falcon

iTrader: (13)

You think I should just go for the 2871? Damn I wish there was more real life experience with these on this site for 1.6's.

Braineack

iTrader: (62)

don't forget the the cams or the IM...


regardless, you should know the math behind it:

Volume Air Flow = (L/28.317) x (RPM/2) x VE

1.6L / 28.317 = 0.0565

8000/2 = 4000

VE = 118% (according to my VE table)
.0.0565 x 4000 x 1.18 = 266.7 CFM /14.47 = 18.43 lb/min

The .64 housing at 2PR (15psi) maxes out around 16 lb/min, where the .84 reaches max efficiency around 21 lb/min, so in this situation, the .84 might be better served.

If you were to stay around stock redline, 7250, then you'd be closer to 17 lb/min of gas turbine flow so it's kinda a toss up since the turbine will be working just over it's full potential without choking up.

falcon

iTrader: (13)

Brain, does that equation work the same with a smaller turbo?

Garrett's site doesn't list the 2860r-5 with a .86 housing. So by the looks of it I may have to go with a 28RS. I'm buying Lev's Blox intake manifold which should help a bit as well.

Braineack

iTrader: (62)

its just volume air flow, it doesn't change. you are always ingesting and compressing the same volume...only the density and rpm will effect it. you just need to see a turbine map and then you can determine what size would be best fit for the amount of exhaust you are flowing.

the general consensus we've determined here is a pretty good rule of thumb.

Newbsauce has a 1.7L with a .64 A/R 2871, at 17psi his TQ, even with an IM, TQ was still dropping off...so maybe it's time for a bigger turbine housing, we kept pushing the timing and there was just no more power to be had up top.

falcon

iTrader: (13)

****... I thought I had it all figured out with compressor maps but now theres something new to learn.

From what I've read as well though... with a v-band TiAL spool is a bit better still? So it may be best to just go for the .86 if I'm going TiAL.

With the head and intake manifold it shouldn't be terrible.

shlammed

iTrader: (8)

the spool shouldnt be that different, but my new 2871 vs my used 2860 spooled the same.

its well worthwhile though

Savington

iTrader: (31)

.63/.48 = T3 housings. a T25 .86 is about comparable to a T3 .63 housing. Nobody in their right mind goes beyond a T3 .63 housing (I think the next step is .81 or something).

Jason has measured really high TIP with his 2560 .64, and didn't BEGi have **** results with their original S6 car (rharris' car) with a .64 housing?

If you're going to push the car beyond 300whp, I'd really consider an .86 housing very strongly.