modded heat exchangers

[69billy]

yey they work now, after trying some copy exchangers and thinking they cant be that bad......yep they are. so ive stripped them down to add more area , this is the second set for the wifes beetle as the mod is fab, I may try on a brand new pair as I couldn't weld the extra plates on only for ease though as the other pair are still ok and not come loose. .ive also started a mould to try and melt ali onto some j tubes :? not sure how its going to work



yes ive replaced the rotten pipe





you can see why there pants as hardly any area to get hot like on the originals,thats 20mm flat bar



chalk and cheese now for heat

 

[aogrady]

Hi!

Thats a good mod, works well then? A mould sounds like a good idea, perhaps cast in 2 halfs, you could even get some stainless tube bent to shape, along with the new alloy fins, get someone to press some outer skins into stainless - you'd have a nice little business right there.

Was it easy to peel it all apart?

We'll make a list for stainless steel repro heat exchangers then?

1 aogrady

:lol: :lol: :lol:

Good work, keep the pictures coming 8)

Alistair

 

[Tofufi]

Good thinking for the mod to your exchangers! I've always reskinned originals rather than trying to work with repro ones.

I'd join the list for good quality stainless exchangers, though you'd not want stainless fins as it's a very poor heat conductor...

1 aogrady
2 Tofufi

:lol:

 

[Dave.P]

Great idea 8)

 

[69billy]

very easy to pull apart, just pulled the strip off each join and 5 mins with a little dremel thing i had for years and never used!! till now :lol: didn't think of casting 2 halves, but how would I join them? ive looked into stainless outers not sure I would get the curvy shape as good I don't think, but im on the case. ive asked a casting place if he cast an inner and outer mould and if it might be strong enough to press together to form a stainless shape as its quite thin to press. ill let you know

 

[Fortunate Son]

Nice work! (Does this mean you won't be wanting mine any more?!)

Andy

 

[aogrady]

very easy to pull apart, just pulled the strip off each join and 5 mins with a little dremel thing i had for years and never used!! till now :lol: didn't think of casting 2 halves, but how would I join them? ive looked into stainless outers not sure I would get the curvy shape as good I don't think, but im on the case. ive asked a casting place if he cast an inner and outer mould and if it might be strong enough to press together to form a stainless shape as its quite thin to press. ill let you know

Hi,

Sounds simple to remove the casing then? As for casting the fins in 2 halves, maybe you could just drill a hole at each end top and bottom, and screw together, with a tapped thread, or just use stainless jubilee type stuff you use when you fit heat proof exhaust wrap. This could also be used to retain heat, would matter if it got wet if you are using stainless outer covers.

I also saw some years back a fibreglass (with insulation) cover which fitted over the stock heat exchanger outer casing to retain heat, i bidded on it, but missed out at the last minuite as usual. You can get all sorts of fibreglass glass material to heat proof turbo's and the like...

Would be interesting to see if you can find someone to cast some fins, and stamp out some pressings. One thought i had, is that you can get stainless J tubes, now with a suitable alloy fin casting, and a stainless outer, bingo! Rust free heat exchangers.

Do you know if the exhaust tubing is straight through on a stock exchanger? I wondered if they was a "kink" or suchlike in the pipe to slow the exhaust gas down and help keep the heat around the fins? Though I think perhaps the speed the exhaust gasses pass through, any heat retention by limiting exhaust gas flow is probably small.

Also thinking, maybe you can get large bore J tubes, and do the same thing, like a "performance" exhaust system, as i understand the "boys with the big engines" tend not to use stock heat exchangers.....

Wonder if a exhaust manufacturer would do a low number run???

Anyway, 50/50 on the royalties then? :lol: :lol: :lol:

Cheers!

Alistair

 

[69billy]

Yes i still want them. Ill ring courier tomorrow (monday) im on nights now then off all week

 

[69billy]

Yes straight through and round but the originals ive opened up go from round at the manifold to oval then round again ?

 

[Alex VW Heritage]

Also thinking, maybe you can get large bore J tubes, and do the same thing, like a "performance" exhaust system, as i understand the "boys with the big engines" tend not to use stock heat exchangers.....

Wonder if a exhaust manufacturer would do a low number run???

Anyway, 50/50 on the royalties then? :lol: :lol: :lol:

Cheers!

Alistair

CSP Already do a big bore heat exchanger:

http://www.vwheritage.com/vw_act_page.render_pageID_1613.htm?startRow=38&startPage=3&maxDisplayRows=15&dcCfcSortSelect=PopularitySort|asc&dcCfcBrandFilter=excluded&dcCfcOriginFilter=excluded&dcCfcPriceFilterLow=excluded&dcCfcPriceFilterHigh=excluded&searchText=&classicSearchText=&classicSearchType=" onclick="window.open(this.href);return false;

Page 3

 

[aogrady]

Yes straight through and round but the originals ive opened up go from round at the manifold to oval then round again ?

Ok, oval makes sense, as the fins and the casing are not round anyway. I wonder if the oval shape is like that for a reason, can't picture how much room there is to the engine, so there must be a reson why its oval. Maybe slightly more surface area than round section?

Alistair

 

[ozziedog]

Do you think it may be to slightly slow down the exhaust gasses to give a little back pressure ?? Or possibly to create swirl. Pretty sure there will be a reason for it :msn4:

Ozziedog,,,,,,,,,, :mrgreen:

 

[69billy]

im not sure what room there is for size, im testing on a rig ,using exhaust gas off a similar exhaust bore and we found the bigger you go they don't get much hotter and less blow for your pound , so maybe the original designers went through this and found the shape/size is the best combo?? even though they look like oh that'll do they fill that gap! :lol: im trying one ive restricted the blow bore to get more ummph..... but I have found stainless takes longer to heat up and looses it quicker

 

[Trikky2]

Yes aluminium is a better heat conductor.

Oval increases the available heat transmission surface on the flatter curved area.

 

[aogrady]

Yes aluminium is a better heat conductor.

Oval increases the available heat transmission surface on the flatter curved area.

That's what i wondered, i assumed there was a reson for the surface area being ovaled

Alistair