turbo tech question

[catmandoo]

taking the turbo off my 6.2 to put on my 6.5 and to make a long story short when i put it on the 6.2 it had no boost and i took it in to check it over and every thing ok turns out gauge was bad. anyway ever since its had a minor leak or should i call it a seep from the intake side of the turbo and tonite i went to move the intake side of the turbo to a different position i took it off to clean it and there was no gasket in there, question is should there be.

[ucdavis]

I believe the plate seals to the housing w/a thin film of high temp sealant.

[catmandoo]

if so there wasn't any in there.also i've heard talk of getting oil from the front of the motor would this be the little plug on the block in front of the pass side cyl head?and what kinda pressure is there in the oil return line and what size should it be at a minimum.

[tom.mcinerney]

Turbo's oil feed my 6.5 from fitting tapped into block ahead of psngr side head, behind timing cover, 1-1/2--2" outboard of FIPump mtg flange.
Return oil line ID about 5/8" ....Assume pressure feed direct from galleries??

[catmandoo]

well i talked to the people that work on pumps and are the local banks dealer and he says that i only need like 5/16 to 3/8 for return but yet my banks uses like a 5/8 so whos right i can easily use either one but would prefer to have it too big as to small.

[DmaxMaverick]

The turbo oil return line is more of a drain, than a return. Too small of a line will result in back pressure, and premature seal leakage. The bigger the drain line, the better. It is also important to have a correctly operating CDR, to make sure that the crankcase is always under vacuum. Positive pressure in the crankcase will also pressurize the turbo's oil seal (via the return line), by adding drainage pressure. There will be little chance for damage leaking seal, but the turbo will pass oil into the exhaust and intake. This causes smoke, and can cause an engine to "run-on", due to the oil in the intake. Not to mention increased oil consumption.

If you have an option between a small line and a large line, choose the large. It may head off future problems.

[gmctd]

Excellent points. Any pressure in the drain return line must be prevented.
In routing the drain tubing, ensure no exaggerated "S" curves which would trap oil, with resulting pressure build-up.
The line must point always downward from the turbo drain outlet to the connection at the engine. Any slightest upward curve to clear an obstruction can become a 'trap' in small-diameter tubing.
If converted from mechanical to electric lift pump, the factory 6.5 turbo drain return\blockoff plate which covers the mechanical fuel pump flange is absolute best choice, providing a direct path into the oil pan

Pressurized supply line tubing can be 1/4" inch, or so, and can be routed as necessary.

The compressor housing is sealed to the cartridge flange with RTV. Coat the flange very sparingly, to prevent an RTV glob getting into the compressor blades at 100,000 rpm.

DMaxMaverick - was that your post a couple years back on technical aspects of R12 vs R134? I would certainly like to see that information re-posted.
Just couldn't remember if you or SoCalDMAX posted it.

jd

[catmandoo]

i was gonna use the drain pipe that was on the 6.2 and cut the bottom 2/3 off then run a piece of hyd hose to the fuel pump block off plate which i am going to tap and put in a 5/8 pipe fitting like off a waterpump.i was told a high temp rtv sealer but i need to get the turbo mounted and then set the flange housing in the direction i need it. what i would like to do is turn the banks air chamber 90 degrees to the left this way i can get the air from the drivers side front corner and turn the flange on the turbo to say the 7 o'clock position as viewed from the front then i can just turn 90 degrees and run under the battery on the right side for an intercooler inlet and out under the left side battery for the outlet and pipe up to the air chamber my first problem is the hold down stud holes in the air chamber are set front to back .any thought on this or problems i may encounter?

[whatnot]

One of these might fix the stud location: intake (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33553&item=2434949403)
What kind of turbo are you using? If you need any pictures of anything on mine, let me know.

[gmctd]

Routing the boost air down the passenger side, across thru the charge-air cooler, then up the driver's side to the boost chamber affords more over-all space in that crowded right front corner, makes insul-wrapping the cooled-air piping easier, and keeps more of it out of the direct radiator blast.
I would take the time to plumb it all up temporarily and look at it for a while from several angles - any problems should be noticeable.
The boost chamber may require some TIG work to allow repositioning, but should be worth the expense.
Or you could cut out a 1/2" aluminum plate, drilled and tapped at 90deg offset, seal it to the intake plenum and the Banks chamber with grey RTV. This could be re-drilled and tapped for several positions, if the first did not work out. Would be labor intensive, but not costly.

Good luck with it.

jd

[catmandoo]

got any ideas on the amount of cfm i would need to flow found an ic that flows 900cfm that should fit

[gmctd]

The 6.5 flows around 405cfm @ 3500rpm, so that one should handle it, don't you think?

jd

[DmaxMaverick]

A 6.5 N/A flows something over 400 CFM at redline. A turbo will add to that considerably. I don't know the formula to calculate the exact CFM with a turbo, but a 900 should be well within the max.


gmctd
It wasn't my post, but I do remember a number of them a couple years ago. It's kinda the wrong time of year now to start the A/C threads, unless you have a specific reason. I do recall having a few A/C gurus on board, though.

