1955cc engine spec

[VeeDubMan]

Thinking of taking the plunge and building a small stroker motor as, fully loaded, my '71 Dormobile isn't too happy with those Devon hills!

Currently, the engine is a 1584cc, Engle 100 cam, stock heads, cromoly push-rods, twin Weber 34ICT's, electric fuel pump + Filter King, stock 26mm oil-pump. Engine case is a new AS41 that is full-flowed, external filter and cooler.

Keen on low-down torque (to get up those hills) as opposed to out and out top speed, but cruising at 70mph would be nice. They'll be a matched gearbox in the equation too (suggestions on spec for this welcome too). Would like to re-use the 34ICT's if I can (re-jetted etc. for the engine spec - 29 venturi).

Crank: 76mm (any preference on spec/manufacturer/journal)?
Crank bearings: ?
Rods: ?
Rod bearings: ?
Cam: got Engle 100. Is this OK?
Cam bearings: got dual thrust at the moment
B&P's: 90.5 Mahle (I guess)
Piston Rings: Total Seal
Heads: Stock, machined for 90.5? - port and polish...valve sizes? Stock?
Compression ratio: around the 7.8:1 mark
Sump: deep sump needed?
Carbs: would like to re-use the 34's. 29 Venturi has been suggested (thanks @atafonso) but what about jet sizes?

I'm after a shopping list basically which I can then tick off I want to enjoy driving my van this summer without worrying about hills and speed too much.

Thanks in advance

 

[atafonso]

Hi Steve

I use the Empi 4340 as it's the same forging as the Scat cranks, they have fatter chicks and are stronger than the CB/SSP/AA cranks. One thing i found is the area where the gears goes is 0.0005" smaller making for a less pressed gears fit, but nothing to worry about, they just don't go as tight as stock.

I use stock VW rods clearanced, they are very strong and simple to clearance, not much needed. You will need a B set of pistons and that will give you a deck height of around 2.4mm. With a combustion chamber of 50cc's, you need a shim of 0.5mm for a compression of 8.1:1, so really easy to assemble and stock width. Ideally we should keep the deck height between 1-1.5mm for proper squish, but that requires loads of head work to adjust the combustion chamber cc. You would get a more efficient/powerful/economic engine as a result, but the work needed is tremendous and costly, also not many can do it. With a taller deck it still works well just not as efficient. For yours as an example, to keet the compression 8:1 you need 62cc instead of 50, it's almost impossible to get that on a stock head before it becomes a semi Hemi head.

Port and polish the stock heads; bigger valves would kill airspeed and your low end torque.

The above suggested compression is for your 100 cam. I don't like the 100 as it has a lot of lift for the stock valvetrain, so things get a bit more expensive and complicated as you need bolt up rocker shafts, single HD springs, retainer and stronger pushrods. I like the Scat C25, i keep the stock valvetrain with shimmed 0.060" stock springs and it works very well. For ultimate low end torque and responsiveness, use the stock cam, but your engine will run out of steam at around 4.5k rpm.

Bearings- mains, and cam(single thrust for stock valvetrain) Silverline; rod Kolbenshmidt or Mahle.

B and p's- i use AA with great success, they are always within 1g of each other. Mahle is most of the time within over 5g, making bakancing impossible unless you buy 2 or 3 sets to mix and match.

Piston rings Total Seal- not needed, but welcome if budget allows. Will make more power.

Deep sump- if possible yes, i like CB thin line or Scat 1.5qt. The other cheap one is too low and not for every Bus but they hold loads of oil which is good for longevity.

Carbs- yours will work perfectly well, 145 mains, 55 idles, f78 and 160 airs.

If you use the entire gen VW cooling tin with the thermostate, if the engine is built right, there is no need for an external cooler.

Abel

 

[VeeDubMan]

I use the Empi 4340 as it's the same forging as the Scat cranks, they have fatter chicks and are stronger than the CB/SSP/AA cranks.

Fatter chicks? :lol: (was that a typo or a technical term??)

I take it the VW Journal version is all I need and not the Chevy version?

I use stock VW rods clearanced, they are very strong and simple to clearance, not much needed. You will need a B set of pistons and that will give you a deck height of around 2.4mm.

B set of pistons? What does that mean? Also, I guess I can get away with the stock 39.8mm compression height (i.e. height of the piston) on a 76mm stroke as opposed to the 35mm versions needed for longer stroke? And the cast versions are OK?

