Some one can explaine why the LT are Better and why the shorts make more power in the topend this is what I read and have search this for like 1000 post but no one have a tecnical explanation of this.
THANKS.

 

Okay, read this at your own risk. I have no basis for this other than looking at a couple of "Optimum header length calculators".

There are two primary advantages of headers over stock manifolds:
1. increased pipe - allows more CFMs of exhaust gas to escape
2. scavenging - each exhaust pulse creates a vacuum behind it, pulling out the next exhaust pulse.

As RPMs increase, the length of time between exhaust pulses descreases. The length of the primary tubes determines which RPM will have the greatest scavenging effect.

A header that is tuned to maximize scavenging at a very high RPM will have shorter primary tubes. One that is tuned for lower RPMs will have longer primary tubes.

To put this in perspective:
Given 350cid and 1.75" pipe diameter:
4000RPM > 54"
5000RPM > 43"
6000RPM > 36"
9000RPM > 24"

So it is true that shorter lengths will help horsepower in the upper RPMs. But shorties are tuned WAY to high for practical application, at least in our cars.

The primary advantage of shorties over manifolds would then be the increased pipe size.

http://www.prestage.com/Car+Math/Eng...h/default.aspx

Again, this could be totally wrong so please correct if I am. Comments?

 

i am not an expert by any means at all, however most people here will swear that long tubes do give generally more power, which they do.

the real question is though...

do you want to sacrifice a little power for 1. hard time passing emmissions, 2. pain in the *** of install. 3. possibility of them being too low, rubbing against ground.

 

long tubes are BETTER, PREFORMANCE WISE plain and simple...

if your worried about the tree hugger test and what not then go buy a honda PLAIN AND SIMPLE

if your not gonna mod you car out the right way then theres no sense doing it AT ALL

 

What if your objective was highend, high speed.. Would shorties be a good route to go then?

 

amen

 

No i beleive that the LT's would perform better then the shorties up top. But i could be wrong.

 

Nope, long tubes make more power across the entire power band than shorty headers.

 

Lts make more high rpm HP than any shorty header will but you might suffer some low rpm tq loss.
Some people might want to get into runner length, primary sizes, thermal dynamics but in short LTs have made a HUGE gain on my car over any shorty with or with out cats!!

97 M6 formula, LTs-Y pipe (press bent) Magnaflow C/B, and a CAI = 13.5s @ 106 w/ 2.28 60 fts and I'm pulling a 9" rear (heavy) behind me.

 

Lts = low end. Shorties high end. But...I believe since most Lt1 cams make their power under 6000 RPM that LTs provide more power over the entire band than do shorties, since 6000 RPM could be considered low-end compared to high reving engines and cams.

If you have an RV cam (low-end torque, then providing 1 3/4 shorties on an Lt1 you might help your top end a bit. If you used LTs on the same cam your low-end would be awesome, but probably not give you much of an advantage over the shorties unless you could put that power to the ground.

So...the LTs are probably superior to shorties on the Lt1 over all, but if you have emissions restrictions, cat location, etc. fitment problems, cost considerations, ground clearance, etc. you need to weigh the advantages of each system. JMHO

 

Thanks
But
Were are the gurus

 

i've got a question
i've heard there are no lt's that are emissions legal for the lt1
well, i saw these and it says they fit in the stock location, but they're still long tubes

http://www.jegs.com/cgi-bin/ncommerc...62&prmenbr=361

any enlightenment on this?

 

Even though the first line of your post is true, the rest is some of the most ignorant dribble I've read (and I've read a lot),

Some states REQUIRE emissions, and unless you have some great hookup, you aren't going to pass with longtubes. Long tubes aren't legal in Cali even if you retain all of the emissions equipment, AND install cats after them. If you can't pass smog, then you can't register your car.
So, according to you, since we can't go all out all the time on our street cars, than we we should just leave them all stock? THAT'S what the tree huggers would want.

 

I dont need to pass any emiemissions I plan to use the car for only weekend night and some drag race. and Im at 4000 Ft city.
this will help more?.
I only have the free mods and a cai k&n.
M6 93.

 

I have mac mid lenghts, and while i love them for price, decent power increase, and plug access, I will probably be switching to long tubes this winter when i do heads/cam, so my advice is to do it right from the start.
Brandon