Anybody here seen acutual dyno data to back up gains or losses with shorties? My bud claims claims shorties will give more HP than long tube headers. I say :bs . Anybody with data to back me up, or do I get a big helping of crow?

 

Sorry, no data to back me up, but you might do a search on "headers". From everything I've read here, shorties will do you no good at all on the LS1, only the long tubes will give you a measurable gain. From what I remember, shorties = 0-5 HP, LT's will get you 15-20. Someone's got to have some dyno results...

 

Shorties are efficient manifolds, they are not real headers.

Longies--real headers--are a tuned device. They connect three timing intervals in the engine, exhaust opening, intake opening and exhaust closing.

When the exhaust valve opens, there is considerable pressure in the cylinder. Facing an open pipe, the pressurized exhaust is quite happy to expand into the tubing at the speed of sound (hot gas). This expansion creates a wave of positive pressure. This positive pressure ave travels down the header until it reaches the collector.

The collector is larger in diameter than the header pipes, and the wave finds the collector at low pressure. Thus, the high pressure wave entering the low pressure collector sends a low pressure wave back up the header. The low pressure wave arrives at the back side of the still open exhaust valve.

Meanwhile, the piston has moved from BDC towards TDC on the exhaust stroke. The low pressure wave arrives with the exhaust valve still open, and enters the chamber. If the timing (RPMs) are right, the low pressure wave finds that the intake valve has just opened. Then the low pressure wave can stat pulling a new fresh charge into the cylinder even before the cylinder begins its downward movement called the intake stroke.

Meanwhile, back at the collector, the high pressure wave has reached the end of the collector and bounces off with a high pressure wave backwards. (part of) This high pressure wave enters the header heading towards the exhaust valve.

Back at the cylinder. The low pressure wave has pulled fresh mixture into the chamber and out the exhaust (valve is still open). Luckily, the high pressure wave off the back side of the collector arrives just in time to push this mixture back intot he chamber just before the exhaust closes.

Presto, free power! Power that would not have been there without utilizing the wave energy of the exhaust.

 

interesting info, Mitch. :cheers:

 

I gained 11 rwhp and 19 rwtq on my heads and cam Z06 when I went from B&B Shorties (with cats) to FLP long tubes (no cats)

I just read a post stating that LG long tubes do even BETTER down low than the FLPs

for reference, the B&Bs gave me 12 rwhp and 12 rwtq on my Z06 stock

hope that helps

 

Wow, with the cats in place then, there was only a few HP difference. Seems to go against the thinking of LT's being the only choice and it would be nice to not have to weld....u sellin the b&b's....if so drop me an e-mail.

 

There was a long discussion on ls1tech a few weeks ago. BBK is coming out shortly with 1 7/8 primaries shortys. The poster was the test mule for these and got over 10 rwhp. Pricing was a very attractive $499 ceramic coated...Considering the high cost and many problems involved with long tubes, I'm willing to give up 8-10 hp for a street legal easy to install alternative...For those interested, here is the link http://www.ls1tech.com/threads/showf...rue#Post371096


[Modified by lost, 12:56 PM 5/4/2003]

 

:iagree:

 

I have also heard that LG makes the best longtube header. However, you get those extra few HP at a cost of $2200, which is $700 more than the second most expensive header you can buy. I got +20rwhp with my FLP headers. I do not think shorties would have given me much gain at all.