850Miata

Hi,

I would like to know what people's opinions are on upgrading from the
GT28RS to a GT2876R, or should i just go to the GT3071R ?

Thanks

Anthony.

Braineack

iTrader: (62)

what are you looking to achieve?

850Miata

well my current setup is

GT28RS
Front mount
MSPNP 90-93
Built bottom end and some head work
deleted AFM
straight pipe exhaust
HKS SSQV
Innovative LC-1

I would like to acheive 350 - 400 farther down the road after tranny and rear end swap.

Am I currect when I say the GT28RS stops flowing efficiently at 15 PSI ?

Mach929

iTrader: (3)

i think it's got more than that in it on a 1.6, my guess without really looking 20ish psi

850Miata

Oh i was told that the turbo wouldnt spool past 16 PSI ?

(never tried)

y8s

iTrader: (8)

3071. the 2876 is nice but go big.

850Miata

Thank you for the opinion, but can you verify what I have been told or am I incorrect ?

y8s

iTrader: (8)

oh i can't verify about the smaller turbo... but i can show you that on a stock motor the 2876R runs out of steam at the top end.

850Miata

Well 3071r sounds good, will it fit without any problem's?

devin mac

iTrader: (2)

can you read a compressor map?

you've got (roughly) 98 cubic inches, at 7k rpm. that equates to roughly 198.5 cubic feet of air per minute.

plugging that into the ideal gas law, with, say 90deg F air hitting your intake manifold, you end up with JUST shy of 30lbs of air per minute...

the pressure ratio of 16psi is just a c-hair over 2, so that puts you right around the red dot in the compressor map, with 16psi at 7k rpms. you're not maxing that turbo out. but more than that and you're starting to run away from where it's efficiency is decent. my vote, go bigger :-)

850Miata

Thank you!

Very good information, next time i will be sure to go to Garrett and look at there maps.

coastertrav

Where the hell are you in PC?

I have never seen another Miata around here without some old lady driving.