Is the standard K10 exhaust a reverse flow or stright through muffler?

[pietro]

Just wondering as I have heard that reverse flow mufflers have merely 60 - 70 percent the flow of a straight-through muffler?

Photo: http://us1.webpublications.com.au/static/images/articles/i14/1474_3lo.jpg

Also is it possible to drill the exhaust (with a massive drill piece) through the exit pipe to the entrance pipe to create a channel for better flow on the cheap?

 

[crogthomas]

Sort of:

http://i5.photobucket.com/albums/y190/crogthomas/silencer.jpg

This is my standard backbox that fell off after a particularly enthusiastic drive to the pub (across a field). Flow enters from the left into the pipe which is capped. It escapes through the holes in the side into the left-hand chamber then flows into the end of the 2nd pipe (on the right). It then flows straight out of the end (far right of picture) but is silenced a little on the way by the small holes along its length surrounded by fibreglass which I’ve mostly removed.

And, yes it is very restrictive. I've measured the exhaust backpressure with it fitted and it went off my manometer scale (30inH20). I measured it with a tyre pressure guage instead and figure its roughly 110 inches of H2O. Without it fitted the backpressure is a more reasonable (but still a bit high) 14 inches of H2O.

Makes no discernable difference to the performance though. Just makes it louder.

 

[Arnold]

Removing the baffles would probably help, but you'd still be restricted by the small tail pipe on the box, unless you decided to chop that off but the volume would probably go up quite a bit!

 

[Ed]

crogthomas thats a brilliant and very interesting post!

 

[pietro]

Nice photos! What did you get 1/4 mile, did you use NOS?

Nice one crogthomas! I saw your photo bucket and see you like playing with the old Micra You also seem very knowledgable on DIY go faster things!

Please share more on the forum!

By the way you said the rear box makes no difference to power, I presume this is with no engine modifications right? What about my big drill idea, could it work? Any more exhaust photos by the way?

(NB: >>ED<< incase your wondering my Super B/Box failed so I went standard for now - can't feel much, if any difference though with standard exhaust?).

My favourite photos of yours (from this album: http://s5.photobucket.com/albums/y190/crogthomas/?)

Rolling Road Graph!
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=MicraPower.jpg

Rear Strut Brace:
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=rearbracemeas.jpg

New dash:
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=dashb.jpg

Never knew this could happen:
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=crack.jpg

Carb playing:
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=temp.jpg

DIY tracking!
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=align.jpg

New wheels (what they from?):
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=wheels.jpg

Side exit exhaust! Make me one!!
http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=exhaust.jpg

 

[K10]

hey crog, how yer diddlin me old fettler- good to see you one here.

i look forward to seeing a sausage update in the near future

 

[kristian]

http://s5.photobucket.com/albums/y190/crogthomas/?action=view&current=strut.jpg

Dont let anyone on here see this...

good idea though.. make any difference?

 

[crogthomas]

Pietro
I don’t think the big drill idea will work im afraid. The large chamber in the box is full of fibreglass and drilling into it would just make a big mess and not make any difference to the flow. Best to just replace the lot. The other one or two silencers nearer the front are of the straight through design (they are on mine anyway) but still a little on the small side.
The strut brace isn’t actually a strut brace. Its a device for measuring the strut movement. Two tubes, one a sliding fit inside the other with a tie-wrap to see how far they have moved. Despite my best efforts, not far is the answer. My way of determining if a strut brace is actually required.
The cracked brake disk is actually my Peugeot 205 (a vastly inferior car to the micra). That’s what happens when you let the disks get to 4mm below the minimum thickness (not me, the previous owner).
The wheels are 13" from a K11 Super S, although I think all K11 wheels should be the same size (well, apart from the 14" wheels that is. I might have to get me some of those).
Exhaust was made from scrap bin parts from the local tyre and exhaust fitters. Surprisingly easy to make.
I’ve been mostly removing weight to improve performance, the engine is still a mostly standard 1.0, but I hope to change that soon…..

K10
How do! How's the landcrab? Wheels rusted yet?

kristian
Too late, the secrets out. Its added camber and castor and did seem to improve grip slightly, but as yet i've not measured the improvement. But I intend to do so using an accelerometer so will keep you posted.

 

[K10]

Not so bad fettler, can't complain (although I do)

landcrab's, well, making steady runs to the workhouse and back so its working just fine at the mo! Yup, the wheels are coming on- road salt and intentionally parking in puddles at the mo, so they should match the body soon enough :grinning:

Back on topic, speaking of exhausts- are there any off the shelf performance type exhausts available for the K10, like an ashley or anything?

I feel my current setup with 2 clamps, a baked bean can, tin foil, exhaust wrap and half a ton of putty isnt doing it much good :upside:

 

[crogthomas]

As far as I know there are no off the shelf exhausts available for the K10, but im probably the wrong person to ask.

Dont under estimate the bean can. My mates Nissan Stanza Skyline (not as impresive as it sounds) got through two MOT's with an exhaust held together with a tin of Wadworth 6X. We had to sample a fair few different brands of beer before we found one that fitted mind you. The hardship.

 

[Arnold]

Remus made a box for the K10. I think Peco did too

 

[pietro]

What about drilling a few holes at the bottom of the exhaust box entry facing downwards to shift 20/30% of the exhaust flow out before it hits the baffles?

This could work right - it could also be repaired if it sounded too loud?

What do you think all?

 

[crogthomas]

I dont think that would work.
The only way to be sure of course, would be to flow test the box and make modifications flow testing after each stage.

But if I were going to guess id say the main restriction seems to be the small holes the the gas has to escape from out of the pipe on the left.
Perhaps this will explain better:

To remove this restriction the only options I can think of are:
1) cut a hole in the side of the box. Drill some larger holes in the side of the inlet pipe, or perhaps cut big chunks out of it with a hole-saw, then weld a patch back over the hole cut in the side of the box.
2) Weld in an alternative inlet pipe, terminating inside the left chamber and with no end cap.

Either way, its a load of ######ing about and welding. You may as well just replace the whole thing or even make your own.

 

[pietro]

Nice explination!

So the cheap fix would be to drill the box pre-inlet - notes taken!

How is your box performing?

 

[crogthomas]

How is your box performing?

Well, it allows the gases out and it hasent fallen off yet, but it doesnt seem to have made any difference to the power output. Anoys the neighbours though.