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[turbob16hatch]

 I have been trying to figure this out for the last few days, and well  i have no faith that i have it understood.

ok well for my DD build i have been looking for a good turbo that will do what i want and was cheap. well i found a older to4e 57 trim for $40 that needed a rear seal and couldn't pass it up. i'm looking for 250-300 whp daily on pump gas. So i began looking at graphing my engine  to the to4e 57 trim map.

engine:
- D16a6
- delta 272
- 75.5 vitara/ls rods
- 7.1:1 comp. roughly

turbo:
- TO4E 57trim 50./48

Now i don't know how to find out what my engine will really push as far as cfm or lbm. so i was playing the guessing game a little.

i graphed it at 7200 as my max flow and 4000 as where i was thinking it "might" spool.  At 14.7 and 20 psi respectivly. i also used the green lines to show the power level i'm shooting for.




Now why does the 20 psi mark go to the right of surge? i'm doing something wrong i know it there, now i'm just thinking it might just move to the right some when actually running this engine. correct me if i'm wrong.

oh and before you guys go shouting  "the 57trim has worked good for years" yeah i know it does work well on the b and d series, but i'm trying to figure out the compressor map crap, so w/e.

[bigwig]

http://honda-tech.com/showpost.php?p=39262093&postcount=23

If you don't feel like reading...toss the 57 trim and get the 50 trim.

[turbob16hatch]

well did i do it wrong? is it that far off? haha

[bigwig]

57 trim is a dog shit turbo.  Been saying it for years.  50 trim is the turbo of choice out of the t04e line.  Then it's wise to jump to the some turbo with a GT40 comp wheel once you out grow the T04e.  Granted, I'm ignoring other options like Holsets, Mitsubishi, Borg Warner, ect.

[dvst8r]

+1 50trim, there is a reason that is all china produces. 

[turbob16hatch]

i agree the 50 trim being better then the 57 trim. but for the $40 i paid for this thing, it makes no sense to swap comp wheel and housing to the 50 trim.

[dvst8r]

Why does it spool faster to 20psi then to 14.7psi? They should follow the same line slope.

[turbob16hatch]

because i plotted them at 14.7 and 20 psi. so the flow is different or w/e. again i was guessing a bit. so i might have screwed up the first dot's.

[bigwig]

Why does it spool faster to 20psi then to 14.7psi? They should follow the same line slope.

57 trim is a fucked up turbo?  Seriously, it defies logic for the most part.  I don't understand it's popularity.  Drag and RevHard started using it YEARS ago and some how it stuck.  I don't understand it.

What VE values are you using?  What are your parameters?  In order to figure out comp maps you need to have an understanding of your engine's VE.

[turbob16hatch]

this is what i used to find out cfm for 7200

172cfm = 97 x 7200 x .5 x .85
                          1728

412.8 = 2.4 x 172

thats my peak at 20 psi, correct?

peak at 14.7 = 344

[bigwig]

Why are you doing shit by hand?  www.not2fast.com  Seriously, don't do the calculations by hand.

PS: VE is over 100% on turbo'd engines.  Shit, Honda engines N/A are around 90%.

[turbob16hatch]

well that might explain alot. thanks for the heads up.

i'm still figuring it out. so i would prefer to do it manually at first to learn it.

[bigwig]

Waste of time.  I promise.  It's algebra.  Did you pass algebra?  Then you can run the math on these calculations.  You want a calculator that will do the work for you so you can change the variables quickly and then see what impact the changes have.  Figuring compressor maps is a stupid art.  You fudge the numbers enough and you can make them say anything.  It takes an understanding of your actual engine's VE to get reasonable results.  Once you figure that out, you can prove why a car make X power at Y psi vs another car making Z power at Y psi.

I might as well touch on VE since this discussion is up.  What does a turbo do?  You can go through all of the technical discussion of how they actually work, but in the end, they are increasing VE.  You have an engine with a set capacity and you are shoving more air in the engine thus increasing the efficiency.  You can enter a pressure of 0psi in a compressor map and play around with VE numbers and use the idea of 8-10lb/min = 10hp.  You can then compare that to a stock dyno and map the VE of an engine.  From there you can add 20-40% to compensate for boost and get some working numbers.  Luckily there for you, there are a lot of dyno charts out there that you can compare your numbers to and verify you are on the right track.

[turbob16hatch]

huh, yeah the math wasn't my concern so much as figuring out how to get to the final step that i was trying out, and learning. plus i didn't understand the v/e so now i can do this with some more understanding of what's going on.

thanks for the help on v/e.