I'd have to disagree with you bill. Small cubic engines benefit greatly from boost! While everyone is quick to say "no replacement for displacement", that isn't entirely true. Boost is the replacement!
I think what's been prevaliant with most I the slant turbo builds is simply overcomplication! For a mild street build I don't see the necessity in a lot if what goes on with these turbo builds.
This setup should be reliable and I imagine it would make near 180-200bhp easily!
I never said small engines didn't benefit from boost. They surely do.... but a 170 is SO MUCH SMALLER (virtually one-third,) than a 225, right off the bat, it has to overcome that diminished size before making any gains on the bigger motor.
To clarify. 1.33 X 170 is 226... but .66 X 225 is only 148.5.. Now I know why I did so poorly in math classes in school...
Engine Builder online magazine says, "Hanging a turbo on a small engine allows a little engine to breathe big. With only 6 to 8 pounds of boost pressure, a turbo can increase power output 15 to 25% or more over a naturally aspirated engine. (225) motor, stock. "
So, with 10 pounds of boost, maybe you can get 33% more out of a 170, but that only puts you up to the output of a stock, non-boosted 225. And, with a LOT of parts, expense, planning, and time.
Makes no sense. Not worth it, for what you get.
You'd be way better off starting out with the bigger motor to begin with, since 225's are so easy to come-by (mine was given to me!)
Now, if you think the amount of mechanical jeopardy that exists by turning that little 170 8,000 rpm, and boosting it to 20+ pounds, is worth the risk.... you can surely make a lot of horsepower, but at what potential cost? RPM kills engines...
Not worth it, probably, for a street engine, I think.
No; I am not in favor of using a 170 for anything but all-out racing in venues such as those that use pounds-per-cubic inch, where boosted or no, the 170 is
absolutely unbeatable! It makes for a GREAT race motor, because it has a short stroke, revs to the sky, and the displacement matches the head flow.
But on the street... it's just too small, when the 225 is the same size, externally, and everything bolts up. Hell, a 225 is really small, when compared with the competition; 454 Chevys, 460- Fords, and 440 Mopars... gimme a break!
And if you
ever think I am somehow NOT in favor of turbocharging these slants, consider this: I was twice warned to "
tone it down" in my discussions of the advantages of turboing slant sixes... with management here, threatening to
ban me for life, IF I didn't quit pissing off the V8 members of this forum... they were getting so many complaints about me.
Not hard to see where my heart is...:violent1: LOL!