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Fri Feb 08, 2008 12:20 am

I took a class last semester in manufacturing processes and materials... I love this stuff.

Fri Feb 08, 2008 12:23 am

Well if AS21 will conduct heat better? does this also mean that it would cool faster? If so maybe that's why they used it...bottom line is the two piece arpm case is Stronger & heavier & better...& plus has thru bolts & six shuffle pin's...My bet for a case would be still an AS21 thickwall back for up to 78 atroke & 94 bore...that's my cut off point...One would have to show how much weaker the 41 VS21...my guess is not very...& I would bet it transfers heat better IE COOLS BETTER..,... I know vw list oiltemps as an operational range & if one runs around with a 300F oil you going to have problems do some reading into lube properties of SAE 30wt @ 180 vs190& it's go away by 50% then 190-200 same 50% again & again to 210 & your oil no longer can really do it job plus your clearences & preesure guage would be ..WOW oil light flickers @ idle...this no good...I have done overhauls on such & it's a ugly picture....center main show signs of moving around IE no machine marks left & even when you send to someone whom has good tooling & does real bang up job or redoing your sace better off with fresh one...VW did "aline bore case's till the very early 70's I believe ...they replaced them...when production could keep up with demand ...then they went to "re-man's"...bottom line is the coolong system is can't handle 3 times the orignal HP & stay cool...this why one need aluminium jugs...they cool a whole bunch better...VW had my 25HP per hole & when there's 50 & your using all 50 there's a meltdown comming...extra oil cooler work somewhat but what the head temps? the air fuel mix does more to cool the head than the fan...I would bet if one were to try out those H2O heads & use d nikasil jugs no fan needed @ all...I have seen folks running aftermarket heads on the street with mix feedback as too temp problems ...less reported when using Nikasil jugs...I have also been told that L&N runs to close of Piston cylinder clearence...I'm splitting the difference on my build & going for Thermo coats where possible for my 2.4L type one & hope to see 225hp & last @ 100K miles with pulling the heads...& so it goes

Fri Feb 08, 2008 2:20 am

Does your period stick...? :lol:

All I can say is that I have a high roof aluminum case and have not had any problems.

Fri Feb 08, 2008 3:10 am

bigashlow wrote: ...head temps? the air fuel mix does more to cool the head than the fan...I would bet if one were to try out those H2O heads & use d nikasil jugs no fan needed @ all...

You've got some seriously misguided views about how the cooling system on an air cooled VW works, and I can barely understand what you're typing. You're probably one of those old school cats who likes to run pig rich under load, because you think it will help to cool the heads, aren't you? :roll:

That's exactly the kind of nonsense I've been trying to steer people clear of my entire life, there's no reason for it. As long as ignition is spot on and your carbs/EFI is set up right, you'd be surprized how lean you can run, and still keep your cool with these engines.

What if I was to tell you my turbo 1915 made somewhere around 200hp, has aftermarket heads, iron cylinders, and runs as lean as 17:1 AFR or more? Nothing is impossible, it's all about attention to detail.

Using fuel to cool a combustion chamber is wasted fuel. Period.

Fri Feb 08, 2008 11:15 am

I think he means the cool air entering the cylinder cools the cylinder more than the fan. Which is correct.
I dont rember exactly but I thought that it was 40% thru the exhaust, 30% thru the Fan, 20% thru the oil and 10% from convection.

The AS-21 was probably used because it is more creep resistant. VW was probably trying to rectify the warping problem of the case to reduce line bores. Also Aluminum prices skyrocketed during that period and perhaps they were trying to save money. But AS-21 is difficult to cast well and there are many defects when using it. It flows like oatmeal at the same temperature that AS-41 flows freely. And everyone knows what happens when Magnesium gets too hot. Instant Flashbang. It is probably why they went back to AS-41.

Fri Feb 08, 2008 12:32 pm

I bet you Don't run 17:1 all day long if you do you are full of it! & yes 17:1 when coasting off it, down hill yep OK...Cooling the combustion chamber? the air & fuel mixture rushing into the head DOES COOL MORE THAN THE FAN! ....Example....old 40hp vw with a plugged heat riser on the manifold...Hmmm...what the heck is all that white stuff on the manifold? It's called ICE....I can't tell you how many times I have worked on old stock bug's & done this repair because the car won't run in winter up here in the NW when it's let say 39F & raining...the carb is a ball of ice as well as the manifold...I have even seen it on my 1982 Van just the other day...it was trying to snow out & had just got about 5-6 blocks when the van started losing power & would not idle....open yhe deck lid & Wham'O...carb Ice big time! just a note...FAA sez & proven many times carb ice has killed Pilots @ 70F because of carb iceing!!! & that's the rest of story...Oh by the way I have an LM-1 & Holy crap made my job that much Ezer!

