MERGE COLLECTORS,WHEN TO USE,HOW BIG A CHOKE AND WHY

[nevdos]

Was wondering when is it beneficial to use a merge style collector, and how do you go about picking your choke point
Are pipemax type program accurate as far as sizing and taper of cones,or do you error smaller to be safe?
Ive gotten some data from pipeamx but it seems the minimum choke is big in relation to some other combos ive seen

Is it worth the hassle to build a set, or would a std collector achieve the same results
Im asking because i believe my collectors may be a bit large at this point so if im to make a change,i might as well go all the way. lol

[67RS502]

pipemax is pretty accurate, but dont expect any real big gains unless would exhsut is restrictive, or sized wrong.

[nevdos]

hey Raff you mind pm me so we can discuss some things
thanks

[englertracing]

With a proper firing order like a 4 cylinder you can go real small like just bigger than a primary tube and then you can attach something like a megaphone and it will run good. You see abrupt large changes in area reflect strong scavenging effect over a narrow rpm range....

Small gradual changes in area can do it over a wider rpm range so you'd use a merge collector to preserve the area increace and spread it along the megaphone.

You only have 6.25x primary tube area to work with.

As for using the choke collectors on a v8. I wouldn't do it with your chitty chitty bang bang firing order unless your working on a set of 180 headers (the bundle of snakes found at the rear of a gt40)

[bigjoe1]

I have had lots of guys come to test headers on the dyno, and some want to try the merge collectors. I never seen anything even cose to what they cost as a result. Usually they are a little better way down in the RPM range, never at high RPM though. A few HP for sat 400 dollars is not a good deal. Pretty much a waste of time and money.



JOE SHERMAN RACING

[Strange Magic]

I have had lots of guys come to test headers on the dyno, and some want to try the merge collectors. I never seen anything even cose to what they cost as a result. Usually they are a little better way down in the RPM range, never at high RPM though. A few HP for sat 400 dollars is not a good deal. Pretty much a waste of time and money.

Ohh Joe, your gonna catch a lot of heat for this one.



But i'll back you up 110 percent. I am one of those who have tested, and personally I think they are a band aid device for an engine that has parts not matched accordingly.

[nevdos]

My concern was that the collectors may be a touch big ,so i was thinking of reducing the collector size and going to a merge style is all
It has a 3-1/2 in collector now,so i was wondering if i go down to a 3" choke ,then back up to a 3-1/2" opening to the muffler would be ok,or if an even smaller choke size would work
I was told that at my elevation and power level ,that a 2.75 "or so choke size would be sufficient
PIPEMAX RECCOMENDS THIS
416ci from 5450 to 7950rpm
Diameter=1.933" to 2.058" Length=26.9 to 29.1"
--------2 step primary pipe specs--------
1st-1.933" length-13.5-14.6"long
2nd-2.058" length-13.5-14.6" long
--------3 step primary pipe specs--------
first step is the same as above first step
2nd-2.058" length-6.7-7.3" length
3rd-2.183" length-6.7-7.3" length

---------collector--------
Diameter-3.525" - 3.775" length- 15.1"
-------megaphone-------
3.025" taper to 4.025" 15.1" long

Best HP & Torque
26.9" length primary

Any opinions on this?
Thanks

[englertracing]

Yeah, scrap it all and build some 180 headers and use even smaller collectors it will make more power and torque all round.

[DaveMcLain]

Buy a set of those venturi collector inserts from Car Chemistry and see if they help, hurt or make no difference.

[nevdos]

Yeah, scrap it all and build some 180 headers and use even smaller collectors it will make more power and torque all round.

Well,building an entirly new set of headers isnt in the cards this season,but the colletors need done no matter what
Possibly over the winter i may try to come up with a different header primary design

[289nate]

I thought I remember some EMC contestants had said they found a fair amount of power in a good collector while testing?

A good merge collector and placing the primaries according to the firing order should help with scavenging the next cylinder. It shouldn't be a restriction because the exhaust gases from the primaries pulse through the collector and don't fire all at once. I can imagine screwed up valve events would not take advantage of the extra scavenging to any meaningful degree. I think this is why you see one person seeing little or nothing from a good collector while another sees very real gains at the track. Just my thoughts and one of those things I want to play with down the road.

[exhausted]

I have had lots of guys come to test headers on the dyno, and some want to try the merge collectors. I never seen anything even cose to what they cost as a result. Usually they are a little better way down in the RPM range, never at high RPM though. A few HP for sat 400 dollars is not a good deal. Pretty much a waste of time and money.



JOE SHERMAN RACING

The principle that is at work in a merged collector is this. The smaller the choke the longer it takes for atmospheric pressure to equalize into the back door of a given engine. It protects your power curve the same way as shorter cam timing and longer primary tubes. Just slipping a collector on with a smaller choke will usually show more power at the bottom of the curve. (which Joe points out)..
The secret is that you can now shorten your header which is how you can make more power upstairs.

Header length is always relative to rpm band but also the size of the choke. Most headers have to be long because the collectors are so large. The longer tubes keep the reflected wave "back" at the lowest point on the power band that the engine has to pull from. Change the collector choke and shorten the tubes and you will see the power. If you can't shorten the tubes, do not blame the collector, and if you need shorter headers, call me...

I am using Joe Sherman's example as what will happen just installing on a existing header. If you can not shorten your header or get one shorter for your application, Joe is absolutely correct, they are expensive and are not a solution in themselves.

[nevdos]

I actually tried to cal you Calvin and the number didnt work?
Ill try again sir

[nevdos]

Big thanks to Calvin for taking the time to talk to me yesterday even though i wasnt his cutomer
He explained some things for me, and even gave me some baseline recommendations
I appreciate it very much sir
Have a great weekened ,and thanks agian for letting me pick your brain

[ptuomov]

With a proper firing order like a 4 cylinder you can go real small like just bigger than a primary tube and then you can attach something like a megaphone and it will run good. You see abrupt large changes in area reflect strong scavenging effect over a narrow rpm range....

Small gradual changes in area can do it over a wider rpm range so you'd use a merge collector to preserve the area increace and spread it along the megaphone.

You only have 6.25x primary tube area to work with.

What do you mean by 6.25x?