Are we arguing? ;) We are saying the same thing from different perspectives. I never said that one sizes for a specific pressure, I suggested that it made more sense to look at the work done, which considers both the mass flow and the delivery pressure. A turbo that delivers massflow X at 2 psi will be very different than one that delivers massflow X at 20 psi.
OK, what size turbo would I need for my stock Dodge 318 in my challenge car? We shall hear from both parties.
Moparman wrote: OK, what size turbo would I need for my stock Dodge 318 in my challenge car? We shall hear from both parties.
Depends on how much power you want... ;)
50 to 100 hp. Probably closer to 50
Sorry, I meant TOTAL hp... :)
well the engine made 175 when new so figure mid 200s.
I"m not really in this conversation too much, but I'm thinking something in the GT40,42 range would push enough air to flow that small block, right?
just get the cheapest ebay turbo kit, and hope you stay under the $201X budget 
That was my plan, but figured I could get some insight here. 
Teqnyck wrote:Rufledt wrote: rule 2 must then be: Crying does not fix broken connecting rods, that's what welders are for.Yeah, about that.Sometimes the rods in my cars don't break. They sure lose a berkeley ton of compression though.
well, duh, that's something that can be fixed with a hammer! No welding needed. just get it somewhat straight, and sell it on ebay as 'slightly used'. Nobody will know the difference.
Why not a junkyard turbo, what motor is this going on? What's the flow rate on the motor? What do you want it to be with the turbo? In other words, have you done your homework yet? 
Moparman wrote: well the engine made 175 when new so figure mid 200s.
I'd say that's awfully conservative. You should raise your expectations and shoot for like 400 HP.
erohslc wrote: Are we arguing? ;) We are saying the same thing from different perspectives. I never said that one sizes for a specific pressure, I suggested that it made more sense to look at the *work* done, which considers both the mass flow and the delivery pressure. A turbo that delivers massflow X at 2 psi will be very different than one that delivers massflow X at 20 psi.
Yes you are tecnically correct, but your method is not utilized in the industry because Mass flow is more important to engine performance than pressure. Flow is considered before pressure is even considered. Even then pressure is considered in the terms of pressure ratio, pout/pin = pressure ratio; or in other words a way of talking about pressure gain. This is used due to the various altitudes that an engine must operate.
The work equations are only considered after a compressor is sized effectively. and a turbine needs to be sized appropriately. Generally done in a simple work balance equation to understand how much power the shaft requires to turn the compressor at the effective speed you need.
Looking at the sizing of a turbocharger in terms of "work" is technically correct, but confusing and has been scrapped by the industry. Mass Flow is utilized when talking about and sizing compressors; not pressure; not work.
If you want me to go deeper, it would take me a while to dig out my old notebooks from when I worked for Cummins/holset.
Moparman wrote: OK, what size turbo would I need for my stock Dodge 318 in my challenge car? We shall hear from both parties.
anything you can find will make an improvement.
So here's my super quick down and dirty, semi accurate, rule of thumb for sizing turbos from diesels to gas engines.
Diesels run about 1/2 the rpm as a gas engine so if say a turbo for a 5.9 cummins should match to something in the 2.0 to 3.0 liter gas ranges. You will need two for your 318 or 1 turbo from a 10 or 11 liter..
Moparman wrote: well the engine made 175 when new so figure mid 200s.
Holset HX40 or bigger. They can usually be found for $200 or less on craigslist.
You can also try to find one of the holset VGT turbos on ebay... there's a couple sellers that usually have them off of "removed for warranty work" trucks for $75. Usually they just need a good cleaning and they're set to go. The cool thing about these turbos is that you have two options to run them.
1) You can try to control the VGT system via an aftermarket controller, or there is a way to do it through Megasquirt
2) You can just weld the actuator arm to hold the turbo at a "size" you deem useful. They can be "small" enough to be an engine brake, they can be "big" enough to make insane amounts of power.
Plus, they LOOK awesome because they're GINORMOUS.
In reply to 1988RedT2:
Not on a 147,000 mile bottom end. Admittedly the bottom end appears sound for its age (no noises and compression bewteen 165 psi and just under 180 PSI), but it still has 147,000. The challenge budget prohibits strengthening.
Teqnyck wrote: I"m not really in this conversation too much, but I'm thinking something in the GT40,42 range would push enough air to flow that small block, right?
Sounds about right for a 318. I ordered a GT40 for my slant six on the basis of flow maps, never having seen a large frame Garrett before. When I took it out of the box and found it was the size of a basketball, I started wondering, "What did I just get myself into?"
So I guess all of those cheap Volvo unit won't work? I am runnimg up against the budget with this project (the entry price was not especially cheap). I really need a used tubro with intregral wastegate for $150 all in.
Here's a good chart for sizing a turbo for your motor and HP goals. These are just references and not intended to be authoritative for every application. They also assume you are planning to run <= 10psi.
http://www.kamikazeracing.org/dl/ZTech/Turbonetics-TurboMatrix.pdf
Here's a bunch of turbo maps to give you an idea of the efficiency range for each turbo listed:
http://www.kamikazeracing.org/dl/ZTech/TurboMaps/turbosupermaps.html
Moparman wrote: So I guess all of those cheap Volvo unit won't work? I am runnimg up against the budget with this project (the entry price was not especially cheap). I really need a used tubro with intregral wastegate for $150 all in.
They'll totally work. It's just a question of how much and how well.
I can’t think of a single turbo that would be big enough for a 318 for challenge budget. Might be some diesel stuff out there that could work, don't know. I think you have to go with twins. My vote is 2 DSM 14b turbos which have internal wastgates. You can get away with 2 50 trim T3s but a better option would be to find 2 60 trim T3’s off a turbo Ford 2.3L or Buick GN. Might be tough finding 60’s for challenge $. You can also look around for used ebay 50 or 57 trim T3/T4 turbos but they might be overkill for your goals. Miata guys tend to try these and find them too big and sell them cheap. Don’t forget to leave some budget room for the added piping, flanges and oil lines of a twin setup.
MadScientistMatt wrote:Teqnyck wrote: I"m not really in this conversation too much, but I'm thinking something in the GT40,42 range would push enough air to flow that small block, right?Sounds about right for a 318. I ordered a GT40 for my slant six on the basis of flow maps, never having seen a large frame Garrett before. When I took it out of the box and found it was the size of a basketball, I started wondering, "What did I just get myself into?"
Heh, they're interesting, huh? I've got a buddy trying to sell a GT42R. It's enormous.
Moparman wrote: So I guess all of those cheap Volvo unit won't work? I am runnimg up against the budget with this project (the entry price was not especially cheap). I really need a used tubro with intregral wastegate for $150 all in.
Big Holset. Seriously.
Otherwise, you're looking at needing twins.
Two of the volvo units might work, but you won't get much in the way of top end, that's for sure.
Two MKiii Supra CT26s would fit the bill as well. They're the second biggest single turbo fitted to a production vehicle to the best of my knowledge. Grand Nationals being the biggest.
In reply to PseudoSport:
Two turbos present budget and packaging problems. The drivers side of a Shelby Dak is tight.
In reply to Moparman:
Who says it has to go on the drives side?
Run a pipe and mounted it where you have space.
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