Thanks again. Making a wish-list at the moment

 

[mike202]

Can you still have heat exchangers with a bigger engine like this? Sounds like a nice upgrade from stock engine!

 

[VeeDubMan]

Can you still have heat exchangers with a bigger engine like this? Sounds like a nice upgrade from stock engine!

Yep. The exhaust valve size isn't changing in this case, so no need to try and get rid of the exhaust gases any quicker through larger diameter pipes.

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[atafonso]

I use the Empi 4340 as it's the same forging as the Scat cranks, they have fatter chicks and are stronger than the CB/SSP/AA cranks.

Fatter chicks? :lol: (was that a typo or a technical term??)

I take it the VW Journal version is all I need and not the Chevy version?

I use stock VW rods clearanced, they are very strong and simple to clearance, not much needed. You will need a B set of pistons and that will give you a deck height of around 2.4mm.

B set of pistons? What does that mean? Also, I guess I can get away with the stock 39.8mm compression height (i.e. height of the piston) on a 76mm stroke as opposed to the 35mm versions needed for longer stroke? And the cast versions are OK?

Thanks again. Making a wish-list at the moment

Not a typo
That crank just like the Scat has more meat at the chicks, which is the portion between the rod journals.

Yes, VW journals as they make the crank stronger compared to the Chevy journals.

B pistons are for stroker engines, if you use the A pistons or the stock compression height you will use loads of shims under the cylinders and have to use different pushrods, adjust the tinware, etc. Loads of work. You could use shorter rods, but would spent more money.

Cast pistons are perfectly fine, also for mild performance aplications.

Abel

 

[K@rlos]

In my experience you can’t beat silverline steel backed main & cam bearings and clevlite or mahle big ends.

As for cam for a mild build I really like the Engle w110 with stock rockers on bolt up shafts. Lots of grunt but will rev up a bit if you want it too. But that’s all down to personal driving style etc

As for crank I personally have an 82mm CB Performance 4340 super race crank with Chevy journals in my race motor. I think you’d do well to break it tbh especially in a mild engine. I opted for Chevy journals as they reduce the amount of material you need to remove from inside the case when clearancing for a big crank but with a 76mm they should drop straight in with little or no clearance work so that’s not really an issue for you.

Remember when building engines there are 3 bits of criteria. Cheap, fast & reliable. You can only have 2....

 

[StefansBus]

Not a performance engine expert but have read quite a bit recently and learned a lot about cams and compression ratios. I have also just had a 1776 built for my '69 Tin Top Westy. I only mention my new engine because I think it does pretty much exactly what the OP wants to achieve but without the need for a stroker crank or a different transmission. Top speed is now 80 mph but I typically cruise at 60 to 65. We have some good hills where I live and it now goes up the same hill in third gear at 45mph that previously required second gear at just under 30mph.

My specs are: AutoLinea case, full flowed, AA pistons (90.5mm), ported 043 heads (AA500 casting), 1.25 rockers on intake side only, elephant feet adjusters, alu HD pushrods, wide mouth push rod tubes, CB 2239 cam, 8.9:1 CR, 1.3 mm deck balanced stock crank, single Solex 34 PICT 3 with 28mm venturi, Ahnendorp CustomSport Exhaust, 123 Tune dizzy with vacuum advance used, external cooler. It runs very well. Idles like stock, but at 900 RPM, has good low end torque, but pulls really strong from around 2700 RPM up to about 5000. I mostly drive it between 3000 and 4500 RPM. I have the stock three rib transmission that was originally mated to my 1600SP engine. It has given me the performance increase I was looking for, mostly for acceleration, hill climbs and passing, but kept the engine stock looking and simple. Torben Alstrup from Denmark wrote the recipe and a local air-cooled Porsche engine builder built the engine for me.

I would think the same would work well with the twin 34s. I also think CR should be closer to 9:1 than 8:1 if a W100 or CB 2239 is used. Also, Torben really likes a tight deck (around 1.1 or 1.2 mm) so I would aim for that for best efficiency.

Hope this helps. Let us know what you end up doing and how it works out for you.

Stefan

 

[atafonso]

Not a performance engine expert but have read quite a bit recently and learned a lot about cams and compression ratios. I have also just had a 1776 built for my '69 Tin Top Westy. I only mention my new engine because I think it does pretty much exactly what the OP wants to achieve but without the need for a stroker crank or a different transmission. Top speed is now 80 mph but I typically cruise at 60 to 65. We have some good hills where I live and it now goes up the same hill in third gear at 45mph that previously required second gear at just under 30mph.

