Aircooled VW South Africa

HI,

I want to re-do my turbo headers myself because I'm not happy with the result from a exhaust shop that did it the first time. What size pipe should I use for a 1776 engine that will rev to about 6500 using a b40 rajay turbo?? Round about 38mm or should I go smaller to about 32mm, don't want to restrict turbo but also don't want to hurt the response. Any advice would be appreciated.

Thanks in advance.

hey

I cant give you a 100% specific size but what I have piced up fromm reading the other forums is that you pretty much want to run a turbo header the same size as you would if it was normally aspirated.

eg, a 2276 with a engle 120 cam (street engine) would run a 1 5/8" header, then if you turbo it, keep that header size.
I would guess your engine to have a 1 1/2" header N/A, so go with that... 38mm OD.
If it is a mild turbo system and you are aiming for about 140hp, and/or low boost, less than 0.5bar, I would go with a 35 or 32mm header depending on whats available.

Please dont quote me, because I dont have first hand experience in turbos, only what I have read......

I use investment cast 90 degree bends for my turbo headers and find them the easiest to use. The ones I used on the fastback measure 36mm ID and 43 od they weld easily and produce nice work. a Beetle exhaust port measures 32 mm and thus 32 id would work. Just remember turbos really like short headers. complicated 4 into 1 exhausts look the part but only produce slightly better numbers. most Factory turbo cars use very simple manifolds. I made 137 kw on a type four with a 50mm pipe linking the two heater boxes and the turbo flange welded to that.
Armand

Not trying to highjack this post, but think the question is inline with the topic...

assuming that you fabbed-up your own exhaust, in a Beetle/Bus, does a tuned exhaust really make such a BIG difference (read: equal header pipes)? The stock exhaust on a Beetle exhaust pipe is not 'tuned' (and not like in :"Hey! Howzit china!? ), hence my question. Does it really make such a HUGE difference or is it necessary?


Cheers!

ZeroAxe wrote:assuming that you fabbed-up your own exhaust, in a Beetle/Bus, does a tuned exhaust really make such a BIG difference (read: equal header pipes)?

There was a very noticable difference when I changed from the stock pea-shooter setup to a tuned (freeflow) exhaust from TNT.
There seemed to be more low down torque (which I didn't expect) and the engine could finally rev nicely which makes a massive difference at 100km/h+.
With the original exhaust once I hit about 100km/h the back pressure limited the top end speed and the fuel consumption increased because I had to push the engine.
With the free flow (balanced) setup the bug cruises nicely at 120-130 without having to push it.

I don't think the balancing of the pipe lengths makes that much difference but the back pressure restrictions on the stock system are a real problem if you want an engine that can rev.

Hi,

Thanks guys I bought some machine bends a while back 1 1/2" about 38mm ID but now I'm not sure if it will be to big for a 1776 engine, its got 044 heads that has been ported a bit but I will have to check what size the ports are. Should I go to a smaller tube size?? or try 38 and see what happens, it's just so much work to waste if it doesn't work properly.

Any thoughts on this?

dont worry about what size the exhaust ports are. They are big enough. Inlets should have a fairly mild port job. Go with the 38 tubes. Unless its a race car (drags) I really dont think the pipes will be too small.
Turbo choice will be a lot more important a decision so make sure your homework is done in that department.

I' m going with the 38mm. Can't find information on my turbo Rajay b40b1, according to what I found the b1 is the smallest flow Rajay made and the 40 is the A/R ratio of 0.40. This sounds a bit strange and I don't know if this is correct. I am still working on the Turbo information but will hopefully get more info. The Turbo is on the car and made nice power before . . . and will again. The sizing can't be to far of if at all. Doing my homework at the moment and will fine-tune the setup after the intercooler and new exhaust is installed.

Still any advice or info welcome. I'm still learning.

Thanks

just keep reading. Do searches for anything you can think of thats turbo related. Read it all and slowly put the pieces together.

Thanks I will do that.

Can't wait to sort it all out though.

Is that the turbo that came with the CB Performance "Cyclone Kit" ?

Hi eben,

I don't know but it is very possible, I bought it brand new separate a while back. Do you have any info on the turbo from that kit? or know where I can find any? Will do a search and see what comes up.

Thanks