Head selection for mild 2275

The port sizes are cool, and I would only suggest that you stay with round intake ports, rather than the wide oval or "D" versions.  Why?  Because the wide oval ports leave precious little "meat" between the two ports, and they have a tendency to suck the gasket material out between the ports, making a vacuum leak between ports - acts just like an external leak, but you can't find it by spraying carb spray around the flange.  

Took me a while to figure that out, and now I've had the manifold flanges milled flat (assumed that the head mating surfaces were flat already and lucked out) and I run no gaskets, just flange sealant.

The ACN and DRD both use the Revmaster 049 casting.  Does anybody have experience with that casting?  They claim it has better cooling.

I'm under the impression ACN gets their cnc'd heads from DRD (hence using the same casting), so I suspect those would be very similar heads (if not the same). I have heard of someone getting almost 160hp with a very large, flat torque curve with those heads- 

http://www.thesamba.com/vw/for...65227&highlight=

The only thing I'd like to see is more combustion chamber cc's so the deck height can be dialled in at .040- .050" (instead of the .080" or so Gerico used). The large deck will transfer more heat to the heads through the quench pads (from the burn happening adjacent to them instead of just in the combustion chamber) and carbon build up (resulting in detonation when it gets hot) can be a problem as the engine gets a little older. The engine will ultimately run cooler and cleaner (and some people say it will have better throttle response) with the tighter deck. I'm guessing these heads would make 5-10 more hp than the super mag round ports, and I don't think one would cool significantly better than the other.

Another head you should consider is CB's Panchito- better cfm #'s than the super mags (close to the L5's) and great port velocity figures as well. I think your 2276 with either of these heads would make a totally kick*ss combo!  Al

Hey Al

I did a side by side comparison of the heads.  The ANC has slightly better flow .350 lift.  The interesting thing is you can buy the head directly from Revmaster for $500M.  I am not really sure if ANC and DRD do anything significantly different then Revmaster.  I did also take a look at the Panchitto.  I didn't see any really flow number that I could compare.  If the Panchitto flow better than the super mag rounds, why are the $100 bucks cheaper?  You also mentioned a bigger combustion chamber would be better.  ANC will do a custom chamber for $40 more.  What size chamber would you recommend?

I believe the Panchitos are cheaper because the ports and combustion chambers are cast, as opposed to the Super Mag round ports being cnc'd. I can't find a lift/flow chart, but on the Panchito web page                                         http://www.cbperformance.com/P...d-94-Bore-p/1673.htm                                        they claim 171cfm with the cnc'd combustion chamber (61cc's). 63cc's and .045" deck height give 9:1 using the CB engine calculator.  http://cbperformance.com/v/enginecalc.html                                                                         If you do  consider the Panchitos it might be an idea to ask if the combustion chambers can be enlarged to 63cc's so the engine will have a nice tight deck.

Bobby-

Welcome to the real madness: ACVW heads.

You're at the pointy end of the wedge, looking at flow numbers. That's one of the important metrics of cylinder head design, but it's only 50% of the total equation. Any monkey with a die-grinder can port for mass flow by hogging out the ports until he gets to 180 cfm, or he can shove a banana down the runner-- whichever comes first.

The magic is in generating target mass-flow numbers, while still keeping the volume of the port small enough to generate good velocity in the runner. This makes the engine "snappy", and greatly improves throttle response. That's the magic of the new 044 Los Panchitos heads-- they flow pretty nearly as well as a mini-wedge port, but have way smaller ports.

As a rule of thumb: on the street, you want the biggest flow numbers possible with the smallest ports you can get. So, you'll pick a target CFM to support the total HP you'd like, then choose (among other things) the smallest runner volume that will still flow that number. There are other considerations (what casting are they using? How do they cool?), but it's hard to be disappointed using this as a baseline. 

For reference, I'd start by considering this chart from thesamba.com:

Also bear in mind that there are no independent testing labs verifying the CFM numbers provided by various head shops for use in charts like the one above.

It's commonly accepted practice is to advertise flow at 25" W/C, so as to compare "like for like". DRD provides (self-tested) numbers at 28" W/C (a stronger vacuum)-- but the chart has listings at 25" W/C, because there is a formula one can use to convert 28" numbers to 25" numbers. I know this is what has happened with the chart, because I did the math and provided it to AlteWagen to post.

