Varible rod ratio verses variable timing....

dstar · Post by **dstar** » Wed Jan 18, 2006 11:25 am

It is mechanically possible to do both, but which one would help
*even out* the powerband and produce more powere across the entire RPM range?

Anyone wish to opine?

Don

Santas Brother · Post by **Santas Brother** » Wed Jan 18, 2006 11:31 am

My unscientific guess is variable valve timing offers
more potentail to change the power characteristics.

dstar · Post by **dstar** » Wed Jan 18, 2006 11:54 am

Well, THAT was EASY!

OK Jake, I guess you can delete this thread now!

BTW Santa, got your head yet?

Don

Santas Brother · Post by **Santas Brother** » Wed Jan 18, 2006 1:43 pm

I've got junk one waiting in Michigan,I'll get it in March
with my Deutz cylinders

;and two good ones waiting
in Mass.One from you,and one from Speedytub.I wonder
if they have matching exhaust ports ?

My sister didn't come here for Christmas,so my parts
are piling up in her basement.

No problem,I'll get all that stuff in March as well.

HAM Inc · Post by **HAM Inc** » Thu Jan 19, 2006 4:34 pm

Variable rod ratio? Am I missing something? How is it possible to vary the rod ratio on the fly? Either the rod length or the stroke must be changed.

Plastermaster · Post by **Plastermaster** » Thu Jan 19, 2006 5:06 pm

HAM Inc wrote:Variable rod ratio? Am I missing something? How is it possible to vary the rod ratio on the fly? Either the rod length or the stroke must be changed.

Len Len Len, It's all about modulouse of elasticity! larger rod ratio is better at higher rpms, so... you make them puppies outa ruibber! The faster the engine turns the longer the rod gets. Of course you need to do some odd deck heights to allow for the stretch, so you also have variable CR to your advantage!

Ron

cnavarro · Post by **cnavarro** » Thu Jan 19, 2006 5:51 pm

I've seen a rod that had a slider in the beam and was adjustable for variable lengths. Did I mention it was billet aluminum. It's sitting on the shelf at R&R (the guys who are doing the billet steel rods for us!) Does that count?

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Class 11 streeter · Post by **Class 11 streeter** » Thu Jan 19, 2006 10:17 pm

Doesn't turbocharging *even out* the powerband and produce more power across the entire RPM range without complicated engine internals?

Oh and since we are talking about variables, how about the variable compression ratio engine, where the head was on a sort of hinge on one side and the head could be brought down to increase or up to decrease the comp ratio on the fly. Of course it would require variable timing and a variable rod ratio to make it work properly.........

Frallan2 · Post by **Frallan2** » Thu Jan 19, 2006 10:45 pm

Yes,

That is the SAAB invention with variable compression and it has a Autorotor screw type supercharger on it too.
Just ingenious! It has very little downfalls except cost to produce in mass, as for today.
Don't think it is using variable timing but that would ofcourse be another nice variable to put in there for the computer and dyno guys to play with.

Dstar, now tell us about the variable rod ratio.
How?

dstar · Post by **dstar** » Fri Jan 20, 2006 5:14 am

Variable rod ratio is a different approach to solve the same
problem that the Predator carb attempted to solve, charge velocity.

I think that, used in conjunction with variable valve and ignition timing,
one could maximixe effiencey of an IC engine.

Don

HAM Inc · Post by **HAM Inc** » Fri Jan 20, 2006 6:53 am

I am in total agreement that a variable rod ratio would be a plus. But how would it function, reliably?

I like the elastic idea! I'll bet someone either has, or is working on it.

Charles, how does the slider work? Is it designed to change the length on the fly?

cnavarro · Post by **cnavarro** » Fri Jan 20, 2006 6:56 am

It looks like you just unbolt the beam, adjust, then loctite- scary if you ask me, but someone had them make it custom. It's a three piece (minus the bolts) rod.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

dstar · Post by **dstar** » Fri Jan 20, 2006 6:59 am

Yes, changing the length of the rod is what I had envisioned, with a swashplate activation(oil pressure diverter) and lock with a cam lock
type setup.

It would lock in either the short or long setting, and change only at
no load.

Variable venturi, ign timing, valve timing and lrod ratio, all with
computer control, would be the cat's MEOW!

Don

Muffler Mike · Post by **Muffler Mike** » Fri Jan 20, 2006 9:06 am

wow, share those drugs. LOL

Actually the only way i can see one somewhat simulating a variable rod ratio is if the rod was made offset and maybe even the wrist pin was as well. (sounds familiar) This may change the rate at different points of the stroke between the up and down stroke.

HMMMM, now im starting to hurt my brain on this. I dont know.

cnavarro · Post by **cnavarro** » Fri Jan 20, 2006 9:23 am

That's a novel idea, but what real length increase or variation would that yield out of curiousity? My brain hurts too! What would that do to the poor pistons? LOL

Only thing I know for sure is that you most definately have too much time on your hands Don.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance