Temperature readings on exhaust manifolds or headers as well as heat wrap help

[ViperGeorge]

Lou has a reputation for being a bit difficult to deal with. I have friends that have had problems with him. I agree with Lawineer, something is going on. Could it be the cats, maybe. The Prefix PCM ignores the rear O2 sensor so you wouldn't get a cat efficiency code. On the stock tune the PCM compares the upstream O2 to the downstream O2. The readings should be different but since the Prefix PCM ignores the downstream you won't throw a code. You can actually remove the rear O2 sensors and plug the bungs.

I wonder if a plugged cat would cause excessive heat. Then again a clogged cat would probably effect engine performance. Personally for a car run on the street I would not eliminate the cats. The smell is overwhelming especially for the poor smuck following you. We have a couple of people in our local club that don't have cats. Most of us try to get them in the rear of the pack when we are travelling or you end up getting sick from the smell. When the cats in my ACR died I would start to get headaches just driving around.

Your heat condition is unusual. There has got to be something going on. Again my ARH headers which are Swain coated run way cooler.

[Jack B]

I have been following this thread, here are some insights:

1. The temps below are not out of line. Typical IR camera readings are inaccurate to the low side. The most accurate measurement is a conductive mechanical probe, Unless you have a high resolution IR camera the temps your seeing are the average of the view of view, therefore, low. In addition, if you are using an IR camera, the emissivity of shiny metal will also show an error to the low side.

2. Personally I do not think you need to remove the headers to reduce the heat damage. I have the sticky/radiant sheet insulation on the frame side and blankets over the headers.This was all done with the headers installed. I have seen zero evidence of heat damage.

3. As far as the cats creating a problem, after-market cats in the sill are not going to generate that much heat in the area of the fuse box or the side of the engine. Cats generating excessive heat are going to directly affect the top/front part of the sill.

4. Header mfg are not going to be supplying a consistent series of cat, they can and will change suppliers. Maybe try to check/compare the cat temps to see if they are similar. If you contact Prefix, they will lead you to the best cat.

ARH IR.jpg

I’m trying to get some temperature readings on stock exhaust manifolds and headers from other guys. I recently installed Belanger headers and had them coated with Swain tech white lighting exhaust coating. On a spirited street ride I had temp readings of 390 degrees F, on a 20 minute track sessions I’m getting readings as high as 640 degrees(readings taken on the header close to the connection to the block). I’m less than impressed with the Swain Tech coatings ,I have reached out to them a couple of times on the problem and have gotten no response. I was planning on wrapping the headers has anyone wrapped them in place or should I bite the bullet and remove the headers and wrap them? Appreciate all help
Here is the link to my original post on the header heat shielding https://driveviper.com/forums/thread...ng-for-headers

Thanks
Dennis

[Lawineer]

If you’re wondering if the cats are the problem, just look inside them. It’s pretty easy to see if they’re clogged.

If they’re clogged, it may be a symptom of running rich or having timing issues.

[ViperC]

I've used Belanger and M&M, both coated, and never used any type of additional thermal protection. I even removed the side sill insulation and have not notice one issue at all.

[SRT_BluByU]

another consideration is the possibility of a leaky injector or more..

[ViperGeorge]

Jack, as usual your explanation of temperature readings is thorough, however, several of us do not seem to have near the heat that the OP has using headers. I don't know off hand what temperature his wrap can withstand but look at it, it is black and crispy. Even if my temp readings are inaccurate I can't imagine they are hundreds of degrees off. I used a laser pyrometer on the Swain coated headers. The Swain coating is a dull whitish color and is not shiny. None the less even without reading the temps I would know my headers are cooler than his as I can place my hand very close to them after coming off track. I haven't touched them but I could get pretty close. At 600 degrees I couldn't get my hand anywhere near his headers.

Something still seems amiss to me.

[Lawineer]

another consideration is the possibility of a leaky injector or more..

For sure. I'm pretty certain a lot of fuel is burning in the exhaust.
Obviously, that could be a million things from cam timing to tune to injector to whatever.


Here's a good diagnostic question: Are they both really hot or just one side?

Is there a big delta from one bank to the other? Or even one primary to another?

