Ceramic coated header and intake

[maxbraketorque]

When things settle in, I would like to hear of some under hood temperature verses ambient temperature.

My XJ intake temps average 135 at highway speed in 85 degree temperature and close to 200 in stop and go traffic also 85 degree ambient temperature.

For similar outside air temps, mine is a bit lower on the highway, maybe 10-20F lower, but its way lower in stop-n-go traffic, about 150F is the most I see for that outside air temperature.

 

[RCP Phx]

I just got back from some "before" testing. With the ambient temp of 110* and running up to 50mph my AIT was 150-155* depending on the throttle position. Nothing else will be done so it should be a fair test as long as it's 110* outside, humidity is about the same/constant this time of year

My XJ intake temps average 135 at highway speed in 85 degree temperature and close to 200 in stop and go traffic also 85 degree ambient temperature.

For similar outside air temps, mine is a bit lower on the highway, maybe 10-20F lower, but its way lower in stop-n-go traffic, about 150F is the most I see for that outside air temperature.

Since I started with a factory air box and my much higher outside air temps I wonder what kind of set you guys are running

 

[maxbraketorque]

Since I started with a factory air box and my much higher outside air temps I wonder what kind of set you guys are running

Stock airbox with isolation and insulation. First I applied Frost King HVAC duct closed cell self-adhesive foam insulation around the entire airbox body and lid, including the bottom of the airbox body. Also put some on the intake tube going to the throttle body. Then I sealed around the front of the airbox to favor pulling air from outside. Its certainly ghetto looking, but I don't care.

 

[plinkerneil]

My old Revolver( I bought a new one for coating) was 4yrs old with no signs of any cracking on it anywhere.

Thanks, that's good info.

 

[techno1154]

Note,...Intake air temperature (I read) average 40 decrees above ambient temperature. Lower for a good CAI. I do not know if that study includes our 4.0L were the intake is just above the exhaust.

In my XJ, intake air temperature is higher because I no longer have the air box. Instead, there is an open cone filter were the air box used to reside.

Intake air temperature is read from the PCM via the OBD port. Ambient temperature is read from the overhead console. I cannot read the engine room temperature,... I do not have the required equipment to measure it.

 

[twinhauler]

Intake looks good in that color!

 

[RCP Phx]

Most of the advertised "cold air" kits are useless that's why I started trying to get the temps down about 4yrs ago with a stock set-up. I'm re-addressing it as we speak and think I can still improve upon it. Pic is from '17.

 

[JohnX]

I would have been curious to see if there is any mpg loss from the cooler air, I've heard rumors the air density can change enough to require extra fuel for proper burn.

It looks damn sexy though.

 

[maxbraketorque]

That's nifty. Looks easy too.

 

[RCP Phx]

I would have been curious to see if there is any mpg loss from the cooler air, I've heard rumors the air density can change enough to require extra fuel for proper burn.

It looks damn sexy though.

It goes both ways, if the atmospheric pressure is higher you will get more HP. A cooler charge allows more air in and then expands creating more HP.

 

[plinkerneil]

I would have been curious to see if there is any mpg loss from the cooler air, I've heard rumors the air density can change enough to require extra fuel for proper burn.

Cooler, denser air gives you better volumetric efficiency. That means you get more oxygen in the cylinder at a given throttle position and RPM. If you back off the throttle and get the same power, your mileage will improve. If you use the extra air to get more power, your smileage will improve.

 

[JohnX]

It goes both ways, if the atmospheric pressure is higher you will get more HP. A cooler charge allows more air in and then expands creating more HP.

Duh, but more power can equal more fuel consumption.

Just saying I would have been curious to see long term averages before and after....probably too small of a change to quantify accurately.

 

[JohnX]

Cooler, denser air gives you better volumetric efficiency. That means you get more oxygen in the cylinder at a given throttle position and RPM. If you back off the throttle and get the same power, your mileage will improve. If you use the extra air to get more power, your smileage will improve.

Smiles per gallon!

 

[maxbraketorque]

Duh, but more power can equal more fuel consumption.

Just saying I would have been curious to see long term averages before and after....probably too small of a change to quantify accurately.

The ECU will run higher ignition timing with a cooler intake charge. This contributes to improved gas mileage, although its going to be a relatively small improvement. Colder intake charge also helps the motor resist det which is a good thing on the 4.0L because it has no knock sensor.

 

[JohnX]

The ECU will run higher ignition timing with a cooler intake charge. This contributes to improved gas mileage, although its going to be a relatively small improvement. Colder intake charge also helps the motor resist det which is a good thing on the 4.0L because it has no knock sensor.

I have a pretty good understanding of all that

Like I said, just would have been cool to see long term comparisons as I have seen some cold air intake info suggesting loss of mpg.


And fwiw, my 4.0 (4.6) has a knock sensor. :confused1

 

[maxbraketorque]

I have a pretty good understanding of all that

Like I said, just would have been cool to see long term comparisons as I have seen some cold air intake info suggesting loss of mpg.

And fwiw, my 4.0 (4.6) has a knock sensor. :confused1

But you didn't indicate recognition of timing improvement in your prior post.

Always good to have a knock sensor that provides useful information. Too bad factory XJ 4.0 never had one.

 

[RCP Phx]

Just saying I would have been curious to see long term averages before and after....probably too small of a change to quantify accurately.

I've got 21yrs of data, I don't understand what your looking for?

Too bad factory XJ 4.0 never had one.

The Renix motors did!

 

[JohnX]

I've got 21yrs of data, I don't understand what your looking for?

Cool, let's see some mpg numbers after you run this setup for a while.

 

[RCP Phx]

My goal is to squeeze every drop of HP of my stroker (+325HP) by trying to reduce the intake temps and maybe also the under-hood temps over-all.

When I talked to Russ last week he told me of a few saying they are getting almost 20mpg, that's what I'm shooting for.

That's a definite!

 

[RCP Phx]

This was from Aug '18 and the last time I checked, I've done a lot of things since.

Well I just got home from my 300 mile trip with great news. I averaged 16.3 mpg on a 325hp/400ft/lb extreme 4.6, way better than what I was getting! Dave said that among other things he adjusted the "torque management curve", I not sure what that means but the shifting points are way better specifically the "down-shift under load" at high speed.