VW 88mm pistons & cylinders on a Corvair

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

aviast

Well-Known Member
Joined
Jun 4, 2011
Messages
150
Location
Brisbane, Australia
Here's the situation: I live in Australia where Corvair engines, and associated parts, are like hen's teeth and need to be imported from the U.S. The shipping costs, plus customs etc., are exorbitant and constitute a significant proportion of the cost of the final engine. On the other hand, Volkswagen cars and engines are common and parts are readily available locally.

So... I was very excited as, watching William Wynne's second DVD, he started talking about using an 88mm VW piston and cylinder. AND this was lighter than the Corvair original AND did not require any modifications to the case. Where do I sign?

But the DVD was recorded in 2001 and things have changed. According to legend (a.k.a. the manual) WW learned some lessons from the VW experience and went on to develop his own pistons and cylinders. But I've still got my freight costs problem. What I haven't been able to find is: what's wrong with using VW pistons and cylinders? Were there any "showstopper" issues?

In this Getting Started post #10 WW says:

We are going to look at three piston and cylinder options and then apply each of them to each of the Closed Case systems above. That will give us 15 basic engine build paths.
Notice how the options expand geometrically as we get a little further along. 15 is actually something of a simplification, as I am not going to get into outdated displacements like 88mm, 90.5mm and 94mm bores.
Why outdated? It's frustrating that all references to the VW option - which was a favoured option only 10 years ago - seem to have been erased.

I see that the late Gary Collins used this combination on his engine but I haven't found much else.

All thoughts/suggestions appreciated!
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
I know that we have some Aussie friends with our engines and components down there...honestly we are looking into makeing large shippments of our standard parts to Aust to assist and improve parts and engine avialability there. Been talking to Peter Ratcliff and others. Looks like we me make a trip there in the next few months in time allows....ship a container with a plane as well. Contact us if you think we can help.
AzaleaAviation.com
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
5,950
Location
Australian
Shirley "outdated" is in reference to him developing his own?

No other reason to make the statement, Scat, Empi, Gene Berg, etc all still sell 88mm kits.

I wouldn't take stock of what the guy says outside of the way he does himself, he has some strange views of other's products and methods.
 

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
954
Location
SC
If I were to speculate I believe that it has much to do with reliable performance. WW has developed his own pistons as he has done a great deal of research on the best quench area, how to get better burn through more turbulence in the cylinder, and lowering the static compression to allow the use of Mogas while still making good power and preventing detonation. Still, I know of no reason that 88's can't be used. But all of this is my guess as I claim no authority.

BTW ... don't take advice from folks on the internet that have never laid eyes on, put a wrench on, or flown behind a Corvair engine. Best for you to go to the source and email William and see what his reasons are. Because he stays very busy sometimes his replies don't come back immediately.

I can tell you that you will love the reliability and smoothness of Corvair power!

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
107.3 hours / Status - Flying
(Myunn is in the "Completions" section of Kitplanes for November 2015)
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
12,277
Location
Memphis, TN
Like all things, depends on what is available. Cheap CNC work form China has changed the aftermarket auto business. Probably still cheaper getting Corvair parts today than paying for the machine work to make VW work on top of buying parts; I bet it is not a bolt-on as is.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
5,950
Location
Australian
WW has developed his own pistons as he has done a great deal of research on the best quench area, how to get better burn through more turbulence in the cylinder, and lowering the static compression to allow the use of Mogas while still making good power and preventing detonation.
This is no where near the thinking of the last 20 years, no top level head shop goes anywhere near swirl or turbulence, it lowers density, uses up energy (that creates heat) and lets part of the charge out the exhaust early. As a higher density remains cooler, compressions can be raised and fortunately the ideal modern combustion chamber and port shapes, also allows a large increase in squish area and has made detonation almost unheard of these days even at what were previously ridiculous compression ratios.

This is what a modern Corvair chamber should look like ..


ChamberClose.jpg

http://www.american-pi.com/corvair/html/machine.html

Go look at all the best in Ford and Chev heads now and you will see nothing looks like open chamber Corvairs anymore.

BTW ... don't take advice from folks on the internet that have never laid eyes on, put a wrench on, or flown behind a Corvair engine. Best for you to go to the source
Oh the irony ...

Since you bought it up, I have read a number of technical articles at flycorvair website, a number are laughable and sometimes display a lack of understanding of how engines actually function at the most basic of levels. Bit of a worry.

But I understand when one builds a couple of hundred of the same engines for 25 years then sure, you will find your way eventually bumbling into knowledge and come up with a reasonable result, how could you not, but that doesn't make it the best result, just "a result".
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
As far as using VW pistons and cylinders, it is really too much work for the value around here..It could be more valuable down under perhaps. There is a bunch of machining and frankly I dont like machining the case and heads to fit VW stuff plus having to modify the cylinders and rods to fit the VWs - It is much easier to use clark pistons and their new cylinders for our stock engines...or our new JE Industires pistons with our New stroked crankshafts for the 120HP combination.
As far as flycorvair.com...internet stuff. Ill put my 2000+ hours as PIC behind our corvairs to WWs anyday. Hes never had a private pilot licence and you will rarely(if ever) see him fly. It would do him some good to fly behind his product. (my 2 cents worth)

Not that we dont have a lot to learn but there are lots of other corvair builders out there that truly understand the engine better and are easy to learn from.

