Coefficient of drag X Frontal area, Bonneville dreaming.

[Bob Holmes]

With Bonneville Speedweek just about a month away, its time for my annual pining for an LSR build. So I ask all of you gearheads out there "which Ford vehicle has the lowest CD and smallest frontal area?"

I've been looking at a Ford 2g Probe for a while as the most likely. Relatively narrow with a pretty good CD number. I'd have to back half it and get the correct wheels driving it, which puts it in the "Altered" category.

[Bob Holmes]

Ah, here's my favorite arerodynamic site for cars:

http://www.mayfco.com/dragcoef.htm

I keep looking at the Ford Fusion, wondering if it would be better?

[Patrick]

I seem to remember something about the Probe being the lowest drag coefficient body as well.

Bob, you really need to build an anal Probe. It would keep Meotchh away.

[Bob Holmes]

I thought Meotch WAS an anal probe.


My recollection is the same. We'd be running against a bunch of records held by '80s Camaros and Trans Ams as well as a Honda. The Probe has a marginally better CD and FA, but I think it has a shorter wheel base. Which is important for stability.

I think I 'd start with a small engine, something under 2.0, that's where the class break is. I could fiddle around down in the 1.5 liter area, as well. The next larger class break is ~3 liters, which means I'd probably look to step up to a V6.

I'd prefer to stay with a blown fuel category. I think it'd be easier than spinning a NA engine to 10,000 plus for 7 miles.

[Patrick]

OOH, have I got a 2 liter Ford old school cylinder head for you!!!

[Bob Holmes]

Tell me more, tell me more!!

[Bob Holmes]

I've been thinking about using the dual plug head, and a lot of boost. The car would run on "fuel" which is anything but the event gas. Could be methanol, ethanol, E-85, Nitro, or gas with NOS.

[Patrick]

I have a fresh Formula Ford 2000 OHC cylinder head from a major pro racing FF engine builder just sitting here. I was holding off for a vintage racer to ask for it. All new stuff with certified numbers on parts.

Basically, a 2000 OHC engiine is the precursor of the 2.3. Ford just multiplied all the dimensions by 15% to get up to 2.3 liters.

[Bob Holmes]

Any idea what it flows?

[Patrick]

My educated guess is 15% less than a 2.3 head.

I also have 1.8 and 2 liter aluminum 2 valve Nissan OHC heads, which survive turbo applications quite well.

[Raven855]

Do a Volvo head with Vizards' polyquad design. Use a Cummins turbo for inexpensive, give it some compression and some good pistons and go have some fun.

[Patrick]

Do a Volvo head with Vizards' polyquad design. Use a Cummins turbo for inexpensive, give it some compression and some good pistons and go have some fun.

How would you get it down to 2 liters? Sleeving it down would add more obsticles. Destroking would mean a very expensive crankshaft and longer rods. Bob, what are the rules? Any restrictions on # of valves per cylinder?

Maybe you could borrow Beck's magic 950 Holley and convert it to a blow through configuration!

[MikeFleming]

Or you could start with a purpose-built new engine that is under 2.0L and already comes turbocharged with all forged internals? Like the 4B11T.

[Bob Holmes]

The rules are basically open when it comes to engine design. The engine classes are segmented by displacement. Then you get to choose whether or not it is NA or force inducted ("blown") then you decide whether you will use the event supplied gasoline, or "fuel" which is anything else.

Driving at Bonneville is particularly tricky as the coefficient of friction on the salt is very low. So starting with a small engine is probably smart. Probably the best thing would be to just use a 2.3t the first year, you're really just there to learn.

I'd like to have a 200mph capable car. I'll have to do the math to figure out the rwhp necessary to do that with a Probe.

[Bob Holmes]

According to the "Mayfield curves", 200mph would take about 400rwhp with a CDxA of 6.39. When the Probe is lowered and receives the aero enhancements allowed in Altered class, it'll have a lower CDxA than the 6.39.

My existing racecar engine can easily exceed that number with a bit more boost.

Someone just called and asked me if I'd sell a bunch of my unused woodworking equipment. There may be a car purchase in the near future.

[MikeFleming]

My existing racecar engine can easily exceed that number with a bit more boost.

You really think you could keep it running for 12 miles?? Or do you run the short track for that speed?

[Patrick]

Mike may be right. 12 miles is a lot to ask from Bob without blowing something up.

[MikeFleming]

Maybe he could enter into a two-engine class and only blow up one of them? After all how often do you get a chance to test your fire system at 200MPH?

[Patrick]

Maybe he could enter into a two-engine class and only blow up one of them? After all how often do you get a chance to test your fire system at 200MPH?

Check the BBQ'd Porsche in-car video hilights from the Watkins Glen 6 hour race on 7/1/2012.

I'd say "very cool", but it got rather hot.

http://www.youtube.com/watch?v=cCa9NoDO_i0

[Bob Holmes]

There are 3 courses running at the same time. Two short courses of 5 miles, one 7 mile. (Yes, I'm ignoring your joke)