calls

I keep reading where you guy's are talking about this turbo and that turbo, a hybrid and or twins. I don't understand this at all. When you say hybrid what exactly does that mean. I see where you guys talk about 14cm and 12 cm and etc. What are you talking about. What do you use and when as well as why. When do you know you need a new turbo to match your mods. I am a LONG way from needing one with the few things I have done to my truck but I would still like to be able to keep up with the conversation. Can you guys please help me out here. I am sorry if this seems simple or stupid to some but I won't ever know if I don't ask.

Thanks for your help.

Iron Horse

a hybrid turbo is mixing and matching parts from differnt size turbos to make a turbo that responds the best to your mods (ie: fast spool up, low EGT).

You usually need a differnt turbo when your EGT levels become too high for safe operation of your engine. Going to a larger turbo, or twins will allow exhaust gasses to leave faster, and compress a larger volume of air into the engine.

98rammer

a turbo.....intake and exhaust. essentially, the exhaust wheel (exhaust FAN) is spun by hot exhaust air- that wheel turns the shaft. that shaft turns the compressor wheel (intake FAN looking thing) on the intake side of the turbo. the compressor wheel obviously compresses air which makes boost. Boost pressure IS intake manifold pressure--you may hear those terms switched, they're the same thing. unscrew your intake to take a look at the intake wheel, shaft, etc. to maybe get an idea of how the turbo works (or search for some pictures).


The turbo HOUSING is that ugly, rusting, semi-round piece on your turbo on the exhaust side.
12cm, 14cm, 16cm, 18cm, 21cm, and some other various sizes of housings. those numbers in cm are the size of the cross sectional area on the exhaust housing of the turbo. a 16cm housing flows more air than a 12cm housing, however, boost pressures maybe be lower (because that shaft will be turning slower).

There are many sizes of turbos. HX35, HX40, HX50, HY35, etc. They each represent different amounts of air flow, pressure and efficiency ranges. Those may take a short while to comprehend the differences between them.

It's all about matching fuel to air. an HX35 hybrid has a HX40 compressor wheel in it i believe, giving you higher boost pressures which lowers egts (as long as you are not out of the efficiency aka "map" of the turbo). however, there's only so far this particular turbo can go until you really need to step up to an HX40 or something better.

twins turbos are exactly that, two turbos. the intake of one feeds into the other, and the same thing on the exhaust. Big to little on the intake side (compounding effect), and little to big on the exhaust (decompounding/expanding i guess). there's so much to add to that though (efficiency #'s, drive pressures, etc. that need to be taken into consideration for a good setup).

hopes this helps some; i suck at teaching people stuff.

Tom

calls

I don't know about that, you just gave me A LOT BETTER understanding of things and for that I thank you both very much

KATOOM

I also thought that was a good job of explaining things but I thought I'd add one thing thought you (and I didnt for a while) might not understand. All turbos, just like an engine, work the best under certain RPM levels. This is what everyone refers to as the MAP of the turbo. When the turbo spins to fast, being out of the effecient RPM levels, it no longer is doing good. Its now producing heat, not cooling anything off. So this is why its no good to crank up your stock turbo (like so many do) to get high boost levels, unless your in the safe boost area for that turbo. But for all changes you make to your engine there is give and take. With a larger turbo you will slow the spool time giving way more turbo lag and bigger turbos are not as good in higher altitude and some arent good for towing. Basically you need more power than stock to spin an aftermarket turbo. Which one is the better fit for your truck, generally speaking? I dont know, thats what the experts that sell them are for.

thumper 549

hybrids- means you are and will see in the future, vanes that change pitch ,turbos with no oil lines to them and water cooled turbos.......all these exist now.Whats next??

Iron Horse

Stupid question: Do ball-bearing turbos have oil lines running to and from them?

wannadiesel

Not a stupid question. Yes, they do need oil, and it has to have a place to go.

AlpineRAM

Iron Horse- Yes they have oil feeds. Only turbos without oil feed I know of were IHI ceramics with gas bearings. Ran on a cushion of exhaust gas. Nice stuff

AlpineRAM

Iron Horse

Another question then. Why do the ball bearing turbos work so much better then the non ball bearing turbos?
Don't the normal ones just operate on a film of oil between two races? Seems like there would be less friction then having to spin all those little *****.

ramtd02

The reason ball bearing turbos work so much better is simply because of those "little *****". Anti-Friction bearings are under most circumstances ball bearings. The film of oil theory is good considering there is no metal too metal contact. However the contact surface of the shaft, no matter how you look at it will ocillate. Very little perhaps, but with close tolerances like that it will act much larger amount than we can comprehend. And not too mention the oil pressure situation, and start up and shut down friction.

calls

Thanks guys, I appreciate all the help here