Back to building planes :)
 

mcrae0104

Armchair Mafia Conspirator
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,149
Location
BDU, BJC
I have read a number of technical articles at flycorvair website, a number are laughable and sometimes display a lack of understanding of how engines actually function at the most basic of levels.
Such as...?

Hes never had a private pilot licence and you will rarely(if ever) see him fly. It would do him some good to fly behind his product.
1) He claims to fly behind his products; are you calling him a liar?

2) According to the FAA registry, he holds the following certificates: A&P Mechanic and Sport Pilot. What is the point you're trying to make about his qualifications?

I don't think it's appropriate for suppliers to use this forum to put down other suppliers.
 

pistoncan

Well-Known Member
Joined
Aug 9, 2008
Messages
90
Location
Vienna, Missouri
Such as...?



1) He claims to fly behind his products; are you calling him a liar?

2) According to the FAA registry, he holds the following certificates: A&P Mechanic and Sport Pilot. What is the point you're trying to make about his qualifications?

I don't think it's appropriate for suppliers to use this forum to put down other suppliers.
I did hear that WW did recently get a sport pilot licence, so what you said and Bill said are true, but before you say to much about Bill Clapp, go back and look at the thread (on here) that WW started to do nothing but slander Bill Clapp.

Us old timers recall when WW sang Bill Clapp's praises when he designed and built WW's first corvair nose bowl (BC worked for WW) but history seems to get rewritten a lot these days, especially after a falling out. I also recall the flap on the corvaircraft forum when WW had to admit he was only a student pilot and Grace was PIC even though he had implied for years he was the pilot.

But I agree with you, I don't think it is appropriate either.
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
Sorry if the intent did not come across right guys. (that the biggest problem with internet) My point was that it is different to say things on the net compared to practical usage and learning from flight experience. I'm not trying to put WW down as he has done a lot for the corvair guys...however, flying behind what you build lends a different view and learning that cannot be had any other way. Over the years I actively encouraged WW to finish his pilots license because this would make him a better mechanic and have a closer tie to his customers. In no way derogatory. I know he tends to burn people, but I want him to become better. It would serve all of us and his customers better to encourage growth and learning. I did check and found that he did get his Sport License so congratualtions to WW are in order!
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
I will answer these directly...

1) He claims to fly behind his products; are you calling him a liar?

William never claims to personally fly behind his stuff (its always a genereic "we") Through all the years knowing him I've never seen him fly or any photos of him flying a corvair powered aircraft as PIC. He was working on his license with his Pietenpol when he and an instructor had the accident that burned him badly. I can see where after that he had much difficulty in returning to flying (either because of fear/emotion/or medical) I am not being accusatory...however he does tend to shade the truth to his convenience. (from personal experience not necessary to repeat here) THe best answer to you is to do your own research and not rely on my word. My point is this...I logged over 300 hours this past year behind four different corvair powered aircraft, three of which were new planes of differing configurations. This gives me information about our products and installations I can't learn from other pilots data. Of my 2000+ corvair flight hours over 500 are in WW engine installations including his 601XLT. I can be critical of his products and installations but purely in an operations way. My goal is to improve safety and pilot competence. Calling someone a liar is not an important or beneficial issue...if someone is or not one is and they have to change. I am not here to be critical any person in any way other than to offer improvement. Otherwise I am just bloviating...

2) According to the FAA registry, he holds the following certificates: A&P Mechanic and Sport Pilot. What is the point you're trying to make about his qualifications?

I knew that WW was an A&P but just saw his Sport Pilot info. So, Congratulations are in order. Somebody posted that he is now flying Grace's Taylorcraft...an airplane I have personally flown as well....nice plane!

I don't think it's appropriate for suppliers to use this forum to put down other suppliers.

[/Correct you are, however I was just bring up that fact that there are things that can be learned only from being in the seat behind your product. The majority of what I have learned and developed over the years came from that and I have more to learn. I think though that I can, for the interest of consumers speak directly about the products and differences with other suppliers, costs, benefits, and such. This thread was concerning availability of modified VW cylinders and why that market seemed to have dissappeared. I was commenting on how our direction is different (because of our experience) and how we can help the Aussie market with our products.I]


(now I hope this ends any perceived personal crticism).....
 

rv6ejguy

Well-Known Member
Joined
Jun 26, 2012
Messages
3,749
Location
Calgary, Alberta, Canada
My friend, Ray Sedman owns American Pi, the Corvair engine building company mentioned in CR's post. Ray is one of the smartest Corvair guys on the planet, he just doesn't build them for aircraft unfortunately...
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
Ray is a smart guy - a true authority in many ways. Ive picked his brain a bit over the years and probably will some more! There are a lot of neat people out there that have great information, done lots of testing, and are great to work with....and there are others. The world is truly made of people! I like Rays head stuff...great for high performance. As we progress into our new head design I am sure I will ask his opinions on some of our design work.
Back to building engines and planes....
 

