This is a case where the ideal gas law can be applied. The composition and mass flow are slightly different on the exhaust side, but close enough. If you know the temperature, pressure, and mass flow, you can calculate the density using the ideal gas law and convert that to volumetric flow and then velocity. However you CAN'T use the ideal gas law to calculate pressure drop through an inter cooler or temperature rise through the compressor.

And you are correct about the adding heat part. For simplicity, just assume the basic Otto cycle where you just add heat at tdc.

 

It would be interesting to see what your calcualtion says. Reguardless what the calculator says, 2.5" will support 2400hp and has on multiple cars. My calculator has worked for the last few years and seems to be right on when the numbers are within the sweet spot.

 

Is that a single 2.5in charge pipe? Ie: single turbo?

Or 2 x 2.5in charge pipes? Ie: twin turbo.

 

Think its 2 x 2.5inch pipes will support 2400bhp.

 

That makes sense. Ive seen 1200hp with 2.5in single turbo but on a jap engine.

 

2 - 2.5" pipes has supported enough power to go 164mph @ 3350 to the 1/8 mile. I have the same crossover on the car now but on methanol with a bigger turbo. Looking for 181-183 to the 1/8 mile.

 

That has 2.25 pipes running in a oval shape with the ends fed in. That thing came on boost very quickly on the engine dyno even though it had tons of area pre turbo. What car are you putting that in David!!

Kurt

 

out of my budget, just a pipe dream although looks more like a PIPE NIGHTMARE!

 

That's a great data point and proves that most people do overkill on the crossover pipes.

Most people don't realize that the pressurized exhaust gas pre-turbine is of far less volume than exhaust on your typical NA engine, so it doesn't need nearly as much flow area.

This makes me wonder what are the implications pertaining to the exhaust port and valve. Can they also be downsized? This may make sense if it means you can fit a larger intake valve in there.

Another myth is that the downpipe shouldn't be oversized because you lose velocity. I know quite a bit about turbines and can assure you that the downpipe can not be oversized.

 

Well now that Ive changed my mind to a 2.25" crossover,,where do I find mild steel 90 degree elbows with a 4" radius ? lol.

 

Are you measuring inside or outside diameter on the pipe? Also what wall thickness? Ive got some 2" stainless steel pipe. It is all food grade pipe. Its 2" outside diameter 1 7/8" inside. 1/16 wall. Will this work on a 5.3 with a t6 s475? Reason for using is I can get all pipe and bends for free.

 

I was also kinda wondering what ID this was all refering to.

 

I've been calculating everything with 16ga wall other than possibly where I was trying to see if I could match some of Phil's numbers and I noticed he was using O.D. just to ballpark some things. Oh hell, I don't know, I might have been using I.D. for that too, I have the I.D. areas of all the different sized pipes on a paper here next to my keyboard. Haha....

I think Phil mentioned that he ballparks his calculations with O.D. just to be simple, and then works with I.D. when he's really fine tuning things.

 

2.5" od sch 40 and 2.5" od 16 gauge would result in vastly different flow calculations I would think

 

I agree, there's quite a difference between the two. 2.47" ID for SCH40 2.5", OD is 2.88" I believe.

 

I personally haven't seen anyone running giant pipe heavy like that for crossovers..... Is it common at all?

 

Nope was just illustrating the difference of ID and OD with various gauges of piping. It was not something I was using.

 

16 gauge is .0625 which is 1/16 thickness.
2.5" schedule 40 is .203 inch thickness.

 

I was looking for 16 gauge 2.25 OD mild steel, it seems that everyone is sold out of loose 90 degree bends. Columbia River's mandrel broke down, that does 2.25 tubing...lol

 

Wolfe Aircraft in Michigan has them in stock and will make them to order