Cylinder head flow - What is crucial in a stocker?
 

I realize that most stock eliminator engines don’t have what we would call “high” amounts of valve lift. But my question is, considering the amount of dwell at maximum lifts due to our day long durations, where is improving the flow and velocity more crucial? Is it low lift, .100-.300 or what we’ll call higher lift of .350 and up? Typical engines we would not consider maximum max lift flow numbers for much more than bragging rights, and would consider the low and mid lift to be more important as the valve passes through that area twice, which yes it still does, albeit extremely fast. Obviously improving it everywhere is the best case, but often what improves low lift can hurt the high lift and vice versa. So what is the more critical area of improvement in these situations?

Re: Cylinder head flow - What is crucial in a stocker?
 

I got the popcorn popping for this one !!!!

Re: Cylinder head flow - What is crucial in a stocker?
 

I predict the sound of crickets more than replies ... hopefully I will be wrong

Re: Cylinder head flow - What is crucial in a stocker?
 

Yep...

Re: Cylinder head flow - What is crucial in a stocker?
 

Has anybody ever graphed their head flow against their cam?


Have a look at this thread


http://classracer.com/classforum/showthread.php?t=76576



Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

Yes, been doing it for years even before computers...using graph paper in the early days.

Re: Cylinder head flow - What is crucial in a stocker?
 

Chris, I thought you used Mr. Armstrong for your machine work. If so, I'm sure he is more than capable of helping you out. You don't get much better than those guys. Don't know if you knew your Chevell is purple because Chris Fuller loved the color. BP

Re: Cylinder head flow - What is crucial in a stocker?
 

I think those crickets hurt our sport sometime. I know people who have spent mega bucks on cars that they can’t make competitive and give up and find a new hobby and that’s one less voice for drag racing. These days when you don’t know how long ya might be around or how long the great smell of racing gas is going to feel the air might be time to let out a few secrets. Lots of great help on here but everyone knows the best secrets are locked in a vault.
Terry

Re: Cylinder head flow - What is crucial in a stocker?
 

Good morning Chip and to all,
Boy did you open up a can of worms on that question.
All I can tell you is - Its complicated!

Respectfully,
Henry Kunz 1534 H/SA

Re: Cylinder head flow - What is crucial in a stocker?
 

Yes, it is! And it will vary from combo to combo.

Re: Cylinder head flow - What is crucial in a stocker?
 

I don't know if this is what you are looking for.
These are my basic rules:
.100" lift, don't waste your time making this flow.
You want the most flow at the fastest piston speed areas from 1/3 through 2/3 of the stroke.
I don't monitor this page much, so any questions, please message me on my FB page.
Thanks
Chris Hardy
RET

Re: Cylinder head flow - What is crucial in a stocker?
 

You can also look at what some call "Piston Flow Demand". This is calculated by using engine RPM (Time) and change in Volume above the piston. This graph is a 305 ci @ 7000 RPM

Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

What I can tell you is this. You can take a sbc stocker combo, put decent shortblock in it, do only the allowed valve job to the heads with best valves and springs, assemble with the latest greatest cam and lifters, put it in the car with a name brand carb, name brand trans and converter and I can almost guarantee you won't be within 7 tenths of the top cars with that combo. SO....heads and intake are 90% of the power. Plus if they really answered your question then they couldn't charge $5000 for a set of stocker heads and $1800 for an intake lol

Re: Cylinder head flow - What is crucial in a stocker?
 

Pretty much the state of the union, right?

Re: Cylinder head flow - What is crucial in a stocker?
 

On the same thought you can and I am guilty of this, give someone the best engine and drive train and be .07 slower than the fast guys. Friends are the cheapest increase in performance.

Re: Cylinder head flow - What is crucial in a stocker?
 

If I may, I would like to make a small correction to your quote;
Listening to friends is the cheapest increase in performance.

Re: Cylinder head flow - What is crucial in a stocker?
 

