TheSamba.com :: View topic

Sat Aug 16, 2008 6:16 am

Hey guys
well first off I'm not a Motor guy so this is a Dumb ??

but I want to put a Turbo on my

1641cc
40X35.5 044 CB heads
duel 40 Webers

So my question is how much Boost can the Bottom End Take??
also Fresh rebuild too.

thanks

Chris.

Sat Aug 16, 2008 6:58 am

If the pistons are 85.5 i understand that they can take 15lbs of boost. Don't try to go over this mark or you will be in trouble. How i know i read it somewhere on a forum and a friend of mine here in jamaica tried it and it worked.

Sat Aug 16, 2008 7:26 am

I ran a turbo kit on a 1641 in a baja bug. I used cb "special heads" they are a single spring with 40x35.5 valves, stock internals. I ran 8psi of boost - pulled very well to 4800rpm. With dual springs Im sure it could run more boost.

Sat Aug 16, 2008 8:56 am

hey thanks guys :)

ok So thats Great I'm working on the Parts Now :)
now I want to use Carbs So what do I have to Change as far
as Jets etc.
and what Do I do about a Boost Controler?
how is that Set up?
Sorry for the Dumb ??
thanks

Chris.

Sat Aug 16, 2008 11:43 am

http://www.lowbugget.com/turbo_new_page_link.html

This site should answer most of your questions

Sat Aug 16, 2008 12:34 pm

Assuming your 69mm crank is counterweighted such as a welded c/w german or similar and not stock non-c/w..

Sat Aug 16, 2008 2:00 pm

i pound on my 1641 reguarly.... I was running 12-13PSI to be on the "safe side" but been running 17PSI for awhile.... it has a stock german non-CW crankshaft, stock rods.... of course i don't really care if it eats itself...i limit the RPMS to 5400..

Sat Aug 16, 2008 9:26 pm

I had a 1641 with a now counter weighted crank in my first drag motor, 7,600rpms no problem!
Now if the crank was out of balance that would be a no..no!!! It’s a good idea to add “extra” counter weights and that seems to be the STD now-days.
My big thing for turbo combos is valve train control and cam selection. The rest… turbo size, compression, ring style etc are all things to keep in mind.

Sun Aug 17, 2008 12:16 am

Hey thanks guys

But I didn't Do the Rebuild on the Motor so I don't know if it's welded
or counter weighted etc.
and there is know way to tell?
so what would a safe boost be then?
also I want to use Carbs and Not EFI
who knows what Jets? I need for a Set of 40mm
also I have heard that the Stock bottom end can only take about
60 hp?? is this true, and if so by putting boost on would make more
then that??

thanks again guy.
Chris.

Sun Aug 17, 2008 2:08 am

chug_A_bug wrote: also I have heard that the Stock bottom end can only take about
60 hp?? is this true, and if so by putting boost on would make more
then that??

thanks again guy.
Chris.

It's not so much the amount of power the stock bottom end can take, but rather how many RPM's it's stable at. The VW T1 bottom end is actually more stout than people give it credit for, but the lack of counterweights is what hangs people up. I wouldn't be surprised if a stock bottom end at 100 turbo HP lived to see 100K miles, so long as the RPM's were kept below 5K. It's when you consistantly go over 5K RPM regardless of power adder that people see problems without the C/W crank. Spinning it fast leades to pounded out mains most times, but the occasional unlucky owner will spin a bearing before they notice the drop in oil pressure.

Sun Aug 17, 2008 7:30 am

Yes, I respect a stock german non c/w crank and in fact would select
a welded reworked German over the best China crank every time!

But if you have control over your build you owe it to yourself to provide a good foundation and the crank is about as foundation as it gets.
When you have an engine that easilly goes to 6g then you will easilly go there with it.

You more than likely have a c/w of somekind since it is standard upgrade
even on non-stroke engines but it would be nice to know.

Just in my opinion, I would never run a stock crank in anything but stock
service. Resonance and harmonics in a non c/w engine compared to a c/w are detectable as low as 4000 rpm in the form of an "engine strain"
kind-of-feel. Or am I the only one that could pick a counterweighted crank
out of a batch of bugs, just by driving it?

I have to go now and remove the pea from under my matress, I can't sleep with that bump there.