14.5 open class engine pictures

Open-RPM

Member
I was able to get these pictures into a format that will work here.
Please excuse the dirt and grime on the block right now, as it's been sitting in my garage for three years, having had no further work done to it. Making the manifold like this is simple, if you have access to a mill. It'll need to have the intake port cleaned up some more from the welding.
 

Attachments

Open-RPM

Member
Thank you; And yes, I used the bolt holes that were already there to position and hold the manifold in place where I wanted it to be. Then I just had a local welding/machine shop weld it. On this particular block, I ended up cutting into the block/ intake inlet surface farther than I wanted, and it took off the lower part of the original flange, and the bolt hole that went with it. I also ended up just machining off the original intake brace as well, and put a block of 7075 billet aluminum in its place. That now is the intake brace, and it and the manifold are all welded together on the block.
 

racer223

Member
What bore and stroke combo will get you to 14.5"? I'm in the southwest and we don't have any classes like this, but it is intriguing as hell.
 

Jimbo

If you talk the talk you should walk the walk
That's an option if you are in love with the flat heads (and that's ok) but consider this.
A Briggs Animal with the stock stroke crank and a bore of 2.833" give you 13.9 CID.
The big bore un-shrouds the valves for much better flow than a flat head will ever allow.
It also can make more compression than a flat head will ever make. Hence, it will make more Horsepower.
The other option is to use the flat head stroke crank in an Animal and smaller piston if you want to get right at the 14.5 CID.
However, the smaller bore will shroud the valves somewhat.
 

Open-RPM

Member
Racer223
In answer to your question, there are a few different combinations of bore-stroke that will get you to 14.5.
One is +.150" stroke/ +.100" bore; Some other combinations are:
+.100" /+.120"
+.200" /+.080"
+.300 / +.025"
 

Open-RPM

Member
Also, another combination that some people like to use, is a Std. stroke / .180" or .190" over bore. This is a very safe, durable way of getting to 14.5, because it allows you to keep the 1.75 to 1, or ~1.85 to 1 Rod/Crank ratio, and there is no extra clearancing that would have to be done inside the engine, like there would be for the stroker. This large bore also does what Jimbo just mentioned, except in this case, it would bring the piston closer to the valves, which shortens the distance that the air/fuel mixture has to travel. This means that more of it will get over to the piston, in a shorter period of time, thus making more power. You can also offset the bore, bringing it much closer to the valves, and this will also improve the geometry inside the engine. This, combined with bigger valves, then cutting down the deck area in the remaining space between the valves and the piston, will dramatically improve the flow in a Raptor, or any open flathead. We're not even mentioning the ports, carburator, combustion chamber, etc.
 

racer223

Member
I have picked up 5 raptor blocks in the last 6 months, and a used Lunati +.150'' crank. I am not in the south, and don't race the Big O, however I really want to make it back there one year to watch. But I thought it might be fun, and possibly gain some interest here on the west coast, to put something together and play. Maybe some folks would get interested in a class like this, since most folks out here poo poo clones and are die hard 2 stroke for like type guys.
 
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