I've been following the Pure Stock Muscle car drags for a few years now.
How does..lets say,one LS6 car run mid 13's at 101-103 MPH and another run mid 12's at 112+MPH?
Now,tuning is key here along with paying attention to detail,but how do they tweak the extra MPH out of these cars? For me to go 10+ MPH faster would require me to spend cash (cam change,head porting,etc)
..and these guys are running stock rockers,exhaust manifolds,etc.
I mean,you can only gain so much with timing and jetting.
These guys constantly amaze me.

Originally posted by mr 4 speed:
I've been following the Pure Stock Muscle car drags for a few years now.
How does..lets say,one LS6 car run mid 13's at 101-103 MPH and another run mid 12's at 112+MPH?
Now,tuning is key here along with paying attention to detail,but how do they tweak the extra MPH out of these cars? For me to go 10+ MPH faster would require me to spend cash (cam change,head porting,etc)
..and these guys are running stock rockers,exhaust manifolds,etc.
I mean,you can only gain so much with timing and jetting.
These guys constantly amaze me. Remember that these cars are not limited to stock stroke. Some have spent the $$$ stroking the engines. More cubes = more MPH. I talked to one of the guys with a Hemi car at the FAST race here in Atlanta earlier this year. I don't recall the specific CID but I think it was around 487 cubes.

EDIT I misread and thought you meant FAST class. My bad...

ENGINE Engine must be correct for the year and model. All major castings, block, intake, exhaust manifolds, and heads must be correct for the year and model. Engines may be overbored .060 . Engine compartment must retain it's original stock appearance, no aftermarket parts, ie. valve covers, or air cleaners are allowed.
All belts must be in place, air conditioner belt may be removed if other components are not affected. Car should sound stock! If your car had a smooth idle when new, it should have one at the track. Any doubts about engines ........ call.

With these rules it would be relatively easy to pick up significant performance over stock.

http://hometown.aol.com/lamgmt/rules.html

Certified Pure stock is what I'm refering to

Look at NHRA stock. The cams thoses guyss run are stock lift. Take a 69 camero with 275hp 350 they are running in the high 12's. They can run headers. The cams are stock lift but the lobes look like a roller cam almost a square lobe. There a whole lot of tricks they can do. I have know one guy that woud run the cast Badger pistons for the 275hp 350 pressed on backwards. To give more hp. This guy had more tricks up his sleeve that a card cheat and the were all legal. BTW they are now running Pro Stock and in the top 15 in points last I checked.
John

I think the cam profile has a lot to do with it. I can remember installing a "cheater cam" from a '71 LS5 motor that ran in NHRA stock into a street driven 454 motor years ago. It was correct in lift and lobe separation, but the factory advertised duration numbers leave a wide window for what actually gets ground. Crower for example advertises a "cheater lifter" that looks like a hydraulic but is actually a solid. Add to that, all the tolerances that are corrected during blueprinting (deck ht., combustion chmaber volume, plate honing cylinders- I assume they can use lite wt versions of stock pistons with low tension rings in these). Probably a dozen other engine building tricks thrown in there.

Another thing I've heard of doing. Is actually cutting grooves in the bearings (crank, rods, cam) This reduces friction by removing surface area that the components ride on.Granted your limited to the number of runs you can make before having to replace bearings. But less friction frees up HP!!

You can gain quite a bit through proper timing and jetting. We used a Innovate AFR meter to tune mine.
Proper assembly and huge attention to every component detail is also a big reason.

I used to work with a guy that ran pure stock (local stuff)in the mid 70's with a 70 GTO RA4,it ran 13.40's thru manifolds and BFG radials 4.56's & stock converter.
The record was 11:70 or so I think.
This was a DS/A most of these musclecar's would fall in that class or lower.
With headers and slicks ran in the mid 12's @109mph.
You have to tune your ride and live at the track for a while.lol
I would think a BBC,Hemi,or should mph higher.

Nick,nice 442 graemlins/thumbsup.gif
Impressive times as well!
MPH you guys pull is amazing!

Originally posted by mr 4 speed:
Nick,nice 442 graemlins/thumbsup.gif
Impressive times as well!
MPH you guys pull is amazing! Thanks, mr. 4 speed. smile.gif
I don't quite qualify for Pure Stock because of the 3" exhaust. Largest you can have in Pure Stock is 2.5".. for now. Other than that, everything else with my car would qualify.
I still need to learn to get my 60 foot times down but I just can't bring myself to dropping the clutch at 4000 RPM. Right now I'm bringing the revs up to about 1800-2000 and quickly getting on the gas and bringing the clutch pedal up.
This year was the first time I'd ever gone to a track (4 days in total - 17 runs) and I found that it has been challenging to have consistent launches with the 4 speed. Started with 2.4 60's (13.30's @ 110) and the last time out got to 2.1's. Not great but I'll work at trying for sub 2.0's next year.

Can you run high compression, i.e. 13:1 vs 10.25:1 stock>?

4 speed, I have talked with these guys via email alot and I have learned many things.

First of all look a the NHRA specs for the engine,
http://www.nhra.com/tech_specs/engine/
I mean anything 1969 has a real advantage, i mean 103CC chambers and a 40.85CC dome piston on the 375 horse 396's. Thats roughly 12-1.

Then in order to make that 12-1 work most guys retard the cam which helps the DCR and also kills some low end torque. Believe it or not low end torque really gets to be a problem when you have a 7 inch contact patch.

All the cars that are certified stock, are stock, no if ands or buts. Camshafts are messured for both lift and duration and starting this year LSA. This engines are torn down checked and reassembled on site.

The heads are allowed a three angle valve job, in which a professional can gain 15HP easy over stock.

Then the exhaust has a X-pipe and 2.5 inch exhaust along with some real good mufflers imo.

So all in all the engines are pretty stock, thats not where the tricks come in.

The tuning is very precise, lots of dyno time, lash and timing curves for the lash settings. ALL THESE guys are masters at tuning.

The tricks come in at the suspension level. Nuts are left loose on control arms and any other lift limiting parts. Sway bars are thin, I mean like a 6 cyl car has. Springs are 6 cyl with A/C spacers more or less. I have been told motor mounts have been moved, I though I have no hard evidence. Front ends are aligned 2.5 inches lifted for less rolling resistance once moving. Trans and conv. are "stock", I dont think they are. That faster cars have deep gears.

1 mag wrote an awesome article about copo pete and shared a lot of knowledge about his ZL1 camaro. Might be CHP.

All in all I respect these guys for there achievements and I love the fact they are representing what racing used to be. I do plan to attend more races and build a car for this racing. I think this racing is the most enjoyable I have ever watched, every one is great!! But in my mind these cars are not fresh from the showroom cars.

I too am in amazement what these guys do with those cars. Its unbelievable!!!!