turbo lag, short v equal length headers.

[kenikh]

Originally Posted by RarlyL8

Yes Don my headers are true equal length from the port to the turbo. The turbo rests in the stock position. I would not have gone to all the trouble for nothing.

Interesting! Brian, you have an email.

[DonE]

Originally Posted by RarlyL8

Yes Don my headers are true equal length from the port to the turbo. The turbo rests in the stock position. I would not have gone to all the trouble for nothing. Take a look at any high end header system vs the Chinese stuff and you will see a distinct trend toward equal length. You will also see superior metals being used.

Latest Project - Headers

It should also be noted that split volute systems are being built as well as twin turbo systems using my headers. A component design allows for options to suit the application.

Oh yah. Have you had time to dyno any motor with your new creations? I am really interested when you hit full boost with the equal length, torque numbers (if peak moves around - yes, I know spark is a major contributor) and if you realize any additional ponies. Thanks mucho.

[RarlyL8]

Don I had a lot of problems with my car due to a tranny swap gone bad. Been working on it every chance I get and have made good progress as it is running much better now.
It was my plan to hit the dyno as soon as the headers were installed. That was at least 3 months ago. I did have one afternoon of driving the new headers before disaster struck and my butt dyno was very impressed. The off-boost throttle response and torque really improved as expected. The car ran like a 3.2L Carrera off boost which is really good for a 930, ha!
I have one final problem to chase down before we hit the dyno. I also need to hook up the LM-1 and see what is going on with my AFRs. One interesting note that I did not expect - my idle mixture was pretty far off after the headers were installed. It is expected to tweak the idle mixture when adding headers but this was a pretty big tweak. I am waiting on feedback from clients to see if thier idle mixtures were also affected. This is something you don't hear much about when adding bolt-on mods that needs to be addressed for the DIY guys.

[WERK I]

Originally Posted by RarlyL8

....................edited to save space.......
I have one final problem to chase down before we hit the dyno. I also need to hook up the LM-1 and see what is going on with my AFRs. One interesting note that I did not expect - my idle mixture was pretty far off after the headers were installed. It is expected to tweak the idle mixture when adding headers but this was a pretty big tweak. I am waiting on feedback from clients to see if thier idle mixtures were also affected. This is something you don't hear much about when adding bolt-on mods that needs to be addressed for the DIY guys.

Was it on the lean side, Brian? That could be a good sign, means new headers are scavenging better.

[RarlyL8]

Yes it went lean enough that the engine would not run correctly. It would start perfectly and quickly degrade as the engine warmed and the WUR pressure rose.

[WERK I]

Checking all the vacuum/pressure hoses reveal anything? I wouldn't that big of a swing in your mixture after changing headers either. When I went with the B&B headers changeover from the factory exhaust, I had to go 1-click rich to bring the mixture in line. Nowhere as efficient as your header setup.......

[RarlyL8]

Yes one click is probably typical. I tore the entire CIS apart looking for leaks and problems. Very long story short there was nothing significantly wrong with the CIS. The remaining issue was the idle mixture, a simple adjustment.

[Speedy Squirrel]

In addition to welding in a divider, you need to keep both sides isolated without a crossover (you need two wastegates). Also, the individual pipes must go all the way to the turbo (no collector). I don"t recommend it for the street. The divider doesn"t last too long.

Quote de Speedy Squirrel

I know that the equal lengths are a waste on an undivided housing, so I wouldn't roll with RarlyL8's setup myself.

But what about RarlyL8's equal length primary and secondary headers with a divided flange Gt40?

[copbait73]

Originally Posted by Speedy Squirrel

In addition to welding in a divider, you need to keep both sides isolated without a crossover (you need two wastegates). Also, the individual pipes must go all the way to the turbo (no collector). I don"t recommend it for the street. The divider doesn"t last too long.

Dude, are you still talking about this museum piece?

[mb911]

Originally Posted by Speedy Squirrel

In addition to welding in a divider, you need to keep both sides isolated without a crossover (you need two wastegates). Also, the individual pipes must go all the way to the turbo (no collector). I don"t recommend it for the street. The divider doesn"t last too long.

funny my divider is holding up well though my car is not a 24 hour car like the 935's

[RarlyL8]

Speedy, you are describing an optimum split plenum header. An optimum split plenum system has no secondaries; each primary terminates at the turbo inlet. VERY difficult design on a 930 but I have seen one with my own eyes. The wastegate setup is awkward to say the least.

I have a dual wastegate option for the split plenum systems we produced in the past and I plan to do the same thing with these headers. The dual origin single waste gate pipe is replaces by a short expension to each secondary elbow and the secondaries remain separated terminating at the turbo flange. This is not a perfect split plenum system but it is a nice compomise for 930 constraints.

[JFairman]

Originally Posted by copbait73

Dude, are you still talking about this museum piece?

..is that some Georgia red clay from Road Atlanta cooked onto those?

[1100sport]

This "piece of museum" as you describe it is the most efficient header system ever designed for the 930. Respect my friend

Originally Posted by copbait73

Dude, are you still talking about this museum piece?

[jimmcc]

What's the origin of this header?

Thanks

[copbait73]

Originally Posted by 1100sport

This "piece of museum" as you describe it is the most efficient header system ever designed for the 930. Respect my friend

Oh, I respect it for it's place in time. Given mid 70s turbo tech it was a reasonable compromise to conditions, however Porsche engine design did not use the same key features 5 years later in their 1980 Indy motor, nor any performance engine since.

[911st]

Der museum piece:

Looks like it was a split system and someone cut a WG off one and cut out the partition between each bank.

Nice longer radius turns out of the heads and a smother bend up to the turbo than a 930 (had to flip turbo to work).

[1100sport]

Porsche racing department. That system was fitted on the 934 (the example shown above is somewhat mutilated).

Originally Posted by jimmcc

What's the origin of this header?

Thanks

[911st]

Here is a better picture of the 934 headers stolen from Flieger's photo page.

It has some positive attributes but I probably would not say it was near perfect.

It is very sexy!

[Flieger]

My photos are free for all to see in high-res

Porsche 934.5 Racecar - a set on Flickr

[zeb930]

935