How to keep your VW engine cool

[Phil West]

Hi all,

I know we've had a few threads partly touching on this but I thought I'd start a new dedicated one (Matt K's idea!).

I use my split van to tow the bug long distance and have gone to fairly extreme measures to keep her cool.  I list below what I've done so far - rather embarrasingly Matt showed me I had not even considered the holes in the tins by the spark plugs.  Therefore there's bound to be other things i am missing.  All of this will also apply to street type 1s.

1967 split van with 1956cc type 1 engine on 1303 box, IRS.  Towing - bug 600kg trailer 400kg total 1 tonne.
Van load 2 adults and shed loads of stuff, pretty much packed to the hilt.  I'm guessing the van weight will be around 2 tonnes.  So total weight for the engine to move is 3,000 KG.  A huge strain to put on it!

First I'm sure the easiest thing to do would be to use a modern engine but I'd rather use the type 1, much more fun with tuning and upkeep and I understand it better if something goes wrong.

Journey time - between 4 and 7 hours towing (156 miles).  Can keep it at 58mph but there's always horrendous traffic - accidents/roadworks/idiots that can't drive/rubberneckers.  Don't get me started there.

Also there's a 30 mile long hill coming off the Motorway which is a real killer on the engine.

So - I cut 8 large circles in the decklid behind the numberplate to move air out of the engine bay.  Then I got a big air scoop and 3" pipe under the rear jacking point that feeds directly behind the colling fan.  Had to cut a hole in the bellhousing tinware for some 2" pipe to go through.  the pipe runs smaller so I get a nice velocity on the air coming in.  So at mph the cold air is flying into the fan.

I added the aluminium finning to the Fram HP1, a sandwich plate with takeoff to a 96 plate MESA cooler with 8 inch fan (switch controlled on the dash).  The cooler is under the floor just forward of where the rear seat in the van is.  -8 oil lines throughout.

Then i cut a hole through the floor inside the van.  Got another big air scoop and fitted it to the rear fresh air vent behind the driver and another 3 inch pipe running from this through the floor directly into the fan above the oil cooler - at 60 the air flow is incredible - there is SO much really cold air going straight into that fan.

I removed the engine and replaced all the tinware.  Spent several weekends on every join, making the absolute best fit for every piece.  Example the breast plate - where the Berg 90 degree fitting comes out the case at the top of the breast plate - I cut the hole in the tin so it fit perfectly around that 90 degree fitting - maybe 1mm gap around the outside.  Then I bent the rear engine tin down - I hate that big gap you get at the bottom of the join to the breastplate - under the pulley where the oil drips collect - lots of hot air must come up there.

Then I wrapped the exhuast header in Thermotec generation II copper coated wrap - used massses of it to ensure a really thick and perfect wrap.  Per instructions I left unwrapped the merged bit just before the exhaust (supposed to for towing).

Then I removed the heat exchangers and replaced with ceramic j-tubes.  Note the exhaust is a single quiet pack (ceramic) and the header is stainless - but only 1.5 inch.  My towbar is a custom fit and won't allow anything bigger - this may be a problem for heat but the revs are so low I'm not sure it has problems flowing required gases out.

I've tuned the motor (with twin Dell 40s) to 13.7 a/f using the LM-1 at 58pmh constant to keep it a bit richer and cooler.  Motor is fairly new, well built (we built it with towing in mind so torque at lower revs) and in great maintained condition, timing 28, valves 2 thousandths well adjusted.  All the jetting/idle/idle mixtures/linkage are adjusted great.  Carbs balanced for all four stacks.

Stock oil cooler in the fanshroud.  Berg deep sump.  Kendall GT-1 oil - level halfway between the lower and upper oil marks on the dipstick.  Regular oil changes, plus HP1 changes.  No oil leaks of any note.  Thermostat working and present.  Bosch 009 with Pertronix II ignitor and blue coil.  Breather box connected to the rockers and oil filler.  Cooling flaps present and working.

Tows at 180F/82C with fan on at 60F on the level at 58mph.  BUT up a 30 mile hill in 85F it's 215/102 at least.  Plus I'd like to tow at just over 60 rather than below.

