On Building A Specific Engine........

Bookwus · Post by **Bookwus** » Sun Jul 28, 2002 3:18 pm

Hiya All,

I have a bone-stock 1970 7 Passenger Bus. 1600sp, 57hp SAE.

Way underpowered for freeway-type driving. I can do 68 mph on the flats with a good tailwind. I can cruise at 55 to 60. About typical for this year and model.

It's fine for around-town driving (and that is where I drive it 75% of the time) but I'll be hitting the freeways more often in the future.

So, is there anyway to boost the hp (I'd like to cruise at 65 to 70 and get up to 75 when I have to) AND still keep it appearing stock?

I don't really want to go to duals or a hi-pro exhaust (Yeah, I know - shooting myself in the foot) but is there a way to boost the output without messing with the carbs and exhaust?

danimal · Post by **danimal** » Sun Jul 28, 2002 4:36 pm

trying to build h.p. while ignoring carbs/exhaust is not the right approach... i think you know that

however, if you keep all valve sizes, and probably the cam, the same... you can run the stock carb/exhaust... while definitely making more torque by increasing the displacement.

as in, run a 1776 for a bus... with stock c.r., just like the factory designed it.

dan
oceanstreetvideo.com

Bob Ingman · Post by **Bob Ingman** » Sun Jul 28, 2002 6:26 pm

Book, like yourself I also have a bone stock 70 camper which I like to keep stock looking.
I loaned it out and the guy put a single quiet on it. Pissed me off so I found another stock bus muffler to go back on it.
You could go to a 1776 single port with an Engle 100 cam and gain a few horses without being seen. Actually the Kadrons are so common they almost are accepted as the same as stock anymore. If you can find single port manifolds.
If you plck up a few more horses you can then go to a taller rear tire such as a 205 or 215/14 to raise the top speed without working the engine badly leading to heat.
I converted to a doghouse shroud w/offset cooler and an alternator. Still has a very stock appearance. All VW stuff. Good luck and keep it single port. Bob Inbgman

carapace · Post by **carapace** » Sun Jul 28, 2002 8:14 pm

Mike! Good to see you on this forum!

The Ruptured Duck could always use some more carburetion, and the Kads are great. Only thing is, you have to port them for vacuum signal.

------------------
Simon Sez
www.carapace-design.com
Bad Dog Racing-www.gregsvw.com

James2 · Post by **James2** » Sun Jul 28, 2002 8:50 pm

The 90.5 cylinders would run cool. Wouldn't give much hp, maybe 3-4, but would give more torque across the whole rev range.

Only bolt on would be 1.4 rockers, again worth 4-5 hp, maybe less though with the stock carb and exhaust.

Truth is , it's going to be hard to get much more power, because the carb is a major restriction on a stock motor. You can only pull so much air in with that tiny carb.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Jul 29, 2002 5:24 am

I do not run 90.5s in busses, I favor machine in 88s for oil temp control, and longer living without warpage and excess crankcase pressures.

Either a 1679(69x88) or 1800(74x88) engine is great for a bus, I recommend a slight increase of camshaft, just to cool off the heads, and a CR of around 7.5:1 to match the cam.

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Jake Raby
Raby's Aircooled Technology
www.aircooledtechnology.com

Pillow · Post by **Pillow** » Mon Jul 29, 2002 7:32 am

The baby Webers have a stock vacuum port. Look at them if considering dual carbs... They also have a good linkage!

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Adrian Pillow
'66 VW Westfalia - "Biscuit"
'67 VW Deluxe Westfakia - "Dino" - FS
'79 Porsche 911 SC - "Cochese" - FS

Post by **Marc** » Mon Jul 29, 2002 8:06 am

You need to set your sights a little lower as regards top speed if you must maintain stock appearance. The stock exhaust has to go for any real top speed improvement. The singleport heads don't help here either, but they are otherwise a good choice.
Increasing the displacement, rocker ratio/cam, or carburetion aren't going to have nearly the effect they should so long as that whale is breathing through a soda straw. The final drive ratio of an 002 trans is roughly the same as that of a swingaxle bus with 1.26:1 reduction gears; in other words your engine needs to buzz about 25% faster than it would to go the same speed in a bug, and the restriction of the bus muffler only makes that harder to do - it's more limiting the larger the displacement, too. A 1679 or 1775 with the stock muffler will give more torque and around-town responsiveness, but for top speed a healthy stock 1584 dualport with a header can outrun either one
(the bigger engine will still do better at bucking a headwind or climbing a grade at ~60mph though).
Machined 88s are the best available bore size for a heavy vehicle; lots of people run 90.5s in busses too and get away with it but there's not much safety margin left - I wouldn't go that big with singleport heads unless bottom-end grunt was the only thing I was after.

Bookwus · Post by **Bookwus** » Tue Jul 30, 2002 10:29 am

Hiya Guys,

Thanks for all the replies. I REALLY do appreciate everybody's contribution. Your input has given me a bunch to think on in the next few months. My current single port is in pretty darn good shape and I'll run it until it gives up the ghost. But, sooner or later, I will have to make THAT decision and your thoughts will be remembered. And I'll probably be asking some more questions.

Thanks again!

Mike

PEPPE · Post by **PEPPE** » Sat Aug 03, 2002 3:03 am

i built various hopped up 1600 for buses.
my recipe is this.
engle 100 cam, a little higher compression ratio (7.7-8:1, one also 9:1 on CNG), modified stock exhaust (internally opend to lower backpressure, modified 34 pict carb (bigger chike and jets).
however you have to go dual port with 34 pict, but think that the engine will work well with a CB performance center section and end pieces for single port.
Remember to give a slight porting to the heads, not a racing porting, just a 10 minutes work.
I reached also top speeds of 85mph with these setups.
Peppe