TheSamba.com :: View topic

Thu Oct 10, 2013 1:36 pm

I think I will make this a topic of its own

Trying to find this data in one place is frustrating when deciding what heads to use for a specific build or if heads have been modified significantly from as cast form.

Combustion chamber volume is ACTUAL chamber cc not including step volume if present. Step height is measurement is in the adjacent column with total advertised combustion volume listed under the miscellaneous column.

Retail listing is for TWO cylinder heads at current market prices as of Jan 2014

If product manufacturers/distributors have more accurate/updated data please let me know and I will update the listing immediately. Any new products will also be gladly added as they become available.

edit: updated sheet
edit: updated again
edit: still updating
edit: did I mention update?
edit: newb clarification
edit: update some more

Thu Oct 10, 2013 4:33 pm

It would be useful to have the available valve sizes in a separate column, as some CB heads are available in different combos
the JPM230 valve size is 48/38. no step
CB street elim 42/37.5, 44/37.5, 46/38 no step

the chart is a great idea :D

Thu Oct 10, 2013 7:34 pm

It would be also handy to add other shops specs too such as DRD's L3,5,6,7 etc

Fri Oct 11, 2013 12:02 am

Hmm, interesting - but you show the Los Panchitos as not having a step and the guys who have bought them say they do, even if bored to a larger cylinder size?

Fri Oct 11, 2013 6:13 am

Mofoco 042's have a step. Roy told me that the step is about .060" high and that on a head bored for 90.5/92 mm cylinders the 53cc volume includes the step. I haven't done the math but he said removing it would leave a chamber volume of about 43cc.

Fri Oct 11, 2013 9:18 am

Quokka42 wrote: Hmm, interesting - but you show the Los Panchitos as not having a step and the guys who have bought them say they do, even if bored to a larger cylinder size?

I know they have a step but couldnt find any measurements other than whats listed at the site. Since they are based on the 043 I will measure the chamber vs step and update the listing.

As for the Mofoco step, Ive read several recent posts that state .050 but if Roy wants to correct that Ill update as well.

Anyone have port volume numbers for the DRD L3-7?

Sat Oct 12, 2013 5:39 am

Excellent information, and nice to see it coming together in one place. The trouble is, there are a lot of information holes that really need to be filled to make this super useful. This is a nice starting point for guys with the appropriate equipment to help fill in the blanks.

If somebody had a flow-bench, and could post observed (as opposed to reported) numbers at .5" of lift and 25" vacuum, as well as accurate cc measurements of the intakes and chambers, we wouldn't all stumble around in the dark when trying to put together combinations.

The same applies to camshafts. If somebody had a profiler and could digitize the various popular grinds, the combination of real flow data and real cam profiles would allow desk-top dyno simulations with real numbers.

We tend to worship in "air-cooled orthodox" chapels of one stripe or another, and there are guys that have observed a lot over many years of screwing engines together. But building combinations and trying them to see how they work is a hideously expensive way to experiment, and it's what keeps guys from coloring outside the lines. As software gets better and better, at least the first stages of experimentation can occur in the digital (as opposed to physical) world and weed out the combinations that look promising, but are fatally flawed in some way.

This is a fantastic step in the right direction. I appreciate the time and effort to share with the class.

Sat Oct 12, 2013 11:47 am

58 Plastic Tub wrote: The trouble is, there are a lot of information holes that really need to be filled to make this super useful

I agree. Since there are only a few manufacturers of cylinder heads out there I wanted to put together a base line list so you could at least see what you should be able to expect "out of the box". There are vendors that improve on the base casting and actually post numbers on what was done which is helpful in trying to compare products.

Does anyone know what lift the CB numbers are at? Ive heard .650 but not sure and have not heard back from CB.

I was adding the DRD heads and noticed his numbers are done at 28" rather than 25" most VW heads are measured at. DRD also list the as cast 049 at 138@ .500 28" [email protected] 28" which converts to [email protected] 25" [email protected] 25". Wondering why he stopped testing at .500, the CE flow sheet went all the way to .600 and got intake [email protected] 25” exhaust [email protected] 25”. The difference in flow bench data really seems to confuse the issue even more.

The same problem is with the Bill Fisher How to Hot Rod book. It lists flow numbers for both the single port and dual port head with various modifications done to show what works or doesnt work. Unfortunately they dont give ANY readings but show some pretty high numbers for stock ports. Single ports were Intake [email protected] Exhaust [email protected], Dual ports were Intake [email protected] [email protected]. Anyone know the depression readings that were used back in the day?

I was originally not going to put flow numbers and just list port cc but since I was able to find some data on stock heads I thought it would be nice to compare and then got carried away. Ideally I would love to have flow readings for all heads at .300, .400, .500, .600 so the typical street guy can make a good decision on what they need. Since not many street cars are running more than .600 lift numbers above that would not be useful.