A word on oil temp - I use a new Autometer gauge, the sender is from the blockoff plate next to the oil pump - this I think is the hottest part of the oil in the engine which is what i want to see, not for example in the top of the Fram which will be much coooler.  i'm thinking the perfect oil temp is 180F/82C i.e. oil does the very best job at that temp.  So I always want to see 180 on the gauge.  Any hotter and I know I am shortening the life of the motor and I want it to last and last!  Only 3000 miles covered

Matt pointed out about the spark plug holes - I use aftermarket leads, they are always missing the round rubber grommets to seal the tins, apparently this makes a fair amount of difference.  So what else have I not considered.  I've replaced all the seals on the engine, no visible gaps all round betweene engine tin and body/trans.

Example - the fuel tank is in the engine bay.  So - the fuel is heating up, producing less power and making the engine work harder so hotter oil.  Perhaps i should try to shield the tank in some way.  Or perhaps shield the fuel lines that run to each carb.

Another - the 40 Dells are air hungry.  Maybe I should enlarge the vents in the side of the van (big sin!) so the carbs don't rob cooling air in the engine bay.

Another - perhaps a smaller pulley as I only rev to 3000 to make the fan spin faster.

Even with genuine tinware, it still fits terribly on an aftermarket engine - example where the oil filler downtube goes, there's always a big hole there which is never round because of the other tin joining there, I've rounded it out and put a grommet there but it still doesn't fit great.  Also I've got small gaps between the fanshround and the cylinder tins in places, say 1 to 2mm.

Anyway has anyone else come up with more innovate solutions to keeping their type 1 motor cool.  I would put in another air feeder pipe to the fan but there's so little room up there it would be a nightmare.  The first hose was bad enough to fit.

I'd love to go for more stroke but insurance and fuel costs here are ridiculous so make it prohibitive for me.  Also a 76mm stroke means there is 1mm on either side of the engine clearance, it's the biggest you can get in without cutting the engine bay.

I'm applying the same principles to my '61 bug as I want to drive it on the street more - that runs a lot hotter so even more important.

Cheers
Phil

[67worshipper]

would a porsche fan conversion let in more cooling air? when you say smaller pulley would that be a power pulley of old?

[Phil West]

would a porsche fan conversion let in more cooling air? when you say smaller pulley would that be a power pulley of old?

Actually I don't know if the porsche fan produces more volume of air, but yes I'm thinking power pulley

[Martin]

on the trouble cab, granted its not towing i used the following combination.

2276, 10.5:1 48 throttle bodies dta efi. 86b cam wedge port heads, 32 degs total timing, this combination pulled 186 hp on my dyno, and 192 ft lb. it pulled like a train from 3000 rpm.

to keep it  cool, i dispenced with the strandard oil cooler and fitted the largest oil cooler with a fan, you can get from vwspeed shop (other shops sell them also).

Standard tinware, standard size pullies. even loaded up in 5th gear on the motorways it never got hot.

from my own experiance, i find that you have to have the following....


1) good tinware fit
2) fan shroud with the correct vains in it
3) the inlet of the fan needs to be a close as posible to the shroud to larger gap and you can knock over 10% of the fans efficiancy right off. (fans used to be my game)
4) a bloody good oil cooling system.
5) tinware to body needs to be sealed.


if you get the above right then you dont have to put extra ducting or drill extra hols. VW did a great job when they designed the cooling system.

that my thought on it.

Ta

off to the Dyno now, see ya

[Martin]

would a porsche fan conversion let in more cooling air? when you say smaller pulley would that be a power pulley of old?

Actually I don't know if the porsche fan produces more volume of air, but yes I'm thinking power pulley

smaller pully on the crank will make the fan spin slower!

[Phil West]

3) the inlet of the fan needs to be a close as posible to the shroud to larger gap and you can knock over 10% of the fans efficiancy right off. (fans used to be my game)

I have not checked point 3.  So if I'm reading this right I need to get my hand behind the fanshroud and have a good feel as to where the back edge of the fan itself is in relation to the back edge of the hole in the shroud that the fan sits in.  If it's over say 1 to 2mm I will try to adjust it out.

Cheers.  And let me know what numbers you pull!

[Martin]

3) the inlet of the fan needs to be a close as posible to the shroud to larger gap and you can knock over 10% of the fans efficiancy right off. (fans used to be my game)

I have not checked point 3.  So if I'm reading this right I need to get my hand behind the fanshroud and have a good feel as to where the back edge of the fan itself is in relation to the back edge of the hole in the shroud that the fan sits in.  If it's over say 1 to 2mm I will try to adjust it out.

Cheers.  And let me know what numbers you pull!

yeah get the fan as close as posible

I'll let you know what it makes........ .gulp

[Phil West]

if you get the above right then you dont have to put extra ducting or drill extra hols. VW did a great job when they designed the cooling system.

