much because it was trashed inside. I missed the Ebay buyer protection thing by 2 days, you must file the claim within 45 days. I didn't file the claim until after i completely disassembled the overdrive. I did find a place to get the parts i need for a rebuild for about $350.00 and they should be here next week as well as the intake manifold. I will write up a rebuild file and take pictures as i rebuild the GV overdrive as it was very hard to find information on the unit and gear vendors only will discuss sending it back to them for rebuild @ $1,000.00. The Gearvendors over drive is a Laycock overdrive with a Turbo400 tail section. The Laycock overdrives were used in the Volvo and Triumph etc. and i found that their rebuild info is usable. I'll post the pictures of the GV damaged parts and the replacement parts when they get here next week.

Now that I've got myself somewhat organized on this project I'll post updates about once a week.

[master53yoda]

This site has an excellent description of the operation of a GearVendors (GV) unit with usable rebuild information. http://www.buckeyetriumphs.org/techn.../JOD1/JOD1.htm. The location that I was able to find parts from was http://www.maximum--overdrive.com/ the rebuild kit that was sent included the cone clutch, all o-rings, new rear transmission bearing, and rear seal, and the necessary gaskets. He also was able to provide a used braking ring. total cost for everything was 355.00.

The two pictures that I have attached are of the unit that I'm rebuilding. One picture shows the condition of the new cone clutch and brake ring as well as the ones that I pulled am replacing. The cone clutch has clutch material on the inside as well as the outside. The inside material is used to transfer power when the drive line is delivering torque to the engine, as in reverse or under compression. This is one of the major weak links of a gear vendors overdrive. as the size of this friction clutch was originally designed for a max 2500lb vehicle.
It is suggested by Gearvendors and I totally agree that it should not be used with hard compression braking or with a compression brake as all torque is delivered through this small friction clutch. the other advise is to not back-up a trailer uphill, over a curb or with the surge brakes able to activate. IF (when ) this clutch fails you will loss reverse and will freewheel under compression.

The outer clutch is used during the over-drive function and forces the torque through the sun gear assembly, torque is transferred through the sprag type clutch in normal operation. If the outer cone clutch fails overdrive will not correctly function as was the case with the unit I purchased. The failure cause for this could come from a couple issues. #1 Dirty oil that slowly plugs the fine after pump filter reducing pressure to the activation pistons and allowing the clutch to slip. I believe this was the issue with the unit I bought as the sump and the total unit was full of sludge as well as metal filings that came after the failure. This type of failure i believe is the reason that Gearvendors maintenance interval is 5000 mile oil change. I will change the ATF in the unit at the same time as the engine oil. I have read on the net a lot of comments about longer oil changes but, there is no sign of damage until it is to late. the after pump filter is internal and not visible when pulling off the sump and cleaning the pre-filter.
#2 The other possible problem that could destroy the outer cone clutch is activating the overdrive and reverse at the same time, as the sprag clutch and cone clutch would both be locked and the weak link is probably the cone clutch although the net does have pictures of some broken annulus gears.

I am going to be gone most of this week and my goal is to get the GV unit installed.

[master53yoda]

Because I had to change intake manifold to a hummer low profile manifold to get the intake piping up under the hump, I now have to also move the secondary fuel filter. It has the Stanadyne filter on the back of the intake at present. Is there a problem relocating it under the engine on the frame rail or using the older 6.2 spin on if I can find one , or is there a better alternative???? I would repipe from the transfer pump , or go to an electric transfer pump as I will already have an oil pressure controlled scavenge pump on the turbo return lines that i could parallel the power with. Any thoughts would be appreciated.

[More Power]

Because I had to change intake manifold to a hummer low profile manifold to get the intake piping up under the hump, I now have to also move the secondary fuel filter. It has the Stanadyne filter on the back of the intake at present. Is there a problem relocating it under the engine on the frame rail or using the older 6.2 spin on if I can find one , or is there a better alternative???? I would repipe from the transfer pump , or go to an electric transfer pump as I will already have an oil pressure controlled scavenge pump on the turbo return lines that i could parallel the power with. Any thoughts would be appreciated.

Relocating the fuel filter shouldn't be a problem. Things to consider is convenience and cold weather. GM located the fuel filter in the engine compartment - in part - to help prevent gelling in cold weather. More convenient usually means the owner will service the filter when it should be serviced.

I read the boost pressure recommendations mentioned earlier, and I agree with them - generally. However, boost pressure by itself is not the only factor to consider. If you increase boost to, say 15-psi, and increase fuel to make full use of that 15-psi, you may be reaching too far. However, if you raise boost to 15, but not the fuel, you'd likely be just fine. It's combustion pressure that we need to think about, not boost pressure alone.

Jim

[master53yoda]

Ok what a project this has been if I can get the pictures posted in line with the write up I hope it will help.

I sized the turbos using Garrets information on their website and then did a search for that part no. and 2 of them showed up brand new on E-bay for $600.00 for both opening bid. I bid 610.00 and was the only bidder. They are 1300 from Garret ea. I have never done that well before and probably never will again.

The first problem was figuring out how to get the intake lines up under the Van Hump. I had to go to a Hummer intake manifold which provided a common chamber and 2" less height .

Installing that required repositioning the fuel filter and I mounted it along side the manifold Easy to get to.

I also Changed out the glow controller to the newer version because the old controller was in the way of the down pipe.

I installed the pyro in the Exhaust manifold itself, I'm planning on putting another pyro on the other manifold If I can switch between the sensors without damaging the gauge as there isn't room for a second gauge on the dash. The Multi gauge reads the boost , digital pyro, and digital temperature that I will probably put on the transmission or the engine oil.
The switches and light below the air conditioning control the Gear Vendor overdrive that I installed on the Turbo 400.

That's about it for up in the cab.

Underneath

I installed a dual oil filter assembly and piped the turbo oil from there, I installed twin intercoolers one on each side These intercoolers where $65.00 ea.

The next picture shows the oil return scavenge pump and the turbo and Air cleaners. I used compression fitting piping with rubber isolation and this may have been a mistake. I may need to re-pipe the oil side but at least know i have a pattern for the hose lengths etc. The turbo oil return pump is tied to the injector pump circuit so that if it blows a fuse it will shut down the engine. It also has a 4 psi switch that feeds an idiot light on the dash. The oil return point is into the drain pan along side the dipstick.

The last picture is from the back before we took it off the lift. The manifold to turbo is 2.25" inlet and 2.5" outlet from the turbos. they merge into a open high flow muffler that outlets at 3"
The intercooler piping is 2". I plan on wrapping the exhaust piping between the manifolds and the turbos to retain as much heat as possible.

The only thing left to do is install the crankcase ventilation capture tank and piping back to the filter for PCV. I hope to do a 100 mile shake down run in the next week.

The exhaust piping was the most expensive single part i had 1000.00 into the muffler shop when i was done. Total hard cost was about 2100.00, plus 4 months spare time, I had about 3 months into the gear vendors by the time I rebuilt it and everything.

thanks again to those that have given me advice along the way.

[arveetek]

Impressive! That's a lot of piping under the coach. Looks very neatly done, though.

I'm anxious to hear how it runs and drives now.

Casey

[Kcustom73]

Nice work on the coach.

I got rid of my 6.2 Class C this year for multiple reason one being performance. I could have never done such a system on mine because of some of the roads I drive on.

Good luck with the testing.