Fri Feb 08, 2008 12:55 pm

I love thermodynamic debates!

Ok, think about this. VW put fins on the outside of the head. They didn't put fins on the intake passages.

Heat transfer is a function of the temperature difference and the surface area. The intake air may be somewhat cooler than the fan air, but only at small throttle openings. At large throttle openings the intake air temperature does not drop appreciably. VW engines tend to have the most heat problems at large throttle openings, so we cannot count on any cooling effect then.

The fin area is much much larger than the surface area of the intake passages.

Thus, the actual heat transfer to the intake air is tiny compared to the heat transfer to the fan air.

Now, you may be thinking of the idea of running super-rich mixtures to "cool with fuel". That is an evaporative process and may actually provide some significant cooling, if you're willing to live with very poor mileage and big emissions.

Fri Feb 08, 2008 3:23 pm

bigashlow wrote: I bet you Don't run 17:1 all day long if you do you are full of it!

Sure do, all day, every day. I don't start to run a slightly rich mixture till around 60-70 Kpa, because then I'm starting to get into the throttle. Full load and on boost I don't run richer than 13:1, because the fuel will just come right out the exhaust (it's not being burned in the combustion chamber, and thus not making power). 13:1 is more than a full point richer than stoichiometric, and there is no evidence of pinging. The cooling system is there to cool the engine. The fuel system is there to provide fuel to the engine, not the other way around. Period.

bigashlow wrote: & yes 17:1 when coasting off it, down hill yep OK...Cooling the combustion chamber? the air & fuel mixture rushing into the head DOES COOL MORE THAN THE FAN!

Wrong again. I cruise at 17:1, sometimes more. Normally this happens at 30-45 Kpa (part throttle), and 3500-4000 RPM on the highway. The highest intake temp I've recorded was a boost run on the freeway-190*F. At that point, I seriously doubt the intake air was doing anything at all to cool the head. If you really think the fan is inefficiet, how about doing a run for me down the freeway without one, and let me know how long your engine lasts? :wink:

bigashlow wrote: ....Example....old 40hp vw with a plugged heat riser on the manifold...Hmmm...what the heck is all that white stuff on the manifold? It's called ICE....

Then you have a carb preheat problem, and you need to fix it. The fact that you get ice on your carb is irrelevant to this subject; Carb ice and cylinder head cooling have NOTHING to do with each other. OK, I'll concede-intake air probably does remove a miniscule amount of heat from the head, but not nearly as much, and not nearly as important as the cooling air provided by the fan.

Fri Feb 08, 2008 10:27 pm

I will say I have no turbo VW aircooled experence..( turbocharged aircooled engines yes).but you also must not be running the EFI with o2 sensor IE (controling the mixture) or maybe just have bung welded in the exhaust system? If your putting a true 50HP per hole your well past maxing the VW stock cooling system , the cooling fan was made to cool an engine making 200HP! hoesepower is heat turbo or no turbo...Say how big is your Intercooler? how many miles have run on this engine? that 190 is your oil temp? how big of extra cooler do have? Bottom line...more HP more heat...no getting around it If your skill's of building engine is that great...better get the patent rights? gas will hit 4plus a gallon after the Nov elections!...give me call & we can talk 360-683 6924 west coast & ask for Eric... this way we both can learn some new tricks? I just wonder why Jake Raby has such good things to say about Nikasil jug when you go to bigHP engines? they work because they transfer heat better? Hmmm....maybe L&N is on to something...I think so I have a set of type I&IV jugs...& 86 cranks for both powerplants

Sat Feb 09, 2008 1:04 am

bigashlow wrote: you also must not be running the EFI with o2 sensor controling the mixture or maybe just have bung welded in the exhaust system?

Correct. I'm still running open loop at this point, as I'm still not completely finished tuning all the areas of my map. It runs very well without O2 feedback, so I imagine it'll be better with.

bigashlow wrote: Say how big is your Intercooler?

Don't have one just yet, that's why my intake temps spike so high on boost runs. Normally, it's within ~50* of ambient, but at 10-12 lbs boost, it gets close to 200*.

bigashlow wrote: If your skill's of building engine is that great...better get the patent rights?

I'm not doing anything magical or original, it's something anyone with the knowhow and motivation can do. The techniques I'm applying to the VW engine have been used on production vehicles for years, it's just that I haven't had the technology in my hands to do it for myself until now.

bigashlow wrote: gas will hit 4plus a gallon after the Nov elections!

Maybe my next engine will be a destroked 1600 with EFI running as lean as possible-I bet I could get some great figures...

bigashlow wrote: ...give me call & we can talk 360-683 6924 west coast & ask for Eric... this way we both can learn some new tricks?

