MHI TD04-18T turbo--Compressor map plots and turbo calculations - page 2 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

#15 by 8v-of-fury on 01 Apr, 2013 18:20
Quote from: RabbitJockey on 01 Apr, 2013 12:56
11.47 psi atmospheric pressure and 30 psi of boost, it would put you around 3.6 on the y axis. i hope that helps

I got closer to 3.9 when I ran the numbers. Pretty much 1 or more higher than you want to be for that, or most turbos..
#16 by 0 Xero 0 on 01 Apr, 2013 20:55
I'm sorry about the location part of my profile. I thought it would prompt me to enter that when I registered and forgot about it. Regarding the squirrel performance calculator, it just seems really off to me whenever I plotted any points in. It doesn't seem to like the AFRs that diesels run. I literally went through every map that calculator has and none of them worked. Granted, I have my ideal AFR set leaner than what most people probably run on theirs, but if the turbo is sized properly for a given application, the engine should run lean and have minimal smoke output. I don't like the calculator because I calculated these equations for plotting compressor map points by hand and I trust my brain and the equations more than the calculator. I'll have to re-run my calculations with a VE of 85 percent and a lower BSFC and see what happens.

RabbitJockey, you're definitely right about the P/R. I goofed on that. After going through all the calculations again, I came up with a MAP of 55.11 PSIA, which equates to 43.64 PSIG and a P/R of 3.8 with an AFR of 20:1. I've looked through some builds, and, as far as I know, no one has used that much boost on these engines. With an AFR of 18:1, I came up with 38 PSIG and a P/R of 3.3. That's still pretty high on most maps. I'm wracking my brain trying to figure out why this seems so difficult because there are people who've made 200 whp on these engines. Perhaps they have a lot more fuel than I'm accounting for. Here are the equations I used from Garrett's site:
http://www.turbobygarrett.com/turbobygarrett/choosing_turbo

Here are my calculations:
Wa = HP x AFR x (BSFC/60)
Wa = 200 x 20 x (0.372/60) = 24.8 lbs/min

MAP = (Wa x R x (460 + T)) / (VE x (N/2) x Vd)
MAP = (24.8 x 639.6 x (460 + 130)) / (0.85 x (4500/2) x 97.6) = 50.14 PSIA - 11.47 PSI = 38.67 PSIG, P/R 3.4

As you can see, lowering the AFR results in a lower Wa, which decreases the MAP and required boost. I would rather not run richer than 18:1 and ideally stay around 20:1 to maximize combustion efficiency. This is obnoxious because it seems like the only way to get near 20:1 is through the use of compound turbos, which I'm not averse to, but I'd prefer to stay with a single. A VGT could help here, but they have reliability issues compared to their fixed geometry brethren. Does anyone know a turbo I can use that will work here?
#17 by 8v-of-fury on 01 Apr, 2013 21:05
So just curious.. why do you want to run 30+ psi??

What exactly are you using this setup in and for?
#18 by RabbitJockey on 01 Apr, 2013 21:22
I think at your altitude unless you run compounds 200hp isn't going to happen. I would sweat the air fuel ratios too much. On diesels it doesn't matter that much so long as all your tenps are ok. I came up with 18:1 just cause it made all the numbers work with dynos I'd seen. I'm no scientist it could be off haha
#19 by 8v-of-fury on 01 Apr, 2013 21:33
Ultimately, yes. All the temps in check will be fine regardless of exhaust smoke opacity.

Isn't 200hp out of a 1.6 like REALLY pushing it anyways? lol

I swear I have read of diesel builds running close to like 14 AFR. Pretty sure it is a number that need not be worried about as it is in a gas engine. The fuel will burn no matter how lean or rich, if you keep the EGT's in check it will be producing maximum power as it can. If you holf back fueling so much that you run a 20:1 AFR then I don't think you will ever make it the power goals you desire. Gotta have fuel fuel and more fuel to make the powers.
#20 by 0 Xero 0 on 01 Apr, 2013 23:35
Quote from: RabbitJockey on 01 Apr, 2013 21:22
I think at your altitude unless you run compounds 200hp isn't going to happen. I would sweat the air fuel ratios too much. On diesels it doesn't matter that much so long as all your tenps are ok. I came up with 18:1 just cause it made all the numbers work with dynos I'd seen. I'm no scientist it could be off haha

Yeah, I think compounds is the only way to unless I did some trickery with a VGT like a HE351 and used a diverter valve on it. That turbo probably wouldn't fit very well between the firewall and the engine in a caddy or rabbit though, haha! The air fuel ratio isn't a variable that can easily be controlled; however, when you're using equations to find a turbo to suit your needs, it is useful because you should ideally be able to find an efficient match. An AFR of 18:1 actually isn't that bad, I just hate seeing people driving diesels around belching smoke everywhere and kids asking how to make smoke because they all equate smoke with power, which isn't true. Yes, a rich engine will make more power than a lean-burn engine, but ideally, they are run lean. Jeff Garmon has compounds on a 12-valve cummins that makes 700 rwhp and it only puts out a light haze at the exhaust pipe.

Quote from: 8v-of-fury on 01 Apr, 2013 21:33
Ultimately, yes. All the temps in check will be fine regardless of exhaust smoke opacity.

Isn't 200hp out of a 1.6 like REALLY pushing it anyways? lol

I swear I have read of diesel builds running close to like 14 AFR. Pretty sure it is a number that need not be worried about as it is in a gas engine. The fuel will burn no matter how lean or rich, if you keep the EGT's in check it will be producing maximum power as it can. If you holf back fueling so much that you run a 20:1 AFR then I don't think you will ever make it the power goals you desire. Gotta have fuel fuel and more fuel to make the powers.

I was using 200 hp as a benchmark more than a goal really. I'd probably be content with 150-175 hp or so, but I won't know until I'm actually driving the vehicle or not. Yes, you can run any AFR you want. Most sled pullers and diesel drag trucks have AFRs from 14-16:1 but that's because heat is what powers a turbo. The top tier classes have guys running huge turbos that are usually more suited for a low pressure turbo in a compound setup, so they throw as much fuel at those engines as they can because it helps spool the turbos and more fuel always equals more power.
#21 by RabbitJockey on 02 Apr, 2013 07:44
nah those turbos are too big and the high altitude makes them even worse for you. vnt can't make up for a surging compressor map, it would only make it worse. i just don't think theres going to be a turbo that will work at your altitude on a 1.6 to make 150-175hp with out being in compound.