Here are a couple of more compressor maps to add to this thread:

The first one is a comparison of the stock turbo to the 38R:

The stock envelope is outlined in magenta and the 38R is outlined in blue.
The green dot shows the approximate air needed fro 375 HP and the red dot is approx air for 400 hp. Both turbos can handle it but you can see how you are reaching the edge of the design envelope for the stocker.



This compressor map is of the H2E:

the dots represent the approx. air needed from 400-500 hp.

 

For thse that are interested,

this guy does a great job at explaining how to read a compressor map. I had to watch it a few times with 2 cups of coffee a few years ago just to get the basics down. I still go back to it once in a while for a refresher since I have killed of quite a few brain cells over the years .......it's not complicated but you will need a bit of time, a pencil, paper and a large eraser......

 

Here is the compressor map for the 38R.......

don't focus on the plotted HP marks here, for some reason 20lbs of boost was used to estimate the presure ratio for 400 hp.

 

But backing up to the OP's original question.

What power level will the 180/100's get you to? 400? 450?

400hp need about 55 lb/min of air. So, if you backwards plan from the target HP number you can get an idea of the air flow you will need. Then you take that air flow number and look at the various compressor maps of the turbos you are considering and see which will be the most efficient based on your requirements.

 

That is a start, now consider temperature as well... that being said the stock charger is sufficient but not efficient, and we all know the motor will go into meltdown if he ever tried to tow with those sticks on a GTP 38.

Tuning is key. I also recommend Gearhead for tuning as they are the only tuner that has listened to me regarding temps.... it doesn't matter if the truck makes 600hp and you cant use a quarter pedal due to egts. Their tunes have been the coolest by far of any, down on power at our request, but that was never our primary goal.

 

Right around400-450 hp. I know both turbos will support it i know the advantage of the 38r is drop in and the h2e is lower drive pressures I would never have to worry about floati ng a valve. Hitting 40 lbs in a 38r (right around what I would be pushing ) is extremely close to floating the valve in back press ur e with it a 1.75 boot to backpressure ratio hole the h2e is 1:1. Is it going to be considerably more "laggy" tho? How do I read that from a chart

 

are you sure the 38R is that high of a back pressure ratio? I would ask Tugly, Meuckster & others who are running the 38R what there back pressure readings are. I don't think Rich (Tugly) has seen anything that high with his 160/100 sticks.......but that would depend on the Turbine A/R.

 

Meuckster ran 180/100's with the 38R for years if my memory serves me, It's still running well as far a I know. I would send him a PM.........

 

Spot on information...they are the only commercial tuner that has listened to many including me.

 

I do not want to get into a pissing match about tuners......but I don't have to back off the throttle from EGT's either. Three FTE members have driven my vehicles as well and could attest to that. The only thing that made them back off the throttle was watching the speedometer act like a windshield wiper......😎😎😎😎

Nothing against Matt & Geahead - he is an excellent tuner. But with the Hydra you are not limited to one tuner.

 

I forgot where I'd seen the back pressure ratio. But one guy with doing a wicked wheel and 1-1.15 ar housing comparison. his boost and backpresssure were 36 and BP was 54stil confused how he made 500+hp with only 36lbs. But he did. And Matt at gearhead is a very methodically programmer. He knows were dumb and lay it that foot heavy as we can in the wrong tunes (ex. Race tunes). He also knows races and truck pulls are started with high rpm let's say 2500 amd only go up. Well the higher the rpm the less torque since we usually peak at 1800 so he he saves fuel for the top he can have a higher hp truck on the dyno and not break rods. He also accomplishes the fact that egts need to be in keep which pulling the fuel out of the bottom is what helps. I like the low grunt presonally. I'm just upset that the zf6 I just put in the 3-4 shift form is broken (((

 

Ok, that makes sense now. If you are not taking the MAP sensor reading and using boost numbers you need to add armospheric pressure since the EBP includes atmospheric pressure. So 36 psi of boost would equal 50.7 MAP at sea level.

Boost = MAP- Baro
MAP = Boost + Baro

Or just use MAP & EBP when calculating your ratio.

See what I mean?

 

Okay so how about this question. What rpm does the h2e turbo start to lite up at ? What kind of boost will it see at what rpms? The stocker with the cam is crazy fast spool ~1600rpm Iv seen 16-18 lbs by 1800 rpm 20+ lbs depending on the load has been more. If the h2e is "lite" at ~2000 that or maybe a tad earlier (15+lbs is my meaning of it) IL go with due to I know the back pressure and egts will be lower other wise I think IL go with kc38r

 

Is the KC38R basically a modified stock GTP38 with the 38R billet wheel and machined compressor housing?

That is what is done with the D66 turbo and Riffraff's RDP66. You keep your stock journal bearing setup that is rebuildable. I asked about doing this very thing years ago before these came to market and everybody shot my idea down. Plus if the factory .84 A/R turbine housing is too tight, you could lower your drive pressure with the 1.0 or 1.15 housings.

I ended up buying a 38R years ago, but its crazy loud with an open element filter. The S&B intake is perfect for my noise acceptable levels. I've also bought the 38R billet compressor wheel but haven't installed it yet. Muekster had good things to say about it, lights up quick and lowered overall smoke amounts.


EDIT:
Just looked up the KC38R, it is basically what I described above, but they use new parts instead of reusing your OEM parts. It also has a larger compressor wheel by 5mm, so instead of being 66x88mm in a 38R, its 66x93mm. It should help with even bigger injectors.

Matt used to have this graph on the website of his tunes, 238/80 injectors and a 38R turbo.

 

Zero lag from my 66mm H2e, and its a hell of a lot stronger then a 38R. Rebuildable too... Of course in the last 220,000 miles I have not touched it.

LOL