1/4 Scale Running Model Offenhauser (Offy) Engine By Ron Colonna
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- Опубліковано 13 жов 2024
- 1/4 Scale Offy 270
This is a 16 valve double overhead cam powerhouse, with pressure oil feeds and dry sump lubrication. It is faithful to the prototype and uses the famous cup type followers. Eleven inches long and seven inches high. 1.032" Bore x 1.094" Stroke. 60 cc Displacement. (3.66 cubic in.) Compression ratio is 9.5:1. Uses solid state spark ignition. (Hall Effect with dual magnets)
I knew a little about the famous Offenhausers, hearing about their conquests at the Indianapolis Speedway while growing up. I didn't get interested in building a copy of one until approached by Bob Washburn after doing my Cirrus article for SIC magazine. At the time Bob was looking for someone to develop the model, do the basic drawings, write machining instructions, and build two copies of the finished engine, in a one year time frame. He sent me all the data he had aquired at the time. I looked it all over, but had to send it all back. I was busy on other projects and it seemed a daunting task that I was sure I couldn't accomplish. I didn't forget the engine though, and some years later, a gift of Gordon White's book on the Offenhausers from my eldest son, put me in the frame of mind to give Bob's proposal a try, but on easier terms. It took me two years to do it all and I only built a single copy of the engine. I put my drawings and machining instructions in book form and published it myself. It has been a successful venture, but I was right about it being a daunting task. I'll most likely never try doing anything like that again. The engine has been, and is being built in many parts of the world. My copy has been running for eight years now and is a fine performer with the throaty roar of it's full sized counterpart.
I marvel at the craftsmanship and dedication of this builder...it's fantastic.
Even includes the famous Offy "growl". The Offenhauser, after 50 years of utter domination against all other engines, was actually "rulebooked" out of Indy circuit racing, beginning in the late 1970's. The Indy league wanted European participation in the league, but the Offy-turbo was invincible on a level playing field, so the European manufacturers declined the Indy invitation. The European-inspired Ford-Cosworth V8-turbo, on a level playing field, was easily blown off the track by the Offy-turbo, so rules changes forced the Offy down to low power and efficiency levels, so that the V8 could survive a 500 mile race and stay in the race. Even at a forced identical HP, the 159 cid 4-cylinder Offy's tremendous low rpm torque, still allowed it to kill the 162 cid V8's out of turns, so as a final change, team fuel supplies were limited to what the V8 used in a 500 mile race. The Offy-turbo, rulebook-forced to run at lower power and efficiency, could no longer finish races on the limited fuel supply. So the Cosworth V8-turbo "beat" the Offy. With the Offy off the track, the European teams came to Indy. When asked about the best engines ever run in Indy circuit racing, Al Unser said, "accelerating off a turn, NOTHING can catch an Offy-turbo".
The fabulous Unser Family Racing Museum in Albuquerque has a vast collection of the cars and engines they drove.
During a visit in 2015 Al Unser Sr. was present, what a great honor to chat with a living legend from such a perilous time in racing history.
Ron, was great seeing this and your other engines at NAMES this past weekend, Thank You for displaying.
it runs so smooth...
really it has to be well built.
I'd like to shake builder hand.
That is SO beautiful. What talent!!
nice engine Ron, i bought a workshop manual of you awhile ago"1/4 scale 270 offy" havnt built it yet but hope to in the near future,thanks for subscribing to my videos,hope you liked my engine, regards bob [bocam57fe]
damn i want one of these just to have it and screw around but after looking up prices they are like $8000.00 lol i paid $5000 for a real corvette engine when i had to replace it
do you have a tach for it? that sounds pretty fast...
Conelly probably makes one. But, they are over $5,000.00 USD
can you buy kits for these engines to build yourself?
1/4 size offy ? shouldn't that be about enough to run a modern car with ?
Turbo?
how many engines have you built?
261Honda I’ll just say a lot. I know the a because he’s my grandpa and he always will make new ones.