And also let's be fair VW never designed their cooling system to work perfectly for towing big heavy loads for many hours or for 200 horse engines etc.

[71CALRIPPER]

Porsche fans often offer to much cooling and dont let the motor warm up etc, the DTM however has been tested and retested and i would recomend one, $450 its not much to ask for a good cooling system.

Rob

[Phil West]

Sorry I'm not familiar with DTM.  Can you give a bit more detail for what that is, cheers

[Jon]

On my Superflow engine I was worried about the cooling. I then decided to get rid of the oil cooler in the fan housing and go for a big Setrab cooler sitting vertically just in front of the left side drive shaft. This may seem very stupid, but the reason is that i wanted the widest fan (from a 1600 w. doghouse) inside a non dog house 36 housing. Then the full width of the fan would be used only for cooling the cyls/heads. It was a tight squeeze but with some persuasion it fitted in there. That engine ran cool with 10.5:1 CR... without the rear tin. A big contributer to this was the thermo tech I suspect. Foam air cleaners (KN( on the IDA's raiced the oil temp with 15°C!! So they cam off!
This was in a full weight type 1 at freeway speeds and above...         

[71CALRIPPER]

http://www.aircooledtechnology.com/cooling/index2.shtml

I trust Jakes results on his testing

[javabug]

Perhaps step up to a vacuum-advance distributor instead of the 009.  Lots of buzz around the Mallory Unilite with vacuum, including reports of reduced temps.  They seem to be very "tunable" for dialing the advance in.  I believe the Dells have easy provisions for a vacuum port.

*I don't have direct experience with this yet, so it is just repeated info.*

[Bruce]

Perhaps step up to a vacuum-advance distributor instead of the 009.  Lots of buzz around the Mallory Unilite with vacuum, including reports of reduced temps. 

I saw no improvement in temps when I switched to a vacuum/mechanical dist.  I don't see any reason why you would expect lower temps.  In Phil's Bus, he would see no benefits to a vacuum dist since it will be running at full load almost all the time.  In a light Beetle, you do get better mileage.

When you are setting your fan closer to the shroud, keep in mind that there are 2 thicknesses of pulley shims.  ½ and ¼mm.  Keep sinking the fan deeper into the shroud until you get contact, then back it up by the ¼mm shim.  If you have an aftermarket shroud, you are doomed.  The opening is not square to the alternator by about 4-5 mm.  Maybe you could "adjust" it with a BFH.

[javabug]

I saw no improvement in temps when I switched to a vacuum/mechanical dist.  I don't see any reason why you would expect lower temps. 

Glad I put a disclaimer at the bottom!

[Jim Ratto]

I think the VW stuff works well on big engines, but yeah, you need a GOOD oil cooling system.
Just dual springs alone are going to raise oil temps above the "normal" VW level. Somehow that extra heat needs to be shed.
Volkswagen motors are air AND oil cooled.

I don't think the Type 4 cooler adapted to the Bug shroud is going to do much. The Bug '71- fan is only going to move so much air, and I would think we'd want to send as much of it as VW originally wanted to go to heads. Opening up the duct for a bigger cooler (dependent on engine fan) is going to reduce restriction there, and send less to heads. So that is the reason I think bigger cc, high hp engines need a good cooler.
Need convincing? Even with the output of the famed "911 fan" on the flat-6, Porsche still felt the hike in horsepower of the 1969 "S" mfi car required an oil cooler (added to engine mount cooler) placed in RH front fender well.
Part of the reason the 911 (and the 4 cam Carrera) motor went to a large oil tank, independent of the engine case, was yes, to allow engine to sit lower in the chassis ( lower center of gravity), and yes to allow an uninteruppted supply of oil to engine despite high g forces, but also to allow for a very large volume of oil, since the engines were about 40% oil cooled. Had Volkswagen planned on increasing output of the Type 1 to 85hp per liter + (obviously through increased rpm as HP is a product of rpm) it would have been ridiculous... no more economy car! But I am sure, through the typical Teutonic thoroughness, VW "would have" engineered the Type 1 to hold more oil, and would have created some type of auxillary oil cooler fed with a blast of cold air. Again, the goal of the Bug was a cheap, light, dependable, easy to mass-produce car for the masses, and its cooling system was engineered as such. A very cheap, yet tough little car, but sorely underpowered, which made it all the more tougher under demanding conditions. If you would have gone to your VW dealer in 1965 and peeked under the fender and saw woven AN-8 or AN-10 hoses running to some Behr cooler, you wouldn't have bought the car. You would have walked over to a 912 or 356 and laid your money down there.
My point is, we crank up these little motors to make mind blowing amounts of power (ok maybe less) but then we have to expect the cooling system that worked for 53hp to cool 153hp. Might work.....  but again, these motors are air AND oil cooled.
Not so hard to improve the "oil" cooling system......  maybe a meter or two of oil lines, some good AN fittings and a cooler. Oh and some spare time to screw all the stuff to the car.