Sat Oct 12, 2013 2:21 pm

AlteWagen wrote: Does anyone know what lift the CB numbers are at? Ive heard .650 but not sure and have not heard back from CB.

From CB's website:

Super Mag: 140 cfm @ .5" @ 25"
Ultra Mag Plus: 165 cfm @ .5" @ 25"
Super Pro: 203 cfm @ .5" @ 25"
Mini Wedge: 182 cfm @ .5" @ 25"
Wedge Port: 197 cfm @ .5" @ 25"
Ultra Wedge: 208 cfm @ .5 @ 25"

Street Eliminator, all intake sizes: 193.5@ 25" (lift unknown)
Competition Eliminator, 48 mm intake: 219 cfm @ .5" @ 25"

There's good information for all the heads except Los Panchitos, and the Street Eliminators. The heads with various valve-sizes available have the flow information listed for the biggest valve size.

Sat Oct 12, 2013 2:40 pm

thats great info, i will update the table with that as it seems more standard and easier to compare. The data I had came from their ad in HVW so maybe the higher numbers were at higher lift.

The info on the panchito was directly from Pat Downs in one of the threads here. I still wish I could find the actual chamber and step measurement separate not combined as published.

Sat Oct 12, 2013 3:01 pm

Assume a .055 step of stock bore size and do the math, it won't be far off.

The super-pro heads sure ought to be killer eh? They look to make the mini-wedge obsolete! Man, I want some!

But what if you want a high velocity 60-65cc intake port to make big torque for a smaller CC engine???? many aftermarket heads are too big already! :x

Sat Oct 12, 2013 3:14 pm

Im waiting for RM to respond with the port cc of an as cast head, the only problem is they dont have stock sized valves. Since it looks just like the old 041 Im guessing 59-61cc.

On a smaller engine (1679-1835) is there any downside to having 40x35 with no port work and an as cast 60cc port? To me the 049 in stock form looks to be the same as the ponchito

Sat Oct 12, 2013 3:36 pm

Depends. If single carb then it's not too big a deal to have a too big port, since the port is a much smaller section of the "intake system"
With IR carbs the port is very important!

The panchito could support a 1600cc to north of 7k rpm! if the port is bigger than needed all you get is less torque, that's all you get, less! :shock:

Sat Oct 12, 2013 4:19 pm

Application wise what would you want for a performance street engine?

1679-1835
110-120 cam
8-9.5 to 1 compression
1 1/2 header
36 or 40 IR carbs

60cc port 35x32
60cc port 40x35

Sat Oct 12, 2013 8:53 pm

Some of the different castings have a little different port shape so the intake CC isn't exactly comparable, for instance the 040 and 041 have a HIGHER port compared to 311, 113, 043, if you compare them.

since this thread is about head castings I will say 043 or 113 or 311, maybe 311 mexicans.

Modified by someone who knows what they are doing, which is a point we don't always agree on, so maybe we open a new thread for that :wink:

Larger intake valves may be a good idea but only in moderation and probably only with larger bore, and depending on lift..... the 120 and 110 are medium lift; you could go either way

Sat Oct 12, 2013 9:18 pm

modok wrote: The super-pro heads sure ought to be killer eh? They look to make the mini-wedge obsolete! Man, I want some!

Yeah. The numbers really look almost too good to be true.

I also agree with you that there'd be a good market for a head with flow numbers in the 160- 180 cfm range (@ .5" lift and 25"), and really modest intake port volume. I'd love to see some real flow number for the Los Panchitos heads, as they seem to fit the bill in both regards.

Sat Oct 12, 2013 11:27 pm

updated chart above

Mon Oct 14, 2013 10:19 am

You need to update the original chart in the first post of this thread.

Wed Oct 23, 2013 9:02 am

A great idea to make a VW cylinder head flow chart. I can help fill in some of the blanks on the chart.

The Fisher book on "How to Hot Rod the VW" lists the head flow numbers for single port and dual port 1600 VW heads but does not have the test pressures. I have a Super Flow bench and I tried all kinds of test pressures to duplicate the figures in the book and failed to match them. They all seem to be too high but the modifications they did all pretty much checked out as far as the gains and losses went. Even lowering the valve seats the large amount recommended by the book worked really well.

Here are some of the flow numbers for the vintage style heads.

Bvilletom (Tom Bruch)

Wed Oct 23, 2013 10:44 am

THANK YOU SOOOOO MUCH!!!!!

By any chance did you save any of the data on the 1500/1600 SP/DP heads? I would love just to have the stock data so everyone knows what they have as a base line.

If not would you mind doing some more flow testing?