Topic: oppy hp max?

[westonedelbrock]

what hp should i expect to have with a 42 splash lube oppy. camed arc rods and flywheel with avs pistons ported polished and carbed. is would be for an outlaw. guys with 50hp inteks say that 50hp is more than enouph even.

[cycloneracer]

50 HP out of an oppy???   

If it isn't on a dyno sheet it isn't true. 

I'm guessing 30 HP would be one of the highest HP oppys out there.

[BIG AL 202]

I believe it's who built it and what has been done. 50 + hp is possible but could be costly and my not be legal in some classes. Dyno time is the ONLY real way to know!

[westonedelbrock]

what would i have to do to make it a 46? crank and rods...?

[BIG AL 202]

Yes, You can use 42 rods and a 46 crank, then cut down the pistons to fit. Or just use 46 crank and rods. If you look around in the flathead section, go back quite aways, you can get the particulars. G-TEAM racing has a build dvd for the 28 singles and the oppys, not bad to learn with.

[westonedelbrock]

avs pistons go with the arc rods right? i didnt know if the crank would clear the block. so get a 46 crank and 42 rods with avs pistons? how much would the pistons have to be cut down roughly? .050? still has the top ring? i relieved the valves on my block not too far above the top ring

[redline]

This post has all the answers you seek...................

http://www.heymow.com/index.php?topic=20143.0

[garrywarber]

what hp should i expect to have with a 42 splash lube oppy. camed arc rods and flywheel with avs pistons ported polished and carbed. is would be for an outlaw. guys with 50hp inteks say that 50hp is more than enouph even.

Look through search well.  It's possible to make 50 cubes using stock parts.  3.5 piston with 46 crank and 40 rods, I think, but shorter rods may be wiser?  You could maybe get 50 HP if you supercharged 8 or 9 psi, but you better use ARC parts then, most likely...  Is boosting legal in outlaw class?
Garry

[royalblu68f100]

 No

[Burton for Certain]

The holdup is the carb and intake. If you could put a carb on each cylinder it'd be night and day difference.

[BIG AL 202]

Not legal in most all classes! but It will make it run, providing you can tune it well!

[Burton for Certain]

He said it was an outlaw mower so I guess it'd be ok? If your rules allow it that'll make a huge difference.

[The Tank]

I found these threads in regards to the oppy carbs.

http://www.heymow.com/index.php?topic=17290.msg178028#msg178028

http://www.heymow.com/index.php?topic=17013.msg177498#msg177498

[Rooster]

If your running against 50 hp inteks, that Oppy wont have a chance!

How much HP depends on alot of factors...best I have seen proven was 37 HP.

On the Dual carbs debate....Yes Dual carbs help, alot!
Anyone who says they ran against one with dual carbs and it was not fast...whoever had the dual carb engine screwed something up!
The biggest hold back on an Oppy is not the carb, it is the manifold, mount a pair of carbs on some straight shot manifolds will cure that problem. There is another cure ....but I ain't giving the secret up yet! 

Crank and rods will make it a 46, but yes the 46's have some additional clearancing on the block for the extra stroke. Alot of the 42 cube engines already have that done to them...but not all. It is easy to check, there will be some semi0circle cuts at the bottom of the cylinder.

[willenglish]

Without stepping on any toes...I just dont see the point. The only thing oppies are competitive with are other oppies. In mod-x a stock appearing opposed isnt remotely competitive...and when allowed to run a two barrel carb...it runs better...but still not enough to be competitive. The singles are getting quicker every day....and more reliable....and much bigger. The premise of how cheap an opposed is to race is  not valid. To try to be as competitive as possible...they are  as expensive as any other engine to run...and the more they are stepped on trying to wring any sembalance of competitiveness out of them...their reliability suffers just like any thing else. Im not saying everyone needs to get rid of them and stop running them. I believe the santioning bodies should make a class just for them.Briggs manufactured a blue million of them....every shop I know has two or three of them laying around...including the one propping open the door. They are cheap...and available and could have some  good racing among theirselves. Be a really good way to get a lot of folks back to racing that just gave up and are sitting out. i know Im gonna get crucified for posting this but its just an opinion. Im sure theres someone out there at a local track somewhere  that has an oppie thats just murdering those 100+ h.p. Kohlers by the bushel.