# Why is heatsoak such an issue with these cars? (is it really?)



## jterpII (Apr 8, 2005)

Been reading a lot about these cars -- trying to decide to buy one or not. I've read a lot about heat soak power loss at the drag strip -- is this really a big issue or just internet hearsay? I've drag raced quite a few cars and realize that weather will affect 1/4 mile times 1 or 2 tenths - but from what I've read it sounds like these cars are much more succeptable (sp?) to it. Is this true? If so, what is the reason? Poor cooling system? Poor air intake location? Poor underhood ventilation? 

TIA


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## Route 66 (May 30, 2005)

Well, dont know if my .02 worth is even worth the .02.
But as long as I have been around cars and the people that drive them......there is always something they dont like about one thing or another on their vehicle.
The GTO is no worse than many cars on the road as far as heat.
Again, this is only one persons opinion. 
Bear in mind, the new GTO is nothing like the old. It is a fast, fairly quick "luxury" muscle car. It (in my opinion) is not built to drag race.
There in lies the problem. Those that take their goats to the track every weekend (and there seems to be a lot of them) and beat the crap out of it will be the first to complain about heat...or axil bolts breaking..or wheel hop..or trannys breaking..or the dilithium crystals keep overheating!  
Its all realative to how you drive it.
Its a damn fine peice of machinery that responds well to some minor tweeking.


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## Braman'sGTO (Mar 14, 2005)

Route 66 said:


> Well, dont know if my .02 worth is even worth the .02.
> But as long as I have been around cars and the people that drive them......there is always something they dont like about one thing or another on their vehicle.
> The GTO is no worse than many cars on the road as far as heat.
> Again, this is only one persons opinion.
> ...


 :agree 

The GTO was not built to run the 1/4 mile against mustangs and F bodies, it was ment to run against the BMW M3 on road courses.


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## mumrah (Apr 3, 2005)

Braman'sGTO said:


> :agree
> 
> The GTO was not built to run the 1/4 mile against mustangs and F bodies, it was ment to run against the BMW M3 on road courses.


It really is meant for the M5. The M3 is not in the same class. 

Check out the performace http://www.rsportscars.com/eng/cars/bmw_m5.asp


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## Groucho (Sep 11, 2004)

Gotta say "Meh" here...due to it's heft, the GTO really can't hold it's own with the M3 on a road course without fairly serious suspension work. It's a GT (Gran Turisimo), more akin to a Bimmer 6-Series and M-B CLK-type.

People who try and make this car, which has a thoroughly modern (if somewhat heavy) suspension and IRS, into a straight-line drag racer and who then bitch about wheel-hop etc are very much missing the point. I blame GM NA and the not-very-bright decision to resurrect the Pontiac GTO badge on this particular car.


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## fergyflyer (Apr 18, 2005)

My experience is that the intake design is the major culprit. There is not enough outside air getting into the airbox, and definately not at a very high velocity which would keep it cool. I did the punch a hole in the front of the airbox trick to get some cool air from behind the headlight, but it is not enough and not moving at enough velocity to make a difference. Another area that I have a concern with is the fuel rail covers. Last time I was at a track I took them off. My car cooled off quicker and ran faster than another 05 GTO. Our first 2 passes were similar, then I took off the fuel rail covers and saw my times drop, and his stay flat. Not very scientific since there were two different drivers, but the difference was .5-.7 which is signifigant. I think the temperature of the coil packs and/or the heads makes a difference for how the computer sets up. 

This car could be modified to be a great drag racer, but I think you could do better. For an all-around great GT car, it is unbeatable unless your willing to spend large cash. And it is tons of fun at the track the way it sits.


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## Xman (Oct 31, 2004)

I cut a hole underneath the airbox into the fender to draw in outside air from behind the fog lamp. Its worked out well and the 100 degree days of Texas Summer don't seem to effect car.


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## jterpII (Apr 8, 2005)

My first post may have been a bit misleading -- I'm not looking to make a drag car out of it. This car will be my daily driver which I may take to the drag strip every once in a while. Also, it will be my backup car for running open track events in (DE type -- not W2W) for when it's raining and I don't want to take my open top Factory Five cobra. 
I am mainly concerned with it not staying cool -- nothing worse than overheating on the track. I also don't want to go out there and have a noticeable power loss after 5 or 6 hot laps. My old '99 M3 (bone stock) was able to tear around a road course forever without noticeable heat soak power loss -- I'd hate to buy a GTO and be disappointed in it in this respect. 

That is very interesting about the fuel rail covers -- I wouldn't think there would be any harm in removing these permanantly.... can you guys think of any?


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## mumrah (Apr 3, 2005)

Anybody look into the throttlebody bypass tube?? I remember reading about this causing heated up air going to the intake. 
Another item is the racing cooler
http://www.racingcoolers.com/corvette.html


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## Route 66 (May 30, 2005)

Groucho said:


> Gotta say "Meh" here...due to it's heft, the GTO really can't hold it's own with the M3 on a road course without fairly serious suspension work. It's a GT (Gran Turisimo), more akin to a Bimmer 6-Series and M-B CLK-type.
> 
> People who try and make this car, which has a thoroughly modern (if somewhat heavy) suspension and IRS, into a straight-line drag racer and who then bitch about wheel-hop etc are very much missing the point. I blame GM NA and the not-very-bright decision to resurrect the Pontiac GTO badge on this particular car.