I think when it comes to performance advise don’t let who is telling you they are the best work on your stuff go to the track and all the cars that you are amazed by let whoever they say is the best that’s who you want working on your stuff. A lot of our drag racing heroes know more than the guys at the machine shop. I know I used to work in a machine shop and when some of the old school drag racers came in and started spitting out cam tech and stuff then when they left I’d be standing there looking like Dewey Cox after talking to Elivis in the movie walk hard.
Terry

Re: Cylinder head flow - What is crucial in a stocker?
 

What percentage of ET do you think is attributed to, suspension, shocks, weight distribution, transmission and overall set up of chassis?

Randy Wells
I/S 5628

Re: Cylinder head flow - What is crucial in a stocker?
 

A decent portion. In my case I am refering to a proven car that has been a second under.

Re: Cylinder head flow - What is crucial in a stocker?
 

So, let's take a small block chevy. How much HP do you think it takes to pick up a tenth? To make it easy let's say a 69, 350/255 hp combo. BP

Re: Cylinder head flow - What is crucial in a stocker?
 

Just a rough guess. Around 12.5 HP.


Let me revise that to around 9.4 HP.



Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

I'm not attempting to doubt Stan's calculation but if we average it through the spectrum of the most commonly used combinations it's going to be roughly 10.0.
So of course based on the original question on flow of the intake and efficiency of the reversion on the exhaust side and based on a 88% + cylinder seal I believe you better have your ducks in a row to compete with the big dogs. One of the keys is chassis efficiency for sure.
If you can't run with big dogs, don't stay on the porch, find out why, it's not always $$$, it's dedication.

Re: Cylinder head flow - What is crucial in a stocker?
 

How did you come up with that number ?

Re: Cylinder head flow - What is crucial in a stocker?
 

You want to manage the air on the outside of the car as well. Case in point on the truck the bed was off to one side. We centered the bed behind the cab and it picked up a little in et and MPH. An easy way to cheat is to cheat the wind.

Re: Cylinder head flow - What is crucial in a stocker?
 

I ran some 1/4 mile drag simulations. After I ran the first one I realized I had used to fast of a car and reran it. Both my numbers are still only guesses. It is possible Frank's number is correct. This number will vary based on the class with A/S being greater than U/S. What is the weight of the car and what does it run for both et and MPH?


Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

Yes anything you can do to reduce Frontal Area or Coefficient of Drag (CD) will show up in reduced et and increased MPH.

Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

I have Chrysler's old formulas and graphs and I made my own with the info that I had back in the early 90s when I had my first machine shop. I'll scan them if I can find them but I seem to remember at 3,300 lbs a 12.20 et is about 10 hp per tenth, a 9.80 at the same weight is almost 17 hp per tenth. I broke it down from 9.50 to 16.0 and different weights can be used, a heavier car at the same et will require more hp per tenth.

Re: Cylinder head flow - What is crucial in a stocker?
 

In the 1980's when I was involved with IMSA and SCCA road racing with the Mazda Factory Team, we were applying an industrial spray-on wax to the car paint finish that was manufactured by either Dow or DuPont, called Microfill. The intent of the wax was to fill the microporosity of the paint, enhancing the airflow over the body surface of the car. As I was told at the time, Mazda had discovered some aero improvement in the wind tunnel by applying the wax. At the time, the cars were being painted with DuPont Imron Epoxy Paint.

Nowadays, there are many products that contain nanoparticles with a ceramic compound that may do the same.

Re: Cylinder head flow - What is crucial in a stocker?
 

So, lacquer primer...not so good, huh? :-(

( I was going to comment on the subject of this thread, but I don't want to stink it up, so I'll start a new one..Meanwhile, I've got to go and buff out my car for next weekend;-) )

Re: Cylinder head flow - What is crucial in a stocker?
 

Remember aerodynamic drag HP loss is not linear. This graph shows what a change from 0.35 to 0.34 for CD does.

Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

LOL! :D

On a small Cessna airplane, waxing the exterior increased the airspeed by 3.5 MPH

Re: Cylinder head flow - What is crucial in a stocker?
 

