Will this work? Advise on engine built and exhaust, please

[StefansBus]

Possible winter project. The bus (stock 1969 bay with 1600SP) could use more torque.

I'm not after high RPMs and lot's of horse power. I just want more pull.

At the same time I want things to look as stock as possible.

How big can I go with the stock exhaust system including heater boxes provided I keep the RPMs low (as low as stock or even lower) without running into heat problems due to too much restriction to exhaust gas flow?

I'm pretty sure 1776cc won't be a problem but what about 1956 or 2017cc?

As you can see I want to go 90.5 on the piston and cylinders.

I would keep head work to a minimum and valve size stock or close to stock. The cam would remain stock or close to stock, too.

I have an aluminum case which should not be needed but won't hurt.

I'm also planning on a quality, forged, counterweight crankshaft. I don't think this engine will need it but I wan't it to be as smooth and reliable as possible.

I think I will have to convert to dual port and while I am at it I would go for a single 37 PICT Solex carb (converted genuine 34 PICT 3). Not interested in dual carbs for this engine.

Will the stock exhaust system work with such a combo?

I've also posted this over on the samba and I'm looking forward to your thoughts on the exhaust question as well as the envisaged concept, keeping in mind I want stock looks, torque and reliability.

Cheers

Stefan

 

[K@rlos]

Stock engine = stock exhaust. Putting 1 on a bigger ego e will strangle the hell out of it

 

[StefansBus]

Thanks K@rlos. Yes, it does seem to be true that there is not much (if any) room for more displacement in the stock exhaust. I'm currently leaning towards this engine from a very well known German Company. Their exhaust is stainless steel, equal lengths, wider tubes for all cylinders, and their 1835 makes 85 hp and 160 NM with a single carb http://www.ahnendorp.com/VW-Kaefer-Typ-1-Motorenteile-und-Bearbeitungen/Complete-packages-VW-Beetle-type-1-engine/1835ccm-Typ-1-Zentralvergaser-Konzept-Ahnendorp-B-A-S--1852.html. The English translation of their website is terrible so I'm linking to the German one. Not affiliated with the company and haven't bought anything from them yet.

 

[atafonso]

With a stock cam and stock valve sizes you should not primarily be concerned with power figures, what it will make if the displacement is increased it's way more torque starting at very low rpm's.
With the stock cam the engine can rev more than 4-4200 rpm but the power curve will drop rapidly, so no sense in revving higher, therefore restriction will not be a great issue unless you plan on running the engine constantly above the optimum cooling range of 3200-3500 rpm. I would convert to a doghouse cooling at least and monitor closely the oil temps but surely it will need extra cooling if pushed hard uphils with a heavy Bus.
Using a single carb, max i personally would go is 1955cc. It will be a tractor
Abel

Ps: Keep the mag case, alu will run much hotter.

 

[StefansBus]

Thanks Abel. Am I not correct in thinking that even when maintaining the stock RPM range then the higher displacement will mean, more air (both cold and hot" will be pumped through the engine at any given RPM, requiring a less restrictive exhaust in order to prevent an increase in head temperatures etc? The carb is not my concern, I can easily get a 37 or 39 size Solex carb, The exhaust is.

I do have an external oil filter and cooler (not full flow) and a thermostat switch controlled electric fan fr the oil cooler.

Do you have any reference for saying that the alu case will run much hotter? I have read almost only good things about the latest generation of AutoLinea alu cases. Yes, a slight temp increase mentioned by some but mostly considered academical rather than relevant in practical terms. The Type 4 case is aluminium and as we all know makes 100hp in the stock Porsche 914 (2 liter) and much more in various performance applications. It is generally accepted to be the tougher engine.

Cheers

Stefan

 

[atafonso]

Thanks Abel. Am I not correct in thinking that even when maintaining the stock RPM range then the higher displacement will mean, more air (both cold and hot" will be pumped through the engine at any given RPM, requiring a less restrictive exhaust in order to prevent an increase in head temperatures etc? The carb is not my concern, I can easily get a 37 or 39 size Solex carb, The exhaust is.

I do have an external oil filter and cooler (not full flow) and a thermostat switch controlled electric fan fr the oil cooler.

Do you have any reference for saying that the alu case will run much hotter? I have read almost only good things about the latest generation of AutoLinea alu cases. Yes, a slight temp increase mentioned by some but mostly considered academical rather than relevant in practical terms. The Type 4 case is aluminium and as we all know makes 100hp in the stock Porsche 914 (2 liter) and much more in various performance applications. It is generally accepted to be the tougher engine.

Cheers

Stefan

Hi Stefan
The fact you will have a bigger displacement does not necessarily mean you will generate more heat at all times. With way more torque you will not have to put the engine under a heavy load to move the Bus. What makes the heat is the amount of load you will subject the engine. Lower load, lower temps overall.
The alu case runs hotter on the type 1 as the magnesium has a better heat dissipation property than the alloy used on the alu case plus the walls of the mag case are thinner. I know that by experience, not by what others say. I said they run hotter, not that they are not stronger. They are stronger but not needed IMHO for engines that makes less than 250bhp. CB Performance at one point was using the alu in their performance builds but they have switched back to mag in most combos. Only on the very high performance all out engines they use the alu. It's also heavier, has loads of cast fleshing that i myself, clean and deburr all when i build one. Also the oil holes to the main bearings are not aligned, requiring some mods. Not for your average builder.

Abel

 

[StefansBus]

Thank you Abel. I appreciate the first hand info.