High performance dual port end castings

[ccowx]

Hi! What are the alternatives for dual port end castings? I realize they are restrictive and basically limited to around 75 horse, but what can be done about it? Does anyone make a set of high flow end castings or do you need to modify the stock ones? I am considering extrusion honing or just plain old grinding, but I am happy to hear any other suggestions!

Thanks!

Chris

[JDMbeetle]

https://www.cbperformance.com/product-p/7367.htm
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71 Super Beetle
74 Standerd Beetle

[ccowx]

Thanks for that! Do they fit a stock center section? I know obviously don't pair them with one, but I am planning to use a PICT 34-3 with a CB S/S center section and I am wondering if it will fit?

Thanks!

Chris

[chrisflstf]

Those would not fit a stock center section, without some sort of adaptor, as those are 2 inch, much bigger than stock end pieces

[sled]

[bugguy1967]

Carb is not the limiter. The center section and end castings are. Just see a Class 11 with an untouched induction make 100 hp.

Just porting them larger won't do anything. Center section abruptly turns the mixture left or right at the tee, and the end castings probably need a larger volume at the turn to slow down the air speed to make the turn. It all needs work, and if you don't have a flow bench it's likely a waste.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[modok]

The carburetor, riser, and tee joint of the center section has far more potential for improvement.
Compared to those parts, the end castings are already a lot "higher performance"

I spent maybe..8 hours playing with the end castings on my flowbench, and did not find any easy improvement. I did find some flow more than others, and some flow unevenly (more on one side than the other), but there is no easy mod or real design problems, it's already close to as good as it gets for what it does. They outflow the heads unless the head by probably 15-25% give or take depending on which of each from the pile you test.


I think I should someday research the center section, but, not looking forward to it. It's going to be a PITA I think, similar experiences have been, wet flow VS dry flow...., and also the fact I don't even like solex carbs. Somebody should do it tho.

[ccowx]

Yes, Sled, this is the same engine. I am working my way through collecting the right parts and planning the build out. I would like to use the 34-3, albeit with a 28 mm venturi, but I do know that the entire induction system needs work. I figure that using a SS type intake center section with a more inverted "Y" center section and generally smoother contours is a good start. I am told that the end castings are also a limitation so I am trying to see if there is something I can do with them. I have seen references to porting them but I don't seem to be able to find anything online about exactly what was done.

I could go with the larger ones, but those are obviously overkill for my purposes. Perhaps a bit of smoothing and/or an extrusion honing would suffice?

Chris

[nsracing]

if you are running a single 34 Pict, I think the factory end castings are plenty for flow.

You are better off porting the heads to gain flow.

[ccowx]

For the heads I was planning to smooth the sharp shelf under the exhaust valve and some general polishing on the exhaust side. Intake I will probably do very little on, other than some smoothing and a slightly rough finish. This will be very new territory for me, so I am going for basics and a general improvement, not competition level work.

I was looking over the end castings and I think that the only reasonably accessible part that will give any benefit is the top, before the split. There are some serious ridges in mine and a general reduction in diameter all the way around. I would say conservatively that there is a ridge about 1/16" to 3/32" all the way around the opening. By grinding that away and generally smoothing it I suspect you could get a significant improvement in overall flow. After the split is already pretty good and about the same size as the ports on the head anyway. There is not much meat there to grind on anyway, so that is a good thing!

Thoughts welcome!

Chris

[Alstrup]

Slightly modified end castings easily flow to over 100 hp along with a slightly modded 34 PICT carb and CB/Empi center section. (In street trim) Race is different.

I am currently working on a 2165 bus engine with a heavily modified Solex (37 mm butterfly) modified center section and Wensings 34 mm ID stock look end castings. We are in the 125 hp range, still with perfect idle at 875 rpm.

A good deal of the trick in such perfoirmance set ups for street use is actually chosing the cam.
I am not sure what displacement you are going for or what vehicle its going in (?)
Here is a dyno print from one of my German colleagues. A slightly spirited 1835 with modified intake and Solex carb.

PS.
Stock (CB) intake and a modded 34 Solex with stock end castings hit a wall around 86-87 hp if you use cams and fuel that are "streetable" With modified end castings you can relatively easy realease 6-7 hp and extend the power curve a little. Increasing the Throttle bore to 37 mm does not give much hp, - maybe 3-4, that´s about it, but it will typically increase midrange torque with about 10 Nm (about 7 lbs) Add a modified center section, and you will typically see more upper end power, from roughly 3500 & up. (This is of course heavily dependant on the engine and displacement. Another oddity with increased capacity in the center section is that you can get by with a little more cam duration without the idle going south. Larger end castings like the Wensing ones are not really that interesting until you reach about 1900 cc and want the engine to rev "high" or you build large displacement like 2 liter plus. Then they really come in handy.
Both Wensing and I have been testing these larger end castings on a couple of different engines. Wensing likes high rpm engines that goes BAAAAAHHH down the Autobahn, so he tried them along with his modded intake and carb on a 1904 with Panchito heads and a relatively aggressive cam, and it really does like rpm. It easily pulls 5800 in third with peak hp in the 5500 rpm area I think. It has not been dynoéd yet, but around 110 hp I would say. (A 100 hp dual carbed 1776 can´t keep up)
The 2165 I referred to above is totally different since it is going into a bus. There I am looking for torque over rpm, so I have chosen a significantly different cam. This engine has some welded and heavily reworked Mofo 042 heads etc etc. The butt dyno is not always accurate, but I would not be surprised to see 200 Nm peak torque from that engine. It pulls hard, and from very low rpms. I´m not sure when I get it on the dyno. You know, Rome was´nt built in a day, and I have a few other things to work with before I can get back to that.

As I have said before, when you work with engines that are fed with stock style intakes you need to think different. If you think the classic "dual carb" way of tuning you will most likely get some rpm power, but you will 90% certain get a crappy running engine overall.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[ccowx]

As always, thanks Alstrup for your ability and willingness to share hard learned information with the rest of us! I have been building this engine on paper for a while and collecting parts for it, so thanks again to you and everyone else for the help!

This engine was covered in this earlier thread, for those that are interested.

https://www.thesamba.com/vw/forum/viewtopic.php?t=741841&sid=ba30b05449088ad141d71fccd2cd481d

I am thinking of using an Aircooled.net Super stock center section and doing some simple porting on the end castings. The rest of the build is in the other thread for those that care to look, but it sounds like 90 or so horses is attainable with the right parts choices and some moderate massaging.

Thanks!

Chris