That was about 4 years ago, when I still believed that guys couldn't just claim whatever they wanted, and nobody would verify it. Al's right, by the way-- ACN's heads are one and the same as DRD's. John Connelly doesn't port heads, he buys them from Darren. Why the discrepancy in flow numbers? See above. There's a lot of stuff about those heads that just doesn't add up for me. Even the port volume numbers are what Darren provided to me, and I provided to AlteWagen.

Since all this, I've come to think that the most sophisticated approach to the "head conundrum" is also the least sophisticated one-- at the end of the day, you'll just have to pick somebody you can trust and go with their best recommendation for your application. If you really want to do this without input, I get that-- just be aware that anybody can say anything they want, and there won't be a single thing you can do about it if it isn't true. A guy who's 180 CFM heads consistently make less than they should on an independent dyno (no Orange County Correction Factor) has a problem with math or veracity (to say nothing of velocity. You see what I did there?).

Welcome to the deep end of the pool. Forewarned really is forearmed. 

Thanks Stan, lots of stuff to digest

FWIW, if it were me-- I'd buy the 044 Los Panchitos heads with the bigger chamber, set the deck for .060 and run 9:1 CR with that W120. It'd run like a scalded cat.

Stan

Are running the panchito on your 2276? what is your setup?

@Bobby D,

I'm not running the Panchitos, because they didn't exist in their present form until earlier this year (although the last generation was no slouch).

My set-up is "unique". My heads are 049 Revmasters, twin-plugged. I had a set of CB 044 Super-Pros, which in my opinion was/is the high-water mark for a 200 h/p head (because of the things I posted above). Most guys aren't aiming for 200, for some very good reasons, so the Panchitos are a better street head that can easily make 160+ hp. That's a good amount of power for a speedster, as after that the other systems start getting overwhelmed. Getting them up to where they need to be will double the price of the car, for a minimal return.

Regardless, at some point the number of cylinders starts to be the limiting factor anyhow-- because to get more power out of a 4-pot motor, the intake ports start growing to the point that they don't have very good velocity at low engine speeds. Subaru motors make about 170-ish, and pull well-- the factory knew what they were up against, and so that was their target. At this point in time, getting more streetable power (after about 200 hp or so) means forced induction, and IMHO it's a bad idea on an air-cooled flat 4 looking for any reliability. It's super-cool as a street-fighter, but you wouldn't be taking off for the other coast with a 300 hp 20 psi boosted Type 1.

I'm not running the 049s because they are better heads. I'm running the 049s because they were available from Revmaster cut for twin plugs. There's nothing wrong with the 049 casting, but while I'm OK with Revmaster's porting, it isn't nearly as good as some of the other CNC (and "as cast) ports available now.

I have a long and well documented post somewhere regarding my experience getting twin-plug heads-- if you do a search for "twin-plug pain" (or something similar), you can follow along with a tale of a man tilting windmills. Suffice it to say, I sent a $1000 set of Super-Pros to a guy who made door-stops (boat anchors?) out of them, and this was by no means the most expensive part of the process.

What you are after is completely reasonable, and your choices so far are spot on. I'd just look at other heads as well before you jump.

Thanks Stan.  I sent an email to Pat to get his 2 cents. But, I think you guys have convinced me on the Panchitos.  The price is good too.   

I think, Bobby, either head (DRD/ACN or CB Panchito) will produce great results on a relatively mild engine such as this (one that only revs to 6,000 or so rpm with power). I'm sure dyno testing the engine with one and then the other head (wouldn't that be fun! you could even sell the set you don't keep) would show slight differences (one might have a little stronger midrange and the other a slightly better top end) but the ol' butt dyno (the most important one!) would probably be more than happy with either. 

You can look at numbers and flow charts 'till the cows come home, but Stan's advice to "pick somebody you can trust and go with their best recommendation" is solid. Talk to Pat Downs and John Connolly(sp?) and see who you're most comfortable with. I'd pay extra to end up with 63cc combustion chambers so deck height can be kept down to .045-.050" (no partial burn/heat transfer on the quench pad areas; now the timing doesn't have to be quite so advanced and the engine is that little bit more efficient). It takes attention to a lot of details for an engine this big to run successfully in a Speedster (along with all the engine sheetmetal being there and fitting properly, adequate air supply to the engine compartment, an extra cooler in the airstream where it doesn't preheat the engine air etc etc) and this is where you start. Al

ALB posted:

I think, Bobby, either head (DRD/ACN or CB Panchito) will produce great results on a relatively mild engine such as this (one that only revs to 6,000 or so rpm with power). I'm sure dyno testing the engine with one and then the other head (wouldn't that be fun! you could even sell the set you don't keep) would show slight differences (one might have a little stronger midrange and the other a slightly better top end) but the ol' butt dyno (the most important one!) would probably be more than happy with either. 

