Race prepped opposed twin build thread

[Greentored 3,201]

Hope you all are doing well!

Been wanting to build a pressure lubed opposed Briggs for the off roader for quite a while- they just 'oil' better for obvious reasons. After much searching, I located a 'big boy' 46CI (20.5hp) pressure lube Briggs opposed twin, in a vertical shaft arrangement, and after MUCH deeper digging was able to pick up a horizontal shaft side cover, oil pump, and lower sump (oil pan) to flip her to horizontal for my usage. I have a knack for making power without spending a lot of money, and use that knack to inspire others to open their toolboxes instead of wallets, and enjoy making their small (or large) engines really honk without going broke.

Well, plans often change, dont they?

I ran across a fella who had a billet flywheel, billet rods, hotrod pistons and custom ground cam for the same style of engine, for about 10 cents on the dollar. Guess this build will be going against a lot I stand for, but its sure going to be fun!

Ever heard an opposed flatty twin at 7 grand? Me neither. Stay tuned, its gonna get silly

[Snoopy11 5,713]

 

MONEY!!!

 

Should make around 40+ish

 

Don

[Pullstart 59,758]

This’ gonna be fun!

[Snoopy11 5,713]

53 minutes ago, Greentored said:

for the same style of engine

I know what engine you are talking about...!

 

Don

[Maxwell-8 4,271]

5 minutes ago, Snoopy11 said:

Should make around 40+ish

The same dude with the selfclaimed 100hp Kohler has a 85hp opposed.

 

52 minutes ago, Greentored said:

Ever heard an opposed flatty twin at 7 grand?

That one sounds good on idle, let alone 7K

 

 

 

[Snoopy11 5,713]

5 minutes ago, Maxwell-8 said:

85hp opposed

Again I say, unless you start with a 999cc 40 horsepower base, you should be cynical of those kinds of proposed power levels... outside of forced induction...

 

With a 457cc engine, I am at the limit of what I can physically do to produce power on this engine without forced induction. RPM increases are what makes power, along with tuning, packing fuel/air/spark, timing, etc...

 

Double your rpms = doubling the horsepower. THEN you can add on some performance goodies for a couple more horsepower. 

 

The laws of horsepower with regard to these engines discounts many horsepower claims out there on youtube...

 

I say that @Greentored will make 40+ish... because he is almost doubling his rpms...

 

He could run 9,000 rpm and only make (approximately) 60 horsepower... just on the way the engine is made... outside of forced induction

 

Don

Edited January 5, 2022 by Snoopy11
more info

[Maxwell-8 4,271]

22 minutes ago, Snoopy11 said:

Should make around 40+ish

I think anything over that wouldn't be useful on a WH tranny. I think even over 30hp.

You can't shift on the go so top speed is limited even if you pulley-swap the cr*p out of it. 

 

But always cool to have more powar! 

[Greentored 3,201]

My expectations are much more realistic, although they will never be dyno proven. I think 30 sounds pretty realistic.

....and a big, wide, flat torque curve that will pull a house down. Thats what 46 cubic inches will get me.

 

[Snoopy11 5,713]

Just now, Maxwell-8 said:

I think anything over that wouldn't be useful on a WH tranny

You make an undeniably good point there @Maxwell-8

 

To that, I would say, there is no legit way to use 51 horsepower.

 

I did pulley swap the crap out of mine, and I spin the tires in third gear at 4,500-7,650. 

 

Don

[Snoopy11 5,713]

4 minutes ago, Greentored said:

My expectations are much more realistic, although they will never be dyno proven. I think 30 sounds pretty realistic.

....and a big, wide, flat torque curve that will pull a house down. Thats what 46 cubic inches will get me.

 

Sounds realistic, but a bit low. I would say 35-40 (maybe a bit more) with performance air filter, jetting, headers... etc...

 

I tell you what, those headers add dyno-proven power.

 

Don

[Maxwell-8 4,271]

What would be the torque increase be on a build engine? 

[ebinmaine 63,231]

Oh boy....

[RED-Z06 2,122]

Curious about the "pressure lubed" opposed twin.  In vertical arrangements they had some models that had filters and a pump that pumped oil thru the filter and back into the sump..but the flapper wheel still performed the lubrication.  On horizontal models the dippers on the rods did the lubing and ive never seen one with a filter.

 

 

But im going to read up on them for sure, never liked digging into these but they usually ran strong and very smooth, i do recall they say there was a full pressure lubed model with the drilled crank, lubed it all by pressure but never have seen a horizontal one

Edited January 5, 2022 by RED-Z06

[peter lena 8,076]

@Greentored  if nothing else that piston / rod set up , looks like a small block chevy , very stout and  matching piston set up . looks like a fun build , good luck with it , pete

[Snoopy11 5,713]

2 hours ago, Maxwell-8 said:

What would be the torque increase be on a build engine? 

