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Pulling the trigger on my dream BIG BORE build... grinning smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 11:15AM

I spent some time on the phone, the other day, with an engine builder.

We went over my dream and specs for a BIG BORE engine build.

If we can come to terms, as I believe we will, we are putting it in writing soon, to start this cool build.
I'm ready to give a deposit.

I still need to provide some more info, like:

1) Tire size

2) Final drive ratio

3) What combinations other Big Bore Ultravan owners have and their outcome

And anything else I might have forgotten...


MY Dream BIG BORE Build will have:

VW Cylinders
New Aftermarket Rods
Full Floating Pistons
Custom grind Cam (might even be a roller cam)
ARP Hardware
Trick Heads
Ted's EFI setup
Much more...

And it will run on Regular... hot smiley



Edited 1 time(s). Last edit at 02/17/2020 02:18PM by MattNall.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 01:38PM

Thought I share this.

Owen provide this info to me:
The 3.1 in #388, the 3.1 in #404, and the 3.1 in #460 all failed.
The 3.0 is still in #292 AFAIK but isn't operational.
Chuck replaced his broken 3.1 with a new 3.0.
Doug replaced his with a 110.
Not sure whether Yocum's have made a decision yet.


I forgot to mention in my first post that we are talking about a 2.9 Big Bore..
I think the thicker cylinders are important - pushing the heavy brick through the wind.. Grin
BTW - I'm also going to run an exclusive external oil cooler.



Edited 1 time(s). Last edit at 02/14/2020 01:39PM by OttawaCorvairGuy.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: vairmech ()
Date: February 14, 2020 04:44PM

If you are thinking 2.9L give me a call I have some suggestions for you.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: v8vair ()
Date: February 14, 2020 05:02PM

My idea for a big motor is a stroker crank,1/8 inch or maybe even 1/4. Long stroke is what makes big torque gains down low. The Clarks Cylinders with 100 over custom pistons. That way no machining of case and heads required. Rod ratio with stock rods still isn't great but doable. The problem is cost. New Billet crank from Marine is $2700. Custom pistons $900ish Not cheap Mike

1965 Crown V8 Racer
1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1979 Mazda RX7

Mike Levine

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 05:12PM

v8vair Wrote:
-------------------------------------------------------
> My idea for a big motor is a stroker crank,1/8 inch or maybe even 1/4. Long stroke is what makes big torque gains down low. The Clarks Cylinders with 100 over custom pistons. That way no machining of case and heads required. Rod ratio with stock rods still isn't great but doable. The problem is cost. New Billet crank from Marine is $2700. Custom pistons $900ish Not cheap Mike


Mike,

If I understand it correctly. The cylinder walls would have to be thin or extra thin, due to the stock cylinder fit.

This can promote heat and more so if used in a large Ultravan.
This heat issue and thin cylinder walls can distort the cylinders and/or cause ring seating issues...

I'm still waiting to hear back from the UV Big Bore owners to try to find out just what happened to cause theirs to fail.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: v8vair ()
Date: February 14, 2020 05:36PM

I hear the Clarks Cylinders at 100 over are the thickness of .040 stock cylinders. But i really think the UV would love a bigger stroke over bigger bore. Anytime you mill away aluminum from the heads it cant be good for Heat transfer. That bigger stroke is really gonna help pulling away and up long hills.
And in my personal opinion aftermarket VW pistons and Cylinders are not even good in VWs let alone corvairs.Unless ther German Mahles. That's First hand experience with VWs over a 30 year period. Mike

1965 Crown V8 Racer
1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1979 Mazda RX7

Mike Levine

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 05:49PM

v8vair Wrote:
-------------------------------------------------------
> I hear the Clarks Cylinders at 100 over are the thickness of .040 stock cylinders. But i really think the UV would love a bigger stroke over bigger bore. Anytime you mill away aluminum from the heads it cant be good for Heat transfer. That bigger stroke is really gonna help pulling away and up long hills.
> And in my personal opinion aftermarket VW pistons and Cylinders are not even good in VWs let alone corvairs.Unless ther German Mahles. That's First hand experience with VWs over a 30 year period. Mike


Thanks Mike

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: Brizo ()
Date: February 14, 2020 06:57PM

Ottawa, Three years ago I had a welded and re-nitride 1/4" stroker done for my FC by Marine Crankshaft for $1,000 and every dimension was perfect, but I can understand why you might want a billet crank for an UV. In what way did those 3.1 engines fail?

Dan Brizendine, Circle City Corvairs
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: The Stig ()
Date: February 14, 2020 07:54PM

????

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: 63turbo ()
Date: February 14, 2020 08:17PM

According to the folks at Pauter machine, the only engines that have a reasonable life running 94mm cylinder bores are vw bus engines with a 7:1 compression ratio, and I seriously doubt that any of the Corvairs running those cylinders actually have the cr that low... In bus engines, they think a reasonable life for 94's is 30000 miles. Those cylinders are paper thin and one is asking for it running those things at cr's above 7:1... they WONT last long!! The thick wall 92mm cylinders, on the other hand are very beefy, and would be expected to have as good a life as stock Corvair cylinders do with a standard bore. If there has been reliability problems with 3.1 liter ultra vans, it is probably caused in large part due to the use of the 94's and elevated compression ratio's, and less than ideal cooling. 92mm cylinders, and 10:1 compression using premium fuel and heads modded for good squish, running my fan ought to live a really long time!!