rv6ejguy

Well-Known Member
Joined
Jun 26, 2012
Messages
3,749
Location
Calgary, Alberta, Canada
Ray is a smart guy - a true authority in many ways. Ive picked his brain a bit over the years and probably will some more! There are a lot of neat people out there that have great information, done lots of testing, and are great to work with....and there are others. The world is truly made of people! I like Rays head stuff...great for high performance. As we progress into our new head design I am sure I will ask his opinions on some of our design work.
Back to building engines and planes....
I like your words "true authority" here Bill and the nice thing about Ray is, he'd never use those words himself. He's a modest, humble, friendly, likable and very nice guy.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
5,950
Location
Australian
, no top level head shop goes anywhere near swirl or turbulence, ........ allows a large increase in squish area and has made detonation almost unheard of these days

QUOTE]
I am no genius, but these 2 statements seem to directly contradict each other.
And so have tuners have thought, and many still do for the last 95 years - Harry Ricardo credited with the early theories and tests around 1920 and in fact his heads were actually called "Turbulent Heads".

What a few guys have moved towards in modern times is concentrating on getting as much charge in as possible via a "Dump and Tumble" which is to aim a narrow and contained flow straight at as close to the centre of the piston top as possible and completely filling the lower portion of the cylinder expending it's energy there rather than flowing out the exhaust.

The shape of the ports, valve and valve chamber area, led to very large increases of desirable squish area, as you can see in the Corvair head picture above.

The large squish area is now what provides the majority of the turbulence, it always did and has been a well known factor since the late 1960's, but the thinking was that it was an aid rather than the major contributor so people kept on looking for the swirl and turbulence factors with precedence over squish. Now that the squish areas are dramatically large, they are well and truly enough to take care of the turbulence with a larger shockwave, and at the right moment too, just when the charge is starting to burn.

A lot more attention has been paid to squish with this new modern thinking and part of the reason many modern cars can now run 10:1+ compressions. Many 4 valve engines now have a much narrower valve angle for more dump and tumble with, of course, more squish area.
 

don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,757
Location
Midwest
It's rather funny reading this post mainly because there is so many opinions on Wy, Who, When, Where about the Corvair engine.
 

don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,757
Location
Midwest
I think guys like WW, BC, ML. are out to do one thing, make there engines stronger and there planes faster thats one reason in my opinion the 145 ci engine is frowned on because the lack of HP. WW can give a few reasons wy not to go that displacement but I dont see any hard evidence other then pistons to slow a builder down. The KR2 was disigned for a 60 hp engine not 110 and many of the newer planes, Zenith, Sonix, ect. would fly just fine on 60 hp engines, Mark I guess thats wy you keep going through cranks on your kr with your flying skills and wants maybe a Starduster or Cap would fill your abilities better. You know just once I'd like to read a post where BC or WW is'nt saying thing negitive about each other, My god you where friends once were'nt you?? The OP's post is about VW jugs and pistons not Ray ect. You Aussie boys should maybe think about a 6 cylinder VW and blow the Corvair out of the picture. Don warhawk p 40.jpg
 

ekimneirbo

Banned
Joined
Oct 31, 2014
Messages
1,009
Location
Deep South
I think WW has made a lot of contributions and done a ton of research for which he deserves a ton of credit. His colleges have done a lot to help people build a movement toward Corvair conversion use and spread the "word". He apparently has decided that a simple basic inexpensive and reliable version is the best way to promote Corvair.
I think that's a good idea, because most builders are looking for easy/cheap/reliable when they first get interested.
Like everything in the experimental aviation, nothing ever satisfies everyone's wants and needs. I think Bill Clapp and some others want to take the Corvair to the next level and fill that niche. It's good to see talented and knowledgeable people working thru the technical maze to bring that to the market. While I realize there are some personal issues between some of the parties as well as some interaction and exchange of information.....and maybe a little "one up manship", the final result is a lot of great resources for us builders. Personally I'd like to thank all of them. Can you imagine trying to start from scratch by yourself and get 1% of all this info together?
 

Bill Clapp

Well-Known Member
Joined
Feb 16, 2015
Messages
300
Location
Valdosta Ga
Hey Don - sometimes my thoughts as well...my first engine const me less than 1800.00 and I flew over 180 hours before modifying...it did have forged pistons but the rest was pretty basic. No reason you can't fly on a simple engine...none at all. However as a business I have to reach different goals concerning standardization and reliability. I think I still have one of Bernie Pietenpols prop hubs around here....he just bolted it to the crank end with the flywheel bolts - and bolted a prop on! used the two carb, fan and everything...it worked...not pretty but worked. (has to a pain to change the belt in flight thought) :)
 
2
Group Builder
Top