Yes - I noticed what was going on with GE jet engines lately

Nordstorm???? Im looking for Neiman Marcus level ;)

Thanks to Sam @ By Design for fast attention and assistance is resolving my clutch situation I was armed with the right parts to proceed promptly
https://cimg1.ibsrv.net/gimg/www.6sp...4c5b4b830c.jpg

Moving right along

Stef a member from the forum I talk to offline is a customer of yours. He is actually quite happy with your product and shares his experience with it on the forums. He mentioned to me Car #2 has a catless Europipe...how they made it catless I don't know. They could have gutted the cats or cut them out completely and replaced it with a pipe. Anyways he mentioned how Car #2 is faster than his with the same or similar mods, one of the differences noted is a "decatted" 3" Europipe. I said we can estimate how much restriction he(car #1) has in his Europipe at his exhaust flow with the information you have posted before. So I calculated what his restriction was at his power level and it came out to "x" psi so I converted that into a HP figure and he said that sounds about right based on the performance delta between the cars. How reliable is my calculation? We do this daily in industry. My conversation with that member was private, if he wants to post about it here obviously he is more than welcome.

I appreciate you posting the additional numbers including Kline now I can make more estimates :D

Yes there are losses associated with the X pipe and yes the tighter (smaller area) the X is the worse it will be like you mention. There is an additional loss not mentioned which is delta pressure taken from a tight u bend and or cheated radius. Anything tighter than a 1.5R/D (Radius/Diameter) is not great.

I have owned 3 exhausts so far (Kline to a BBi to a Kline again). I moved to the BBi because it was ful 3" and I wanted to gain additional headroom in flow capacity as my project grew. However the droning in the cabin was just way too much, I think it lasted a week max 2 weeks on the car. Material and construction was excellent, outside sound was good, exhaust tips were perfect...drone was terrible (to me). Luckily BBi was nice enough to refund me the money. I turned around and bought the same exact Kline I had before. Europipe was actually on my list as I can appreciate the quality in the part. However it was more than I wanted to spend on the exhaust obviously this does not take away from the product just my personal choice.

In all honestly, I will only be 100% happy with something I would build myself however the hard reality is I'm just too busy now with my career and my free time I dedicate to my family. Maybe one day I'll make something. While I was going through engineering school I also worked designing, prototyping, testing, and approving production of aftermarket hardware including exhaust. I can relive the glory days hilarious

Doing some research - I came across this thread

https://rennlist.com/forums/996-turb...e-settled.html

Keep in mind this particular guy's set up uses the slightly smaller cats than the europipe system

Doing my research on the PE 153mm cats on the europipe they are rated at 900 hp per set and they cost about $950 each

I am unsure at what power level the europipe cats would become a limitation - however - after doing my research it seems as if they are without any doubt the best high flow cats you can get for these cars

Obviously a straight tube is the best exhaust system but the obnoxious sound and fumes are what leads us to compromise and seek a more refined exhaust system

08957 this is the exhaust I was referencing maybe on another thread, I can't keep all of these posts straight lol. My comments were if you can make the cats large enough then you can maintain good performance however you will find limits as you go up in exhaust flow.

Cats being rated at X HP is absolutely terrible and almost useless lol. But I understand this is done to make it easier for a customer to pick one and it helps protect part of the IP. What we actually need is a restriction curve to properly apply them. Having a plot of restriction as a function of exhaust flow will now let you pick the right one. This would be provided by the suppliers as you are spec-ing new engines and they are bidding on the business.

Since we don't have that I'm using Stef's published numbers to back that out and make my own.

I am not disagreeing with anything that you say

I just note that after careful research I looked into the HJS web page and noted that the cats that Europipe uses are the highest HP rated and highest flowing cats that HJS makes - period. I can not verify the 900 hp figure but by way of reference these 153mm 100 cel cats used by Europipe are the highest rated high flow cats of any sold by HJS - in fact they are made by a 3rd company and sold by HJS

There is no doubt that a high flow cat of any kind is going to cause some thermal load and possible restriction in flow

However, if you look at the tread I posted above at the kind of power levels I am targeting at least one tester tested the next smaller sized HJS high flow car vs. a straight 3" tube back to back on a dyno and saw no gains of any kind

We can take the discussion off line, its like intercoolers...just run whatever you like right? best practice lol.

