Macs Mids to LT's
 

What would i gain ? i searched and saw afew good threads from afew years ago. i want to squeeze as much out of my setup as possible. would the gains be noticed on a setup like mine (specs in sig) or even worth while ? options/insight would be appreciated thanks

The MAC mids are arguably the best designed mid-tube header. Upgrading to long tubes will net you maybe a handful of HP, but it won't be substantial. I upgraded my MACs to Jet Hots.

IMO, go with the long tubes and have done with it.

maybe 5-10hp at the peak.

id personally just do duals off the mids then swap them out for LTs

i was thinking about going with ebay headers, everyone says there good. the only trouble is i dont want to lose room to my spark plugs. i was also thinking about upgrading it to true duel from my 3" catback. i want to try to get everything i possibly can out of my setup. its fast... just not fast enough lol

It's def noticeable. I ran the Mac Mids at first then went to LPP LT's and it made big changes up top. Go with the LT's!

The mid tubes and the LT's will have nearly the same peak power. LT's usually a 5-10 points more.

However at lower and mid RPM's, the mid-tubes do not make nearly the amount of power that LT's do. The LT's have much better savaging down low and the gains are not just a handful, they are tremendous.

Here is a graph of before and after. I was running AS&M mid-tubes and switched to LT's:
http://i140.photobucket.com/albums/r...midtubes-1.jpg

Look at the differences under the curve.

When I put the LT's on, it had so much more low and mid power you would swear there were 2 more cylinders in the motor.

So the answer is yes. There are huge gains when switching from mid-tubes to LT's when you factor in the big picture. The proof is in the graph.

IMHO, the only reason to have mid-tubes is if you need to be emissions complient. Or if you are lowered.

What happened at 6000rpm?

opti :secret2:

awesome information wrd1972! i now have something to look foward on doing after tires and brakes get freshened up :) maybe true duel 3"? :D

Severe valve float with the PAC 1218's. As you can see the power fell off of the cliff.

For full disclosure, there was a spring change (now that I remember) in addition to the header change being represented in the graph. I installed Patriot extremes and that 100% cured the float problem and extended the very upper power to 6.5K or so. I would not expect the spring change to show any difference on the graph from 6K down.

But you can see, the header difference represented is striking.

Flawed info.

"Flawed info."

Yep, the problem is the valves could have been doing a dance and not seating properly until they really went South.

Yes it is possible. But I have never heard of anyone really having valve control issues under 6K RPM.

I swapped my MACs for Hooker LTs a few years back, it was a huge SOTP difference at the top end.
At the time, I had a 350 with LE2 heads and an LE1HL cam.
I did the swap after driving in a friend's TA with similar mods + LTs.

The sound alone will make you happy u went LT'S.

what mids are better mac or rksport?

The RK's have 1 3/4 primaries" and the Macs have 1 5/8". Both have a 2.5" collector so I would guess they are nearly the same. The Mac has much MUCH better plug access and install easier without headaches.

Probably because there aren't a whole lot of anyone who really know whether or not they are having control issues at said RPM. Valve springs can become harmonic at any given engine speed which can lead to out of control valve events.

http://cranecams.com/?show=newsLetters&no=239

my buddies car used to break up under 5500 all the time. after fighting everything we could think of, tune, springs, more springs, plugs, wires, opti, ect, it turned out the rockers didn't like the cam at all. he was dynoing 423 to the wheels and not reving over 5400-5500. it used to break up anywere from 5200-5600.

his car also was swapped over from mid lenght to long tubes years ago with back to back dynos and picked up 2 hp and 2-3 trq.