[Jim Ratto]

Re-read your post again B.W.   coupla more thoughts....

I think you need to fatten your fuel curve up. For a VW 13.7 is a little lean. I'd shoot for high 12's.

Yes your plug holes need to be rubber-ed up. Imagine cutting a similar size hole in the tops of your cylinder shrouds (in front of and behind fan housing.... you'd SEE those and you'd be worried. We don't see the plug holes, so we tend to negate the effect of them being wide open.)

A lot of work into your vehicle, and thought too! Fatten it up and seal those holes...   

[Fasterbrit]

With the price of fuel now over 10 Bucks a gallon in the UK, I bet Phil wont be too happy to richen up his A/F. Bear in mind his RPM and 13.7 isn't too scary. I run even leaner than that on my 1776 cc Bus motor on a cruise with no signs of pinking or det and cool oil temps. However, the 2276 I am in the process of building will have to be on the money A/F wise.
I did some dyno work the other day with the Bus (1776) and found a good increase in power by up-jetting from the low 14s A/F as you would expect. But any richer than 13.2 and the power stayed the same. No increase, just more fuel burnt. Bear in mind that this was a really mild motor. A performance 1776 would have benefitted from the richer fuel mixture for sure.

[Phil West]

I just checked my local fuel prices and it costs $10.09 equivalent for 4.55 litres of normal unlead, and £10.89 for super unlead.  Pretty scary stuff.

Diesel's an amazing $11.71 for the same...although I won't be needing that!

Fuel cost was mainly my reasoning for keeping it leaner.  I suppose I could try a run with it at say 13.2 and compare mileage numbers and oil temps.  The van towing is all 2 to 3k revs fully loaded all the time.

When I seal up the spark plugs I'll have a good look for any other small cracks or holes elsewhere that I left as 'acceptable' before.

Fortunately I have a genuine fanshroud so hopefully should be able to adjust the fan correctly.
Cheers
Phil

[andy M.]

Phil,

is your box a 1303 or 1303s?

a lot of people put the S box in buses but with alot of weight the gearing is all wrong, just a thought,

with the 3.88 r/p the fan speed is to low to cool a hard working bus motor.

[Phil West]

It's just the 1303.  Big Pete did the design work!  Actually with my rear tyres the gearing seems great for driving while towing - fairly low revs for good consumption.  Need to check my data sheets but I think it was 3,000 revs at 60mph.  I think it is a 3.88.  Which means you're right my fan isn't spinning very fast while I am driving!  I made a mistake on my earlier thread when talking about power pulleys - what I need is a bigger (taller) bottom pulley than stock or a smaller top pulley or both!  No idea if I can get either of those but more fan speed would be lovely......Driving at 3,000 and getting the fan speed of say 4,000 or more revs sounds nice....I've put an Empi 75 amp alternator on there (running a fridge inside the van), I've heard it doesn't push much voltage (or should that be current, I'm crap with electrics) at the lower end of the revs so perhaps if I get it spinning more I'll get better output.  I've not noticed any charging problems but it would be nice to get the best out of it.  If I can get a well built top pulley that has a smaller internal diameter I could swap the pulley out if I am not towing and want to give her some more revs, to be sure of not damaging the fan.

[Zach Gomulka]

No idea if I can get either of those but more fan speed would be lovely......Driving at 3,000 and getting the fan speed of say 4,000 or more revs sounds nice....

...get a well built top pulley that has a smaller internal diameter I could swap the pulley out if I am not towing and want to give her some more revs, to be sure of not damaging the fan.

Yes you can, on both accounts. The new Berg crank pulleys are slightly larger in diameter than a stock pulley, and you can replace the generator pulley with a 356/912 unit. If you use both be sure to use a welded/balanced fan, as it will be turning some healthy rpm's.

[Phil West]

great stuff, many thanks.  I see some purchases on the horizon.....

