Home Built Exhaust, Not a motorcycle But Surely A THUMPER!

This is my little brothers speedway Sprint. 500cc jawa alcahol burner. They run these on the speedway bike track on the same day as the speedway bikes, there's three classes, pro which is the jawa 500, restrictor (jawa 500 with 25mm intake restrictor) and intermediate which is a 5hp motor.

My brother is 14 and runs the restricor class.

The stock pipe is 2" and runs about a mile well more like 48" through the foot pan and out the other side of the kart into a 12" packed muffler.

We built something I dreampt up. Kind of hard to explain but its a cone a straight then a reverse cone inside or the main body towards the rear is a cone with like 1/2" clearance to the body.... And the guy who runs the track/built all of the cars was talking smack calling my "original design" which my dad then interpreted and built has a slider for adjustable length. A Campbells soup can....

IMAG0247_zps69c662a6.jpg

My brother reports stronger bottom end with this pipe, go figure its a 1 3/4" pipe vs 2"

That jackwad who thinks he knows about everything because he builds the cars pisses me off everytime he says its a Campbells soup can. the sissy doesnt even work on his 410 sprint car motor, bah what a daisy.

So I felt inspired to build a pipe my way.

Laid the pipe out, converted all of my desired diameters to half circumfrences,

scribed it in some 18ga sheet

cut it with the pnumatic sheers

used my friends bead roller to roll the edges 90*

DSC00016_zps8dd4cbee.jpg

and tuned the edges up with pliers and a hammer.

my buddy welded it (hes a professional sorta, didnt blow any holes in it)

I wanated him to tig it but he cried since i only brought him a 6 pack and told me how terrible his electricity bill would be running the tig, thanks for being a daisy gary.....

next inflation

not mine but you get the idea.

but he didnt break his 90 degrees first.

DSC00021_zps8a19ad1e.jpg

Yeah I know i said my buddy was a professional right????

well it looked good at first but every 5% you inflate it beyond the first 75% it gained about 400 pin holes so it got another full pass of weld..... then the leaks got welded about 5 times!!! so i dont want to hear anything about the atrotious welding :p i already know allllllll about it.

IMAG1046_zps20b1ee89.jpg?t=1362896304

the header didnt come out round, and or good in any way, and my reverse cone caused some crinkiling. I dont know what i should have done with the header, but i know the reverse cone's transition from the diffuser should have been radiused.

so i cut the header off and the reverse cone.

IMAG1049_zps1abfe77f.jpg

pops likes to steal the tool whenever im working on anything..... haha....

IMAG1050_zpsd30abf43.jpg

you can see the wrinkle in the reverse cone

IMAG1058_zps3f9349c2.jpg

checking it out!

IMAG1061_zps8a0055fa.jpg

now were getting somewhere!

IMAG1068_zpsf9d1380e.jpg

the pilot of this rocket ship is sitting in the background there,

IMAG1071_zps8fb40b74.jpg

and the reverse cone mocked up, I think im going to make it wicked oversized and rivet replaceable covers on so he can try different sizes.

The dimensions are

1 7/8" for 9" from the valve,

step to two inch for 9"

a 4.5* taper for 9"

a 5.5* taper for 9" bend occurs here

a 6.5* taper for 9"

a 45* end cone with a 3" opening in the picture.

the idea is that it will pull hard to the top with the short header all the way to 10,000

but make good bottom end with the 6.5* taper on the long end..

Taken into consideration was also the lower egts of the methanol when i designed the pipe.

anyways just wanted to post up because i enjoy reading about others projects such as numb hands, swiss and others,

hope you enjoy, more to come.

Edited by englertracing

Good work there!

I like the way you made up the cone section, never really occured to me to use hydraulic forming to get a nice tapered section, would be a good way to make tapered headers... Got me thinking now!

What did you use to generate the pressurised water to expand the welded together sections, and what sort of pressure did you have to get up to?

You'll have to let us know what happens to the power delivery, I've never used a megaphone design like that so would be interesting to see some powercurves vs the previous design....

Looks smart with all the welds ground down and tidied up though, and is a super tidy install :thumbsup:

Edited by englertracing

That's an awesome car. Where and in what class do you run that ? The speedway engines are so cool and I alway thought under utilized for stuff exactly like this :thumbsup: :thumbsup: What transmission/drive are you using ?

test ran it today had to hear it lol....

loud.

all the brackets need to be finished, without the tie wire.

Sounds awesome :thumbsup:

Are there any vid's of these things racing on youtube ?

Edited by BruceD_500

Good work there!

I like the way you made up the cone section, never really occured to me to use hydraulic forming to get a nice tapered section, would be a good way to make tapered headers... Got me thinking now!

What did you use to generate the pressurised water to expand the welded together sections, and what sort of pressure did you have to get up to?

You'll have to let us know what happens to the power delivery, I've never used a megaphone design like that so would be interesting to see some powercurves vs the previous design....

Looks smart with all the welds ground down and tidied up though, and is a super tidy install :thumbsup:

a 1600 psi cheap electric pressure washer

I became fustrated with the quality of the welds on the header. Im going to buy a tig welder :/

I think it would have looked awsome leaving beautiful welds all over it but OH well its my first try :) I might build another for the other car.

That's an awesome car. Where and in what class do you run that ? The speedway engines are so cool and I alway thought under utilized for stuff exactly like this :thumbsup: :thumbsup: What transmission/drive are you using ?

Well They run at Victorville speedway track WHEEL 2 WHEEL RACEWAY.

Right next to the 3/8 mile dirt track thats not being used right now due to the economy

http://www.wheel2wheelraceway.com/

The guy was a big speedway racer and got sick of getting hurt.

he got into sprint cars you know 410s and then decided to do speedway sprints. they just use a primary chain to a clutch than a secondary chain to the axle. theres about 35 or so of these cars floating around socal here.

heres the 500 non restricor class race starts at 4:30

the guy in the red 7 car runs the track and builds the cars, and also calls peoples pipes campbells soup cans

heres an outside view. they dont start till about 4:00

Ill tell you what, I used to drive dirt stock cars, and won a championship

I got in both my brothers cars without the restrictors.... there a spooky ride with no suspension there a real hand full. I dont know how the hell they drive them. The track owner john in the 7 car says there harder to drive than his 410 sprint car

Edited by englertracing

Yea when they drop the hammer at 4:30 in that first Vid things really get moving. That is really cool stuff !

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now