De-stroked engine?

[JRoberts]

quote:Originally posted by 64Avanti

"Do you really think anyone would go to all of the trouble to destroke a Studebaker engine?"

Of course they would!

My Bonneville engine is a destroked over bored 259 that is right at 260 cu in. This was done to keep the displacement under 261 in cu and have as large a bore as I felt was safe for a suppercharged engine. This was done by offset grinding a 259 crankshaft to a "Honda journal size". The stroke is 3.15 inches.

I hope to some time in the future build a 183 cu in engine for use in another Bonneville car. However I must first set a record at over 200 mph with the Avanti.

David L

What soft "F" record are you going after?

Joe Roberts
'61 R1 Champ
'65 Cruiser
Editor of "The Down Easterner"
Eastern North Carolina Chapter

[PackardV8]

Hi, Dan,

Just a point of clarification - Silvolite and others list certain replacement pistons as "de-stroked", meaning they have raised the pin bore location slightly as required. The goal is to end up with OEM compression ratio after the engine has been over-bored .010", .030", .060", whatever, and the cylinder head milled and the block decked.

thnx, jack vines

PackardV8

[DEEPNHOCK]

I stand corrected.
The number is closer to six destroked Stude engines.
But for the street?
My question still stands as to the original intent of the original post.
I put the caveat about a race engine in my original reply.
I know that it can be done, and how,and for rulebook reasons.
I just wonder 'why' on a street engine..
I still think parts swapping was probably done and some measurements could answer what memory has forgotten.
The rest is just forum speculation.
And I am guilty of that, too.
Jeff[8D]

quote:Originally posted by 64Avanti

"Do you really think anyone would go to all of the trouble to destroke a Studebaker engine?"

Of course they would!

My Bonneville engine is a destroked over bored 259 that is right at 260 cu in. This was done to keep the displacement under 261 in cu and have as large a bore as I felt was safe for a suppercharged engine. This was done by offset grinding a 259 crankshaft to a "Honda journal size". The stroke is 3.15 inches.

I hope to some time in the future build a 183 cu in engine for use in another Bonneville car. However I must first set a record at over 200 mph with the Avanti.

David L

http://community.webshots.com/user/deepnhock

[Dan Timberlake]

Hi jack pines,

yeah, raised pin bore = shorter deck height or compression height.
http://www.autotech.com/images/products/jepistons2.jpg

If the engine in question had open style combustion chambers, or piston to deck clearance > 0.06 inch to begin with, then the compression ratio reduction would be effective in maintaining the octane requirement. In the rare (car) engine with tight deck/squish clearance ( <0.045 inch) the "destroked" piston could increase the squish clearance to the point it lost its anti-detonation effect, and in the end induce detonation by attempting to avoid it, and RAISE teh octane requirement. Some of my 2 stroke off road bike engines have had deck clearance set from the factory at less than 0.04 inch, so their broad squish bands actually could work properly to stave off detonation.

Only those who care to measure such things during their engine's assembly can know for sure.

Dan T

[64Avanti]

"What soft "F" record are you going after?"

The 260 cu in engine is of course an E class engine. There is no record in that class. I hope to go at least 175 this year and then 200 next year.

The idea behind the F class engine is perhaps to run it in the Avanti, however at this time F class engines are not allowed in Classic Production Suppercharged. I am not too sure why not since the turbocharged Corvair would fit in that class.

The reallity is that I might consider building something to put the 183 cu in engine into. Anyway that is off in the future, first things first.


David L

[JRoberts]

quote:Originally posted by 64Avanti

"What soft "F" record are you going after?"

The 260 cu in engine is of course an E class engine. There is no record in that class. I hope to go at least 175 this year and then 200 next year.

The idea behind the F class engine is perhaps to run it in the Avanti, however at this time F class engines are not allowed in Classic Production Suppercharged. I am not too sure why not since the turbocharged Corvair would fit in that class.

The reallity is that I might consider building something to put the 183 cu in engine into. Anyway that is off in the future, first things first.


David L

I never have quite figured out why there are any engine size restrictions in any class. I know in mini-pickup there was a fear of the short wheelbase trucks being unstable at high speeds, but I think they have done away with the restrictions in that class. Both classic and truck classes need some revamping, in my opinion. The ECTA uses basically the same classes and engine breaks as does the SCTA. Some are very confusing.

Joe Roberts
'61 R1 Champ
'65 Cruiser
Editor of "The Down Easterner"
Eastern North Carolina Chapter