Turbo sizing, deeper discussion

SmokinCAT said:

I proved this to myself this past week, tried to different turbos on my 3406, first was a garrett tv8511 with a single entry 1.39 housing, pretty similar in spec to a GT5518 and the performance was less than desirable, then switch to a HC5 holset setup as would have came on a K series, E trim turbine and 40cm twin entry housing.

This turbo is almost as responsive as the S410 that used to be on the engine, and was rather surprising to me.

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And being bigger than the OE charger that come on the 3406, the HC5 probably made a little less overall boost? And Ill bet the engine brake works better too?

Chrisd91 said:

Weston, instead of pestering you for tidbits of information, is there some reading you would recommend for further education beyond basics most can pick up from reading this and other forums? There was a link posted to a book earlier in this thread, but are there any you would personally recommend?

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This...yes please.

:redx:

The problem is different manufacturers have different ideals from the engineering standpoint, and short of being familiar with each and how they compare, there is no way to simplify much of the information.

murphy41 said:

And being bigger than the OE charger that come on the 3406, the HC5 probably made a little less overall boost? And Ill bet the engine brake works better too?

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Still up in the 40psi range, I haven't gotten the jakes wired in yet, but I figure it won't be noticeable as the jakes preform poorly by design.

SmokinCAT said:

Still up in the 40psi range, I haven't gotten the jakes wired in yet, but I figure it won't be noticeable as the jakes preform poorly by design.

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They're definitely not an ISX Cummins by any means. LOL But with a turbo change I did on a 3406 for my buddies dad I was working for, it woke the engine brake right up. But it wasnt an H5C either.

murphy41 said:

They're definitely not an ISX Cummins by any means. LOL But with a turbo change I did on a 3406 for my buddies dad I was working for, it woke the engine brake right up. But it wasnt an H5C either.

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I have been looking for a set off of a later engine to get the next generation set of jakes.

I have been looking at the turbine side of things and have been playing on the calculators available (Matchbot/ boost adviser) as I don't know properly how to do the math:doh:

When selecting a turbo for a given application it is "relatively" easy to select the comp side using maps available given the air mass requirements and the PR needed to reach the hp goal, well I have been looking at the available turbine maps and have been trying to figure out how to do the same.

I have noticed that most of the maps plateau between 2 - 2.5 PR, as in they will flow no more lbs per minute even though the PR is rising so should we be using this as a very rough guide in turbine and housing selection? and how do you go about it?

my guess is working backwards housing can flow 3:1 max pressure ratio for X lbs per minute, find lbs per minute requirement (more questions on that soon)

14.7psi atmo multiplied by 3 gives us 44.1psi absolute or 29.4 psi gauge pressure for "drive pressure" before turbine inlet.

This "back pressure " is required in order to achieve max shaft power at the compressor. How do we do it with compounds?

assuming max ideal PR of both turbines is 2.5 would it work as follows.
14.7atmo x 2.5 x 2.5 to give us an ideal max drive pressure at the manifold before the secondary of 77 psi gauge pressure?

and back to exhaust mass flow I have come to the conclusion that it is roughly 40% of the masss flow going in? is this enough to get in the ball park?

Ill leave it there for now :blahblah1:

On edit I think I have the PR idea sort of close but I am way off on the exhaust mass flow part, that is a function of PR but I don't know how????

You might understand it better if you try to forget term "drive pressure". It's just backpressure that is not driving anything. If you want engine to breath, try to keep deltaP positive.