[Hawk]

I am getting consistent temp readings on both side of the engine . The cats show no sign of a clog and the temp reading have been consistent since I first started the car with this exhaust system. I don’t believe I’m running all that much hotter than a stock car from the reading I have gotten from another owner with the stock set up in a track environment . If it wasn’t for the much lower readings everyone else is getting I might not think I have much of an issue. As a note on disassembly two of the bolts connecting the headers to the collector were slightly loose perhaps that minor leak made that side of the motor hotter where I had the insulation burn up or the adhesive attaching the heat shielding to the body pan let go and it fell onto top the collector, but this would not explain the matching high temperatures on both sides of the car. I just talked to Prefix and he suggested doing a fuel pressure test to see if I’m running too lean due to a faulty fuel pump or some type of clog. I looked thru the service manual but can’t seem to find out where and how to test it.
I really appreciate everyone help on this issue. I’m sure in hind sight it will probably be some fluke issue
Thank you
Dennis

[Dan Cragin]

Exhaust temps on Gen 5's go sky high, in fact we run "open loop" tunes on all the race applications as the O2 sensors simply burn up. These engines make best power on the lean side, which makes the EGT's even higher.

The combination of a performance calibration and headers, makes for really high EGT's, a function of the extra power being made.

Belanger headers are mild steel and run cooler than SS, they will distort if wrapped.

The best results I have seen is to use an inconel heat shield with about a 1 inch air gap between the header and the shield. This allows some heat to escape but will not cook the under hood wiring.

Also, if you have a six vent hood, remove the plastic grills, this will improve airflow.

From the pictures, it appears you are not letting any radiant heat disperse, which is superheating the exhaust. Technically its best to keep all the heat in the exhaust, but in my experience, not in this application.

[Hawk]

I had a long interesting conversation with Lew Belanger (he’s defiantly gets revved up when talking about this stuff) and he seems to think it’s the Prefix controller ,he is not a fan of their controller and he indicated to me the stock one is better? Possibly the stock pmc will throw a code if there is some other issue going on with the downstream O2 sensor connected? I’m going to try and give the old controller a try however I will need to get new down stream sensors and extension wires first. I have a friend coming down this weekend with a fuel pressure testing kit to try and eliminate that
Any additional suggestions?

[Dan Cragin]

Higher EGT's with the Prefix controller for sure.

With the stock controller you may get catalyst codes due to the aftermarket types used with the headers.

[ViperGeorge]

Higher EGT's with the Prefix controller for sure.

With the stock controller you may get catalyst codes due to the aftermarket types used with the headers.

I performed back to back track tests on my 2015 TA 2.0 with Bellanger headers a few years ago. One with the Arrow PCM and one with the stock PCM. No appreciable difference in heat in terms of oil or coolant temps. 265 oil and 245 coolant. Not sure this translates to exhaust temps but if the exhaust was cooler with one PCM I would think coolant and oil temps from heat soak would be different. My ACR-E with 9 liter extreme never runs that hot.

[Hawk]

George
When you did the back to back tests did you notice a performance difference? Or was it more the additional benefits like higher rev and skip shift lock out ? Wish I had the funds for the 9L
Thanks
Dennis

[Lawineer]

Unless you have "internal" mods, a good rule of thumb is stick with a factory tune. It's definitely the most reliable, and they have no reason to pull any punches at WOT. WOT/Open loop is not regulated by emissions. There may be a few horses to gain by getting aggressive with spark timing, but generally not worth it.


That's a very broad stroke and rule of thumb but I've heard it from very well respected tuners.

[ViperGeorge]

George
When you did the back to back tests did you notice a performance difference? Or was it more the additional benefits like higher rev and skip shift lock out ? Wish I had the funds for the 9L
Thanks
Dennis

Truth is I was more focused on temps. My TA 2.0 ran hot in about 15 minutes on track. Common problem with other TA 2.0s at the time. Since it was an open lapping day traffic had more to do with lap times than the PCM. If I remember correctly the Arrow PCM raised the redline a couple of hundred rpms. This would allow you to stay in a gear longer. This can be helpful at some tracks.

My ACR either before or after the 9 liter swap never ran anywhere near as hot. Worst I've seen on a very hot day was about 223 coolant whereas my TA 2.0 would get to 245 or so in 15 minutes. Mark Jorgenson thinks it may have to do with the bigger splitter on the front of the ACR pushing more air through the radiator. The TA 2.0 would also cook the insulation that was installed to prevent heat damage from the headers. Insulation around the upstream O2 wires would get real crispy even though I was using DEI very high temperature wrap.

