Microlighters

HI ALL

I am still struggling with the oil temp on the voloksie motor.

I have fitted an exra oil cooler,extra sump and a separate duct ontop of the cowl for ram air into the top oilcooler but all I am gaining is extra weight and an extra dose of frustration cause 15 minutes in the air and my oil temp reaches 130 degrees.

Is there any calculation available for the cowl as to the amount of air intake and expulsion underneath or is it all thumbsuck?

Boet, jy mag net n positiewe antwoord gee

Brian wrote:HI ALL

I am still struggling with the oil temp on the voloksie motor.

I have fitted an exra oil cooler,extra sump and a separate duct ontop of the cowl for ram air into the top oilcooler but all I am gaining is extra weight and an extra dose of frustration cause 15 minutes in the air and my oil temp reaches 130 degrees.

Is there any calculation available for the cowl as to the amount of air intake and expulsion underneath or is it all thumbsuck?

Boet, jy mag net n positiewe antwoord gee

When I had a VW in the KR2S I had to replace the oil pump with a high volume one, that helped a lot !

Hope you can sort your problem out, I know how frustrating it can be.....

Brian wrote:HI ALL



Is there any calculation available for the cowl as to the amount of air intake and expulsion underneath or is it all thumbsuck?

Boet, jy mag net n positiewe antwoord gee

Hi Brian,

if intake area is 1(One) then outlet area should be 3(Three) because hot air expands.

This is a ballpark figure but will give you something to work with.

Kind regards,

Gunter Rostek

Hi Brain

Sounds like something else is heating your oil. Check your cht and egt. My experience, you cannot keep your oil temp down if your mixture is too lean. ( big problem when using carburettor with wrong needles and or settings.) The better way is to go for fuel injection. Check your timing this will also heat up your motor if setting is wrong.

Hope this helps

Hi Brian,

By now you will have seen that cooling the volla motor is not easy.

Aproach the problem by looking at the cooling SYSTEM air part of it as well as the oil part of it.

Pay paticular attention to the exhaust port area as max heat is generated here.

Then make sure you have no air leakage from the top inlet side of the air to the bottom outlet side of the engine,making sure all air passes through the cylinder heads and around the cylinders on its way to the bottom of the engine.

Next make sure that the deflector plates at the bottom of and between the cylinder heads are in place.

Make sure you have that rough 1:3 inlet outlet ratio for the air.

Now moving to the oil side here it pays big dividends fit a larger volume oil pump as Rudi recommended because 25% of heat generated by the engine is removed by the oil.
so fit high volume pump,larger oil cooler, place oil cooler outlet in a low pressure area to help removal of hot air , design oil cooler outlet as a diffuser, supply fresh air to oil cooler inlet side via its own dedicated fresh air supply, make sure you have no leakage from inlet side of oil cooler to outlet side of oil cooler.

Then be prepared to invest many many hours of experimeting time before you have a sucessfull cooling system.

And finally copy succesfull installations. Go look at european motor gliders with Limbach motors.

These VW installations reach TBO and cost as much as a Rotax and the Rotax has the advantage of lower installed weight compared to a Limbach installation.
Limbach TBO is to the tune of 1000 hours with probably a new set of heads in there along the way and valve guide replacement every 300 hours or so.Rotax will probably go to TBO with only minor replacement items.
Why? because a water cooled motor dissipates heat better and does not suffer the same heat stress as an aircooled motor so components on a watercooled engine last longer.

The TBO of your personal VW installation is going to be in direct proportion to the amount of experimenting and testing you do before you are satisfied with all the safety aspects.

I am sorry if the last part sounds negative but unfortunately it is something to bear in mind.

Also remember all this experimenting costs bucks

Now ask yourself the question "Do I like fiddling or do I like Flying"

I hope this is a of help to you.

Kind regards,

Gunter Rostek
PS
I like the VW motor but have come to realise that this cheap motor will cost approx the same as a Rotax so why bother? just my opinion.

All parts for the VW need to be imported and I would not consider doing a VW AERO engine with used cases and overhauled heads and all the other used parts, but that is also just my opinion.

I peronally LOVE VW cars and more specifically the 4 cylinder water cooled engines. As for the air cooled combi motor - I share Boet's boat anchor sentiments and will never get into an airplane that has one bolted to the front. Too many valve seat dropping issues on those for me to be comfortable. As for the cooling issues - you need to have the correct baffle plates in place otherwise it will not keep cool.