[gmctd]

The original post disappeared into the ozone layer, along with about 10,000 others.
Would be good to repost that one in the 6.2L area, where upgrading from R12 to R134 is often necessary.Thanks anyway

jd

[richard7]

DmaxMaverick,
A normally aspirated engine can't fill the cylinders completely because of intake restrictions (air filter, intake manifold, intake valve and valve timing, etc.).

Because of that, a 6.5 N/A does not flow 400 CFM @ 3500 rpm. The filling efficiency is about 75% at this engine speed, leading to about 320 CFM. The 6.5 turbo will push about 25% more in the cylinder with a 4 psi boost, swallowing about 400 CFM.

[catmandoo]

now it has 2.5 inch inlet and outlet pipes is this gonna cause a lag as the pipe out of the turbo is 2 inch? i took the turn signals out today to do a little checking and the pipe for the intercooler will go right under the turn sig lites the factory hole for the air inlet would take a 3 inch pipe if need be.just turnin the corner under the turn sig would be the problem with that big of a pipe.

[gmctd]

Lag is more of a problem when the turbo doesn't spool up quickly, as in a non-wastegated unit.

Your system will have considerably more tubing area, which means more volume to fill, so you'll need to try it to see what the outcome.
Try to maintain same (2.5"?) tubing diameter between the compressor and the 'cooler. The 'cooler outlet tubing can be larger to match the Banks air box, but do not vary the diameter in either run. This will prevent flow losses, which will increase lag.
If you need 2.5" out of the 'cooler for clearance, take it all the way to the Banks air box, then increase the size there to match. You can find silicone rubber couplers on the 'net to do just that thing. 2.5" will reduce the static volume, compared to the 3" tubing.
Reduce static area volume, reduce lag.

The cooler will recoup heat-of-compression losses, so the power you feel will be the power you would lose without the charge-air cooler.

jd

[catmandoo]

that last statement brings up a question. example; in your tires you lose 1 lb of pressure for every 7 degrees temp drop so in effect would you lose say 7lbs of boost if the temp was 150 into the i/c and 100 out of the i/c? as air expands when heated. wouldn't it be better to have a little smaller piping out of the i/c to keep the pressure up? just weird thought i had today

[patrick m.]

the engineers wil have to explain why that theory doesnt work for charge air tempurature cooling.
what i can give you is how my boost was affected by adding the I/C.
before I/C-12lbs
after I/C-9lbs
of course, 9lbs was just not going to get it, so a call to Mr. Kennedy gets me his boost controller. (elec 6.5). I naturally turned the adjuster untill the S.E.S light came on, and then backed it up a bit.

so, we have all read that boost temps at 10-12 psi can reach 300F, lets say we are only getting to 250F. The Intercooler manufacturer claims to bring charge air temp to with-in 30F of ambient, lets say 90F day, equals 120F intake inlet temp.

the math,,,,,,250F turbo outlet temp
120F intake inlet temp
equals---130F temp drop
a 130F temp drop with a drop in psi of 3


this exaple may not holp up under the examination of a scientist, but it is one real world testimony :D

[gmctd]

The tires contain a fixed volume of air, where the turbo is contsantly compressing fresh air.
You'll lose about 1-3psi total dropping from 250-300deg to ambient. The resultant flow volume is still considerably denser than ambient, and more than adequate for the flow capabilities of the engine.
Your thinking is correct - maintaining minimal tubing size is important, as you will be attempting to reduce static volume. Less plumbing (length, diameter) = less compressive volume. This reduces lag.

You're on the right track, so just keep after it. You'll enjoy it.

jd

[catmandoo]

well as i said it was a weird thought i had while driving down the road today.when ya drive 200 to 300 miles a day you come up with some strange and sometimes bizzare thoughts.i'm looking at possibly a spearco i/c the one i was looking at isn't gonna fit as to go 3 inchs thick it can only be about 14 inchs long. i'd like to at least get 22 or so inchs in length and height about 10 would fit without cutting up the support bracket that holds the hood latch mechanism.widths gonna have to be 2 1/2 and then i still might have to chew out some of the grill but after i chopped out the gmc emblem and put an alum mesh infront of it you won't be able to see it anyway. might have to make up something out of styrofoam and cut to fit and see just how big i can go. another question is piping is there anybody that can bend to fit or is it just buy some used powersrtoke or cummins pipes and cut and patch to fit.

[gmctd]

Any well-equipped muffler shop should be able to handle 2.5" tubing.
As you're in Iowa, one of the shops that cater to the tractor\truck pull crowd may have a mandrel-type system - makes bends without the crumple effect, and can do short-radius bends.
That's like a 90deg bend within 1.5 pipe diameters.
What year\style is your vehicle?

jd

[catmandoo]

92 1/2 ton ext cab 2wd with 5spd, with 8 inch ss 454 chrome wheels and the w-30 olds style hood that i currently have my air intake ducted to and when the turbos done i'll have an air cleaner box on the fender right under the hood duct