My specs are: AutoLinea case, full flowed, AA pistons (90.5mm), ported 043 heads (AA500 casting), 1.25 rockers on intake side only, elephant feet adjusters, alu HD pushrods, wide mouth push rod tubes, CB 2239 cam, 8.9:1 CR, 1.3 mm deck balanced stock crank, single Solex 34 PICT 3 with 28mm venturi, Ahnendorp CustomSport Exhaust, 123 Tune dizzy with vacuum advance used, external cooler. It runs very well. Idles like stock, but at 900 RPM, has good low end torque, but pulls really strong from around 2700 RPM up to about 5000. I mostly drive it between 3000 and 4500 RPM. I have the stock three rib transmission that was originally mated to my 1600SP engine. It has given me the performance increase I was looking for, mostly for acceleration, hill climbs and passing, but kept the engine stock looking and simple. Torben Alstrup from Denmark wrote the recipe and a local air-cooled Porsche engine builder built the engine for me.

I would think the same would work well with the twin 34s. I also think CR should be closer to 9:1 than 8:1 if a W100 or CB 2239 is used. Also, Torben really likes a tight deck (around 1.1 or 1.2 mm) so I would aim for that for best efficiency.

Hope this helps. Let us know what you end up doing and how it works out for you.

Stefan

Surely a good recipe, suited to your driving style Stefanbus

The problem is, if you ask 100 people how they would build their engine, you would get 100 different opinions :shock:

Your builder has to match the engine TO YOUR driving style, so don't let anyone choose that for you or you will be disappointed. Explain what you want, if you towing, looking for cruising at higher or lower speeds, what rev range you will be driving mostly, and above all, how much money you can spend and if you need to use any of the parts you already have. Those factors are really important and if your builder does not ask those questions and suit the engine to fulfill those needs, i would be concerned. After all, you are the only one that will part with the money and will either be a happy camper, or a frustrated one

Abel

 

[StefansBus]

I agree Abel. And I'm glad Torben worked with me exactly for those reasons. As you say, the result is exactly what I wanted and may or may not be what the OP is looking for.

In any event I think trying to get the CR and deck hight to optimum values is always a good idea so as not to leave power and efficiency on the table. Those would be my only remarks to the build the OP has in mind. Oh, and the exhaust. Stock is restrictive. I would recommend something a bit less restrictive and with equal length headers. The Ahnendorp is good, but expensive.

Stefan

 

[VeeDubMan]

Remember when building engines there are 3 bits of criteria. Cheap, fast & reliable. You can only have 2....

Great mantra to have! Works perfectly

 

[K@rlos]

I like to think it's a good approach to have. Hope it all works out nicely and you're happy with the outcome 8) just don't spoil it with a vintage speed exhaust :msn4: :lol:

 

[atafonso]

I agree Abel. And I'm glad Torben worked with me exactly for those reasons. As you say, the result is exactly what I wanted and may or may not be what the OP is looking for.

In any event I think trying to get the CR and deck hight to optimum values is always a good idea so as not to leave power and efficiency on the table. Those would be my only remarks to the build the OP has in mind. Oh, and the exhaust. Stock is restrictive. I would recommend something a bit less restrictive and with equal length headers. The Ahnendorp is good, but expensive.

Stefan

Glad you had been helped to achieve your goal, Torben is a very knowledgeable person in the ACVW community and has been using technology and advancements to improve our engines, which is great specially because he shares his findings helping others.

I also agree with the compression and deck height subject, the engine will make more power and use less fuel with a tight deck. All my performance engines have a deck of 1-1.2mm max. Problem is when going bigger and using a milder cam and compression, is almost impossible to make the combustion chamber big enough to maintain squish. The chamber almost become a hemi cut, defying the purpose. On higher compression and cammed engines you can rework the chamber and achieve good squish due to not needing to reduce the chamber size so much and also the cylinder bleed due to the ******** intake closing ATDC resulting in less dynamic compression.

Try to take for example the 90.5x76mm 1955cc engine and stock cam i suggested. You need a chamber of 67cc to achieve the 1.2mm deck height with 7.5:1 compression, impossible. Even with 8:1 you need 62cc which is a lot of work to get too. Also it would not work with the stock rods, the stock pushrods, etc, so way more money and much, much more labour pushing the engine price very high.

