This post is a little long, so please bear with me as it contains some interesting info that may help to increase your N/A S197 GT's hot weather performance.
I'm sure that most of you already know that our N/A cars suffer from decreased performance when the weather turns hot, and that it's caused not only by the less dense air, but also by the PCM pulling timing when the IAT exceeds a specific temperature.
And we all know that nothing can be done about the hot weather except to drive when things turn cooler(or move to Alaska).
However, you may not know that reducing the IAT during hot weather is something that can be done very easily, and with little or no expense for most owners with CAI equipped N/A GT's.
So as Paul Harvey used to say "And now, the rest of the story...."
Yesterday I was checking the fluid levels on my 05 S197 GT when I noticed that the foam rubber strips on the top of my C&L Street CAI's heat shield had contact marks in only a few spots from the underside of the hood due to the irregular shape of the underhood insulating pad.
Obviously, this indicated that there were some apparent gaps between the underhood pad and the foam rubber that has been allowing hot engine compartment air to easily flow into the CAI when the car is at a standstill with the engine fully warmed up and idling.
This of course means reduced performance when starting from a red light, drag strip starting line, etc., due to excessively high IAT's.
And were they high when the car was at a standstill with a fully warmed up engine in hot weather? You bet!
Data logging with a Predator tuner at an 82 F ambient temp showed the IAT quickly jumping from 82 F to 100 F when stopped for as little as 10 sec. at a stop sign, and soaring above 120 F while waiting at a stop light for only 30-45 sec.
So with equipped with some heavy duty polyethylene sheeting, some high temperature duct tape, a few basic tools, and a little imagination, I installed a taut plastic covering over the top of the heat shield that extends to the front of the car.
I used the heat shield's foam strips, a few existing car bolts/washers, an existing removeable rubber cushion on the fender, and duct tape along the front of the car above the headlight to secure the sheet firmly in place.
There were also 2 gaps between the bottom rear section of the shield and the fender that were filled in with fine sponge.
The end result is a fully shielded CAI that now sucks in cooler outside air mainly from the opening below the headlight(Sorry, no pics).
And accessing the air filter for cleaning will not be a problem since the heat shield's foam strips, the fender's rubber cushion, and a bolt or 2 can be easily removed, and the sheet can then be folded completely away from the heat shield.
I also made sure the sheet remains taut by having my wife rev the engine to 6K rpms.
Time for some IAT data logging.
Ambient - 82 F.
Got the engine fully warmed up, did a few hard runs, and parked the car with the engine idling for 1 minute.
The IAT rose a mere 14 F from 84 F to only 98 F.
After another 30 sec. it went up to only 106 F.
Got underway, and 1/2 mile down the road it had already dropped to 94 F, and then down to 84 F within another 1/2 mile.
And most importantly, the car's performance is now much improved when stopping for 1 min(max stopping time for red lights in my area) with the engine fully warmed up and idling.
Needless to say, I'm very pleased with the results.
I'll just have to frequently check the installation during the next few weeks to make sure everything stays secure, and the sheet(melting point - 110 C) does not start losing its tautness in the high temperature environment(If it does, then I'll research high temperature plastic films).
so let me see if i understand what your saying which i dont think i do but would really like to.so you take a towel or sheet and make like a roof or shiled over the top of my cai.and put some foam put somwhere did not really understand where just some opening.i will have to read this again and walk out and take a look under my hood.this seems weird i would think geting more air would be better to cool than trying to block air.i think most of us dummer memebers will need pics.but i live in alabama it is over 100f heat index here i would love to try this.
its built in the mass air meter. F/I guys relocate it to the blower intake. I live in houston,tx and get readings up to 150* so im curious how you did this too. PICS PLZ!
This post is a little long, so please bear with me as it contains some interesting info that may help to increase your N/A S197 GT's hot weather performance.
I'm sure that most of you already know that our N/A cars suffer from decreased performance when the weather turns hot, and that it's caused not only by the less dense air, but also by the PCM pulling timing when the IAT exceeds a specific temperature.
And we all know that nothing can be done about the hot weather except to drive when things turn cooler(or move to Alaska).
However, you may not know that reducing the IAT during hot weather is something that can be done very easily, and with little or no expense for most owners with CAI equipped N/A GT's.
So as Paul Harvey used to say "And now, the rest of the story...."
Yesterday I was checking the fluid levels on my 05 S197 GT when I noticed that the foam rubber strips on the top of my C&L Street CAI's heat shield had contact marks in only a few spots from the underside of the hood due to the irregular shape of the underhood insulating pad.
Obviously, this indicated that there were some apparent gaps between the underhood pad and the foam rubber that has been allowing hot engine compartment air to easily flow into the CAI when the car is at a standstill with the engine fully warmed up and idling.
This of course means reduced performance when starting from a red light, drag strip starting line, etc., due to excessively high IAT's.
And were they high when the car was at a standstill with a fully warmed up engine in hot weather? You bet!