I fly with a VW Type4 with standard oil cooler and pump and I cannot get my oil temp over 80c so I know the standard stuff works. I must add that I had problems in the beginning with high oil temps but this was caused by problems with the engine (too high compression). I've learnt over the years that when something's wrong with the engine you will see it on the oil temps.
Check for:
- Timing (28deg @ 3000rpm is best for VW)
- High Compression ratios (ratio's above 8:1 make the engine run hot)
- Sticking valves (common on just overhauled engines)
- Warped heads - causes lean mixtures (check this by doing a compression test)
- Lean mixture (carb or leaking inlet manifolds)
- Valve timing (exhaust valves not closing properly) this happens after 10 hours on overhauled engines- retorque heads and check valve gaps.
- Make sure the engine turns freely (crank end float)
- Make sure the engine is getting enough air to keep it cool and check for leaks in the baffling.

Hope this helps

Post some pic's of your installation I'm sure it with help evaluated your situation.

I have had 5 deadstick landings that is in 45 years of flying. They were all behind VW engines . If you pull to many horses out of them they stop. Personally I believe 60 hp is enough any more you start getting hot areas in the engine especially around the valve guides and seats and then the famous valve that breaks off. Blowbye of the pistons is also a great source of high oil temps. Good luck but I go along with Grostek get an engine that has a modern cooling system. The Rotax 912 fulfills that criteria.

Cheers Oupa-G

Boet is right next to me and refuses to comment on the matter except that you should fit a hooter for all the forced landings you are still going to make on the high ways.

Thanks to all the guys for the advise and comments. Seems I should really be scared of the vw but I am not the type of person to give up. I bought the plane as a project 99% completed by the previous owner and I basically did the finishing touches. The previous owner actually bought the vw motor from a very well respected member on this forum who at the time did not have too many isues with said motor.I would like to see a show of hands from both sides of the vw fence as to whether I should replace the offending motor or sort out the oil heating problem which is actually sooooo close.

I did not mention that I have flown about 7 hours with no problems. It is only in the afternoons with ambient temp at approx. 35 degrees that the temp problem arises.

Awaiting an unbiased response

Brian

Hi Brian,
Sort out the oil temp problem and then fly the motor and please keep us informed as to how it is performing as the hours clock up.

That way we will all learn something.

There is an awfull lot of experience with these motors on this forum both good and bad.

If you started with a motor build by a respected engine builder then your chances of getting high hours out of the motor are very good indeed IF you don't have cooling problems.

Cooling is the Achilles Heel of these motors. Good cooling = long life.

Approach the problem in a systematic way and make a list of possible causes of high oil temp.
Then work down the list one item at a time untill the problem is solved when you have found the culprit for high oil temps.

A lot of good suggestions have come out of this thread which all can be put on the list and checked.

I sincerely hope you get the problem sorted out and that the motor gives you the hours that you expect.

I believe many members of this forum are supporting you and wish you well. Focus on the positive.

Kind regards,

Gunter Rostek

PS

Here are some links to help you in making your list.

http://www.littleflyers.com/engcool.htm

http://home.hiwaay.net/~langford/faq/ch ... cool2.html

http://bobhooversblog.blogspot.com/2006 ... ffles.html

http://bobhooversblog.blogspot.com/2007 ... ating.html

http://bobhooversblog.blogspot.com/2007 ... lters.html

As a matter of interest, I was reading on the Sonerai list about a formula-V racer powered by a 2.1l VW.

When racing he runs at 4100rpm, producing 100hp (measured on a dyno, and verified by fuel consumption at 34l/h). Temperatures all well within limits. So it IS possible to cool a VW at very high power levels! (OK - I suppose it helps to have a 200mph air stream to do the cooling .)

-justin

Hi Justin,

I agree with you, but feel the acid test of any sucessfull VW cooling system is going to be the taxi phase while on the ground, eg. being asked by ATC at larger airports,to wait in line until they give you clearance to take off, like happens at Flyn inns.

By the way this applies to all aircooled motors, not only VW's.

So it is important to design the cooling system for worst case scenario .

Kind regards,

Gunter Rostek

Brian, sit asseblief n foto op van jou enjin installasie. Ek wil graag sien waar die olie koeler sit. Iets snaaks is hier aan die gang. Daardie enjin het BAIE goeie performance gegee, en met die verkoelingstelsel wat ek aan hom gesit het, het hy nooit met my te warm geloop nie. Dalk kan ek jou help. Moenie te gevoelig wees oor ek jou ketting so dan-en-wan n pluk gee nie. Sal graag tot hulp wees.

Dit was toe al die tyd nie die enjin wat te warm geloop het nie. Ek wil darem wragtig se, by MY het hy NOOIT warm geloop nie. Ek het baie met daai enjin gevlieg. Een van die beter ombouings gewees. die fout????? .........MGL...... Daar was so n "compatibility" foggapie.