Engine Sizing Question

[ManFromNapa]

Hey guys... I'm looking for some advice and opinions.

I have a 71 bus with a 1600DP engine, 34Pict carb, and SVDA dizzy. I bought and use this bus to go camping. I like to drive it around town, but heading 3 hours in to the mountains with my 3 kids, maybe a couple of their friends, 2 dogs, and all our camping gear is what I love most.

It's getting time to thing about a rebuild, and it got me thinking if 1600 is the way to stay. I think I might want to go bigger.

My goals:
Add some power to help with long / steep climbs

Increase my top end speed a little (Not super important)

Avoid an engine size that runs real hot

Try not to kill my fuel economy

That being said, I'm looking for recommendations for:

Piston size: I'm thinking a modest bump to 90.5

Stroke: Again, I'm thinking a modest bump to 76, but is this enough?

Cam: Not sure what size to go with.

I'd also love to know what your highway MPG is, and what your engine setup is.

Thanks.
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[Glenn]

1776 is a great size. If you have a larger budget, then a 2110 is the way to go.

Both can be built with decent mpg and both can run cool.

Heads, cam and carbs all need to be carefully picked and matched. I would suggest using a well known builder like Chico @ CPR who knows what will work in a Bus.

Go for the 2110 if you can afford it... you'll not be sorry.
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[bugguy1967]

You didn't mention if keeping your stock carb, exhaust, and heater boxes are a must. If so, a 1679 (69x88 Thickwall) or 1776 (69x90.5) would work fine. Make sure to add tuning to your budget. I'd put aside at least $400 for that.

Speaking of, what's your budget? A 1679 or 1776 will cost only one or two hundred more than a stock rebuild, all else equal.

Expect to pay at least $4000 in parts and machining for a complete stroker engine

[FreeBug]

Just to stir the pot a little: a few thoughts on bus engine sizing

Bore-here I would go as big as possible in thick walls, so stock, 88mm or 92s.

Stroke-here I would be more consevative than most... bus engines spend their lives cruising at relatively high rpm, say 4400, for hours on end. As stroke goes up, the mean piston speed goes up, and that just can't help. I see vw only went up to 71mm when they made their 2 liter.

I have a 69 x 88 in my bus, cb 2280, stock heads with a little work, generally happy, but would like to step up to a 92 x 74, with 37 x 32 valves, same cam, twin kads.

Just thinking out loud, but I don't think mean piston speed is given enough consideration, especially as to how it can increase heat. Max bus stroke is 76 imho. Pot stirred?

[Dan Ruddock]

I would go 78X88=1900cc. The bigger the bore the hotter they run but stroke adds little if any heat and a 78 fits well in the case without too much pain. 5.325 rods would also keep engine width within reason. Dan

[jfats808]

A 1776 isnt enough trust me. On flats and highway, any engine will pull its merry way. Until u hit hills or are loaded up is where the engine will feel very lacking. Building bigger already warrants carb upgrade regardless. Stock set ups wont cut it after stock carbs and barely suffices even then.
My suggestion is a 1904/2017/2110 line. All sizes will very in price marginally. Youll have to assess line bore and open your cyl bore. Thats a given, possibly thrust as well. Small ports with either well flowing 37 or roundport 40s is the most. A cam with no more than 285 duration and koderate lift would be my suggestion and a cr of between 8.5-9. 36 or 40 dells will work great with this combo.
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[Brian71]

Its seems to me that far too often people overlook the value and benefit of going with a larger stroke. Yes, an increase bore diameter will result in greater HP , but its results in the torque department aren't squat in comparison to an equivalent increase in the stroke. The larger the stroke, the easier your top end can move that rotating element, giving you more power and placing less wear and tear on your bearings, journals, etc. This would be especially beneficial given the size and weight of your vehicle. I understand some people have a limited budget or may not want to hassle with the additional work involved, but if you are going to go to all that trouble anyway, no sense in short changing yourself.

