548whp Repu dyno after dumping the wastegate
 

After looking over my last dyno graphs I decided to dump my waste gate (the re-rout was at a 75* or so angle about 20" from turbine exit which is not at all optimum) I had some spare time today and put the truck on the dyno just to get some numbers with no tuning. At the same boost levels as before it dynoed 10-15 hp more. I ended up turning up the boost by 1 psi by the second pull to see what it would do and it hit 548 on my daily driven 1 year old 10.5 ngk spark plugs, I should have brought my good ones like I did last time I dynoed... All in all I was pretty happy with the extra hp even though its a good bit louder.

26psi falls to 25 @ 6,700rpm (need to adj gain), Old T66, REW, pump 93, water/meth





Attachment 632448

Wow!
Are you dowel pinned?

No extra dowel pins, just a junk engine built out of 7 different engines that I had sitting around.

That's sick!
I was hoping my motor would hold 500whp. It's a13b-rew, extended street port(not sure how's that different then a regular street port).
2mm 2pc Atkins apex seals. All the oil and cooling mods to the housings.

Could you go into more details regarding what you you did to the wastegate plumbing. Why was what you had not optimum?

The external wastegate dumped immediately back into the down pipe was at a very sharp angle that most likely was affecting the flow from the turbine. I originally did the rerout because my wife could not stand the noise from the atmospheric dump, now that she won't step a foot in the death trap I figured I would go back to atmospheric to chase some free hp. Here is a ruff sketch of how it was, and is now.

Kool.... I just may be doing the opposite. I want to quiet my Fd a bit for mostly street tuning, so I may be routing my atmospheric dump to the downpipe. I have always had it atmospheric and dont know what it sounds like with it to the downpipe. I have also considered keeping it atmospheric and purchasing / making a mini muffler for the end of the pipe.

Do you know of anyone that has done this?

Yep, quite a few people (even stock Porsches) have put mufflers on a atmospheric dump. Look for a stainless construction with very little restriction for the muffler. If you do the reroute, do it at a very low angle (around 35ish deg) and in the neighborhood of at least 28" down stream of the turbine and you should be fine with very little power loss. With the reroute you will also want a bellow or flex pipe in between the waste gate and down pipe for expansion/contraction. Double check your manifold boost pressure afterwards, as it could rise a tad with the reroute so you would need to adj your boost controller. Good luck!