whats going to happen if i put a gt 3071 r on a 4.0 l cherokee engine? where is it going to start spooling and where is it going to reach 7 psi of boos? any ideas?

 

my semi-educated guess from my experience with this turbo: with the 56.5 mm .86 A/R housing i'll say start about 25-2600, and 7psi by 3000. (as with others, depends on tune, and load) the t25 flange seems small.

 

so the .63 housing wont help to get 7 psi at 2000 rpm either (i use the jeep for towing). can i do the gt2871r with the .64 housing?

 

that diesel of gas ??

 

The .63 may drop it a couple hundred rpm....... my numbers were just an educated guess based on other projects. There is a turbine map on Garretts site that will help, but it requires some math, and accurate info on your 4.0(VE, EGT's)
How much weight do you tow? What trans? Tow in OD? EFI? How will it be tuned?

 

poor 4.0. lol

 

its a i6 243 cuin 97 cherokee gasoline engine rated at 235 lbsft (3200 rpm) and 185 hp (4600 rpm). That means ve of 85% and 75%. at 2000 rpm and 7 psi boost we are looking at 110 hp and 12 lb/min (my best guess without intercooling). typical operating range is 2000 - 2500 rpm and thats where i want more torque, if max power is only 230 or so, i dont mind. i am talking engine hp by the way. i dont want to go into the tuning issue, there are just too many possibilities (i even have a motec m8 somewhere, although there are guys who just do injectors and a 2 bar map and drive it). i dont really understand the turbine maps, i donk know what temperature they are corrected to (doesnt make to much difference on the compressor side). if i take the 12 lbs/min and add the fuel i get 13lbs/min. assuming a pressure ratio of 1.6 accross the turbine, id have to go to a gt22 to get what i want. kind of doesnt make sence.

 

Sounds like you have it figured out, but here is what I came up with: 243 cid @ 2500rpm and 75% VE corrected to 1000* is 16.478, and 2000 is corrected to 13.878 (quick calculation, and ballpark #'s...... not sure on VE at that rpm). With the 2871 .64ar it should be well into boost @ 2500 rpm with a pr of 1.75, and 1.50 @ 2000. The 56.5mm 3071 looks to be about 4-500 slower.

I just started reading turbine maps, so correct me if i'm way off here.

 

thats what i get with intercooling.

i found some dyno data on apt's site. on a 2.0 l vw engine the 3071 surprisingly spools as fast as the 2871. but i also noticed that bothe turbos seem to reach 7 psi at a power level of 160 - 200 hp at the wheels. thats really weird, as a am expecting to have 110 engine hp at 2000 rpm.
well, maybe i should get a t3/t4 after all.

 

there are just too many variables. a charger off a GM 3.8 would work great for towing...... too bad they're not easier to mount.