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 08:58PM

Brizo Wrote:
-------------------------------------------------------
> Ottawa, Three years ago I had a welded and re-nitride 1/4" stroker done for my FC by Marine Crankshaft for $1,000 and every dimension was perfect, but I can understand why you might want a billet crank for an UV. In what way did those 3.1 engines fail?


Thank you Dan.

As I posted above: I'm still waiting to hear back from the UV Big Bore owners to try to find out just what happened to cause theirs to fail.

My Guess: Is heat and over pushing the engine...

However, I would like to know for sure.
I hate to send thousands and have an engine fail.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 09:09PM

63turbo Wrote:
-------------------------------------------------------
> According to the folks at Pauter machine, the only engines that have a reasonable life running 94mm cylinder bores are vw bus engines with a 7:1 compression ratio, and I seriously doubt that any of the Corvairs running those cylinders actually have the cr that low... In bus engines, they think a reasonable life for 94's is 30000 miles. Those cylinders are paper thin and one is asking for it running those things at cr's above 7:1... they WONT last long!! The thick wall 92mm cylinders, on the other hand are very beefy, and would be expected to have as good a life as stock Corvair cylinders do with a standard bore. If there has been reliability problems with 3.1 liter ultra vans, it is probably caused in large part due to the use of the 94's and elevated compression ratio's, and less than ideal cooling. 92mm cylinders, and 10:1 compression using premium fuel and heads modded for good squish, running my fan ought to live a really long time!!


Thanks Kevin.

As of right now, we are talking 2.9L with VW 92mm and 8.5:1 and no more than 8.75:1 pistons.

On my Ultravan engine build; I've always planned to run only an external oil cooler, again exclusively, with no factory oil cooler.

I want the fan air for the cylinders and heads only and a larger surface for cooling the oil.

My hope is that this will be an added help with any heat build up.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: 63turbo ()
Date: February 14, 2020 09:52PM

Forgive me if I missed something, but 92mm cylinders and a stock late crank
stroke is 2.97 liters, and this rounds to 3liters. Using 90.5mm cylinders and the same stroke is 2.88 liters and rounds to 2.9liters.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: OttawaCorvairGuy ()
Date: February 14, 2020 10:00PM

PM Sent

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: vairmech ()
Date: February 15, 2020 06:01AM

You don't need VW cylinders to get 2.9L! The most machining needed is to the small end of the rod. Maybe a little to the head.

No need to reinvent the wheel again.

I can tell you why the other engines failed, The new owners were not really car people and even if they were they were not in tune to what to do or how to handle an Ultra. They probably wanted to travel with traffic and pushed the engine to hard, didn't watch the gauges, didn't listen to the coach and treated it like a modern car with no issues to worry about.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com



Edited 1 time(s). Last edit at 02/15/2020 06:11AM by vairmech.

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: 63turbo ()
Date: February 15, 2020 12:04PM

There seems to be some significant rounding error's going on with respect to what piston and cylinder combo's give what displacements in liters. Here's what these combo's actually produce in cc's.

Battle of the Big Bores, using a stock late crank

Stock displacement is 2682.7 cc = 2.68 L
Clark Cylinders,
with .1" overbore is 2841 cc =2.84 L

with 90.5mm is 2882 cc =2.88 L
with 92 mm is 2978.5cc= 2.98 L
with 94 mm is 3109 cc = 3.11 L


All else being equal, increase in displacement is proportional to both torque and power as long as the heads can flow equally well at the larger displacement, and depending on what is or is not done to the heads and cam can screw all the assumptions up, or do better than the assumptions.

here's the % increase in displacement from stock (stock = 2682.7cc)

2841 cc is a 5.9% increase
2882 cc is a 7.4% increase
2978 cc is a 11% increase
3109 cc is a 15.9% increase

if it wasn't for the short life associated with the 94's this would be the way to go. The thick wall 92's are a better choice than the 90.5's as the amount of work and expense is the same, and the wall thickness is the same

and the Clarks cylinders would be the best choice if funds are limited although
gives the least displacement increase.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: vairmech ()
Date: February 15, 2020 01:02PM

Using Clark's cylinders and GM pistons so there is no block or head mods or cylinder mods other than boring the cylinders.

3.542" bore = 173.8 cu. in. or 2848.0717232 CC or 2.848L rounded to 2.9! LOL

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: v8vair ()
Date: February 15, 2020 01:59PM

3.537 Bore with 1/8 over stroke gives you 3 litres without boring the case or heads.
1/4 stroke is 3.1 If money doesn't matter this is my choice. Mike

1965 Crown V8 Racer
1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1979 Mazda RX7

Mike Levine

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: chris ()
Date: February 16, 2020 07:20AM

Mike, I agree with you on increasing the displacement both ways, as that would be about ideal. I previously spoke with Clark’s and the tech stated that their full fin cylinders can (and have been) be bored to 3 9/16”/90.5mm.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: hot smiley hot smiley Pulling the tigger on my dream BIG BORE build... hot smiley hot smiley
Posted by: BobV66Vair ()
Date: February 16, 2020 10:27AM

Not to muddy the waters here. There are now 92mm cylinders that are made to be bored out to 94mm. If you leave them at 92mm, they have a much thicker wall and will last longer under stress. Worth looking at. You might also consider having some advanced head work done. You can get much more power from heads that a big bore. if you do head work, select a builder who is very familiar with Corvair head work.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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