[ManFromNapa]

[ManFromNapa]

[earthquake]

If that exhaust system is the one I am thinking of it is loud.
If you are not going to revving this motor past about 4500rpm I would check out a DPR 73mm crank, they are cheap. this would give you a 1878cc motor using 90.5 Pistons and cylinders, Then add a set of Weber ICT's and a mild cam [Cheater cam]. you would need a set of Chevy rods but I think A&A has them cheap. I think this would be a pretty good set up, maybe even use a set of SP heads.


http://dprmachine.com.s152704.gridserver.com/products/crankshafts-type-i/
http://aapistons.com/shop/connecting-rods/5-x-forged-chromoly-i-beam-connecting-rod-set-chevy.html

Casey
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[Brian71]

I had a 2110 with an engle 120 and weber 44s in my 71 bay window. That thing was built like a brick shithouse and ran strong all day everyday. When I got rid of the bus, I kept the motor and put it in my Baja- still runs strong as hell. Be wary of the nay-sayers. Most people with a skeptical attitude can't site one goddamn bit of personal experience. This is how we learn.

[jfats808]

[Danwvw]

Rich, Did a 76mm stroke engine for his camper and here he was driving it out to California and back here in this thread: Road trippin to Cali!!!.
Your going to have to spend some money on Dellorto's or Webers though! I did the 74mm stroke and stock valve size heads. Thinking of upgrading to L3, Heads or Steve Tims 39mmX32mm Valve heads.
When mine was a 1641cc engine it climbed those highway hills in third gear at 50mph, Now with the 74mmX88 Piston & Cylinder and the Dual Dellorto 36mm carbs it's climbing a lot of highway hills at 65mph but still will slow down to about 54mph on the steep ones but I'm in 4th gear on them now.
Most of the head guys here on the samba are telling me that big valve heads would not really work on mine that I would loose torque! But a few guys have done it Rich above and another bus I know of has the 044 heads and a CB-2232 Cam. He is claiming 24mpg I think he is using Weber IDF's 40's. I have been getting about the same gas millage in mine as with the old 1641cc with stock solex 34 Pict-3 did. Around 20-21-22 MPG. A little better on trips. But man what a difference with those Dual Dell's! It will zip right up to 80mph on the flat in no time.
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[VWCOOL]

Manfromnapa,

of course I'm not sure how much you know about engines, but if you are handy with the spanners, a quick and easy upgrade would be to install 40mm Kadron twin carburettors and an extractor style exhaust onto the 1600 engine you have - assuming it is good condition, of course. I have done this with several Beetles (not Kombis, admittedly) and the extra zooom this provides within the standard rev range of the engine is surprising

This will be an afternoon's pleasant spanner and if the result may be exactly what you desire. Kadrons have been around since the early 1970s and are just about idiot-proof. Your light-load/part throttle driving economy will improve... but use the power and it will cost you just a little extra

But if you need a bigger smile get a 1916 built. For almost the same component and machining costs as a 1776 you get plenty of extra useful capacity. The 1916 retains the standard VW crank (and works very well up to around 95hp with standard heads, too) so you do not carry the expense or long-term quality risks of an aftermarket and/or stroker crank.

The 1916 is a tried-and-true engine building formula that has been successful for more than 30 years in street driven Beetles, Kombis and motorsport VWs. There is also some myth associated with this engine package... usually cut 'n pasted from the interwebs!

And the new carbies and exhaust you fitted at first will be perfect on the 1916 so you haven't risked any money or components.

Hope this gets you thinking!

[VWCOOL]

[VWCOOL]

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my advice is and has always been to go as big as you can on the bore FIRST, then start stroking. So if it's a bus, you may conclude that 92TW is your size, so budget for the P&Cs, and the machine work on the case and heads. If you still have $ left over, budget for 74mm, then if still $ left over, go 82mm.
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[Danwvw]

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[bugguy1967]

No one ever PROVED anything. Proof requires extensive testing, taking into account many factors, such as ambient temp, variations in building tolerances, octane of fuel used, oil thickness, oil makeup, differences in parts, induction sizing, exhaust sizing, cooling systems, cooling across all four cylinder banks, a/f ratio, ignition timing, advance curves, I could go on...

By just saying, "I built a 1776 and it ran cooler to the touch than my 1915" doesn't mean squat. Not too many of us can do that kind of testing, or even care to. All I know is when I was in my 20s I put at least 30,000 miles on a used 1915 that had another 5 years of daily driving on it. After I sold that engine, someone else continued to use it after me. That was in a heavier Super Beetle.