You can look at numbers and flow charts 'till the cows come home, but Stan's advice to "pick somebody you can trust and go with their best recommendation" is solid. Talk to Pat Downs and John Connolly(sp?) and see who you're most comfortable with. I'd pay extra to end up with 63cc combustion chambers so deck height can be kept down to .045-.050" (no partial burn/heat transfer on the quench pad areas; now the timing doesn't have to be quite so advanced and the engine is that little bit more efficient). It takes attention to a lot of details for an engine this big to run successfully in a Speedster (along with all the engine sheetmetal being there and fitting properly, adequate air supply to the engine compartment, an extra cooler in the airstream where it doesn't preheat the engine air etc etc) and this is where you start. Al

 

AL

If I am going to use 82mm crank with 5.40 rods and "B" pistons, is the 63cc combustion camber size still good.  I have no idea what the deck height would be without a mockup.  I think CB standard option is to is 61cc on panchitos.  I know we can adjust compression ratio by adding spacer to the jugs base.  What happens if the deck height space to large to start and you need to reduce?  And is 9.5 to 1 too much compression?

Al

I found this chart.  I think it is show the theoretical deck height with no spacers.

http://www.thesamba.com/vw/for...wtopic.php?p=7523453

So for 82 crank and 3.4 rod the deck height would be approximately -.026 

Bobby- using the CB Perf engine calculator http://cbperformance.com/v/enginecalc.html                                                         we plug in the essential info- 82mm stroke, 94mm piston, 9:1, .045" deck and we get 63cc's for combustion chamber volume. Using 61cc's and .045" gives 9.3:1 and 61cc's, .050" deck and you get 9.2. My big thing here is to keep the deck as tight as possible so most of the burn happens in the combustion chamber and not on the quench pads, as this allows more heat to be absorbed by both the head and the piston. Then the engine oil isn't having to deal with that much more heat, as it's created power and then gone out the exhaust (as it should). It also takes a degree or 2 more distributor timing to burn the fuel air mixture on the quench pad, as it takes more time for the flame front to complete the burn. With more deck the engine will still feel like it makes good power, but the combo won't be quite as efficient as it could be.

I'm using 9:1 here as a safe number for the W120/1.25 cam/rocker combo (together they provide 255-256'@ .050" lift); you could set the compression as high as 9.5:1 but then you have to be more vigilant that the tune is spot on all the time (more time spent in the garage and not driving), there's no buffer should you end up with a tankful of bad gas and now the car isn't as "jump in and drive anywhere, any time" as it could be.

And you are right, for initial deck height numbers you have to mock the engine up to get useful measurements. Cylinder seat heights aren't the same from engine case to case, and if those surfaces have been reconditioned or cut oversize the only way to find out is through mock up. In the event you want to decrease deck height, the bottom sealing surfaces of the cylinders have to be trimmed, and this is a job for a machine shop (or someone with a lathe...). It's not unheard of to have to shorten cylinders in a build like this. More later. Al

Set the deck for a good burn, not to adjust CR. If the deck gets bigger than .060,  it will negatively impact burn.

Set CR with chamber volume. If you can't get enough chamber volume,  dish the pistons.  Resist the urge to just increase your deck to bring the compression ratio down.

9.5:1 is pretty aggressive for a street engine running a W120. It would be perfect for an FK8, but you want the 120 cam or one very similar (Pat may have a similar cam CB manufactures). 

When you love this stuff, it's really hard to not overthink it. Really, at this point the best thing you can do is just call Pat.

Following the discussion here (just barely), having gone through the process once, it occurs to me that most new folks to the Speedster market have no idea what this is all about and that these are far more important questions to be asking than, "should I get a 1776cc or a 1915?"

