Questions on CB CNC Heads on street motors driven long range...

[Taylor]

Wait, was this a rhetorical question?

[Udo]

wow.. Totaly forgot the main question on the thread! ( and a interesting one!)
Abaut the heads, mine's JPM 230 4" ( more precise, machined for 102mm. JE pistons)
Who I think are superior in cooling, compared to some aftermarket raceheads,
say sf, ce, angle flo, or 910, and so on.
But not as cool running as a pair of 044!! (And that was the hole point)

magic

Another question - If you have those heads on the street and 102 bore. How much air can get through the heads and cylinders ? What i mean is , how much power does your fan need when the air can not get out of the fan housing and how is the cooling under the heads and cylinders ?

Udo

[rick m]

UDO,

Great question.  When building these big motors stock tin fit is something to look at.  Keep in mind the tin was designed to go around an 85.5 barrel.  Does anyone look at the air gap around an 85.5 and they try to maintain that same gap around a 94mm barrel?  I bet it is something not to many look at.

Rick M

[Udo]

Because of this i only build street engines with max. 90,5 and heads that have some holes for air getting through the heads . When crusing it will work with other parts , but in germany you can go fast on the street . The head temperature goes up very fast when driving uphill with higher rpm's . this is what we found out 20 years ago 
When you drive slowly it does not make that much temperature
Also i found out that 94 bore makes more heat in the heads and the oiltemperature gets up .
Udo

[magic]

Hey Bruce,

No you're not!   I'm driving a 2,7l type 1.  What is "big distance"? In the summer months I'm  often on 100, 200, 300kms. trip and at least once a year it's a 1000kms. one.

While that is a pretty big engine, those are all short trips.
Get your map out and locate Vancouver Canada.  Then locate Cancun Mexico.  Round trip is about 14,000km.  I think that trip was either 6 or 8 weeks.  On my last trip, I drove the Pacific coast highway to Acapulco, then back through Mexico City.  Elevations top 3500m, and temps approach 40ºC.
I usually watch the oil gauge and slow down when it gets to 230ºF (110ºC)
Oh ya, I forgot about Jim.  I bet he drives his car more than anyone else in the club.    

Hey Bruce / Rick M.  

WOHOW...... You win this one for sure!!!!  
14000km....40*c....1000miles one direction...3500m elevations... WOW

(1)
Those trips you describe, they are taken straight aut of my dreams!!!
I really hope that I, just once in my life, get the opportunity/money for the classic roadtrip across the USA!!!!  But.. It will not be in a rented car, that's for sure!
It will be in a Beetle or an early Porsche!!! ( And the dream in a dream) :End the trip by shipping it home!!!

(2)
I don't think I will make that journy with an engine like the one I have right now!!!  
And now we're talking about dreams... No, I will begin another thread about dreams.........

Regards. Magic.

[magic]

Hello Udo!

You're right! I've spent a great deal of time on the "tin"... There's no original oilcooler on a 2,7L type 1, as you're completely through the oilgallery between cyl. 3 and 4. So I had the opportunity to put extra air deflectors??? in the fan-shroud where the cooler used to be. I'm also using the original side-reflectors. They are modified to fit. Of course I also use the middle air deflector under the cyl. I have modified the fanshroud and cyl. shroud so there are no "leaks" at all!.... 
Sorry for my poor tech English!!

 Cheers. Magic

[magic]

UDO,

Great question.  When building these big motors stock tin fit is something to look at.  Keep in mind the tin was designed to go around an 85.5 barrel.  Does anyone look at the air gap around an 85.5 and they try to maintain that same gap around a 94mm barrel?  I bet it is something not to many look at.

Rick M

Hi again Rick M

I have had the same thoughts about the stock tin and 85.5 vs. 102mm barrel and yes, the gab is nearly non-exist on the 102 combo...
So here is my question for you all: Does the forced "extra" volume of air between the finn's(??    ).... equal the lack of air above them?

Regards Magic

[rick m]

Magic....In my opinion...NO.  The factory designed the motor to circulate air around the cylinders.  I took a lot of time when doing my tin work to ensure it has flow similar to what the factory created on the stock 1600.  UDO is right about the 94 and larger bores.  They do put more heat in the motor...but you can cool them if you get the air flow right. 

[magic]

wow.. Totaly forgot the main question on the thread! ( and a interesting one!)
Abaut the heads, mine's JPM 230 4" ( more precise, machined for 102mm. JE pistons)
Who I think are superior in cooling, compared to some aftermarket raceheads,
say sf, ce, angle flo, or 910, and so on.
But not as cool running as a pair of 044!! (And that was the hole point)

magic

Another question - If you have those heads on the street and 102 bore. How much air can get through the heads and cylinders ? What i mean is , how much power does your fan need when the air can not get out of the fan housing and how is the cooling under the heads and cylinders ?