Outside of a dyno test, the only real way to get an approximate torque range is mathematical calculation (emphasis on approximate)...

 

To calculate the approximate torque of an engine based on the horsepower, you multiply horsepower by 5,252 (conversion between foot-pounds and horsepower), and divide by the RPM of the engine.

 

You want that in English, don't you?

 

A 40 horsepower engine would make approximately 30 ft-lbs of torque at 7,000 rpm.

 

Don

[Snoopy11 5,713]

@Greentored... one question that I should have asked sooner.

 

How do the babbitt bearings look? Do you think that you might need to purchase new ones?

 

Don

[Jeff-C175 7,195]

7 hours ago, Snoopy11 said:

babbitt

 

Silly babbit, Trix is for kids!

 

[kpinnc 10,810]

I'm hoping to just sit back and learn something while following this thread. 

[Greentored 3,201]

14 hours ago, RED-Z06 said:

Curious about the "pressure lubed" opposed twin.  In vertical arrangements they had some models that had filters and a pump that pumped oil thru the filter and back into the sump..but the flapper wheel still performed the lubrication.  On horizontal models the dippers on the rods did the lubing and ive never seen one with a filter.

 

 

But im going to read up on them for sure, never liked digging into these but they usually ran strong and very smooth, i do recall they say there was a full pressure lubed model with the drilled crank, lubed it all by pressure but never have seen a horizontal one

 

Ive heard of some form of those 'filtered' engines but have zero knowledge of them. The one I'm building is indeed full pressure, with the drilled passages. Theres horizontal models out there but they are rare- mainly used on higher end commercial welders, trash pumps, etc, and to my knowledge they did not make a big boy 46ci in that configuration.  It took months and a TON of digging to find a horizontal cover and pan.

[Greentored 3,201]

13 hours ago, Snoopy11 said:

 

 

A 40 horsepower engine would make approximately 30 ft-lbs of torque at 7,000 rpm.

 

Don

And hopefully a heck of a lot more down low

[ebinmaine 63,231]

33 minutes ago, Greentored said:

And hopefully a heck of a lot more down low

I should think it would be quite a healthy amount more than that.

 

Torque specs on the 1974 c160 with the Tecumseh engine lists it at 25.1 ft pounds at 2,800 rpm.

I don't have the Kohler engine specifications right handy. I've read that they're in the neighborhood of 28 ft pounds or 26 ft lb but it was at a slightly lower RPM.

 

 

If the cubic inch to torque ratio comes out somewhere near the same you should end up with just over 40 ft pounds...

[Greentored 3,201]

1 hour ago, ebinmaine said:

I should think it would be quite a healthy amount more than that.

 

Torque specs on the 1974 c160 with the Tecumseh engine lists it at 25.1 ft pounds at 2,800 rpm.

I don't have the Kohler engine specifications right handy. I've read that they're in the neighborhood of 28 ft pounds or 26 ft lb but it was at a slightly lower RPM.

 

 

If the cubic inch to torque ratio comes out somewhere near the same you should end up with just over 40 ft pounds...

Thats about right on what Im hoping for!

[RED-Z06 2,122]

I took a gx200 honda and threw all the hot parts at it, ill see if i can find the sheet but it was turning i believe 9600rpms and getting 28hp on a water dyno, on 93, torque was incredibly flat after 5500, it pulled so hard.

 

Higher revs though...its hard on them.

[Snoopy11 5,713]

5 hours ago, ebinmaine said:

you should end up with just over 40 ft pounds...

I concur.

 

Very hard to tell outside of dyno test though... (horsepower on these engines is more proportional to rpm increases and other tuning modifications... thus we can give a more exact number range).

 

Torque depends on the particular engine and how it responds to modifications (different on every engine). Torque values using math are VERY... shall I repeat... VERY conservative.

 

Don

Edited January 6, 2022 by Snoopy11
Subject/verb agreeement error...

[Pullstart 59,758]

On 1/5/2022 at 4:53 PM, Snoopy11 said:

Outside of a dyno test, the only real way to get an approximate torque range is mathematical calculation (emphasis on approximate)...

 

To calculate the approximate torque of an engine based on the horsepower, you multiply horsepower by 5,252 (conversion between foot-pounds and horsepower), and divide by the RPM of the engine.

 

You want that in English, don't you?

 

A 40 horsepower engine would make approximately 30 ft-lbs of torque at 7,000 rpm.

 

Don

 

Is that a gasoline calculation?  Diesel must be a much different animal..