merge collectors

[cjperformance]

Got a pic of your headers or specs?
Cheers

[englertracing]

I lost faith in merge collectors about 3 years ago when dynoing an 18 degree 434 sb chevy. After tuning with our pos weld it yourself kit roadster hedders the thing clicked off 814@7200 which for our dyno is pretty stout. Then switched to his $1500 long radius, stepped tube, merge collector hedders custom built for this engine and after several pulls with some tuning changes it kicked out a blistering 775@7300. Put our hedders back on and without even changing the tuneup hit 808@7200.

do you remember the specifications on these headers?

[proheader]

I lost faith in merge collectors about 3 years ago when dynoing an 18 degree 434 sb chevy. After tuning with our pos weld it yourself kit roadster hedders the thing clicked off 814@7200 which for our dyno is pretty stout. Then switched to his $1500 long radius, stepped tube, merge collector hedders custom built for this engine and after several pulls with some tuning changes it kicked out a blistering 775@7300. Put our hedders back on and without even changing the tuneup hit 808@7200.

May I ask who built the long tube headers and merge collectors?? Can we see a picture of them?? and did you rejet the carb or change the timing for the new headers on the dyno?? Seeing that kind of drop would make me think you put on a header that really leaned the engine out .....

[Ron E]

I've seen good merge headers pick up a tenth in ET while showing the same peak HP as regular headers on the dyno. A major benefit of a good header is helping the recovery RPM range.

[Strange Magic]

I've seen good merge headers pick up a tenth in ET

I've witnessed the same thing when taking the factory cast iron manifolds off.

[Ron E]

I've seen good merge headers pick up a tenth in ET

I've witnessed the same thing when taking the factory cast iron manifolds off.

This was on a BBC stocker. The replaced headers were conventional race headers. I really don't care. I don't make headers. I get no money for this. Next time just let me know if conflicting real-world results should not be posted.

[RevTheory]

Assuming you have a well-sorted cam and optimized ICL for the old headers, if your new merge collectors are pulling harder than the old ones, would the valve area during overlap need to be addressed before deciding that "merge collectors don't work"?

[hoffman900]

I've seen good merge headers pick up a tenth in ET

I've witnessed the same thing when taking the factory cast iron manifolds off.

This was on a BBC stocker. The replaced headers were conventional race headers. I really don't care. I don't make headers. I get no money for this. Next time just let me know if conflicting real-world results should not be posted.

I think when one observes results like that, they need to ask "why?".

As has been pointed out several times here, if the headers were designed well, then it will require a different cam... maybe even more than that. Fancy headers won't work alone for the same reason a 'trick' cam
out of a Nextel Cup engine won't make a street car faster. It's the system of parts, not the individual parts.

The quick to discount and the 'don't cares' quickly leave one running mid pack while the rest of the field moves on.

[Ron E]

"your results may differ" needs to be pasted on every part I guess. I have no parts or services on the stocker mentioned above. The engine builder is a very good friend. The tenth was picked up with only a header change. That only proves his existing combination was better suited for the new headers. I'm not claiming anything other than that. The car had 3 seasons of typical sportsman-level refinement up to this point.
Its not a "mid-pack" car. It was record capable prior to the influx of the new cars.( I.E. among the best of that particular combination.) I'm not quick to discount anything here. I'm reacting to a off comment about real-world results I'm privy to. Nothing else implied.
A custom set of merge/tri-y, stepped headers is probably only justified in a class racing/ non-index environment. I don't think there is much argument otherwise.

[Racing68]

I don't want to post names as they do make a beautiful hedder just didn't work in this app and have heard alot of people see gains with theirs. The set was made specifically for that engine and were tuned on the dyno for max power with that set, which was down in power over the entire rpm range on the engine. What i do remember about them they were about 2 inches shorter than ours, they were stepped 1 7/8 - 2 with long radius tubes if i remember right nothing shorter than 6" radius. Our hedders are 1 7/8 straight tube and a 3 1/2" 4-1 collector, lengths are 32" primary and 18" collector

[Ron E]

I don't want to post names as they do make a beautiful hedder just didn't work in this app and have heard alot of people see gains with theirs. The set was made specifically for that engine and were tuned on the dyno for max power with that set, which was down in power over the entire rpm range on the engine. What i do remember about them they were about 2 inches shorter than ours, they were stepped 1 7/8 - 2 with long radius tubes if i remember right nothing shorter than 6" radius. Our hedders are 1 7/8 straight tube and a 3 1/2" 4-1 collector, lengths are 32" primary and 18" collector

Man, that has to be a hard pill to swallow. I'm not questioning your results in the least. But, the worst I've ever seen is no gains on the track, and that is upsetting. As much as they cost to have made, it would be good for everybody concerned if there was a better way to predict the potential. With the sheer number of variables, I have no idea how that could be done or if its even possible.
It sounds like its a crap-shoot without a development budget reserved for the very few.

[dirtracr5]

I've seen good merge headers pick up a tenth in ET

I've witnessed the same thing when taking the factory cast iron manifolds off.

This was on a BBC stocker. The replaced headers were conventional race headers. I really don't care. I don't make headers. I get no money for this. Next time just let me know if conflicting real-world results should not be posted.

Thats just the way this clown acts. Hard to take anything he says seriously.

[proheader]

I don't want to post names as they do make a beautiful hedder just didn't work in this app and have heard alot of people see gains with theirs. The set was made specifically for that engine and were tuned on the dyno for max power with that set, which was down in power over the entire rpm range on the engine. What i do remember about them they were about 2 inches shorter than ours, they were stepped 1 7/8 - 2 with long radius tubes if i remember right nothing shorter than 6" radius. Our hedders are 1 7/8 straight tube and a 3 1/2" 4-1 collector, lengths are 32" primary and 18" collector

As Elston would say....."we do not race dynos"... do you have some track results with these custom headers?? From experience, I have seen a longer header on the dyno show better power but drag itself down the track once you start seeing real air in the carb....

[Walter R. Malik]

I don't want to post names as they do make a beautiful hedder just didn't work in this app and have heard alot of people see gains with theirs. The set was made specifically for that engine and were tuned on the dyno for max power with that set, which was down in power over the entire rpm range on the engine. What i do remember about them they were about 2 inches shorter than ours, they were stepped 1 7/8 - 2 with long radius tubes if i remember right nothing shorter than 6" radius. Our hedders are 1 7/8 straight tube and a 3 1/2" 4-1 collector, lengths are 32" primary and 18" collector

As Elston would say....."we do not race dynos"... do you have some track results with these custom headers?? From experience, I have seen a longer header on the dyno show better power but drag itself down the track once you start seeing real air in the carb....

I have never witnessed an engine come out of a vegicle, be put on a dyno and tuned with different parts or what have you to make more power in the same ranges; and then go slower in that same vehicle ... NEVER.

However, I have seen vehicles totally mismatched to a new engine power range as removed from a dyno, then need to be changed to more match the vehicle where it is to be run.

It is simply a matter of what one is willing to change for improvement, the vehicle or the engine.

[Racing68]

We did offer to borrow him our hedders for a test day but he declined. I would have liked to see the results of that test also. My opinion on the custom set is the primary was too big in diameter with the step to 2"