Hey Udo

There is a gap of aprox. 3mm. between the cyl. walls.
I'm constantly improving on the engine, and for this season I will make small holes in the heads. Including the space between the intakeports and combustion-chamber and valvetrine-chamber,
with a mini deflector underneath, like the original.
Fortunately the JPM heads are designed so it may be done, even on the 4" heads!! I know it's close, but it can just be done!
It's not much, but little is better than nothing... and if you have a lot of "them" it ads op...

Regards. Magic

[magic]

sorry! double post....

[magic]

hmm ... it's all a bit new to me! Can not delete my post ... sorry 

[magic]

Hi Rick M

 You and Udo are right about the big bore and heat. It is pure mathematics. Since a large circle has eksproportiornalt more surface than a small one. and in this case, therefore, more surface to transfer heat. This also applies to the cylinder heads. and of course the cyllinders and pistons! It's the physics all who will go for big bores must fight against. So once you've decided on a big engine, there's nothing else to do than to find ALL the small and big things that can help you the other way, toward the cold ... . And then, my intuition tells me that I need to restrickt the airflow around the outsides of cyl.walls, to force more air flow in between them. in light of the lack of flow option with cyl. sit so close. And a street engine MUST have air all the way around!
 Anyway, I have nothing but intuition and ideas to back up my theories .... So I think it would be cool if anyone knows anything about this, or just has ideeres. let us know! as I said, "it's all the little details that count when they are put together.

 regards Magic

 P.S. I think I'll abduct this post to start a thread more specific about people's experiences with heat problems and solutions at 4 "engines. it's ok with you Rick M?

[Phil West]

Am I the only one who drives a VW big distances with a big motor?

Rick, my heads are the CB castings with the thick intake flanges.

I think the biggest reason they're reliable is all the extra mass everywhere, especially around the chambers.  Sure they have slightly less cooling fin area, but I think the mass helps offset this.

You can improve them.  Make sure you port the cooling fins.  Use your cutoff wheel to clean up the casting flash between the fins, beside the exh ports.  I also used lots of drills around the exh port.  I don't specifically remember about the area between the intakes, but if there's room, I drilled holes.
Another improvement you can make is to make a plate to go on the underside of the fins between the two cylinders.  Factory heads have a small steel piece there.  The CB heads have nothing.  This piece forces the cooling air that passes between the chambers to continue through the fins before dumping out.
On long trips in hot weather, I use a reinforced 36hp lower pulley to speed up the fan.

Although I don't have a head temp gauge, the highest I've seen the oil get is 260ºF, but that was a long time ago, and I don't go near that range anymore.

The worst I've subjected this engine was about 7-8 years ago, while in the Sonoran desert.  I held it at around 115 mph for 15 min.  I'm sure the heads got pretty hot then.....

Currently there's 70k miles on the engine.

I see what you mean about the flashing.  I'm doing a pair of 044 roundports at the moment.  Here's some photos of the flashing - air flow holes seem a bit poor on these heads.  I've taken some shots of some old 311 heads - no flashing cleaned out.  Certainly the old VW heads seem better.

[Phil West]

Here's the 311 between the chambers, the 044 with the plate added, the 044 inlet (no hole) vs the 311 inlet

[Phil West]

And the 044 above the exhaust port (no holes) vs the 311 (4 holes).

I've drilled out existing holes a bit - has anyone been brave enough to cut through the inlet as in the vw heads.  Any pics?

I need to get a long reach thin grinder to clean out the flashing between the chambers a bit more.  Every little helps I suppose.

Cheers

[rick m]

All of this cleaning out the flashing helps. The VW engineers put air flow passages there for a reason. As with all aftermarket parts,  production volume and just turning parts is more important than the engineering aspects.  I see this in my Industry, non-VW related, where copycat parts are made and no one follows tolerances and critical issues.  They just want to get the parts out there to turn a profit.  That is all ok providing they are building something that meets original factory specifications or parts specifications.

The bottom line is that more care must be taken when assembling a modified motor and all issues, oiling, cooling, tolerances, product quality, etc., must be checked. This is what I appreciated about the BERGS approach over the years.  They have never assumed that the parts they receive are made correctly.  They do a quality check on cases, heads, etc., to ensure what they are helping you build your project around is correct.

Anything you can do to ensure proper flow around the heads and cylinders will help things work properly.

