OK. I'm starting to get a bit of a picture here.
Really, if I'm at around 1880cc (80 thou bore, 120 thou offset grind, from
my calculations) and wanting a useable rev range of 2500 to 7000, and decent
power available from 3500 to 6500, 130 hp may be my tops (unless I turbo...
Huh!) And for this application twin 40 DCOEs would be most adequate. Even at
140 hp.
So the 42s are starting to sound like more trouble than they'd be worth,
(though I will check the parts availability again, cause I wouldn't be
suprised if the specialist guys here are making or turning down chokes for
them. They actually mod new 40s to be 42s and sell them for those special
applications. But that doesn't solve the problem of 5 years down the road
when they stop doing this. It sounds like all the experience is there with
the 40s as well.)
Anyway, I have some questions...
What other things did you have to do in order for 8000 rpm not to break
things. I may consider trying for this but I expect there is some expensive
mods required. Is 7000rpm going to pose many problems?
Why did you use 6 inch and not 5.7 inch chev rods? I measured up for 6 inch
and thought there was no way I'd find an off the shelf piston that small.
What is the magic article on the 2000cc rootes engine?
Regards head sealing..
I run two engines at 80 thou bore at the moment with standard head gaskets
with no problems, but maybe our head gaskets are a different pressing. I
wouldn't go any bigger though. I can get special ones made at about $NZ100 a
pop, which is a bit steep if I keep pulling it apart to play with it more.
One person here in NZ is racing a hunter (bored and stroked to 1994cc, 7200
max revs, 150hp) and he in the end dry decked the block and head by welding
up all the water openings, and running the water out the back of the block
into the back of the head. I think his bore was about 160 thou, mitsi
pistons or something. He had no gasket problems after that. I thought it may
have caused even more problems because the temperature difference between
the front of the head and the front of the block would be pretty high, but
apparently not. He still needed a special gasket too though.
Greg
Jarrid wrote...
> Well, 130 to 140 BHP is still going to need some revs.
> The 2 liter engine you describe will still need 7000 RPM to make your
> 140BHP.
>
> Wide power band and 140 BHP wont come in the same package, sorry, we
> only have two valves here.
>
> I have used 6.0 inch chevy "carillo" rods with with 2.0 inch journals, and
> 7/16 inconel cap screws. Certainly a way to make a bulletproof bottom
> end, but then again, I was building an 8000 RPM motor. This also BTW
> make for some VERY short and rather lightweight pistons.
> The rods although many times stronger, and .365 longer still weighed in
> less than the stock pieces.
>
> I looked into the big bore thing a while back, and it looked to me that
> bores beyond .060 were beyond what I would call an acceptable sealing
> area on the head gasket.
> This means you will need over .5 inch stroke (.250 offset grind) to get
> from 1725 to 2000 CC.
>
> Many of us have read the magic artical on making the 2000cc rootes engine,
> but nobody has ever told us what the author used for a gasket.
>
> I calculate the one could attain 1856cc with a .080 overbore (if it
seals),
> then with a .200 stroke (.100 offset ground), one can attain a 1913cc
engine
> within the confines of what CAN be done with a factory head gasket, and
> the amount of meat on the crank.
>
>
>
> Jarrid Gross
>
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 08:45:09 CDT