Re: Merge collectors
 

Calvin, a couple of questions. I've got a set of your 4-2-1 headers on my 327/275 stocker motor and want to spend some time on the dyno this winter doing some camshaft work.

- Is backing up the exhaust duration by 4 degrees is a good place to start. Your thoughts?

- If an engine really is over scavenging due to the header design, what are some of the things to look for on the dyno or the track?

Thanks for joining in. -Al

Re: Merge collectors
 

I tied a set of headers together on Line's dyno and picked up five foot pounds of torque with no other changes. A two into one set up. Back to Jack Davis, he told me he made a set of two into one collectors for a NASCAR team. When they ran their car at Michigan the car was so much faster that Nascar banned the two into one set up. Hence they went to the "X" pipe. All we are trying to do is to keep fifteen pounds of atmospheric pressure from running back up the pipes. The fewer openings you have for the exhaust pulses to exit the better headers and collectors will work. Just think of how small that exhaust pulse is at six to eight thousand or more r.p.m.

Re: Merge collectors
 

I'm not understanding what you're trying to say. If X cfm of air and fuel is going in then X cfm of air and fuel must be coming out. The exhaust pulse may be getting faster(and stronger) but it's not getting smaller!

Re: Merge collectors
 

So, we are supposed to buy the trick of the week header, then build an engine combo around that?

Re: Merge collectors
 

Ed you hit the nail on the head! I've been saying that for years. Here's a bit of wisdom from Scott Burton who once told me when we were discussing this subject, "You will never spend more money and get less gain than with headers." Nuff said.

Re: Merge collectors
 

Ed, I know you work more than most people on your combo, you are very innovative, and it shows. I think what is being said is really right up your alley. When you change one thing on a car it affects other areas (Law of Unintended Consequences). For instance if you found 50 hp with a new fuel injection system you may need to work on the chassis/suspension, or even the camshaft to lower the ET or possibly find even more power.

I had a highly, highly respected engine builder tell me, in front of another engine builder, I was stupid for even thinking I knew more than him about headers... the headers he recommended were the best for the combo. Well Calvin's headers were .13 faster than the headers the engine builder recommended, and we did find more. With our small block we went 4 years before we lost a heads up race, and that was totally my fault for taking the competition for granted.

Some who have worked their a$$e$ off refining their combinations with Calvin's headers (as well as others) have found significant HP by keeping all events on the cam the same and only closing the exhaust lobe earlier. Mind you these are people who were already at the top of their game.

When you are already at the top of your game how much money/time would you spend for 15 HP? The exhaust on a Stocker/Super Stocker has not changed much since the classes inception. Yet the engine development has changed radically. Why would you not work on an area most overlook because "it is just a set of pipes."

NASCAR was revolutionized by Calvin's headers. One of NHRA's winningest drivers has used Calvin's headers for numerous wins and speed/ET records. These are teams/engine builders/drivers who are paid to be innovative, or they have no job.

Bill

Re: Merge collectors
 

We've talked a lot about diameter but what about length, is equal length still the standard or is there any experimentation in tuning length to each cylinder?

JimR

Re: Merge collectors
 

You bring up a very good point with this question. Look at the stocker intake manifolds, do they have the same runner length?? NO!! so when the header builder like Calvin ask you to stagger jet, you ask him why?? Well thats why. Different cylinders will appreciate different tube lengths. Especially in a step header, stagger the steps and watch it pick up power!! The easiest way to see this is with your EGTs on the dyno.... well then again, everybody doesnt dyno...

Carry on.....

Re: Merge collectors
 

Maximizing each cylinders potential is what the fastest engines are best at. The dual plane intake and short/long intake runner ports create a real challenge to this goal. We have been stagger jetting, varying the lash and timing to compensate, as well as having multiple pattern cams of late. Cylinder specific tuned headers has been on my mind, and even suggested as a "cure" for the runner issues several years ago to me by a person who's opinion I respect.

Sneaking up on advancing these combos and with all the R&D that has been exhausted (pardon the pun) over the years, I can't begin to imagine the potential curve balls that await header tube per cylinder tuning. Anybody want to spend a month on the dyno with a header fabricator? That's out of my budget.

Re: Merge collectors
 

Don't need a month on the dyno. Did it with Jenkins about 8years ago when I worked with those guys now known as black arrow racing engines. We staggered the steps on certain tubes in an effort to equalize collector pulse timing and it worked!!!

I will jus sit back and let Calvin share his knowledge. He is far ahead of me. Yet some guys won't even listen to him.... I don't think there is a combination he couldn't speed up for any racer who frequents this forum. In the long run,he would save people a bunch of money and testing.... Well we know that story all to well...