My TA 2.0 had Bellanger headers that were ceramic coated but not wrapped. My ACR has ARH headers which are Swain coated. Swain coating, as you know, is substantially thicker than other ceramic coatings like Jet Hot.

[ViperGeorge]

Unless you have "internal" mods, a good rule of thumb is stick with a factory tune. It's definitely the most reliable, and they have no reason to pull any punches at WOT. WOT/Open loop is not regulated by emissions. There may be a few horses to gain by getting aggressive with spark timing, but generally not worth it.


That's a very broad stroke and rule of thumb but I've heard it from very well respected tuners.

It has been a while but I think there are a some other advantages with the Arrow PCM that might cause someone to want it (remember developed by Dick Winkles the guy that developed the OEM one and I do believe he knows what he was doing). First it eliminates the skip shift, two it eliminates the need for the rear O2 sensors, three it raises redline which allows you to stay in gear longer, fourth it (if memory serves) leaned out the engine some to adjust for the overly rich stock tune, and last improved throttle response from the drive by wire system.

Given these benefits I would think it might be worth keeping it. I remember discussing heat issues on my TA 2.0 with Dick and he said he was certain the Arrow tune would not effect heat given the entirety of what they did. This seemed to be proven out with my testing.

[ViperGeorge]

By the way, with my TA 2.0 Mark Johnson at IPSCO installed some little scoops on the underside of the car near those round holes in an effort to push more air up onto the headers. Never really determined if that worked or not though but it seemed like a good idea. Maybe the biggest factor is the splitter. More air pushed into the radiator should help keep everything cooler. So a bigger splitter on the OP's TA (if he doesn't have one already) might help.

[blingnoring]

excuse my ignorance, but how do you measure the fuel pressure on a gen v? most cars seem to have a fuel port where you screw on the pressure gauge but i couln't find it on the Viper.

[Lawineer]

By the way, with my TA 2.0 Mark Johnson at IPSCO installed some little scoops on the underside of the car near those round holes in an effort to push more air up onto the headers. Never really determined if that worked or not though but it seemed like a good idea. Maybe the biggest factor is the splitter. More air pushed into the radiator should help keep everything cooler. So a bigger splitter on the OP's TA (if he doesn't have one already) might help.

Usually, aero hurts cooling. It makes the air go faster and more laminar under the car (and not up into the engine bay).

I'm 100% guessing here, but I'd also venture to guess that you need to be real careful about adding scoops under the car. Getting air out is just as important as air getting in (and where it is let in/out). If the design is for the air to come in through the front and exit through the back, and you put scoops in the back, you basically just created an air wall and you'll get less air flow.
I worked on a vehicle design that we just couldn't keep cool. Turns out, the problem wasn't that it didn't get enough air into the radiator, but that the engine bay was so tightly sealed up (plates underneath, tight packaging, etc), the air couldn't get out. No air out = no air in.

[ViperGeorge]

Usually, aero hurts cooling. It makes the air go faster and more laminar under the car (and not up into the engine bay).

I'm 100% guessing here, but I'd also venture to guess that you need to be real careful about adding scoops under the car. Getting air out is just as important as air getting in (and where it is let in/out). If the design is for the air to come in through the front and exit through the back, and you put scoops in the back, you basically just created an air wall and you'll get less air flow.
I worked on a vehicle design that we just couldn't keep cool. Turns out, the problem wasn't that it didn't get enough air into the radiator, but that the engine bay was so tightly sealed up (plates underneath, tight packaging, etc), the air couldn't get out. No air out = no air in.

Well either way, my ACR still runs cooler. If it isn't the splitter forcing more air through the radiator and into the engine bay I have no idea why my ACR runs cooler. It runs cooler than a friend's stock GTS on track as well. As I said I could never tell whether the small scoops on my TA worked or not. They didn't seem to hurt any that's for sure.

[Hawk]

Would the smaller under drive pulley be causing this?

[ViperGeorge]

Would the smaller under drive pulley be causing this?

No. I have the underdrive pulley on my ACR and had it on my TA 2.0. It will only slow down your accessories a little. Actually helps on track as you don't buzz the accessories so hard when you are running high rpms. The IPSCO underdrive pulley is the same spec as was used on the Comp Coupes and ACR-X I believe.

[Aevus]

Just took a temp reading on my wrapped headers and reads from 370f to 420f (middle one), pretty cool weather cloudy 50f.