Hi all,

Didn't really know where else to put or ask this. Sorry if this isn't advanced enough for this section.

Saw this the other day and something struck me a odd about it.

"How the heck did he get to a 260" SB2??"

The article talks about using a 2.454" stroke which makes sense, but Keith would have had to use an enormous rods on something with a deck height of 9.025". Turns out he used 6.350" rods. Wow.

Hmmm that's a rod stroke ratio of 2.6....that's getting to be F1 territory.

I understand that the long rods are a function of the stroke and deck height, but do you think there are issues (increased BDC speed/crank vibration, weird ignition curves) that would have to be addressed for that thing to live on the salt flats?

Also getting an LSR valve train to live at 9500-9800rpm is pretty impressive too, but another day/thread.

Thanks for any ideas....kind of scratching my head over here.

Ocean

 

I don't think he was really worried about rod/stroke ratio when designing that engine. Most professional builders couldn't care less about it. With such small engines, high rod/stroke ratios are pretty much inevitable.

 

Hi Oceanside, thanks I enjoyed Keith's site.

My guess is a ALM SB-2 "short deck" block, I will ask Keith.

My friends in England used a 1.35 R/L in their 20K RPM engines even shorter at times.
They used Valve Springs made of AIR, thus little mass.
They, some teams, had Camless engines with Poppet Valves
They use different rules today, I am sad that art was not further developed.

Lance

 

Hi Lance,

If you could ask Keith and find out more info that would be great! I kind of have an interest in screamer motors and not a lot of info around them.

Thanks!

Ocean

 

We have built some 290ci or less SB2s and 13-18* engines for asphalt outlaw late models. We have the tooling here to finish up the GM aurora blocks down to a 8.200" deck height. They make good power and camshaft can be a bit funky to create a smooth not so tweeky power band.