Kreissieg Spiral Y-pipe for 2.7. Gimmick?

I like the spiral one only because of the shorter collector. I can't see it making any difference if it were made with the same collector and -not- crossing over.

 

+1 ..... on the shorter merge ...... I would think the price delta would partially reflect the labor involved for each .... lastly if the crossover version is trying to create a 'swirl' effect ... the swirl would quickly be diminished by the butterfly .... so I would think a no on my swirl suspicion ...

 

Wow, $$$$. My F355 y-pipes are about 50% of those prices. Still SS and TIG welded.

 

Kreissieg is artwork when it comes to exhaust systems. The real question is, should you put a japanese exhaust on an Italian car?

 

I don't see why not. After all, the factory put in Japanese alternators.

 

I can't speak for Capristo. I do have a Kreissieg valved exhaust on my 348.

 

It kinda looks like the spiral has smaller pipes to begine with based on the relative size of the bypass.

Someone smarter than me can comment but I would think if this is the case the velocities would be greater and the power would be slightly improved.

 

Its on the top rack. Give me a day or so to get it down and I'll post a few.

 

Velocity is not a measure or indicator of improved flow. You want big pipes, sweeping bends resulting in low back pressure.

The twist is also a gimmick, but collector design is sensitive to flow, and without flowing the pipes I would be hesitant to comment. I have seen results that were un-expected from flow tests, but even if the merge of the twist pipe resulted in better scavenging, it would be highly unlikely be enough to justify the cost.

 

Not sure if we are talking similar but on my old superbikes no exhaust made less power on top end so from my experience you need some back pressure.

Maybe cars are differant.


This supprised me because of what you said above so i think there must be a limit on how large you go based on the engine

 

The engine never wants backpressure. If too large it can lose velocity. Wrong length/design can hurt pulse scavenging. Optimized, there will still be no backpressure.

 

Exactly!

 

Years ago, I put headers on a modern Z-28 and lost some low end torque. So, I developed the understanding that smaller pipes helped developed some back pressure to increase torque. Am I not understanding this issue correctly? Are you referring to HP and not torque?

 

That understanding is wrong, but could describe the effect on the engine as a system. If it was a carb'd Camaro (or L98/TPI injection) its possible the increased scavenging and decreased back-pressure caused it to be lean, that will cost you torque.

 

Back pressure never increases power anywhere in the rpm range. You are literally restricting the engine, inducing pumping loss and minimizing scavenging.

A properly designed/sized header will usually gain power across the entire rpm range.

For example (not exact numbers, just for discussion).

If you take a new Camaro and install headers 1 3/4 or 1 7/8 diameter with 28" long primaries and a nice collector, gains will pretty much be up everywhere.

If you then install headers with 2.125 diameter and 14" long primaries you will likely lose a ton of low end and midrange (and possibly peak hp) due to primary length being ideal for very high rpm (outside of the redline of the engine) and oversized tubes reducing velocity.

That doesn't mean the engine likes or needs backpressure as it would still be measured at near zero with the 1 3/4 headers. It means when properly sized you have found the ideal balance of optimizing velocity/scavenging without creating backpressure.

 

Only if you like the look. I don't care for it personally.

I like using a short merge collector rather than the first photo of slicing/joining the tubes into a long collector. Forces the exhaust go into the bypass and -pull on the other bank rather than giving it an easy path to cross over to the other bank.
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Wow, very nice!

 

Interested in selling a custom made Y pipe James?! Looks great, does it increase the exhaust note any on the bypass now?

 

Ditto. I'm Awaiting some special stuff from Jim - he knows what he is doing and is an excellent TIG welder to boot