Data logging with a Predator tuner at an 82 F ambient temp showed the IAT quickly jumping from 82 F to 100 F when stopped for as little as 10 sec. at a stop sign, and soaring above 120 F while waiting at a stop light for only 30-45 sec.
So with equipped with some heavy duty polyethylene sheeting, some high temperature duct tape, a few basic tools, and a little imagination, I installed a taut plastic covering over the top of the heat shield that extends to the front of the car.
I used the heat shield's foam strips, a few existing car bolts/washers, an existing removeable rubber cushion on the fender, and duct tape along the front of the car above the headlight to secure the sheet firmly in place.
There were also 2 gaps between the bottom rear section of the shield and the fender that were filled in with fine sponge.
The end result is a fully shielded CAI that now sucks in cooler outside air mainly from the opening below the headlight(Sorry, no pics).
And accessing the air filter for cleaning will not be a problem since the heat shield's foam strips, the fender's rubber cushion, and a bolt or 2 can be easily removed, and the sheet can then be folded completely away from the heat shield.
I also made sure the sheet remains taut by having my wife rev the engine to 6K rpms.
Time for some IAT data logging.
Ambient - 82 F.
Got the engine fully warmed up, did a few hard runs, and parked the car with the engine idling for 1 minute.
The IAT rose a mere 14 F from 84 F to only 98 F.
After another 30 sec. it went up to only 106 F.
Got underway, and 1/2 mile down the road it had already dropped to 94 F, and then down to 84 F within another 1/2 mile.
And most importantly, the car's performance is now much improved when stopping for 1 min(max stopping time for red lights in my area) with the engine fully warmed up and idling.
Needless to say, I'm very pleased with the results.
I'll just have to frequently check the installation during the next few weeks to make sure everything stays secure, and the sheet(melting point - 110 C) does not start losing its tautness in the high temperature environment(If it does, then I'll research high temperature plastic films).
That’s what I was afraid of. Where I do agree that the improved/sealed CAI setup is a step in the right direction the testing process is flawed.
The IAT sensor is located too far away from where the IAT needs to be located to get a true idea of the cooling effects of any CAI setup. By the time the intake air charge makes its way past the MAF, through the TB, winds its way through the intake and then gets to the intake ports of the heads it will heat up dramatically. An intake air charge drop of 15 deg measured at the OEM IAT sensor can be completely wiped out or reduced dramatically by the time it gets to the backside of the intake valve (which is the only spot where the IAT matters).
To truly test this sort of setup IAT would need to be measured inside the intake port of the head. I have my data acquisition system set up to do just that but I have not wired everything up yet so I don’t have any data to quote.
Of course reducing the IAT never hurts. It’s just a matter of if the gains achieved (if any) being worth the cost/effort.
__________________
I get asked why I carry a gun. I tell them its because stabbing people is gross.
That’s what I was afraid of. Where I do agree that the improved/sealed CAI setup is a step in the right direction the testing process is flawed.
The IAT sensor is located too far away from where the IAT needs to be located to get a true idea of the cooling effects of any CAI setup. By the time the intake air charge makes its way past the MAF, through the TB, winds its way through the intake and then gets to the intake ports of the heads it will heat up dramatically. An intake air charge drop of 15 deg measured at the OEM IAT sensor can be completely wiped out or reduced dramatically by the time it gets to the backside of the intake valve (which is the only spot where the IAT matters).
To truly test this sort of setup IAT would need to be measured inside the intake port of the head. I have my data acquisition system set up to do just that but I have not wired everything up yet so I don’t have any data to quote.
Of course reducing the IAT never hurts. It’s just a matter of if the gains achieved (if any) being worth the cost/effort.
Primary reeason I relocated the IAT sensor to the intake plenum. Taking a temperature at the MAF is just asking for trouble (especially if FI).
A lower IAT at the MAF definitely increases the engine's power output simply because the PCM starts pulling timing at an IAT of 100 F(+/-), and the lower the IAT the less timing the PCM pulls.
I realize that it's not proof definite, like dyno graphs or 1/4 mile time slips, but after suffering from reduced performance over the last 4 summers and part of this summer, my butt meter can definitely feel a noticeable performance improvement with this mod when accelerating after a stop in hot weather. The sluggishness has obviously not been completely eliminated when compared to cool weather performance(50 F and lower) due to the summer air's lower O2 content, but it has been reduced.
This mod is blocking only the hot air from the engine compartment, which should have been blocked in the 1st place if the CAI's heat shield was properly designed to make a complete seal against the underside of the hood.
However, it's not blocking the cooler air that flows inward from the opening under the headlight, which is far exceeds the engine's max air flow requirements.
