so i have a 50 trim on my yet to be installed turbo. what is the difference between a 57trim and a 50trim. i know from reactions that the higher the trim the "bigger" in a sense the turbo. can someone shine some light on this? calling mr. bufkin aka turbo messiah!

I'm certainly not any kind of a turbo guru, but I do know the answer to this question (and I think I know why you are asking so I'll go into that too).

The number describes the size of the top of the compressor wheel relative to the bottom. Its not a percentage of the diameters. Its a ratio of the areas. You must know the base diameter of the compressor wheel for this number to be of any use for you. With the trim, you can calculate the top diameter of the wheel. Obviously a larger trim means a more open wheel and a smaller trim is a casted that is smaller at the top.

Trim is the top diameter squared divided by the bottom diameter squared times 100. Or the area of the inducer(top of wheel) over the area of the exducer(bottom of wheel) times 100.

So... IIRC the 50 trim T04E wheel has a base diameter of 76.2 mm (which happens to be 3") According to the formula the calculated topside diameter is 2.12"

A 57 trim T04E has a topside diameter of 2.26"

Its important to always consider that larger is not always better when it comes to compressor wheels. It all depends upon the size of the motor and the target HP and torque goals. A giant large trim compressor wheel initially seems to flow more air which can't be a bad thing can it?

It can if the engine can't consume that quantity of air and the turbo isn't spinning fast enough to contain that air pressure. Physically a larger wheel has more open space to allow for air to flow in at high turbo RPMs. Likewise this open space can just as easily allow air to escape backwards resulting in an inability to maintain pressure at low turbo RPMs. A large wheel needs to actually spin faster to contain the air that its flowing and build boost; otherwise the air escapes backwards out the intake and you make less boost. This is compressor surge. A smaller wheel would be spinning faster at the same flow rate and could contain the air pressure and build boost. So the compressor wheel is sized to deliver both Airflow (matched to the motor) and a target Pressure Ratio. Just like anything in a turbo there are compromises.

Thats how I would describe it in laymans terms.

BTW. the wheel in my K28/27 hybrid is a 3050. which is 3" at the base and 2.12" at the top.

actually this was a more, "i want to know more" kinda question. i've been engaged in Corky Bell's turbo book and i've been absolutely overspun!! The bad thing is that i understood most of the concepts in that book but it helped to see it on paper. talking to you and stealing info from other people has mad me a budding turbo child of my own.

btw, i got the big turbo MAF hose on the turbo compressor inlet. I just got the flange machined from that hairline crack that it had, its now a 6061 Aluminum machined flange. the oil drain and oil inlet flange is on its way. All i need is AN hoses. Javad I believe has what i need. I wonder if its cheaper to buy them from him? I've gotta get the watermanifold tapped pretty soon and i'm going to the machine guy so i don't break my arms trying to tap it myself. does it matter where i tap it on the manifold? where's the optimum spot?! I'm waiting for someone to call me back on a RS2 manifold that they found in europe for $400 dollars. hope to see it soon. its coming together very nicely but i'm gonna hit a brick wall when it comes to software. damn Mihnea for living overseas. porsche i believe uses the same bosch motronic ecu so a custom porsche tuner should be able to do the same things to my ecu as mihnea ... for now.

so you welded up that cracked aluminum garret oil drain flange? That should work okay. I recall two cracks in it.

I'm not sure about Javad's oil line kit. I think he sells flanges with it, which you don't need. You already have the Fittings at the turbo for the water line.

Sounds good except for the Porsche tuner. I'd be cautious about that.

James

i didn't weld it ... i had a new piece machined for me. it looks great! i'm very proud ... of having it made for me.

hmmm .. if Javad sells oil flanges too ... then maybe you should send me that site again .. you gave it to me over the phone but i can't remembe what it was. laserwholesaleparts.com?!

argh. well if Mihnea doesn't come to the states soon .. i'll be quite slow for a while. might as well get the piston rods in by then ... i'll have no restrictions then and can jump straight to 400+hp whereas before i'd have to get it tuned to 360hp .. stay there for a bit till i buy and install piston rods ... wait for mihnea to come back and to reprogram the chip. hmmmm ... decisions. i've been having a nagging problem of the car not boosting correctly and found a hole in the Mich. Man hose. I temporarily fixed that and then took it out for a spin. holy cow ... if i get anywhere nearer to 400hp i'll have to replace all my bushing and suspension, tranny/motor mounts till i feel perfectly safe in it. she's a beast.

ps. james, i need AN6 and AN9 houses correct?! any idea of length?

Okay lets see. YOu have the Aluminum oil feed flange at the Engine. You also have the aluminum flange at the turbo. IIRC those are tapped for 1/4" NPT(double check that). I thought I sent at least one 1/4" NPT to An-6. If not you need two of those. The oil feeds into the top of the turbo so you should use a 90 degree AN-6 hose end. At the oil pump I think a 45 is good there AN-6 hose end cause the line has to turn up and go over the turbo. About 30" of An-6 line for the oil feed should be plenty.

Oil return use the two garret oil drain flanges. One for the block and one for the turbo. They use 1/2" NPT to AN-10 fittings. Use a An-10 straight at the block and probably a 45 degree at the turbo. You only need about 18" of AN10 hose for the drain with an RS2 manifold

Water lines are all AN-6. Get a Clamped hose end for the freeze block drain. I've sent you two 3/8" NPT to AN-6 for th turbo so that takes care of the water drain. You'll need about 18" of AN-6 line for the water drain. You'll need a straight AN-6 swivel for the water drain.

Water supply is tricky. Easy if you can weld. You should find a water source up by the water manifold where the water enters the head. There are numerous things you can do here. If you have any threaded plug or cap then remove it and weld on a AN-6 bung. If its a common thread, you can get an AN-6 matched thread adapter. Two more swivel hose ends and a length of An-6 line dependent upon where you tap for water.<ul><li><a href="http://www.bufkinengineering.com/fittings.htm">http://www.bufkinengineering.com/fittings.htm</a</li></ul>

ok then i'll start the process of ordering parts. do you still have that website where they sell the AN hoses? thanks a bunch james.

List of parts needed:
(1)AN-6 90degree Hose End
(1)AN-6 45degree Hose End
48" total of AN-6 Hose (stainless steel)
(1)AN-10 Straight (swivel?!) Hose End
(1)AN-10 45degree Hose End
18" total of AN-10 Hose (stainless steel)
(3)AN-6 Straight Swivel Hose End
AN-6 Hose length according to where i tap the water manifold

Prices:
6.95 each AN-6 straight swivel hose end
7.20 each AN-10 straight hose end
13.90 each AN-6 45 Degree hose end
19.90 each AN-10 45 degree hose end
12.40 each AN-6 90 degree hose end
3.99/ft for AN-6 hose (stainless steel performance)
6.52/ft for AN-10 hose (stainless steel peformance)
For all of that I got a quote of $111.01 from a local aeroquip supplier called Fast Lane. not bad i say. what do you think?