Since you enjoy the engineering and physics part, what I would suggest is study what is behind those cats ...compare that to some comments I made about losses. What that test shows you is the cat wasn't the limiting factor at that airflow...maybe nothing is maybe something else is.

My exhaust swapping experience was from full 3" BBi to my Kline 76mm/70mm combination Sam came up with I saw zero change in my datalogs. Back to back and even weeks later. I took easily 25 logs expecting to find something...honestly the car ran exactly the same fueling(BSFC), vane position, spool up time, etc...telling us pumping work was little to no change. My 60-100mph time was unchanged. I have not had the opportunity to play around with larger cats yet its something I have thought about of course just to keep the smell down (its not too bad TBH).

If I had a Europipe and was stretching power, 800+, I would just add bypass valves (not saying its needed, just my solution). Maybe this winter I'll make something with large cats, we will see. Based on your power targets today maybe just leave it alone. When you get the bug again then look at your options then.

Looking forward to it Sam !!!!!

I am already assigning some time to visit the track at the end of this month . . . it has been a while since I have been there

I like your idea about the bypass valves - kind of like a best of both worlds option

However at the end of the day I may just go the same route that you did now that I am trying to approach 700 whp with my new set up and run some good numbers at the track

Stef your comments on the X cross section are accurate and quite common. Very few X pipes are done with enough area to accommodate the flow targets. I know of maybe 2-3 good examples.

So on the comparison with my BBi full 3" (I'm sure you are familiar with the design) to my 76/70mm Kline I could not pick out any difference in the data no matter how hard I tried at the specific airflow I was at the time(~600-630whp). The BBi is full 3" all the way back to the tips and the Kline yes as you point out ended at 60mm to allow for OEM tip use. I would have bet anyone I would have made less power on the Kline...the data proved me wrong, again at the airflow I was. Yes this is not laboratory type measurements here, its Cobb datalogs but even if there was a difference it was small enough the calibration was not adjusting for it AND my accel times were the same.

Now as you know...this just tell us look further upstream not in the tailpipe section. It could be both exhausts are X designs, it could be muffler design,etc. I haven't tried running exhaust dumps essentially to see how much more power we can squeeze out of it LOL.

Thanks for posting all your information as well.

There are a few good exhausts out there for this platform, take your pick guys :D From the 2 I tested, I chose Kline twice. If I could ever make it to a Porsche meet maybe I can check out the Europipe in person as well.

Maybe someone can chime in on this who has more engineering experience than I do (none) I am very curious about hos this X pipe thing works and why it is so restrictive - from this helpful chart it looks to me like it is fairly open and not so restrictive - maybe I am missing something ?




https://cimg0.ibsrv.net/gimg/www.6sp...729ef23c58.jpg

I also found a slightly different looking design here which looks interesting


https://cimg0.ibsrv.net/gimg/www.6sp...9576bb1c66.jpg

Oh no...you opened the flood gates hilarious Everyone who makes x pipes will jump in and non x pipe guys will take advantage as well hilarious

Super high level cause I want to jump off this bus already :D Basic trade offs. More blending = more exotic sound = more delta pressure and vice versa. Problem number 2 on this application is the tight u bends you end up needing to use for fitment there. Like I mentioned anything tighter than 1.5 R/D is getting lossy. Problem number 3 some x pipe designs on these cars have cheated radius cuts to make that u/x which is also lossy. Those are the basics.

I'm officially jumping off before the firestorm hilarious

I really do not understand why something as old school - which has been around the normally aspirated V8 scene for decades would be so controversial here?

I am thinking that being a boosted system that is running with more pressure a lot of the assumptions that apply to N/A cars are less relevant to forced induction and x pipes?

Further - in my years and years of modification and tuning of turbo platforms most were inline engines. The only one not being a inline engine was the Subaru and they did not run any x pipes in Subaru as they were all single turbo

I certainly hope that my curiosity on this subject would not create a firestorm but then again I understand that people like you are motivated simply to gain knowledge and enhance their car's performance - I think it is when those with financial stakes in the game get involved that the heat gets turned up ?