Originally Posted by Howard Coleman CPR (Post 10554169)

as i was exchanging PMs w a potential engine customer he disclosed that he was seriously thinking of going w a BW EFR 67 mm...

previously he had bought a GTX35... given the GTX35's map (around mid 70 pounds per minute) i figured he liked the lighter hotside wheel and some of the neat features and that he was trading one turbo for something of approx equal, or perhaps a touch more, output.

i have a feeling he did too.

i wanted to check out the trim on it and a few other details so i visited the site and started looking thru the 120+ page document.

http://www.full-race.com/articles/efrturbotechbrief.pdf

as most know the EFR series turbos do have lots and lots of neat new age features and truly there are 112 pages of yummy reading re the details.

of course then there are the numbers and on page 113 forward my eyes opened wide.

there are a series of compressor maps and on each map the inducer exducer sizes are disclosed.

so map 2 (page 114) is the "67 MM EFR"................ o k, here's the turbo my guy wants to trade his GTX35 for. let's take a closer look at the details.

inducer 53.9 mm
exducer 67 mm

max air? 44 pounds.

and here "TURBO CONFUSION" re-emerges.

when we think 67 mm turbos... we think of the A-Spec GT500r, we think of the TO4r and the TO4Z and the PT67.

these 67 mm turbos have 67 MM inducers, not exducers and they make mid 70 pounds per minute+, not mid 40s.

this is not a knock on BW, which i like, nor Full Race, it is merely an attempt to draw your attention to the continuing confusion re turbo nomenclature.

that's why i did my stickied thread entitled turbo comparisons... using a better comparative yardstick.

so if you are looking at the new line of BW EFR turbos do reference pages 113 to 118. check out the actual compressor inducer and exducer sizing.

another item that many of us are aware of but it justifies repeating... take the hp numbers and divide by 1.3 for the rotary.

changing over piston hp to rotary and using BW's figures:

62mm (T3) 450 piston 346 rotary
67mm 500 piston 384 rotary
70mm 550 piston 423 rotary
76mm 650 piston 550 rotary (500 rotary)
83mm 750 piston 577 rotary
91mm 1000 piston 770 rotary

this post is not to paint the new turbos negatively (or positively) but to point out that given the unusual method of referencing the compressor sizing board members will need to make the correct decisions.

i will be updating my turbo comparison thread w the apples to apples.

it will of course be interesting to see how they perform. i will say i am not overly impressed w the comp maps but the maps are not necessarily the definitive statement and there are some very neat (esp the lowered turbine mass) aspects.

howard

Originally Posted by lastphaseofthis (Post 10580907)

Reminds me of when AMD start labling CPU's at an "efffective" clock speed. while intel just labled them all by the exact mhz/ghz. shame. yet another thing thats long been needing a standardization. right?