MBH motorsports

You have 1.75" primaries.

vipermike

Wait, when did you start making your headers with the 1.7/8'' primarys?? When I ordered them from you I was discussing having you make a custom set for me with the larger 1.7/8'' primarys and you had said you would need time to R&D and fab to insure proper fitment, at that point I decided to save some $$ and go with that used set you had...

MBH motorsports

I don't know why I put a "now" in there. All of our headers have a 1.75 primary for the 55's. I think you got it a bit mixed up 1.75" = 1 3/4

vipermike

Oh yes, I was using '/' and you were using '.' , sorry for the confusion.

Let's go back to my original question and I'd love to hear everyone's input on this please.

So here is what I plan on doing to my beast:
180-185 pulley range
ported heads & cam (down the road when my warranty runs out)
90mm tb
custom intake
massive cooling mods

What are the thoughts on this setup with the 1 7/8 primarys and 3'' merge collector?

Here is what I have now:

MBH LT's with 1 3/4 primarys and a 2.5'' merge collector that flairs out to 3'' and a full 3'' exhaust with X-pipe, no cats. Here's my concern, I raced two different AMG's that had WAY MORE mods then I did and they both had custom LT's with 1 7/8 primarys and full 3'' merge collectors and I pulled on both of them (the cars had sat for a few hours and cooled equal time, so no heat soak excuses) several times on a highway runs from 30-140mph?!?! So now I don't know what to think, I do not want to spend money to step backwards... Should I just keep the system the way it is or do you all think I should go bigger based on what my future plans are??

e55amgrocket

I think your fine where your at with that setup honestly.

whipplem104

I think what you are asking is about the 2.5" restriction at the merge collectors? This is actually a megaphone. It prevents reversion back into the primary. If done properly good and not bad.

Hammer Down

Do you think that it's possible to make more power with a 90mm vs a 82mm? I think your current exhaust setup is fine. I don't think it's worth the $$ to find out either way.

MBH motorsports

I'm no expert on throttle bodies. However the 80 and 82mm TB's have shown gains. So I would guess a 90mm would help. A question that keeps coming to my mind about this is... When does too big start to hurt you? If I stuck a really fat tube on my household vacuum you would think it wouldn't clean as well.

There are other platforms that use 90's and they work out well. So IDK? Without any real testing its hard to say one way or another.

Personally I don't think 90mm is too big, but like I said I got no supporting data one way or another to know for sure.

vipermike

The user Forestgump did the 90mm and it worked, I think he was just working out the kinks. I used to have a 4.6L Cobra with a ProCharger blower on it and when I did the ported 110mm TB it made crazy power!

e55amgrocket

I had a Cobra with a whipple and the crusher inlet with the 160mm tb. It looked like it could suck small kids in lol. I'm working on a 90mm right now for my new build also and might be able to get the 90mm up to around 95mm.

vipermike

Again great info guys!! Thank You

Let's hear the input on the primary tube size:
MBH is using 1 3/4",
NPI is using 1 7/8",
TTM ARH is using 1.7/8",
BenzWorks is using 1.7/8"

This is why I'm digging at this, is it a fad with people thinking bigger is better, or is there some real data to show why all these fabricators are using the larger primaries?? If $$ is not a factor, which is ideal with for our modded 55's?

305-E55

+1

e55amgrocket

I believe its a fad for the most part. Bigger isn't always better and there's usually a trade off somewhere. Thats where stepped headers really shine too. The exhaust ports aren't that big on these heads and everything needs to work well together. 1 7/8 are fine but your trading some low end for sure. I'd love to do some back to back testing on some different headers to see what they do compared to others. For a reference a friend has a 410'' SBC with a F2 procharger making over 1000hp and a switch from 2'' headers to 2 1/8'' cost .05-.08 in the 60ft and the car was running about the same slower in the 1/8th so they went back to the old headers and performance was back where it started. You would think a motor of that size and power would need something BIG.

chawkins2001

Just run electric cutouts off the headers, like moir For the record I have Floored Fab 1 5/8 with a 2.5" collector and mid pipe, and I am making 711rwtq.

e55amgrocket

As we all know know torque is what gets the car going. We just need to find the trade off in power and torque.

AgSilver

You might just want to study this design:

kustom2k1

55k headers from Japan

RedBullJnky

BRH AMG

18,000 RPM

SterlingE55

Since we're posting formula car headers. Saw these at MSR Houston. There's not a lot of reference for size but they're atleast 2". Glorious looking piece. Doesn't apply to us as they're for a small displacement, NA, high reving engine and we're the opposite of that. Cool to look at none the less.

AgSilver

True, however, the point is that the multiple increases in tube diameter and then the final reduction at the collector is applicable to any engine. The overall lengths are primarily determined (as you correctly imply) in relationship to the RPM and rarefaction pulse.

I spoke to Mike at MBH about this last year asI thought he might have been incorporating this technique from one of the photos I saw of he gorgeous headers.