Re: Titanium Valves in SS
 

According to the class guide, the P/W factor is 7.65. That is SS/D.

The confusion may have started because of the two different methods to determine class when replacement heads are given a different power rating.

Method 1: If you say that the calculation is based on shipping weight, then the classification for the aluminum head is calculated by the different power rating divided into the shipping weight and results in a new P/W factor not listed in the Class Guide. (65 Corvette 396 shipping weight is 3022 lb / 411 = 7.35 or SS/C. The car can run in SS/B, C or D. This may be how Jimmy is getting the car classified in SS/B.)

Method 2: If you say the calculation is based on the P/W factor listed in the Class Guide, then the classifications stay the same as indicated in the Class Guide, but the weight changes. (65 Corvette 396 P/W factor is 7.65 SS/D so it runs SS/C, D or E. The minimum weights for the classes is based on the power factor with aluminum heads aluminum heads.).

I have had this ongoing conversation with people from NHRA tech for several years and the opinion/answer changes. The last statement from them was number 2.

Re: Titanium Valves in SS
 

Dwight - with all due respect, there is only one method and that's to look at what it says in the NHRA classification guide, see that it says 7.65 @ 411 and to abide by it. No need for a calculator.

Now if anyone feels the 7.65 was put in the guide by error, then take it up with NHRA and hash it out. In the mean time, this combo should be raced at 7.65 with a HP rating of 411.

Re: Titanium Valves in SS
 

I bet if it had been another make the tune would be different..

Re: Titanium Valves in SS
 

As I said, I have been having this conversation with a variety of people at NHRA Tech for a long time and the method/opinion has changed back and forth depending when and who you talk to. I agree that the current consensus is to use the P/W factor found in the Class Guide to determine the class, and use the power factor to multiply to find the race weight.

It has not always been that way.

Re: Titanium Valves in SS
 

Straight from the rule book, "The power-to-weight factor is the shipping weight of the vehicle divided by the advertised, or when applicable, the factored horsepower for the OEM-assembly-line cylinder heads. NHRA-accepted aftermarket cylinder heads carry a horsepower penalty that is calculated to the weight of the vehicle and does not change the class of the vehicle."

I'm not sure when this verbiage was added, but it's in the 2017 and 2018 rule books.

Edit: just realized this quote was already posted on the last page, oops.

Re: Titanium Valves in SS
 

I'm all about rules, but this is getting mighty expensive!

Re: Titanium Valves in SS
 

I would be all in for the option of running titanium valves. I change both intake and exhaust after every season. Blowups like the above pics keeps me awake at night.

Re: Titanium Valves in SS
 

The 5/16ths stems on the Hemi valves is definitely scary. A broken engine in the traps with a 68 race Hemi running close to 160 mph could cost a life. A diaper can hold some of the oil but a 4 spd car could lock up the wheels almost instantly. At that speed it only takes a second to get a car out of shape.

Re: Titanium Valves in SS
 

You wouldn't change them if you could use titanium?

Re: Titanium Valves in SS
 

Dyno, if you are going to hang around with WALDO, don't stay up at night. All my KABOOMs were self inflicted. Two step unhooked, throwout bearing too long. Yata Yata BUT it would be nice to get the steering out of the motor, kind'a like the new cars which go as fast or faster. Had to fill out NHRA oil down sheet after Indy, "kind'a hard to pull over with a connecting rod jammed on your drag link."
Had to use a bigazz hammer to get it off. This is Holt's stuff, which use to fit perfect. Jane wants me out so we will see. That draglink tube intrusion happens in the traps, ya'll could have had a RIP thread. ME3