1QwkSport2.5r

It looks like it must be 18mm diameter on one end and 15mm on the other. I wish they did state the length of their headers. It would help determining fitment.

Nitrovein

Maybe 18mm in diameter at the pipe end (outside). 41031 is that.

Nitrovein

Isn't it time someone convert this engine for car use and put in a monster truck?
http://www.novarossi.it/2012/index.p...c/to-be46.html

1QwkSport2.5r

It's even a long stroke engine. That thing sure can rev, but it would need a small toothpick prop to get to the rpm they claim..

1QwkSport2.5r

I'm just curious - what advantage do the conical headers have over the cylindrical headers?

supertib

Yes...it has something to do with the bend in the pipe.......all these manifolds canhave different widths to fit different cars so I am guessing this is Nova showing us which is which

Nitrovein

Don't you think most of the manifolds, apart from the Mugen ones, are the same in size?
I don't have a lot of Novarossi manifolds to compare, but my guess it's only the diameter of the manifold. But I can be wrong...

Nitrovein

The manifold will let the gases expand, so they start to expand before the pipe.
The transition between the pipe and manifold will also be better, as an abrupt area change can disrupt the pipes work.
The peak torque is much about how the engine sees the volume, so a conical manifold should make most difference before and after peak torque.
At least in theory! How it behaves in a real world scenario is best to try out in each situation.

1QwkSport2.5r

I figured it had something to do with the gas expansion. I assume it adds a little extra "oomph" to the reverting pressure wave too by compressing the charge slightly going back into the exhaust port.

f16man

Notice the size of the side transfer ports? They don't look that huge but for a .46 very substantial along with the sleeve and crank port work, what would really would make that a thumper would be a rear drum valve into the crankcase,,, also would add some big dollars to the sales price!!! also front ex. would be a big plus for boat use...

Anthoop

If you read some of the stuff from Jennings/Bell/Yamaha about exhausts you will find that they all recommend an exhaust that has an increasing volume from the port....think about a pipe that is the same width along the length, then it has a narrow rpm band within which it will work....sure you can "tune" it to produce massive power around that rpm window ( hence early racing bikes with many gears ( and cylinders)).
Read the links that Nitrovein put before please Tim.

1QwkSport2.5r

Yeah, I have a lot of reading to do. My wife has wanted me to take up reading for quite some time now... Probably a good time to spend reading this stuff and fill in some of the blanks.

supertib

its not the diameter for sure.....

Nitrovein

I'm not sure we are talking about the same thing...
I measured a 021 and a 031.
For the 021 it was 13mm inside and 16mm outside.
And the 031 was 15mm at the engine and 18mm at the pipe in outside diameter.
Just like it says on Novarossi's homepage.

Nitrovein

The gas puls reacts to the increased area, not volume, so if it changes a lot it will increase peak amplitud but at a narrow band.
The divergent cone also influence the bottom end the most.

1QwkSport2.5r

Does the O.D of the header really matter at all? I would think not?

Nitrovein

Not sure why, but that's the only way I get the numbers to make sense...

supertib

I agree..... on the conical they list the measurements at the big end

Anthoop

You lost me...given any section then by increasing area then you increase volume and vice versa. Basically I was pointing out that a paralelled walled manifold is not ideal.

The ID is most important but wall thickness can matter ( along with material ) because of temperature and how it affects flow speed.

1QwkSport2.5r

Gotcha Ant. Thanks for clarifying.

Found a spec of swarf blocking the oiling hole in the conrod!! Removed with top of Xacto knife. You can barely see it in the palm of my hand below the conrod.

supertib

Good catch.... I check every engine I modify, but in the past I have lost a few engines from that exact issue !

1QwkSport2.5r

That's why I tear down every engine I ever buy, car, aero, or otherwise. I've found some crud that would take out a liner in one run.

Nitrovein

Sorry, missed your post.

The two variables are area and volume, length is the sum of the two.

As most pipes for car engines of this size has an inlet area that's larger then the outlet of the engine, yes, a straight manifold is not the best solution.

1QwkSport2.5r

FWIW, I put my 41016 Nova header and Dynamite 086HS pipe on my SH .28 P6 powered LST2 today. The pipe and header fit nicely, the muffler hanger needed to be made new. I used some .035" piano wire and heated/bent it to work. I only ran two tanks on this setup, but it did run quite well. A bit warm - 275F, but it ran well. Definitely faster than with the Losi header and Losi HT pipe. I still need to tweak it a little bit to get the needles set just perfect, but overall I'm pleased. I have some tranny work to do to the other LST2 before I install the Picco and move the 086/41016 to that engine and truck. Should make for an interesting experiment.

1QwkSport2.5r

I'll be looking at ordering a Nova 28-8 in the future, and the 9886 pipes are in stock now. The question is which header should I use. I have a Dynamite 086 and Nova 41016 medium length header intended for the Picco .28 I have. Should I use the same header on the Nova 28-8? Would I be better off with the longer 41017 header since it's going into a heavy LST truck? I put the 41016/086 on my SH .28 and after running a couple tanks think there is a possibility the header may be too short for that engine. Will the 41016 be suitable for the Picco? I have to use the on-road headers on my LST truck since the exhaust port on the engine is on the left side of the truck. My picture above shows the Losi HT pipe/Losi header next to the 41016/086. The 41016 is considerably shorter than the Losi header, which should significantly help top end.