Drag Race Engine

[CNC-Dude]

Extrude honing and acid porting both kinda' fall into a "grey " area. Acid porting is mostly done under the valve area in the bowl, which is harder to detect and see. I think what the tech guys look for is the textured as cast porosity of the cast iron, and any variation. Extrude honing leaves a different look and texture to the parent metal, and could possibly be flagged as "suspicious", and might even require that the head be removed completely for a closer look. Another thing that might lead to a racer getting noticed at all, is by how fast he/she is running. If he/she isn't even running close to the index, or under it, then they might not even get a second glance from the tech guys, other than what can be seen externally. Its usually the racers at the top of the ladder that get the shadow of suspicion cast onto someone how they think is threatening their position, or is running faster than they think that person should be running, especially if they just come out of nowhere and start running the index #'s. The tech officials have a tough job, no doubt, but you would be surprised at how many phone calls they get in a weeks time from other racers crying and complaining about someone else they think is cheating, when they themself are really the guilty party. You would think that racers would be in a more professional atmosphere and conduct themselves more maturely, but its just a bigger sandbox with more expensive toys....

 

[Buddy Rawls]

I did not read thru the whole thread, but I saw comments regarding the stock camshaft. If this is standard NHRA/IHRA stock eliminator, you can do anything you want concerning the camshaft. The only requirement is that the valve lift checks legal for the requirements of the year and horsepower claimed. duration, phasing, etc are wide open. there are some nearly square lobes. And there are stock configuration valve springs that have much better response and load.

I am intimately "familiar" with several cams (see how I skirted the obvious) on the small block Fords. Also the crate motor IHRA class is also allowed this. We had to dig pretty deep to find the intake lobes for this set-up (.422 hyd roller at the valve). Anyway, what i was getting at was that these 5.0L hyd rollers (the stock cam configuration) are running .050 duration in the 240's and 250's. They are so inlet flow limited they need serious help on the intake lobe and correct placement of the exhaust. Also there is some leeway in lobe selection, because when you really check at the valve, the lift can be as much .020 less than calculated.

 

[sctty1986]

which cam are u currently suggesting for the best performance in your class?

 

[Buddy Rawls]

which cam are u currently suggesting for the best performance in your class?

I am not sure if you are referring to me or to the original poster or other poster.

If it was me you were asking about the cam, it would require information of the flows, port volumes and cross sectional areas to determing the true restriction the cylinder pulls/pushes thru. In stock and super stock the engine combinations are so regimented that it is true that a cam in one of the motors will likely look similar to the others (within any specific engine combination). If that did not come out right, what I am saying is that a 64 200hp 283 stock eliminator camshaft will nearly always look pretty similar within the bounds of valve train technology. Not that a stock eliminator 250 six cam will look like a 283 or 289 or a 427 etc.

what does the 250 head flow with the legal carb on it? What does the exhaust flow with actual header installed? given the inlet flow capability and the range of lifts within a range of bench static pressure settings, some gains may can be realized by adjusting the header diameter and then recalculating the valve event needs.