[Torben Alstrup]

The stock 1303 (1300) transmissions has a good ratio for towing. depending on your tyre height your rpms are about 3000 at 60 mph. which is good. - Your car must look like Swiss cheese underneath with all those holes in the sub body.  most of what you did will aid in keeping the fish chilly back there. The air duct up to the fan being the most important.   Mid 13 A/F ratio for towing at
3000 rpm is ok. It´s not at wot unless you are on that hill of yours. At WOT you would like to go down to about 12,8 or so.

WRT vacum advance. It really depends on how "easy" the rig is to tow. I.E your throttle plate position. If you are still on solid idle function, the vacum will pull the ignition back and help creating a good temp in the heads. If you are on your way out of the idle system, it wohnt do squat, because it will then be without vacum.
T

[Phil West]

not near WOT most of the time.  Interesting on the idle circuit - not always easy to find out where the transition point from idle to mains is - I think I will use the LM1 and put a huge mainjet in - then test her on the drive - rev to 2,000 for 10 seconds, then 2,500 for 10 seconds, then 3,000 for 10 seconds.  See if i can see where the effect of the big main kicks in to figure out when my carbs transition.  Then I can test her again in jumps of say 200 revs to find the point with accuracy.  Then check my revs at 60mph and I'll know if I'm driving on the idle circuit or mains.

In terms of jetting, if I am on idles, if I then need to tune my a/f ratio for towing I only need to change the idle air bleed size.

[Torben Alstrup]

I wish it was that easy. But at 3000 rpm youre definitely in the upper part of the idle circuit, and there it has begun to nip from the main system. the besrt way to determine how close you are to the main system, is actually to check the vacum signal from the carbs outlet to the distributor.
Driving solo, no problem. With the tow car behind, its very hard to say.
T

[Zach Gomulka]

On my Superflow engine I was worried about the cooling. I then decided to get rid of the oil cooler in the fan housing and go for a big Setrab cooler sitting vertically just in front of the left side drive shaft. This may seem very stupid, but the reason is that i wanted the widest fan (from a 1600 w. doghouse) inside a non dog house 36 housing. Then the full width of the fan would be used only for cooling the cyls/heads. It was a tight squeeze but with some persuasion it fitted in there. That engine ran cool with 10.5:1 CR... without the rear tin. A big contributer to this was the thermo tech I suspect.
This was in a full weight type 1 at freeway speeds and above...         

I didn't know a doghouse fan could be stuffed into an original 36hp shroud, that is cool stuff. Great idea.
I think I read that VW designed the non doghouse shroud to be used with the cooler in it, when it is taken out the airflow is disturbed and the 3-4 side runs hotter??? Has anyone verified this?
A 36hp shroud, doghouse fan, and a 912 oil cooler would make for a simple and possibly effective cooling system for a not-too-crazy street motor...

[Jon]

I didn't know a doghouse fan could be stuffed into an original 36hp shroud, that is cool stuff. Great idea.

Well, as I wrote... it took some persuasion  . First i mixed and matched with the shims to get the fan as close to the backing plate as I could, as it knew it would be a tight squeeze on the other side. Then I placed a split brake drum on the floor, facing down, and placed the 36hp shroud over it,facing up, carefully aligning it to be in the center of the drum. Then I placed some old fan in to the housing to distribute the "deformation" evenly, took a piece of hardwood and wacked it with a good size hammer. After a few blows the housing took the wide fan without problems. and from the back it looks just like stock.
Using only this fan shroud and just the tins above the cylinders I have never had any oil temp problems, even with CR up to 11.3.

I'm now in the proses of fitting all the tins to the engine, to do it right.. but the wide fan stays put...

[Jim Ratto]

mockup of an oil cooler cold air duct I made today, it mounts near RH torsion tube and feeds Setrab (up near trans on LH side) via two 50mm Volvo preheat hose.

[Phil West]

I can confirm 40F drop in head temps after fitting the smaller Porsche top pulley.  No noticeable delay to initial warmup.

I machined down the centre boss that comes in the 3 piece kit as it was too long for my stock washer to fit over so would not have clamped down the outer top pulley section correctly.  Once machined to stock VW pulley specs it all went on fine.  Keeping a close eye on the pulley as I am aware some people have had problems with build quality.  However seems fine after decent amount of use so far.

New pulley meant I had to find a smaller belt.  After a couple of tries I managed to find one in an 895 pitch length that fitted nicely.

Cheers
Phil