I think you almost got " it " . I went tru all dyno sheets from this forum what i coud find . Best GT35 kits has 300-500 rpm better responce than this kit on "static " dyno pull . Only few of those.
Most set same responce like Gt4088. "it" is with lowest turbine side back pressure !
Broken reco....Tru , But to get good responce you dont always need to go smaller turbo ..If all is done like i wrote ..you can pic up bigger one to get same responce.
First dyno session with stock 10,2 comp engine i got 403 hp at 3,6 psi boost .Almost same responce . Now three so many updates it makes even better.
GT 35 ...No i am in dangerous zone, but i woud not pick up any garret turbos from "box" ! Compressor/turbine sizes are not in balance. However if you use Gt35 turbine shaft for 2 l turbo engine and proper 53-57 mm compressor wheel > You got something what has exelent responce and power . Turbine side pressure will stay under boost up to rev limit.
Power lever ..yes it use to be trade/and sale /loose /win but it is getting better and better . 2 l car "normal power" is 400hp easy with any turbo, 500 hp modern engine with correct turbo, responce is like OEM. 600 hp you will loose 350-500 , but you will get 500-1000 more rpm range at top end.
I have gone through most of all the dyno graphs posted on prime as well as have many other private dyno sheets of various setups.
The twinscroll GTX4088 gets to peak torque around 800rpm later than a single scroll GTX3582, not 3-500rpm.
A twinscroll GTX3582 should spool even quicker and would make for a better comparison (or both being a single scroll). It's not really fair to compare a twinscroll GT40 vs a single scroll GT35.
You seem to be very narrowly focused on peak power numbers at a given boost level. If that impresses you, then you will always be drawn to larger frame turbos which make more power with less boost, at the expense of transient response and low-mid range power. You seem to be completely ignoring the majority of factors which affect the driveability, response, and character of a turbo and it's powerband. Turbos are far more complex than NA or Superchargers due to 'lag' and thus looking at a WOT pull of a dyno really does not tell you much how it is going to respond or drive.
I hate to sound like a broken record again, and it doesn't seem like we are understanding each other all that well, but:
The key when sizing a turbo is determining your target power goals, the application it will be used for, and the fuel that will be used. From there you need to analyze the VE and characteristics of the engine (and actually the exhaust system) to properly size the turbo.
It does not have to be like that ! And using small turbo you will loose so much at top , building lots of heat , knoc sensitivity ++bad things .
If you want chance C30A natural beheaviour then go 30-35 . Turbo set is complete paggage JUST NOT only turbo.
"loosing too much power at the top" is relative. You can't make that blanket statement without defining the power levels. If your goals are 400whp, depending on the fuel used, a GT30 will give you by far the best response and will be efficient and optimized for that power level. A GT40 making 'only' 400whp will be extremely laggy and inefficient. A GT35 making 400whp will be less responsive than the GT30, but will make that power at lower boost levels and make less heat. Which might be a better option if you track your car in 110*F weather in Las Vegas using crappy 91 octane fuel and you dont' have a good intercooler.
OK "there " is two cars front of pit and now you need choose what car you woud like to use in race , track is "common" style circuit .Not a parking lot race.
One with Small turbo system with poor desing and one with big turbo all done by book. Bigger turbo car has 500 rpm lower responce than small turbo car.
But this bigger turbo car has 1500-2000 rpm more power range area at top and 100-200hp more power at same boost.
That is a horrible apples
ranges scenario which is not much better than saying:
"What would make a better race car with 400whp: a 2.0L i-4 motor with a giant GT42, or a 5.0L V8 with a single GT35 (which only needs 1psi to make 400whp)?
As I said in bold above, you need to define your intended use, power level, fuel, etc... I've done that with my 400whp example with the GT30, GT35, and GT40. Now if my goals were to make 600whp, the GT30 won't be able to do that, the GT35 will require a lot of boost, heat, and octane fuel to accomplish that, but will be far more responsive than a GT40 which will require less boost, make less heat, and require less octane to make that power level.
There will always be a compromise.
"static" dyno pull low or high compressio in same engine does not give you big advantage . But when you are in "war" zone huge differece like stunman has found out.
I did toyota 7M-GTE engine overhaul and we raised compression 9>10,5 (ethanol) and in the dyno it was only litle better . But driver told my it is way better now.
I'm not sure what a "war zone" is, but it sounds like the driver of that 7M-GTE liked the improved transient response 'way better' with the higher compression ratio -which reduces 'lag' and improves spool. As I said before, these are the qualitative aspects of turbocharging that you can't really see in a dyno graph.
FWIW, one of the best turbo engineers in the world decided that a GTX3582R - FP HTA 3586R is ideally sized for a target of ~500-550whp on pump gas and 600whp on race gas with the best response possible.
Similar power with same boost level ?
9180 : Exelent Wheel ratio ! Comp exd is too big for NSX boost level. after 650-700 hp your will blow up you stoch power line anyway..
GT4088: correct turbine size is 77/70,5 mm . not 84/77
GT42 physically TOO big for that Place BUt i woud love to pick up Gt42 turbine wheel and used it with GT40 compressor ( it cant be done)
As i told i woud not pick up any garrets from box ( any engine) . Gt4088 was in performance turbos list where it shoud be ! Vol 5 Garret . VOL 6 is dropped out !
BUT do you know what ? it is from DAF Truck !
My bad, I just found this site and the 77mm wheel with 84 trim =
77.0mm/70.6mm turbine wheel. Almost identical to the GTX4088R's 77.00/70.40 (83 trim) wheel
https://www.extremepsi.com/store/product.php?productid=19769
Since our conversations are quite circular, I don't really have anything more to add that hasn't already been said. I understand your quest for the most power with the least boost, but it's probably not the best to recommend larger turbos for people who are looking for more response at lower power levels.
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