1275 Exhaust Design

[KalKat]

Why not consider a transverse silencer box and short exit pipes - I seem to recall some french cars doing this, and of course the ubiquitous Beetle

[Innovator]

David Vizard probably has published more on exhaust design than anyone else. He also knows a lot about the complexities of the A series with it port designs.

He has also written many general articles a quick search brought up this one there are many others......
http://www.popularhotrodding.com/engine ... index.html

Baiscs are the system must have minimal or if possible negative back pressure to achieve this it must flow I think 2.2cfm per bhp.

[chrisryder]

thank's for the link Innovator, will give me something to read

[Kevin]

i baught all my bends and made the whole system, the manifold if a lot more free flowing then a maniflow one and looks better

As mentioned how do you know it flows a lot better than a maniflow one, did you check yours on a flow rig ? as maniflow designs have a lot of history going back to the 60's with ongoing development.

[bmcecosse]

There is absolutely NO point in splitting the tail pipes like this - in fact - it will likely LOSE you some power.......and all that extra weight and cost - crazy! You will be MOST unlikely to beat Maniflow for flow efficiency......... And if your Engineering course is worth it's salt - it should have taught you by now that angled dampers are a really BAD idea!

[chrisryder]

you may be right.

the angled dampers came on the car with what looks like a van rear crossmember welded to the floor of the car to mount the teles.

i never planned on flowing better than the maniflow system. you can't beat them at their own game.

i am a realist, absolute power corrupts absolutely. i would happily sacrifice some horses for looking/sounding good. maybe it makes me a poser, but my minor is always seen, it's not always driven flat out.

and my engineering course hasn't covered angles of dampers yet...

[bmcecosse]

" and my engineering course hasn't covered angles of dampers yet... " - it's O level geometry...........

[Alex'n'Ane]

Bmc i think we are all aware that vertically mounted dampers are superior due to load forces and maximum travel. And this is the kind of thing that isnt always taught, rather assumed knowledge.

[Alex'n'Ane]

Sorry that was abit off topic. However i have been following this closely as was planning a similar design for the project, so will be very interested to see the solution

[bmcecosse]

" we are all aware that vertically mounted dampers are superior " - except unfortunately the Cos that sell kits with angled dampers - and the mugs who buy them!

[Alex'n'Ane]

Surely they are angled to make them easier to fit and possibly produce, making them cheaper and easier for people without good welding skills or equipment to install. Bmc originally fitted angled dampers to their vans did they not? For what reason? And i'm sure they must still be better than nothing!

[chrisryder]

i was under the impression that angled dampers gave the effect of damping out side to side movement of the axle, aswell as up and down movement.

as for O-level geometry... i did GCSE's

[RobThomas]

There is enough room under a minor to run a van system. Is it legal to have a pipe out the side, though? As mentioned, as little back pressure as possible but not so short that gasses can get drawn back up the pipe and cool the valves. VW aero engines run 12 inch long pipes (from the valves) and can be made quiet with minimum back pressure. Less than that and cold air can get back to the valves. Keeping gas speed fairly constant helps with scavenging. I found an extra 50 rpm at full throttle on the aero engine simply by running a 4-into-1 system to the engine.


I managed to get away with this Midget system since there was no room underneath the car to fit anything (except about 2 inches of air!)

[chrisryder]

impressive exhaust... does the door still open?!

not sure i'd get away with one like that on my minor. what silencer is it?

[RobThomas]

Naw. Doors are just skins, rivetted at the tops and glued at the bottom to the foam cores of the side-impact protection material. No windows so you just hop on over the side to get in.

Can't recall which superbike it came from. Weighed very little and quite noisy at max.

[bmcecosse]

" angled dampers gave the effect of damping out side to side movement of the axle, aswell as up and down movement. "
One of the common misconceptions I'm afraid....... dampers damp suspension movement - that is all!

[chrisryder]

but is there anything wrong with them?

[ratrodmog]

but is there anything wrong with them?

No. To put it simply. As said, they won't stop the axle from moving side to side but work well at damping over the standard set up. Obviously the vertical damper kits are better but require much more work to fit them (need towers to house them) so as a bolt on option the other kits are good. I believe that the bar that they are mounted to under the floor has several mounting positions so try and mount the dampers as upright as possible. In summary, a good kit for the money.

[chrisryder]

you're thinking of the owen burton kit, which has a series of holes as you say to adapt angles. mine is literally the standard setup for a van or pickup, with the dampers at a fixed angle. i'm keeping them for now, but may replace the dampers for some stiffer ones, or adjustable ones. *waits to be told that adjustable ones are a waste of money*

[RobThomas]

Imagine your legs coming out at 45 degrees from your pelvis. They would still work, but, the ends (hip joints) would suffer unless the knees were redesigned, the kneeecaps strengthened, the thigh bones thickened (if you see what I mean). Legs come straight down from the hips, loads are fed lengthways down the bones.
Not the best analogy but you can maybe see that those dampers are designed to go in/out only and nor rotate about the bolts at the ends. Keep the dampers vertical and they are moving in the manner that they were designed to.


My current Lenham Midget rear axle.
http://www.spritespot.com/gallery/view_ ... d=panhardc