The Original PERRIN Part...
Its been a long time since we did anything new to the classic and best selling PERRIN Uppipe. We felt it was long overdue and it needed some love! To make our Uppipe even more desirable the latest change we implemented has to do with FLANGES! The new flanges are just like they have always been, 304SS, CNC machined and faced off, but now we have added counterbores to the back side. This makes for a smoother transition for the exhaust to go from the header to Uppipe and then turbo! Which in tern, more power and better turbo spool!
Below is some info I put together showcasing this change. There is tons more info about the PERRIN Uppipe located on our site in the JEFF NOTES SECTION.
This covers the history of the part as well as explains why we built the the part the way we did!
This is what our current uppipe looks like but what you can't see is the latest change we did to it to make it even better. The flanges!
Years ago we started out with 3/8" Laser cut 304SS flanges then quickly moved to ½ thick flanges. This was done to control the flanges warping when welding. It happens no matter what, but bumping up the thickness to ½" and CNC machining them (not laser cutting which added heat) controls this problem to an absolute minimum. Which actually we purposely leave the small amount of warping in the flanges as this helps create a better seal!
During the machining process a second step is taken to face-off or mill-off the main mating surface. This removes the rough mill finish to ensure a perfect seal between your header and turbo. This is a time consuming step in the machining process but once again, is worth it to ensure your PERRIN Uppipe is perfect!
These are things we have been doing for years and now we have added these counterbore to the flanges. This makes the transition from the header to the turbo an even smoother process. The tube butts up next to this lip and leaves far less of a lip for exhaust to flow over. A small detail that for most people will go un-noticed.
Here is a shot of the ID of the uppipe. This shows the tube sliding right up to the flange as well as the super shiny, super smooth faced off surface.
With this new change to our flanges, its important to explain a feature of the PERRIN uppipe that goes unnoticed quite often. Because we use the proper size tubing (that best matches your OEM header outlet and turbo inlet) it also means we have proper sized ports on the flanges. The OEM gasket is a very high quality gasket and its designed to sit back from the extreme temps of the exhaust. When you over-port your flanges (or use huge sized tubing) the OEM gasket is exposed to the extreme temps and will burn out very quickly. This then creates a loss in boost and a creates huge variables for your tuner if you get a dyno tune.
You can see below an example of an oversized/overported Uppipe that has issues with both ends of the flanges sealing. This customer tried new gaskets, 2 gaskets and even using RTV to seal it up!
Here is a picture of a PERRIN Uppipe that has many years of service on it and you can see that there was no exhaust leak! This is a picture of one of the original uppipes we ever made!
Its been a while since we have really promoted this part so here is some info to help refresh your memory on what makes our Uppipe the one to buy.
No Flex joints!!
In years of research we have never found a flex joint manufacture that rates a flex joint to 1600F continuous at 40PSI. This is why all Uppipes that use flex joints eventually give out! The problem is the flexible part of the flex joint consists of very thin layers of Stainless Steel. These super thin "bellows" don't hold up to temps that cause steel to glow red hot while being under the pressure you exhaust sees under heavy load. Eventually they fatigue and blow out.
What is amazing about this part is that you can see right through the middle of the flex joint where the hole/holes are! This is what happens after a few years of service.
Guys that use the OEM Uppipes in race conditions also find that they don't hold up, because they too have a flex joint in them. You may not know this, because it's buried under all those heat shields! The only reason why the stock part holds up for a reasonable amount of time is that there is a shield on the inside to help deflect heat away from the fragile bellows.
Most companies use flex joints on their Uppipes to solve fitment problems. We solved this years ago by just making the part properly. On a part like ours that fits solidly between two solid points, it's important that it fits perfect! While this takes extra effort to ensure a proper fit, it something you can see others skimp on and just add a cheap flex joint that is not rated to do the job. This allows the part to fit even if the fabricator made it wrong. What you can't see is on the Aftermarket Uppipe we show above is the offset in the flex joint. This shows how it was not fitting good but the flex joint made it fit. BAD NEWS!
We were the first (I think only??) to provide hard back to back data that an uppipe (PERRIN) makes power on an STI. This is very important to understand because it was once thought that that an aftermarket catless uppipe wouldn't make any more power than the stock catless uppipe found on STI's. We proved this to be wrong. It was a surprise to us also, but during some heavy testing on our STI, we did a quickly swaped out the OEM catless uppipe with the PERRIN Catless Uppipe. It made a repeatable 10WHP! WOW! This was on a completely stock ECU tune! We prove our parts on our dyno, not with a flow bench.
From the beginning of time I would see these Uppipes where people would just make them as big as they can, or make them to match the size of the gaskets. Which is completely is the wrong way to approach this. The important thing is exhaust gas velocity, and keeping it the same or speeding it up slightly. Since the first Uppipe we have made the ID of the pipe best fit the OEM Exhaust manifold and turbo inlet. Its not a huge secret but the 1.75" tubing we use is the best size to use for the Uppipe on cars that use stock headers and stock location turbos. This matches the ID of the OEM exhaust manifold so the speed of the exhaust gases don't slow down (going into a bigger tube) or speed up and get restricted (going into a smaller tube).
Look at a PERRIN Uppipe you will only see one weld on each flange. We see many uppipes with welds on the inside and outsisde and like clockwork, they crack. This is because when you weld SS it shrinks. Welding on one side then the other causes huge amounts of stress on that short little piece of tube between the welds. Its just a matter of time before it causes a crack. Cracks are bad as this causes a leak in the exhaust loosing precious exhaus pressure, which means bye bye boost!
Using the feature "Mandrel Bent" is kind of a no-brainer. In this day and age, if you don't use a CNC Mandrel Bender to bend your pipes you are living in the dark ages! But where we one-upped the competition is by making tube have 2 bends not just one which makes for a super tight restrictive bend. The 2 bends made for a much smoother path from the header to the turbo. We were the first to make the par this way and you can tell how others followed by looking at the Uppipe and how similar to ours.
The PERRIN Uppipe Today
We have stepped it up again with these new flanges. The ½" thick, faced, 304SS flanges with counterbores on the back side, makes our uppipe better than its ever been and also the most powerful its ever been. While these features add a bit of cost on our end (not yours) its worth it to us to keep our Uppipe the most sought after Uppipe on the market!