Hey Guys,,Since I got a set of cat delete pipes,not on yet,TimNYC brought a good point up to me about the diameter size of them.I am worried about the step of the larger OD exit to the smaller ID pipe.
The ones I got have a 3'' ID flange with a 3'' pipe into them,so that means it is a 2.850'' true ID..I believe the maker also sells these same ones with his exhaust .
Problem is the stock turbos have a 3.150'' diameter exhaust outlet on them and even Tials are a 3'' diameter outlet.
So,have you checked yours?? My Milltek exhaust matches up to turbos diameter.
Does this matter,,I would think it all adds up..
Now I dont think I want to use them.

 

Hi John,

We make our own flanges and they are flow matched to the turbos on both our cat bypass pipes and our catalytic converters, as well. We bump up the 3" stainless pipe to match the turbo. Below is a picture of how we do it - I'd be happy to make a set for you, if you need some....

 

Yes John those look like the way they should be to get the most out of them..

 

Going from cat to catless is all that counts here, the OD means nothing on a smaller are even larger setup unless its 2" OD to a 3"+ outlet; and the power goal is 1000rwhp... John I would not worry about it at all.

I've ran the SAME set of AWE 3" straight pipes on my car the last almost 4 years, the only difference between the GT3076/K24, PTE5857 (made a flange to go from stock to a v-band), and GTX3582's is that on the GTX's we hacked the stock flange off to make a v-band connection. The only time it was watched up to the pipes was to make sure the V-bands fit... That is all...

Now I'll let the engineer's come pigeon hole this (the truth) because it doesn't make sense.

 

Thanks,you are a stand up guy.
As I said to you,it was my fault about not asking,so nothing against you..I do appreciate it though for putting your post up like you did..

 

Thanks for your input on this little issue..
BUT you Big Dogs dont mind killing some of your HP to give us little guys hope,so we need every little thing to help make more..LOL..

 

John honestly on the GT3076/K24 kit I was making a tiny bit more 666rwhp on MS109 though. The gains are MINIMAL (within 1-2hp if that) and I mean that in the most sincere way. That is if you gain ANYTHING. Trust me we try to pull as MUCH as we can out of my car. I don't have the budgets like some where I can call, next day and not worry about price. We have to do as much as we can with what we have, and sometimes its down to as something as small as this.

If I knew it was a HUGE gain we would have done it and so would have anyone else. All this is meant with no disrespect just trying to help others out.

 

Thanks for your insight again.
Since I got your attention here...
Do you think going from my 5'' HJS 100 cell,rated at 350hp each/700 total, cats going into the 2.75 inner muffler piping >to the cat delete will make a difference?

 

Remember the 5" area is filled with all the honeycomb catalytic junk so the size will fool ya. The 2.75" will outflow it hands down any day of the week. If I get by the shop tomorrow I'll take a picture of my AWE straight pipes with the OD to give you an idea of what's the true inner OD and what it will flow.

The main concern some have with any cat delete setup vs even high flow cats is that there will be a little less back pressure. So of course it CAN FEEL (but in reality it is a slight bit extra time to spool (milliseconds)) the difference on the low end, but on the top end is where you see the power gain. Less back pressure the better at that point.

I don't think you'll notice the spool difference if you have high flow already but some people do. On the dyno you will see the power improvement, and of course the sound. I've seen some people on bigger setups think that straight pipes are not as good as a catless exhaust because it feels slower from the start. Low end torque is lost but horsepower is gained up top.

 

That small of a difference in size won't hurt horsepower at all. There's a mathematical formula to calculate the flow measurements based on pipe diameter with all other aspect being equal, but here's a page with some basic measurements, and you can infer from their charts and numbers that the difference between the sizes you mention is miniscule.

http://www.exhaustvideos.com/faq/how...diameter/#easy

 

Hi,Yes I have them and the flow rates of pipes also..I wasnt worried about that,Thanks anyways......Maybe I wasnt clear at first of my concern..
It was the step from the bigger diameter turbo outlet to the smaller ID of the cat pipe that has me worried because that would be very turbulant with all that flow/pressure hitting it to cause some type of restriction and not a smooth flow transaction..

 

John, I understand where you are comiong from...That is exactly why we manufacture our cats and pipes the way we do - to eliminate turbulence and improve the flow characteristics of our systems...

 

The Tials have the larger turbine outlet as well. Near 3.25" ID if I recall. Picture of the last system I made for an A28 powered car, notice the swage stepup by the turbine flanges. Main pipe diameter is 3"

The AWE straightpipes are the same, swaged open at the turbine flange to eliminate the flange step into the exhaust flow.

Does it make a difference over 3" pipe, don't really know as I don't dyno stuff here after building it(pretty much all custom/one-offs here). But I always think it's nice to see that someone put the effort into thinking about it and removing it from the equation, thus why I do it myself in my fabs.

 

Nice system..Looks mean..lol.
Todd told me the Tial alphas were 3'' diameter..

 

Thanks. It finally made it on a car after a few months, a members GT2 here.
Yeah a 3" pipe will slip into an A28/A30 turbine housing with some room to spare