The displacement itself means almost nothing compared to the details of how parts are selected, matched to each other, and maybe most importantly, fit together by someone who knows what they're doing.

I'd bet well over half of the engines in the Speedsters on eBay and CL are crate motors that were slammed together without any of this careful matching of parts and fitment being done. It explains why the 'stock' 1915 in my VS had no more power than a friend's well-built, single port 1600.

These dry, technical discussions tend to get lost in the archives, but they're some of the most important research a newbie should be doing before plunking down a great wad of bucks on something bright and shiny.

You are right, Mitch, there is an awful lot to learn if one is (or about to become) a new Speedster owner and hasn't played before with cars of any sort. For someone from the watercooled world (whether V8, ricer, European or???) the learning curve is much shorter, of course (provided they accept the fact that the basics are the same but the details are a world all their own).

One of the basics- "displacement equals power" is true no matter what you drove before. This is a good rule of thumb in any automotive realm and is a large part of the difference between one man's "sunny day drive for ice cream at the beach" mobile and another's "canyon carver". And as to why your friend's 1600 seems to run as well as your old 1915- parts selection being one reason, with gearing, car weight, and driving style (what have I left out?) being some others possibilities. Do you have a parts list of (or do you know) what was in your 1915? Do you know the gearing details of both cars?

I realize that some of these threads are over the heads of some of the guys (and there are those that don't need to know the details, and I get that), but if each time we have 1 of these "technical" discussions the light comes on for someone, then we've done well.

"These dry, technical discussions tend to get lost in the archives, but they're some of the most important research a newbie should be doing before plunking down a great wad of bucks on something bright and shiny."

A newbie doesn't have to understand it all, but asking a lot of questions so he/she has a grasp and can make intelligent decisions goes a long way to becoming a happy Speedster owner! Isn't that what we're here for?

Guys

I love these little chats.  I learn a lot each time.  I am lucky to have a father-in-law who is a certified master mechanic.  He was an avid race car building in his younger days. He will be there to help my son and me along with this build.  I have spend countless hours on Youtube watching guys like VWDarrin and EZGZ building engines.  I am looking forward to fun and challenges. 

Looking at the theoretical  deck height projection chart, an 82mm crank with 94 b pistons and the standard 5.4 rod length would yield a deck height of -.026, meaning the piston would stick out the top of cylinder by .026 inches.  The Panchito's can be optioned with 61cc combustion chamber.

So using the CB Perf calculator to get a compression ratio of say 9 to 1 I would need a deck height of .057. So to achieve that height I need to take .057+.026=.076 spacer. So a 070 or 080 spacer would probably work.  This all assume the theoretical initial deck height is -.026 as per the chart.  I am thinking this correctly?

Also, my father in-law want to put a copper ring between the head and cylinder.  I know there is some debate about that copper ring.  I would also have to take the ring size into consideration when calculating the spacer requirements.  

Good stuff!

@Bobby D,

I'd recommend not getting too far in the weeds here. charts like that assume a lot of things-- your case being properly decked, etc. In the real world, they might be different side to side.

I'd mock up the engine and see where it lands before I got carried away with theoretical shims. Once you mock it up, measure everything and get the shims you need. There are places that can make custom shims to get you exactly where you need to be.

I personally have no beef with copper head gaskets. Some guys love 'em. Some guys hate 'em. They are what they are. If you use them, set up for zero deck with the cylinders. Then use the shim as your actual deck, and go from there.

I'd have no issue with an .060 deck on a mild 9:1 2276. 10 years ago, everybody acted like your pistons would be kissing your heads with an .040 deck. The tighter the deck, the better the "quench" (assuming the heads have quench-pads and no step). The idea is to keep initial combustion in the chamber around the spark-plug.

Good luck.

Sounds right to me, Bobby. I don't believe in the need for copper "head gaskets" eithers; as long as the barrels sit on the case at the same height and the surfaces in the heads are cut properly (the same height and parallel, like the case), the heads will seal to the cylinders, especially in a fairly mild street engine as this. Tell your fatherinlaw that there have been literally millions of VW aircooled engines (a lot of them logged well over 100,000 miles) over the years without, and it worked. Common practice is to lap the tops of the cylinders into the heads with valve grind compound to make sure they will seal. Other than that, nothing special is needed. Al

Al, we are all newbies in something sometime... only advice I have.. KEEP reading... you'll get there.