27 replies to this topic

[lookforjoe]

Hmm... quote button isn't working...

I don't know what wall thickness/ID pipe this is, I bought it from LG Speed.se, I never measured it.

I'm wondering about your turbo positioning with the collector flange level - I didn't have much room with the offset of the LG - compressor barely clears the water pipe. I'm assuming you're using a larger turbo for your power goals

[Teo5R]

lookforjoe, on 23 January 2012 - 12:20 PM, said:

Hmm... quote button isn't working...

I don't know what wall thickness/ID pipe this is, I bought it from LG Speed.se, I never measured it.

I'm wondering about your turbo positioning with the collector flange level - I didn't have much room with the offset of the LG - compressor barely clears the water pipe. I'm assuming you're using a larger turbo for your power goals

Are equal lenght the pipe?

[lookforjoe]

Teo5R, on 23 January 2012 - 03:07 PM, said:

Are equal lenght the pipe?

No. Equal length is not the most important criteria, from what I have been told

[Teo5R]

lookforjoe, on 23 January 2012 - 05:39 PM, said:

No. Equal length is not the most important criteria, from what I have been told

explain your criteria theory. I'm really interested

[bpray9223]

Teo5R, on 23 January 2012 - 07:07 PM, said:

explain your criteria theory. I'm really interested

:popcorn:

[lookforjoe]

Teo5R, on 23 January 2012 - 07:07 PM, said:

explain your criteria theory. I'm really interested

Sorry, I'm not an engineer

There have been many discussions on this over the years, and there are numerous threads on headers & designs if you care to search. The last comment (from Chuck) on this I recall is from my LG Speed Header Install thread.

"Whats far more important is a short collector. Equal length serves no point as long as they are tuned. Don't get me wrong, I am 99% sure that is not just saying. That said, that is one ugly manifold. Will be interesting to see the numbers though."

[ozzimark]

Teo5R, on 23 January 2012 - 07:07 PM, said:

explain your criteria theory. I'm really interested

Each cylinder will have a different VE, AFR, slight variations in ingition advance/spark strength, CR, etc. It all adds up, and effectively, the speed of the pulse through each runner is a little different. From what I understand, each runner would be tuned to match the particular cylinder's characteristics. Also, don't forget that 18" through the centerline of a straight pipe is different from an 18" length through the centerline of a straight pipe with 2 90º bends, which is different from an 18" length through the centerline of a pipe with 4 45º bends.

So.. it depends on how perfectly perfect you want it to be.

[Fishey]

I am more a beliver in exhaust pulse vs exhaust length in terms of spoolup times. My experience with RX7's certianly taught me the imporatance of exhaust pulse. When your 1.3L gets on full boost with an 70mm turbo by 4000rpm your doing it right. That being said my experience with Porsche has taught me with the 951 you have almost 3.5 feet of pipe before the exhaust reaches the turbo (Out exhaust ports, Down headers, into cross over pipe under the bellhousing, up to turbo under intake manifold) and I have taken one and removed the battery box and moddified the firewall and ran the turbos almost directly off the headers. The turbo spooled only slightly faster then when it sat under the intake manifold. I think most of this though was the result of the exhaust system after the turbo being only 4 inches long vs almost 7 feet long. However, we did not move it for improved spoolup but because of other problems that were caused by its unfortunate stock location under both the intake manifold and the brake master cylinder.

Edited by Fishey, 24 January 2012 - 02:32 PM.