Groucho,
Forgive me if I misread....but I agree and disagree.
Agree with everything but the last statement.
I think the GTO in now much closer to what it's name actually stands for.
I think the early cars would be better named.....GDO (Gran Dragstero Ohmygodo). :lol: 
I think GM hit the spot on this one. Just not what the rest of the world expected. :cheers 

Bill


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## gameover (May 13, 2005)

mumrah said:


> Anybody look into the throttlebody bypass tube?? I remember reading about this causing heated up air going to the intake.
> Another item is the racing cooler
> http://www.racingcoolers.com/corvette.html


That's one helluva idea! Never seen that before  Think I gotta have one!
Thanks mumrah! :cheers


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## Route 66 (May 30, 2005)

jterpII said:


> My first post may have been a bit misleading -- I'm not looking to make a drag car out of it. This car will be my daily driver which I may take to the drag strip every once in a while. Also, it will be my backup car for running open track events in (DE type -- not W2W) for when it's raining and I don't want to take my open top Factory Five cobra.
> I am mainly concerned with it not staying cool -- nothing worse than overheating on the track. I also don't want to go out there and have a noticeable power loss after 5 or 6 hot laps. My old '99 M3 (bone stock) was able to tear around a road course forever without noticeable heat soak power loss -- I'd hate to buy a GTO and be disappointed in it in this respect.
> 
> That is very interesting about the fuel rail covers -- I wouldn't think there would be any harm in removing these permanantly.... can you guys think of any?


Sorry, guess we got off topic a bit.
But like I said before...The GTO is what it is. Its not a dragster, and in some respects, not a road course car. Its a 'luxury' muscle car. Heat soak?....yes. Is it bad?..In my opinion, no. I firmly believe with an aftermarket air box (MPD or Lingenfelter) with the IAT sensor relocated...The issue can be remedied.
Sady. the GTO is hard pressed to find its niche. Example only: if you want a drag car....Cobra. If you want a road course car...go back to an M-3.
The GTO fits somewhere in between. But I dont think it will disappoint.


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## mumrah (Apr 3, 2005)

gameover said:


> That's one helluva idea! Never seen that before  Think I gotta have one!
> Thanks mumrah! :cheers


No Problem. We are all here for the sharing of info


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## jterpII (Apr 8, 2005)

Route 66 said:


> Sorry, guess we got off topic a bit.
> But like I said before...The GTO is what it is. Its not a dragster, and in some respects, not a road course car. Its a 'luxury' muscle car. Heat soak?....yes. Is it bad?..In my opinion, no. I firmly believe with an aftermarket air box (MPD or Lingenfelter) with the IAT sensor relocated...The issue can be remedied.
> Sady. the GTO is hard pressed to find its niche. Example only: if you want a drag car....Cobra. If you want a road course car...go back to an M-3.
> The GTO fits somewhere in between. But I dont think it will disappoint.



So the consensus is that the GTO does have a cooling/ventilation problem? That is disappointing...


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## RiceEater (Jun 21, 2005)

Personally I dont know about the drag thing... the GTO seems like a very powerful drag car with luxury and road course elements rather generously thrown in. I know of 4 guys who own newer model Cobra's, and not one of them has out-accelerated my 05, so I would think the GTO is the better choice for dragging. 

As for the heating problems it's mainly a matter of where you live. Here it gets rather hot in the Summer, but there is also a lot of humidity in the air which seems to help keep the car from getting hot. Now I could see that if you live somewhere out West where it's hot and dry, then yes you may definately have some problems with heating.


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## Groucho (Sep 11, 2004)

Route 66 said:


> Groucho,
> Forgive me if I misread....but I agree and disagree.
> Agree with everything but the last statement.
> I think the GTO in now much closer to what it's name actually stands for.
> ...












My only point is that unfortunately "Pontiac GTO" had come to mean "crude, fast boulevard burner" -- muscle car-- rather than the excellent _Gran Turisimo_ that it is.


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## anmracing (Feb 9, 2005)

Heat soak does seem to be an issue for people racing these cars. Whether its GT or drag racing and also for just everyday driving around here in Phoenix….

Removing the FRC helps also doing the T/B bypass, especially here in Arizona. Also taking the rubber gasket out from the underside of the hood by the windshield helps air flow. Some have put washers under the hood hinges to help with this.


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## HTRDLNCN (Jul 1, 2005)

Has anyone tried running a cowl style scoop to vent heat or even running without the hood just to see what difference it makes.Seemslike all the GTO hoods with scoops are to push air in not to vent heat out?

And yeah,people who take Luxury Sport Coupes and make them fast are pretty insane..