PM me, I'll try to answer any questions you have. :wink:

bigashlow wrote: I just wonder why Jake Raby has such good things to say about Nikasil jug when you go to bigHP engines? they work because they transfer heat better?

Jake is right to use Nickies on high-hp engines, they transfer heat much better than iron. If they weren't so damned expensive, I'd already have a set. According to Jake, once you go over 96mm of bore Nickies are a good asset.

I could go on and on about EFI, but this isn't the right thread.

Sat Feb 09, 2008 7:50 am

Quote: I just wonder why Jake Raby has such good things to say about Nikasil jug when you go to bigHP engines? they work because they transfer heat better?

For the same reasons Porsche has used them for over 4 decades... The aluminum has 4X better thermal conductivity than cast iron. This gets the heat out of the components and into the cooling air stream faster, reducing heat soak.

The Nikisil reduces friction severely which also doesn't create heat that has to be shed. The properties of Nickies TM allow us to run insanely tight piston/ cylinder clearances (less than .001!) as well as unbelievable ring gaps. Both of these things increase power and eliminate the negative aspects of a forged piston in a street engine.

Quote: Hmmm....maybe L&N is on to something
They have been for years. It was 9 years ago when I got a phone call from a couple of guys who wanted to make these cylinders. Today we have used more of the LN cylinders than anyone in the world and have done the majority of the development work and new product testing for LN.

Nickies open doors that conventional iron cylinder keep closed and locked away. The entire engine changes with Nickies and you can't use 30 year old practices to assemble it correctly, to it's max potential and benefit.

Heat soak is the killer of aircooled engines, Nickies have been found to combat this better than any coating, procedure or cooling system available..

No cooling system can do it's job without an engine having proper "cooling capability".

Sat Feb 09, 2008 2:23 pm

Jake Raby wrote:
The properties of Nickies TM allow us to run insanely tight piston/ cylinder clearances (less than .001!) as well as unbelievable ring gaps.

That's not so much because of improved cooling as it is because of similar coefficients of thermal expansion. Aluminum cylinders and aluminum pistons expand at the same rate, so you do not have to allow for the slower rate of expansion of iron cylinders in determining piston clearance. Ring gaps can be virtually zero at room temperature, because the cylinder material will expand more than the ring material.

OTOH, one scratch on the bore sends a nikasil cylinder into the trash can. They are quite tough, but make sure that nothing breaks in there!

Mon Feb 18, 2008 6:59 pm

GeorgeL wrote:

OTOH, one scratch on the bore sends a nikasil cylinder into the trash can. They are quite tough, but make sure that nothing breaks in there!

Or just get them re-plated?

Tue Feb 19, 2008 9:20 am

DiabloBlanco wrote: GeorgeL wrote:

OTOH, one scratch on the bore sends a nikasil cylinder into the trash can. They are quite tough, but make sure that nothing breaks in there!

Or just get them re-plated?

Possibly, if you can find a re-plater that can match the original material. My BMW airhead motorcycle had nikasil cylinders and the dealer mechanic, normally a frugal type, wouldn't use replated cylinders. He said that a fair percentage of the replated cylinders would fail, taking everything else with them. It was cheaper to bite the bullet and buy the $$$ factory nikasil cylinders

Mon Feb 25, 2008 6:40 am

Sorry to change subject a bit but small Q .... earlier in this thread when full flow was mentioned welding was included and i was wondering whether someone could clear this up as i have read abit about the process but not heard welding mentioned before??????????

Sun May 04, 2008 1:33 pm

Well...we make some thermodynamic debates and more. But, for a dayly drive turbocharged (~2l) engine, wich one is the best?!

Sun May 04, 2008 1:34 pm

I had an old mag case- it cracked. Now I have the CB aluminum case, and it's good to go.

Mon May 12, 2008 11:38 pm

VWBrasil stopped the cast of any mag case in the Anchieta plant around 6 years ago. The foundry building was closed down at that time, and they don't have any plans to bring it back operation there.

So any case you get made in Brasil was cast before around 2002, and from stockpiles of OEM who will eventually run of in some time.

Then we'll be left with only one option, the Aluminium cases.

Fri May 16, 2008 7:56 pm

Conjecture, opinion, rumour, BS, refute...repeat...

LOL! No offense intended, there appears to be an awful lot of informed people posting here, but it sure isn't a post that you read to learn anything!

Sat May 17, 2008 1:58 am

bobsmyuncle wrote: Conjecture, opinion, rumour, BS, refute...repeat...

LOL! No offense intended, there appears to be an awful lot of informed people posting here, but it sure isn't a post that you read to learn anything!

Experience is the best teacher as always, but the point of these stickies is so people with no experience can get insight. It's still up to the individual weather they want to take the things we say at face value, or not. There's good things about both cases, it's really a toss up if you ask me.