Tune plus downpipes, worth it??

[nikhsub1]

Back to reality... The OEM cats are not high flow cats. I've seen 1500 cel thrown around, like I said before they are dense and do not flow well, no matter what kind of temper tantrum forzda1 wants to throw. Most of the after market cats are 200cell, or over 7X less dense than OEM. I have a race cat sitting on my desk, it is 200 cel and I can see through it. Now, I have no OEM cat from the Raptor here on my desk but I would venture to say, you could not see through it at 1500cel count. Anyway, there may not be tons of gains from a high flow cat on this application, I don't think that is the case but it's possible. For anyone to say that the cats are fine and don't cause any restriction without testing is just asinine.

I'm not trying to beat a dead horse or be difficult, but no facts have been presented one way or the other even though forzda1 keeps saying he has presented facts. If I've missed them somewhere, please point me to them.

 

[RaptorFlipper]

That makes sense to me. When examining the oem vs the new setup(mine was kooks downpipe and magnaflow exhaust) there was a noticeable difference in the size of everything.

 

[FORZDA 1]

The aftermarket 200 cell cats are 4" in diameter, or 5 sq-in. The OEM cat is 8" in diameter, or 50 sq-in. The "flow" area within the OEM cat is 10 times larger than the Hi-flow version. If we take your 200 cell and multiply by 10 we get 2000 cells. So technically, the OEM 1500 cell cat has as more actual "flow" area as the aftermarket cat. I'm still not saying the OEM cats are "Hi-flow" just that they do not result in any power loss due to their "flow rate".

 

[RaptorFlipper]

Interesting. So then there is lees flow in the supposed "upgraded" exhaust? Does that mean less power in theory?

 

[FORZDA 1]

Interesting. So then there is lees flow in the supposed "upgraded" exhaust? Does that mean less power in theory?

If referencing the cat then, in pure mathematics, yes. But in reality no, because the OEM turbo isn't moving enough air mass to result in any "restriction" to effect a reduction in the mass flow.

If we were to blow enough air through the cats/pipe(s) to produce a measurable reduction in the "air mass" going in vs the "air mass" coming out then there would be a true restriction. Otherwise it's just someone looking at shit on their desk...

The killer of exhaust "flow" is the turbulence within the pipe that forces the air mass to turn tight (90 deg)corners right near the peak mass flow. That is why the pipe shape right out of the turbine is the most critical to maintain the mass flow rate. If the OEM down pipe wasn't straight through to the cat and fairly straight out of the cat, then we would have issues.

If designing a "race" pipe then short and straight is the "best" where the diameter isn't as critical unless exaggeratedly smaller than the turbine outlet. 2.5" vs 3" isn't a big deal on the STOCK size turbine.

 

[RaptorFlipper]

Ok. So in your opinion, the "upgraded" downpipe/exhaust is giving no extra power? Just different sound? Or is there some other value in doing the downpipe/exhaust? It obviously worked really well in 13, as i have the gains to show it, but the turbo situation is different? It's not about forcing air faster in and out? I thought that is how a turbo creates its power.

 

[FORZDA 1]

Ok. So in your opinion, the "upgraded" downpipe/exhaust is giving no extra power? Just different sound? Or is there some other value in doing the downpipe/exhaust? It obviously worked really well in 13, as i have the gains to show it, but the turbo situation is different? It's not about forcing air faster in and out? I thought that is how a turbo creates its power.

The relatively tiny OEM turbo can't move enough air to make the OEM piping cause a significant reduction in potential power. Thusly, the aftermarket piping doesn't make a significant improvement. The turbo makes more power by moving MORE air by compressing it. THE restriction on a turbocharged engine is the size (and shape) of the turbine wheel and housing. If the exhaust/piping diameter is smaller than the turbine outlet diameter, then you should consider opening it up to the minimum turbine outlet diameter.

This is why the SPD adapters were introduced. Technically they should be an improvement however, the perceived "restriction" is so tiny that they're essentially not worth the effort.

You can spend the money to install ALL of the bolt-on aftermarket parts and will likely be able to measure a slight increase in power (if tuned to take advantage of it). If you take that same money and invest in a slightly larger turbo (turbine and compressor) while leaving everything else the same, you will see a large improvement that will be worth the effort.

Note that the slight improvement will likely only be seen on a good dyno, not in any actual performance increase. Hence why I recommend a simple timed acceleration test preferably at a sanctioned track where the timers are certified.

 

[nikhsub1]

The aftermarket 200 cell cats are 4" in diameter, or 5 sq-in. The OEM cat is 8" in diameter, or 50 sq-in. The "flow" area within the OEM cat is 10 times larger than the Hi-flow version. If we take your 200 cell and multiply by 10 we get 2000 cells. So technically, the OEM 1500 cell cat has as more actual "flow" area as the aftermarket cat. I'm still not saying the OEM cats are "Hi-flow" just that they do not result in any power loss due to their "flow rate".

The cell count is the count - it doesn't matter if it is 40 feet in diameter, 1500 cel is 1500 cel. Without flow testing, we have no facts either way so not sure why we are arguing.

 

[wjn]

The aftermarket 200 cell cats are 4" in diameter, or 5 sq-in. The OEM cat is 8" in diameter, or 50 sq-in.

I double the diameter, and get a ten times bigger surface, no sir. The 4" dia has 12.5 sq-in, 4 times difference, not ten. (Formula is pi * r2.)

And as stated above, normally the cell count is in CPSI (cells per square inch). Your example for flow difference is good, but maybe better turn it around: 1500 devided by 4 (difference in surface) equals 375. If the stock cat has 1500 cpsi and 8" diameter, it will flow (approx.) like a 375 cpsi with 4" diameter. In this case a 200 cpsi with 4" diameter will have a better "flow".

 

[FORZDA 1]

I double the diameter, and get a ten times bigger surface, no sir. The 4" dia has 12.5 sq-in, 4 times difference, not ten. (Formula is pi * r2.)

And as stated above, normally the cell count is in CPSI (cells per square inch). Your example for flow difference is good, but maybe better turn it around: 1500 devided by 4 (difference in surface) equals 375. If the stock cat has 1500 cpsi and 8" diameter, it will flow (approx.) like a 375 cpsi with 4" diameter. In this case a 200 cpsi with 4" diameter will have a better "flow".

CRAP! Yes, I know the formulas. I was hastily doing all the calcs and writing them on a scrap of paper. Looks like I grabbed the 2.5" diameter pipe area from my paper. Thanks for catching it right away!