My suggestion for the 1955cc with the stock cam and almost stock valvetrain makes a stump puller with loads of torque down low to push the heavy Busses with ease and having great reliability with a low price tag. Stock cooling system and no external cooler is most of the times what's needed. And 2 years warranty too lol Not for everyone though, as it runs out of steam at around 4.5k rpm, but for most mature Bus owners(i say mature for us old farts lol) is just how they drive and what they need.

Abel

 

[VeeDubMan]

So, cams that have been mentioned so far:

- Engle 100
- Engle 110
- Scat C25

All other things being equal, what sort of driving style/performance/torque/power band can I expect from each? I like acceleration/torque and comfortable cruising. Don't know if that's at all possible in what I'm looking for? I'm 47 this year, so starting to appreciate the comfort more!

(btw, I built a 1776cc, Engle 120, twin 40 DRLA's, 041 heads (40/35.5) in my old '67 bug on the stock 1200 box. Now that was fun!!)

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[K@rlos]

So, cams that have been mentioned so far:

- Engle 100
- Engle 110
- Scat C25

All other things being equal, what sort of driving style/performance/torque/power band can I expect from each? I like acceleration/torque and comfortable cruising. Don't know if that's at all possible in what I'm looking for? I'm 47 this year, so starting to appreciate the comfort more!


(btw, I built a 1776cc, Engle 120, twin 40 DRLA's, 041 heads (40/35.5) in my old '67 bug on the stock 1200 box. Now that was fun!!)

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A w110 with stock ratio rockers is nice in a bus, plenty of bottom end but will pull over 5000 rpm if you want it too

 

[Tofufi]

Having driven about 10-15 miles in a bus with a 1955cc engine built by Abel (Atafonso), I'd say his advice is pretty much spot on.

Stock cam gives loads of torque down low - it's not a screamer but easily torquey enough to keep up with traffic up and down hills all day.

Matched with a 5 speed Porsche gearbox it goes like a modern car.

Another thing - get everything balanced accurately. It makes a huge difference to the engine smoothness!

 

[JimVeeW]

Having driven about 10-15 miles in a bus with a 1955cc engine built by Abel (Atafonso), I'd say his advice is pretty much spot on.

Stock cam gives loads of torque down low - it's not a screamer but easily torquey enough to keep up with traffic up and down hills all day.

Matched with a 5 speed Porsche gearbox it goes like a modern car.

Another thing - get everything balanced accurately. It makes a huge difference to the engine smoothness!

Hi tofufi, can I just ask what Porsche 5 speed gearbox you had fitted? Cheers Jim

 

[ozziedog]

Having driven about 10-15 miles in a bus with a 1955cc engine built by Abel (Atafonso), I'd say his advice is pretty much spot on.

Stock cam gives loads of torque down low - it's not a screamer but easily torquey enough to keep up with traffic up and down hills all day.

Matched with a 5 speed Porsche gearbox it goes like a modern car.

Another thing - get everything balanced accurately. It makes a huge difference to the engine smoothness!

Hi tofufi, can I just ask what Porsche 5 speed gearbox you had fitted? Cheers Jim

Hi Jim,
Tofufi did a little ‘how to’ somewhere on here about fitting this five speed, I’m sure with a little searching, it should pop up.

Ozziedog,,,,,,,,,does sound great dunnit :mrgreen:

 

[JimVeeW]

Having driven about 10-15 miles in a bus with a 1955cc engine built by Abel (Atafonso), I'd say his advice is pretty much spot on.

Stock cam gives loads of torque down low - it's not a screamer but easily torquey enough to keep up with traffic up and down hills all day.

Matched with a 5 speed Porsche gearbox it goes like a modern car.

Another thing - get everything balanced accurately. It makes a huge difference to the engine smoothness!

Hi tofufi, can I just ask what Porsche 5 speed gearbox you had fitted? Cheers Jim

Hi Jim,
Tofufi did a little ‘how to’ somewhere on here about fitting this five speed, I’m sure with a little searching, it should pop up.

Ozziedog,,,,,,,,,does sound great dunnit :mrgreen:

Had a look but will have another, thanks.

 

[ozziedog]

Hi Jim

http://forum.earlybay.com/viewtopic.php?f=4&t=60286&p=593563&hilit=Porsche#p593563

Ozziedog,,,,,,,,I hope this is it :mrgreen: