Debating on buying headers with standard vs merge collectors for my B-block, 500" B1MC headed wedge Daytona clone for Bonneville 2017. I'm looking for max hp for a few minutes at a time to make 240+ mph on the salt, so every little bit is needed. I know it is hazardous on a stock block...got it...but that is what I'm doing. Don't want to spend the extra $$ on merge collectors if normal (probably TTI) collectors will do the deed.
Also, will crankcase evacuators pull any vacuum at say 7000+? Thanks and Merry Christmas!

Merge collectors are built for a engine.. it
works in a small rpm range... to buy a merge
off the shelf is a waste... if someone says
they picked up it was most likely because they
had new headers built and not due to the merge
gaining anything.. I tried building a bunch of
different merge collectors and tried them on a
set of headers I built.. I didnt see any gains
from them.. a standard collector will cover a
wider rpm range.. just make sure the collector
is about 18" long.. if you build the headers try
to get the tubes equal length for max power and
the proper length for the engine.. a shelf header
is made for a wide range of engines but it really
is designed for one and is made to fit in the car
so they arent equal length or the proper length for
most engine

I had a small 1-2 mph gain going to a merge from a Dynomax collector muffler.

Many top NHRA Super Stock, Stock and Comp Eliminator cars run this guys headers / collectors. He does sells collectors separately. His work is beautiful.

He also builds the headers that are on the Ken Black (Anderson, Line and Butner) Pro Stock Cars.

Mark is a nice guy and I am sure he would talk to you about your project.

http://www.perfweldheaders.com/

Performance Welding Racing Headers
5898 Melody Lane
Foresthill, CA 95631
Phone:
(530) 367- 4124
Mark Lelchook / Owner

It sounds like you have fun project you have going, good luck with it.

Bill

I think Mark had some merge collectors marked down on his Facebook page.

Excellent, thanks fellas. Thoughts on header crankcase evacuators?

Your trying to build a max effort engine.. a evac
on the header will pull a max of 5"hg..not enough
for a max effort engine
EDIT
Put a Star vac pump on it

I agree with mr. P... you're gonna need a pump

Yep, what they said. No way pan evac in the headers will do anything but harm IMO.

what would the harm with pan evac be?

Won't need evac or pump with a dry sump.

Along time ago when I went from a stock stroke to a 4.15 stroke, I had more trouble with the exhaust blowing into the crankcase. It actually created pressure instead of vacuum. And before you ask, yes I had the one way valves that went on the collectors. When I disconnected the hoses,everything was fine. I was only topping out at 6800 RPM back then, not 8000 +. Vacuum pump for that RPM and B1/MC heads is a good idea and necessary IMO.

merge collector do work as part of a "system". changing just the collector may not gain anything. I build a set for my engine and the results were interesting to say the least. I have a 512 methanol MFI BBM with B1 heads running a cam that has .806 lift 282/290 @.050. So after reading about theory behind merge collectors, I decided to build a set. My original headers were 2.125 x 30 with a conventional 4 inch collector. My merge collectors are 2inch x 11 then 2.125 x12 with a 3 inch merge, a 9 degree taper and the pipes running in a circle.

So had the engine on the dyno, replaced the old headers with the new, on the 1st pull the engine went into severe detonation, looking at the data it was way way lean. Added fuel back into the engine and ended up gaining 3hp and caring out the RPM range another 200 RPM. But here what I seen, the BSFC on the old headers was .995 and with the new it’s 1.14 (o2's now reading the same). So i now have a new cam in it with a lot less exhaust duration and will test it as soon as i have time and the weather is good.



If you have some time, read this tread
http://speedtalk.com/forum/viewtopic.php?f=1&t=41105


Joe

I will be using merge collectors on my B1 headed 572 in 2017 but I won't be able to give any comparisons as this will be a new engine combo.

I hope you talk to the company to get ones that are designed
for your engine.. those are one thing that one doesnt fit
all engines.. diameter, length, tapper rate on both ends
all come into play.. if you ever made expansion chambers
for a snowmobile you will understand what I'm saying.. I
made a set of chambers that had a TON of torque but ran
out of rpm at 6000 rpm.. but that sled stood up right on
end at the hit.. then I built another set that didnt have
much torque but had great high end power

Thanks for the explanation. I'll keep that in mind for some future projects.

Going from a 2 1/4 tube into a non merge 5 inch collector VS a 2 1/4 to 2 3/8 to 2 1/2 into a spd merge with cone was worth 18hp on a 1075hp hemi. Tested on the dyno.

When testing like this I wish you would have tested the
2 1/4 tubes into the merge.. being that you went with the
step header then into the merge its hard to say what did
what.. I did some testing back at work with just adding a
few different configurations of merge on the same engine
and the same header.. most didnt do anything.. and one
hurt the total power output.. it gained 3hp for a 1000rpm
range down lower but hurt the max output by 7hp

We all need to remember that what works on the dyno may not help in the car Do the test on the dyno and then redo it at the track
I've seen that more than once in my testing, K&N extreme lid on a single four barrel air cleaner lost 8 HP doing the same test two different engines and dynos and adding the lid at the track was worth .03 ET and .2 MPH doing A,B,A testing

I understand what you are saying BUT a dyno is a
way to get repeatable data on different days or
even the same day to control all the input factors..
remember its just numbers we are playing with.. if
it goes up its up down is down.. going to the track
has to many variables to control true data. sure the
track will(in most cases)see a difference