[oldman]

http://www.chevrolet.com/performance...parts/z28.html
http://www.hotrod.com/news/1503-lt1-...016-camaro-ss/

The LT1 looks the same but with a 4 bolt collector!

[TrickracenLS3]

are you trying to say that the z28 headers are the same at the LT1? if yes, Where are you getting this info? anyways, those are shorties. But please clarify what you meant.
thanks

[oldman]

I said similar, which they are, but I appreciate your caution in misinformation propagated via the Internet. I know the bolt pattern on the cat is different and I know they are made by different processes and I have no idea if the LT1 flange is the same at the head, I'm sure we will all know soon. The are similar and I would expect them to flow a similar amount of air. The Z/28 were good to a whole bunch of HP. I will also note that Hennesse and Ligenfelter both do NOT change the exhaust system on the base and their +1 supercharger kits (Camaro or Vette). So around or above 700 HP are these two companies going into the stock exhaust upgrade. Just food for thought.

Also they are obviously shorties, There is NOTHING wrong with shorties especially for supercharged applications. You do know that the hype equal length long tubes can't possibly work on a domestic V8 right? These engines are ALL odd bank fired engines and there will NEVER be equal or tuned pulses from the collector propagated back up the pipe. If you want that you need a GT350 or you need to cross the primaries under the pan. Both offer huge advantages when going to equal length 4 to one. But sorry on the LT1 the two center pulse waves will be always be interrupted as the bank is 180-90-90-180. So two waves will have twice the uninterrupted flow duration and two waves will have a longer (but interrupted) pulse duration due to the 90 paring.


BTW these headers are technically Tri-Y which isolate the above wave to (180+180)+(180+180) => collector. Leading to a nearly equal negative pressure wave propagation back from the collector. Very short though, I would speculate that there is no primary resonance at all, or at an RPM higher that the engine can rev. My other ride is a Type R with a sleeved 2.1 liter that puts out 275 HP at 9200 RPM from a Tri-Y tuned length but with step sequential pipe (the vogue in 4 banger racing) vs even fire pipe that is under discussion.

Please let me know where I'm off, I'm getting old and drag racing is not my primary field of expertise, heck, it ain't even my tertiary field.

[jimmypop13]

This has been known since last summer

[oldman]

what has been know, that they are similar, or that the share the same bolt pattern to the head?

just checked and the exhaust bolt pattern is all new:
http://www.hotrod.com/how-to/engine/...best-sbc-ever/

[Mr. Wyndham]

Chevrolet's header/exhaust design has developed extensively in the past few years. They equipped the LSA with cast aluminum (as opposed to iron) "manifolds" that started to look at little more like shorties...And when they showed the LS7 for the Z/28, the engine had revised Tri-Y exhaust tubes....then when the LT1 was displayed, it featured a similar design.

Interestingly...these developments are not featured on the Corvette's LT1...which suggests that the Corvette has a more efficient breathing setup...and these parts are required on the larger-engine-bay-Camaro, to match those hp figures. Maybe?

[oldman]

Originally Posted by Mr. Wyndham

Interestingly...these developments are not featured on the Corvette's LT1...which suggests that the Corvette has a more efficient breathing setup...and these parts are required on the larger-engine-bay-Camaro, to match those hp figures. Maybe?

It is interesting, I think it has more to do about Noise, vibration, heat (NVH) and cheaper to do the cast Vette style 4 to 1 shorty manifold vs the cast / extruded multiplies triY which IMO actually flow better and make more HP and allow a more tailored fit for non Vette applications where the engine mount and K member may get in the way.

So the Vette setup has better NVH and is cheaper, probably has slightly better topend power (large short tubes with good size and taper).

The Camaro setup better low end, mid range power (features of triY) but has more NVH, is more expensive. can be better tailored to space.


We can go back to the LS7's cast 4 to 1 for the Vette vs the triY for the Z/28. IFAIK, the HP was the same but the Z/28 had 10 ft / lbs more torque? Think so gotta check later.

[oldman]

From Kooks
"Kooks headers and Exhaust has been in the business since 1962. We are three generations of family deep and are still run by the man who founded it all. We can say that we have been through it all; from motorcycle exhaust, to street cars, drag cars and are now the only spec approved header of NASCAR. We have literally taught our competition everything they know about headers and are continually pioneering different header and exhaust combinations to fit and perform the absolute best. We invite anyone to come take a shop tour of our 50,000 square foot facility and see the Kooks Advantage first hand! With our years of experience we have built Tri-Y headers in the past, but based off our experience we do not feel these are the best fit for your average enthusiasts looking to get the most out their application. Kooks Headers are designed to be the best performing, best quality, and best fitting headers on the market.

Tri-Y Headers or 3-collector headers are designed for maximum performance for a specific engine combination, desired engine RPM, race track, etc. For a Tri-Y header to have the proper effect the cylinder firing order must be properly paired so that the next firing cylinder is separated. Sequential pairing is optimum, example the LT-1 firing order is 1-8-7-2-6-5-4-3 so pairing of the 1 & 5 and 3 & 7 cylinders on the passenger side and the 2 & 4 and 6 & 8 cylinders on the driver’s side would be the proper sequence. You also need to have the proper primary size for the engine displacement and application. The collectors also need specific convergent angles (7-20 degrees) for optimum efficiency and cannot be a random bend angle. We have seen horsepower and torque numbers dramatically affected by these angles in Tri-Y headers. In our testing we have found the primary head pipes (First Section) must be between 17” – 21” in length for proper pulse scavenging, anything more than this has shown no increase in performance.

The data we have collected over the years proves the Tri-Y design does have advantages in race applications with the right vehicle and the right engine combination on the right track. Most professional teams will have several sets of headers and engine combinations for different tracks and conditions.

Testing performed by top NASCAR engine builders on a 650hp LS engine in a K & N race car showed that a Tri-Y header versus a 4 into 1 header in a side by side comparison with all factors being the same, proved the horsepower and torque numbers were within 1 hp across the entire RPM range. The reason we went with the Tri-Y on these cars is for packaging in the car and ground clearance. These are not factors in a production street car.

Running a Tri-Y on a SCCA World Challenge car (No cats and side exit exhaust) where the engine stays in the 4500-8000 RPM range constantly, the Tri-Y really shines. Keep in mind these are custom built headers in a race application that are built to exact specs for the engine combination and race track.

Running a Tri-Y on a production street car where the design of the primaries and merges is limited by the restraints of the car is not optimal. Also with a Tri-Y header there is no one size fits all too truly see the benefits of this style header. A street car with modern technologies like cylinder deactivation, catalytic converters and typical driving styles, a 4 into 1 header with the correct size primary tubes and length is the optimal choice.

If anyone wants a custom set of real Tri-Y Headers built around their exact motor specifications, driving or racing style or anything else please contact us. We will be more than happy to accommodate you."