Math w/ SXE369 and 12v.

[bellabulldog]

I've watched some of the PDD videos and have been attempting to get a rough estimate of the power my truck is capable of running a single SXE369.

My assumptions are 7whp per lb air/minute.
4000 RPM

4000rpm x 179.5 cubic in/revolution = 718000 / 1728 = 415 CFM x .75 (estimated mechanical efficiency) = 311.6 cubic ft/min

5K Ft elevation = 12.4 PSI atmosphere
4.2 pressure ratio x 12.4 = 52.08 true pressure - 12.4 = 39.68 gauge pressure, will round up to 40 just to be simple.

http://www.full-race.com/store/image...-content-6.jpg <--- turbo map for SXE369

4.2 PR to approx 85 lbs/min of air has an efficiency of approx .7 according to map.

4.2pr x .7 efficiency = 2.94 density ratio

2.94 density ratio x 21.5 lb min engine is producing at 4000 rpm = 63.21 lb/min x 1.45 (stock intercooler efficiency estimate) = 91.65 lb/min x 7 = 641.58 whp.

I'm a little confused on calculating efficiency number from turbo map and 641 whp seems quite high for my truck but I don't have a dyno or race track nearby to test it out.

Is my math off or am I missing something?

Thanks,

Andrew

[bellabulldog]

Furthermore using the same probably flawed math with a pressure ratio of 5.0 (my truck at 5k elevation boosts to a little over 50lbs) and an estimated map efficiency which is just a guess of .55 since the map doesn't go that high, only shows 97lbs of air moving (vs the 91.65 @ 4.2 PR and .7 efficiency) and with the decreased efficiency only yields an estimated 670ish whp really illustrates how once the turbo is out of map all you're doing is blowing hot air.

[Woody35]

Where is this number coming from? 1.45 (stock intercooler efficiency estimate)

I realize you said it was a estimate but at the risk of sounding ignorant wouldn't this number be below 1?

[bellabulldog]

It's what the guys at Power Driven Diesel use in their first video and they explain that diesel engines generate tremendous heat unlike gas engines due to the high levels of boost they run and thus an intercooler is able to cool the air and thus make it much more dense. http://powerdrivendiesel.com/videos/turbo-school/ It's on episode 1 and I believe it is about 23 minutes or so in. Without the intercooler you would only be using the 63.21lb/min number and would thus only equal about 442 whp (63.21x7=442). If it didn't increase your density ratio why even both having an intercooler to begin with?

[56cummins]

What you have calculated is your air potential. To actually hit the numbers you have to work on fuel, timing, backpressure.....and a hundred other tuning tweaks. I think I read PDD hit 728hp on an s369 on the bookface.

[JQmile]

Get a GTECH or VBox, or phone app, do a quarter mile run, then plug trap speed and weight into the compd calculator. That will probably give you the most accurate guesstimate.

[Big Blue24]

Originally Posted by 56cummins

What you have calculated is your air potential. To actually hit the numbers you have to work on fuel, timing, backpressure.....and a hundred other tuning tweaks. I think I read PDD hit 728hp on an s369 on the bookface.

That was a shift spike meaning it converted engine RPM (rotational energy) into a momentary HP spike at the rollers when we did a full power 3rd to 4th locked shift. Real sustained HP has been mid 550 to 575 HP on a stock manifold .80 AR wastegated T3 housing.

We've been testing all week and will upload quite a few testing graphs and videos the first week of August when all the data is compiled, overlaid, etc. One thing is becoming evident, the 369sxe with a choked down .80ar wastegated T3 housing barely outperforms some of the smaller SXE models and has a more lag due to the larger heavier 73mm turbine. Hopefully the 369 comes around powerwise with the bigger T4 housings because it has been a let down so far here at 5700' elevation....

[Drothgeb]

Is the 550-575 corrected hp?

[badbowtie]

Based on Will's other past posts I would guess that's a real number not some corrected imaginary number.

96 3500 5x018 7mm dvs 62fmw

[Big Blue24]

Originally Posted by Drothgeb

Is the 550-575 corrected hp?

Real HP... corrected is around 650 HP. To be honest, our uncorrected numbers are about 5% lower than track time average HP so somewhere between 550 and 650 is the true peak HP number....


All I know is the more we test turbos, the more impressed I become with the Junker's low 800 HP uncorrected numbers.... it must be a freak.

[bellabulldog]

How much difference in size is there between a T3 .8 and a T4 .91? I get the feeling that a T3 .8 is probably like a 12 or 14cm, vs a T4 .91 is going to be like 16 or 18cm?

[DISTURBED]

Over the weekend an engine I built did 677/1302 on a 12v with 5x18 and a 1.05 cf

[bellabulldog]

Originally Posted by JQmile

Get a GTECH or VBox, or phone app, do a quarter mile run, then plug trap speed and weight into the compd calculator. That will probably give you the most accurate guesstimate.

Would do something like that but I can't spool my turbo right now, need a higher stall converter. Can only brake boost truck right now to 5lbs at 1700ish RPM. Work in progress.