Dear SSDiv6,
I will throw this add up to your paint preparation subject and just for discussion or the fun of it (with no disregard to your point) an even if this isn’t in direct relation with the title subject.
I was at the Napierville Nationals Open Series few years ago and I was taking a close look at the NHRA “open tech barn” at the back of the tower. A certain stocker had his engine check for the approval of new E.T. record, for the second year in a row.
While waiting and checking the Tech’s work, the car parts, suddenly a small detail pop-up… The golf ball effect…The car had a good or important orange peel surface…

Re: Cylinder head flow - What is crucial in a stocker?
 

I was once told by a racer that after he had a vinyl top put on his car he picked up MPH...?...
Fact?... or fiction?...

Re: Cylinder head flow - What is crucial in a stocker?
 

Earlier in the thread somebody mentioned price. I bought my heads from another racer. So I don’t know. But is that accurate $5,000 for new stocker heads and $1,800 for an intake? And is that assuming you supply them with good cores to start with? I’m just curious. If you think about it. Even if you knew how to do it and what do do. By the time you bought all the equipment to do it. You’d have to do probably 100 sets of heads or more to break even on used equipment. So in the end for most of us it’s still cheaper. Although expensive. Plus you theoretically get all their R&D as things advance over time. Again I’m just curious at some point I’ll get a new set. But for now these ones I have will have to do. If you don’t want to say here. Feel free to PM me.

Re: Cylinder head flow - What is crucial in a stocker?
 

Air is different than water, or is it? anybody that messed with overpowered outboard boats knows that primer is faster than smooth and shiny on the pad and the lower unit, 4,5 or 6 mph and how you go from stuck in the upper 90's to breaking triple digits......that "theory" that has been proven also applies to cylinder head ports...but what do I know? the "experts say, size matters more", not flow

Re: Cylinder head flow - What is crucial in a stocker?
 

You missed one, velocity. CFM, CSA, and Velocity are like the 3 sides of a pythagorean triangle. If you know any 2 the 3rd is easily calculated.

Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

Stan I wouldn't argue anything about machine work with you, but I disagree on the HP needed. Maybe in a lightweight car. But in my 40 plus years of running stockers I'd say more like 15 to 18HP. The point I was going to make if someone can pick up .7 with an intake and heads you must have some pretty bad heads to begin with. Just a few years ago it was 8hp difference with an intake on a small block stocker. If someone is getting much more than that I would love to see it in tec at Indy.
Using the 15 hp number to go .7 you would need to pick up 105hp. That would be 97 hp from head minus the intake. I think I use one of the best out there but if you have someone that can get me 100 hp from a set of heads please let me know. BP

Re: Cylinder head flow - What is crucial in a stocker?
 

Barry,
I don't have time to optimize these simulations.


60 Foot ET = 1.3610
330 Foot ET = 4.0108
1/8 Mile ET = 6.3058
1/8 Mile MPH = 106.6345
1000 Foot ET = 8.2990
1/4 Mile ET = 9.9840
1/4 Mile MPH = 134.2295

60 Foot ET = 1.3746
330 Foot ET = 4.0519
1/8 Mile ET = 6.3693
1/8 Mile MPH = 105.5199
1000 Foot ET = 8.3839
1/4 Mile ET = 10.0866
1/4 Mile MPH = 132.8920


Race weight with driver 3375 #. 17 HP difference


Stan

Re: Cylinder head flow - What is crucial in a stocker?
 

Thanks Stan, it looks like you have a couple of my times slips. Excluding 60-foot times. And it was about 16hp difference. BP

Re: Cylinder head flow - What is crucial in a stocker?
 

Stan I just sold my business. I'm helping with the transition but I'm only working about 20 hrs. a week. Down from 10hrs a day 7days a week. I had 19 employees. What a weight off my shoulders. I'm 66 and feel I should've done it 2 years ago. Don't wait too late. Get out while we have our health. BP