Re: How about those ford cj's at vegas
 

Will we be seeing more CONVERTIBLE Mustangs?

Re: How about those ford cj's at vegas
 

normally you would be right but they went 1.40 under the SEA LEVEL index

Re: How about those ford cj's at vegas
 

Kenny, 1.40 under the sea level index at any track is automatic HP.

11.30 index
-1.40
9.90 or below

Re: How about those ford cj's at vegas
 

They won't have to carry 112 lbs. more because they will only be legal for AA/S and AA/SA with their new factor of 7.38. They will only have to add weight to get to the 7.50 AA/S and AA/SA factor. In A/S and A/SA their class minimum weight was 3400lbs (8 x 425); now their class minimum will be 3293lbs (7.5 x 439). As I see it, the main effect will be that they will have to run off of the much tougher 10.90 AA/S and AA/SA index instead of the 11.25 A/S or the 11.30 A/SA indexes.
Bill Seabrooks - superfan1
Bridgeport, Ct.

Re: How about those ford cj's at vegas
 

After taking a second look at the Classification guide, at 425 HP the CJ convertible has a factor of 7.82. When the 14 HP is added, their factor will be 7.57, so they will still be a "natural" AA car; therefore the convertibles will still be able to move down to A/S or A/SA.
Bill Seabrooks - superfan1
Bridgeport, Ct.

Re: How about those ford cj's at vegas
 

EVAN; Your comments on effect of altitude on a supercharged engines performance are correct, except that you forgot to mention the offsetting effect that helps to keep these cars faster at tracks such as Las Vegas. Since a blower takes HP to compress the ambient air, less dense air will lower the blower output pressure, but will also lower the Hp needed to compress it. The power needed to run a blower is significant, so the 'gain' from reduction in load is also significant.
Steve

Re: How about those ford cj's at vegas
 

Steve,

Can I assume that you've measured the differences at different boost levels in order to report these findings? In theory you are right, but we are talking about small changes in boost level from good air to bad air. Probably 3-4 psi on the CJs from sea level to Vegas. The cost to drive the blower for that extra 3-4 psi is very, very small.

I've tested over 100 blower cars with all types of blowers over the years and while I've not measured crank hp, save for one time on a 1,200 hp engine, I can tell you the loss in power from adding a few pounds of boost is not a lot. In that case it took upwards of 250 hp to run the blower. I would guess a change in boost, even at that level, would have very little effect on overall power loss/gain. Again, in theory you are right, but in practice the gain/loss is not what you think.

Most blower engines are designed to run with boost pressure so even if you removed the blower it wouldn't give you a fair result on power because the engine would likely be inefficient with no boost.

Evan

Re: How about those ford cj's at vegas
 

I was just wondering if anyone else noted the increments on Don Fezell's CJ in Richmond. To compare go to http://www.nhra.com/livetiming/livetiming.aspx and click on Race Archives. Find Virginia NHRA Nationals and click results. Compare Friday's Q1 increments to Sunday's R2 increments. They are pretty amazing!

Re: How about those ford cj's at vegas
 

robert pond can run the 2-4 setup!!


Stephen Johnson #2162
Horace Johnson #2167
SS/D 427 Ford Fairlane NHRA-IHRA

Re: How about those ford cj's at vegas
 

The guys complaining about horsepower numbers must be GM guys.Take a 375hp,396,same specs as a 425hp,396,soooooo.Think of the many hp factors for basically the same 350 chevy engine.NHRA has always facrored according to who makes the most noise and who is their biggest sponsor at that time! JMO,got out of "stock" in the 70's when it was getting stupid! ROY.