any heat issues on downpipes

[cnes]

I have read somewhere that, catless downpipes (without any ceramic coating on them) can cause more heat in the foot area of the car, so your feet get hotter..

can anyone confirm this? so is it better to go with the ceramic coating?

thanks

[DavidGP]

No, this is not true.

[Justin.AutoTalent]

Definitely not true at all! I daily drive my car in California.... I've never experienced any kind of heat by my feet. There's plenty of heat shields surrounding the downpipes that prevent that

[cnes]

gotcha, I think I read that on the e90 area.
any thoughts on getting them coated?

[DavidGP]

Originally Posted by cnes

gotcha, I think I read that on the e90 area.
any thoughts on getting them coated?

There is no need for coating and IMHO its a waste of money.

[cnes]

Ok thanks

[Fast4d]

I don't see how getting rid of a catalytic converter can INCREASE heat.

[hotrod2448]

Originally Posted by Fast4d

I don't see how getting rid of a catalytic converter can INCREASE heat.

Way back in the day it used to be a possibility because cars weren't smart enough to adjust the a/f ratio for the increased scavenging that came from the drop in back pressure and they would run really lean. Not really a problem with modern cars.

[mike@x-ph.com]

Originally Posted by Fast4d

I don't see how getting rid of a catalytic converter can INCREASE heat.

+1
Going catless will actually help with any heat issue

[Tiago@VRSF]

I can also confirm this isn't true. Catless downpipes eliminate the restriction which helps with temps, not hurts

[CaryTheLabelGuy]

Because there are no cats in the aftermarket catless downpipes, the heat in that area is drastically reduced.

[STR8-6IX]

Originally Posted by hotrod2448

Way back in the day it used to be a possibility because cars weren't smart enough to adjust the a/f ratio for the increased scavenging that came from the drop in back pressure and they would run really lean. Not really a problem with modern cars.

even a modern ECU would have trouble adjusting the A/F ratio optimally though. you still need a tune for it to get the other half of your gains.

heat wrapping is really only necessary for naturally aspirated cars where the headers are inside the engine bay. heat wrap on a downpipe cant hurt, but its probably useless.

[CaryTheLabelGuy]

Originally Posted by STR8-6IX

even a modern ECU would have trouble adjusting the A/F ratio optimally though. you still need a tune for it to get the other half of your gains.

heat wrapping is really only necessary for naturally aspirated cars where the headers are inside the engine bay. heat wrap on a downpipe cant hurt, but its probably useless.

The Bosch MEVD17.2.G DME used in the N55/S55 is fully capable of adjusting to aftermarket downpipes all on its own. The DME works almost entirely in closed-loop feedback and has 2 wideband O2s sensors (one for each bank/turbo). The DME is VERY fast at making changes and is constantly monitoring AFR and adjusting fuel trims to meet the target AFR for a given condition, even during WOT.

There is a brief period that the DME enters a spool mode (during WOT spool-up) where the DME enters a limited open-loop, but then resumes closed-loop feedback once target boost is achieved.

ECU's of old did not work like this as closed-loop feedback was only for idle and part-throttle conditions of light-to-medium loads. Therefore, at WOT, the ECU would go into open-loop and totally ignore Lambda info (most didn't have wide-band primary O2 sensors) and instead relied on how the fuel tables were tuned along with some various compensation tables. The Bosch DME is extremely advanced/sophisticated, very fast and is easily the most impressive DME/ECU I've ever seen at work, to-date.

Now, if your argument is that AFR should be tuned a little leaner with downpipes and therefore the DME would not do this in its own, you'd be slightly correct. The DME's target AFRs are typically in the rich side, even with the stock downpipes in place and therefore with a tune, could stand to be slightly leaned out anyway (at WOT).

[STR8-6IX]

Originally Posted by CaryTheLabelGuy

The Bosch MEVD17.2.G DME used in the N55/S55 is fully capable of adjusting to aftermarket downpipes all on its own. The DME works almost entirely in closed-loop feedback and has 2 wideband O2s sensors (one for each bank/turbo). The DME is VERY fast at making changes and is constantly monitoring AFR and adjusting fuel trims to meet the target AFR for a given condition, even during WOT.

There is a brief period that the DME enters a spool mode (during WOT spool-up) where the DME enters a limited open-loop, but then resumes closed-loop feedback once target boost is achieved.

ECU's of old did not work like this as closed-loop feedback was only for idle and part-throttle conditions of light-to-medium loads. Therefore, at WOT, the ECU would go into open-loop and totally ignore Lambda info (most didn't have wide-band primary O2 sensors) and instead relied on how the fuel tables were tuned along with some various compensation tables. The Bosch DME is extremely advanced/sophisticated, very fast and is easily the most impressive DME/ECU I've ever seen at work, to-date.

Now, if your argument is that AFR should be tuned a little leaner with downpipes and therefore the DME would not do this in its own, you'd be slightly correct. The DME's target AFRs are typically in the rich side, even with the stock downpipes in place and therefore with a tune, could stand to be slightly leaned out anyway (at WOT).

who makes the MSV90 ECU, siemens i think? is this a good ECU?

for example when I deleted my secondaries, and the same for installing a magnaflow muffler the ECU needs roughly 500KM to adjust properly and it did a very impressive job. you can tell that every 100KM the cold start would have a nicer tone to it and it stopped adjusting after about 500 k so it takes some time. full throttle pulls help this process alot. I just heard of N54's i believe running very rich after a catless downpipe install and needing a tune.

so for the N55, you need a tune to get rid of the CEL but not actually tune the ECU itself? how about the n54?