RM

[Phil West]

Success!  After a careful measure up I've drillled a 6mm hole between the inlets.  As you say, it all helps.

[Zach Gomulka]

Mount up your cylinder head tins. The hole pictured above is directly under the spark plug deflector, you know the upside down "V" that guides cooling air to the plugs.

Now, please tell me how that hole does any good at all.

[rick m]

Hmmmmmmmmmmmm.....good question.

RM

[Bruce]

Maybe not enough to measure, but it can't hurt.
I'd drill it bigger.

[Udo]

It is not only the holes in the heads , the bore itself heats up the engine. 94 makes more heat in the chamber than 90,5. what does 101 do ?
 It is also a different when only cruising or go on a german autobahn with higher rpm's

Udo

[Phil West]

Mount up your cylinder head tins. The hole pictured above is directly under the spark plug deflector, you know the upside down "V" that guides cooling air to the plugs.

Now, please tell me how that hole does any good at all.

Hi Zach,

I just got some original head tins and mounted them to three sets of heads - original VW 311 heads, some 043's and the 044's.  On all three mountings there are some air gaps to provide air flow from the fan to this hole.  Even without any gaps the air would still flow over the v plate and then over and in to the inlet tops as a secondary flow.  It's difficult to describe where the gaps are - basically to the sides of the v cowling and a bit between the v and the side of the head.  It does seem that the V deflector may not be specifially designed to just funnel air through the hole - however it could have been an afterthought in VW design.  Either way there's definitely air going through the hole whent he fan is operating.  It would be interesting to ask the original VW engineers if they had any purpose for that hole when they made it in their dual port heads.

[Bruce]

Now, please tell me how that hole does any good at all.

.... and it makes the heads lighter.  So there!

[andy198712]

i found the same with my CB 044's horrible quality control. sat theme side by side with my spare V heads too and its a kick in the face lol

is anyone tempted to drill the fins in the heads? providing the hole is the correct size and actually increases area....?

[Zach Gomulka]

Now, please tell me how that hole does any good at all.

.... and it makes the heads lighter.  So there!

[Bruce]

is anyone tempted to drill the fins in the heads? providing the hole is the correct size and actually increases area....?

While it does increase the area, it also reduces the heat sink mass without increasing the air flow.  All the work Phil has done has increased the air flow substantially, with an insignificant reduction in mass.
Holes in the fins are heat flow blockers.  The heat within the Al has to conduct around the hole, so the tips of the fins won't be able to reject as much heat.

[andy198712]

is anyone tempted to drill the fins in the heads? providing the hole is the correct size and actually increases area....?

While it does increase the area, it also reduces the heat sink mass without increasing the air flow.  All the work Phil has done has increased the air flow substantially, with an insignificant reduction in mass.
Holes in the fins are heat flow blockers.  The heat within the Al has to conduct around the hole, so the tips of the fins won't be able to reject as much heat.

good point, i was working on if the holes were smaller in dia then the fin was thick it would increase surface area.
maybe putting lots of semi circle grooves around the outside would help.... maybe its really not worth the hassle

[Fasterbrit]

Anyone tested a cylinder head coated in a flat black paint for temp drop? Needs to be a non-Ceramic type paint, though...
A flat-black surface area dissipates heat better than a bare metal. A polished metal surface dissipates heat less than a matt metal surface (ie beadblasted). In the past I have beadblasted and flat blacked VW heads with good success. They need to be beadblasted in order for the paint to key properly.
Interestingly, the Jpm heads I am working on at the mo are coated flat black. Johannes is always On the ball 

[Phil West]

Anyone tested a cylinder head coated in a flat black paint for temp drop? Needs to be a non-Ceramic type paint, though...
A flat-black surface area dissipates heat better than a bare metal. A polished metal surface dissipates heat less than a matt metal surface (ie beadblasted). In the past I have beadblasted and flat blacked VW heads with good success. They need to be beadblasted in order for the paint to key properly.
Interestingly, the Jpm heads I am working on at the mo are coated flat black. Johannes is always On the ball 

Interesting Matt.  Also applies to rocker covers and pushrod tubes.  I'm planning on blasting Scat polished stainless Scat rocker covers at least on the inside, and paint black on the outside.  Ideally I suppose pushrod tubes should be black inside and out too.  I think over time any black paint may start to come off the inner surfaces and mix with the oil so best left unpainted there.  Cheers

[Fasterbrit]

Hi  Phil. You will need to blast the outsides of the stainless covers, too. They will need a good 'etch' otherwise the paint will flake off for sure 
Cheers, Matt