The reason why I did not post any pics is because I'm still using the dinosaur Windows 98 OS, which is incompatible with the software that came with my wife's new digital camera. I know, I know. I'm living in the dark ages, but it still takes care of all of my needs(except posting pics). I should be able to work around that by using my friend's XP system. I'll try to get them up in the next few days.
hey thanks ski i would love to see a pic so i can try this i understand what your saying now by blocking the hot air coming from the motor.so would making a sheild arround the cone filter like the stock air filter is in not work.well no because then your not geting any more air in than the stock one.i dont know just thinking out loud i will be waiting on pics as i live in the very hot humid south.
For the time being, the below pic of a CAI and heat shield from C&L's website, and my following description are the next best things that I can substitute for a pic of my installation.
Prior to the mod, the locations on my car where the hood was making a good seal with the foam rubber strip on top of the heat shield were in the 90 degree corner along the top of the heat shield, and at a point on top of the heat shield directly above the centerline of the CAI inlet tube. The remainder of the foam strip had no marks indicating that there were gaps between the foam strip and underside of the hood. In fact, I coated the top of the foam strip with Vaseline to confirm that the above locations were the only places where good contact was being made.
And since hot air rises, it was easily being sucked thru these gaps into the engine while the car was at a standstill, which quickly increased the IAT, and reduced the engine's power output.
Regarding the installation of the polyethylene(PE) film, I cut a section that would cover from at least 2" beyond the back of the heat shield to 2" beyond the grill on the front of the car, and from at least 2" beyond the left side of the heat shield to 2" beyond the edge of the right side of the hood.
Next, I removed the foam strip from the top of the heat shield, placed the left and rear sides of the PE film on the top of the heat shield, and reinstalled the foam strip onto the top of the heat shield, which secured the PE flim along those 2 sides.
Next, I stretched the PE film toward the right fender, cut a small slot in the PE film directly above a rubber cushion which is mounted in the fender directly below the edge of the hood(center of the right side of the pic), removed the rubber cushion, stretched the PE film over the rubber cushion's mounting hole, and reinstalled the rubber cushion.
Next, I stretched the PE film toward the front of the car, cut a slot in the PE film directly above the cylindrical shaped rubber hood support(black object located directly between the air filter and the headlight in lower center of the pic), and pushed the PE film down over this rubber support.
Next, I removed a bolt and washer near the front of the fender below the edge of the hood(located in the lower right corner of the pic), stretched the PE film toward the bolt hole, pierced the PE film with the bolt, and reinstalled the bolt and washer.
Next, I removed another bolt and washer located above the headlight next to the black plastic piece in the lower left corner of the pic, stretched the PE film over the bolt hole, pierced the PE film with the bolt, and reinstalled the bolt and washer.
Finally, I tucked the excess of the left edge of the PE film under the black plastic piece in the lower left corner of the pic, trimmed and taped the front edge of the PE film to the car, taped the back edge of the PE film(that's not secured by the foam strip) to the back side of the heat shield, trimmed off any excess PE film that would show when everything is buttoned up, and stuffed 2 pieces of sponge into 2 gaps between the back side of the CAI and the fender.
Note that if your CAI has a different size and shape than mine, then it will probably require a slightly different installation strategy. But the above description should give you an idea on how to tackle it.
Also, you have to keep in mind is that the main function of this mod is to improve performance after the car has been stopped with the engine running. Thus, you will not notice any improvement if you go WOT after you've been driving steadily at 35 mph or faster for at least a few miles.
And it will not make your car feel anywhere near as responsive as it does in the cooler, drier air of the winter months, because the winter air has a denser O2 content, and nothing can be done to increase the summer air's O2 content when it's hot and humid.
A lower IAT at the MAF definitely increases the engine's power output simply because the PCM starts pulling timing at an IAT of 100 F(+/-), and the lower the IAT the less timing the PCM pulls.
I realize that it's not proof definite, like dyno graphs or 1/4 mile time slips, but after suffering from reduced performance over the last 4 summers and part of this summer, my butt meter can definitely feel a noticeable performance improvement with this mod when accelerating after a stop in hot weather. The sluggishness has obviously not been completely eliminated when compared to cool weather performance(50 F and lower) due to the summer air's lower O2 content, but it has been reduced.
So it’s a good idea to “trick” the IAT sensor into not pulling timing so it will run stronger? Doesn’t the PCM pull timing to eliminate spark knock? How do you know you have not created a situation where you are getting pre-ignition but not enough to hear it?
And the most obvious, why not just add the timing through your tuner opposed to building a box?
__________________
I get asked why I carry a gun. I tell them its because stabbing people is gross.
So it’s a good idea to “trick” the IAT sensor into not pulling timing so it will run stronger? Doesn’t the PCM pull timing to eliminate spark knock? How do you know you have not created a situation where you are getting pre-ignition but not enough to hear it?
And the most obvious, why not just add the timing through your tuner opposed to building a box?
I don't think that's the case. He's actually provided cooler air by doing this.
Hot IAT Solution??? 
.i think most of us dummer memebers will need pics
.but i live in alabama it is over 100f heat index here i would love to try this.
waiting on pics as i live in the very hot humid south.