:seeya:


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## MuhThugga (Jun 26, 2005)

I don't own a GTO but am very interested in getting one of the '05 rollovers at the end of the year after I have some money and sell my Stratus R/T. I was thinking that would it be possible to maybe push for an aftermarket hood that has the scoop in the front much like the Corvette z06 or the Viper SRT-10. This would allow for the intake to look more like this:










That could bring in more cold air to the engine, or to the engine bay. Whichever is desired.


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## RiceEater (Jun 21, 2005)

Give it some time. I have a feeling GM or Pontiac or someone is going to come out with a mod kit that would put those hood scoops to real use. Something like the RamAir system.


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## WanaGTO (Sep 7, 2008)

Okay im resurrecting the heatsoak threads. How can we fix it? I noticed it TERRIBLY today and i want to get rid of it. I want my car to run like it does 10mins after I start it everytime. What can I do?


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## LOWET (Oct 21, 2007)

fergyflyer said:


> My experience is that the intake design is the major culprit. There is not enough outside air getting into the airbox, and definately not at a very high velocity which would keep it cool. I did the punch a hole in the front of the airbox trick to get some cool air from behind the headlight, but it is not enough and not moving at enough velocity to make a difference. Another area that I have a concern with is the fuel rail covers. Last time I was at a track I took them off. My car cooled off quicker and ran faster than another 05 GTO. Our first 2 passes were similar, then I took off the fuel rail covers and saw my times drop, and his stay flat. Not very scientific since there were two different drivers, but the difference was .5-.7 which is signifigant. I think the temperature of the coil packs and/or the heads makes a difference for how the computer sets up.
> 
> This car could be modified to be a great drag racer, but I think you could do better. For an all-around great GT car, it is unbeatable unless your willing to spend large cash. And it is tons of fun at the track the way it sits.


I have spent a lot of time doing ON LINE research on Heat Soak related to the LS1s and LS2s & even LT1s ever since I installed an Alloy intake.
It seems like the heat soak issue is more talked about or complained about amoung LS1 & LS2 owners when compared to LT1 or LT4 people. Don't think the heat soak issue has to do with the design of the intake as much as it does the material and a few other items. 



Not too long ago the Automotive Industry along with the Aerospace Industry discovered that some metals can be replaced with Composite [ plastic ] Materials in different situations . This new Composite Material is cheaper to manufacture , produce and process .
They also liked it for it's strength and in some cases it's ability to act as a insolator when in contact with other heated or hotter materials then itself. 
In the case of a Automobile Intake manifold, it does a much job of insulating and deflecting engine heat when compared to Alloy .This is where it becomes a double edged sword. It does a very good job of deflecting heat and it will take more of a effort to heat it up, but when it does get hot, it does a very poor job of releasing that heat.The heat gets stored and just can't escape as quick as alloy. 

Whether this is the cause of Heat Soak issues with our cars is just not known for sure 

Another contributing factor to heat soak is the placement of our fuel lines. having them run along the sides of an intake manifold is not the greatest idea

I have an alloy intake on my car. The 1st thing I noticed after install was the fact that it got hot much faster then the Composite one. Not only did it get hot faster, it also felt like the actual temp was higher to the touch then the Composite intake. 

The alloy intake will heat up quicker and get hotter then Composite material.
but it will disapate the heat faster.

Composite intakes will do a much better job of deflecting and rejecting heat , Heat will have a harder time of penetrating it.
But once the heat gets obsorbed. It will just stay there longer.

Relocating the IAT sensor and placing it in an area where it will register cooler air may aide in when the computor system starts to pull timing, but it won't do anything in actually reducing the manifold heat.
Just my 2 cents


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## WanaGTO (Sep 7, 2008)

sounds very plausible. I prefer the way the plastic performs though. As far as relocating the IAT...does that eliminate our heatsoak completely?


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## LOWET (Oct 21, 2007)

WanaGTO said:


> sounds very plausible. I prefer the way the plastic performs though. As far as relocating the IAT...does that eliminate our heatsoak completely?


The Composite intakes [ FAST ] do work very well. It's the only after market Composit intake available for the LS Motors. It's performance is due to it's design and not the material used. 

As far as relocating the sensor to reduce heat soak. The best way I can explain it .

When our IATs reach a certain degree 
[ 86 degrees/stock tuned 04/06GTO ] our engine management system will start to reduce timing which in turn lowers HP. In the stock position, our sensors are subject to more direct engine heat and it also takes a while longer for the stock sensor to react to air temp changes..
If you move the sensor to a location that is closer to the hood opening or to an area that is as far away from direct engine heat as possible but still be in the path of incoming intake air the sensor will detect a lower temp and not reduce as much timing. Also, an after market sensor such as the Omega Thermister Element reacts a lot faster then the stock unit and will help in the way timing gets reduced and regained.


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## svede1212 (Nov 1, 2005)

the logic of a plastic intake releasing heat slowly is very flawed. if it released it slowly or so slowly to be not at all it wouldn't be a problem as transferring heat to incoming air is one of the things we're talking about. the slower the better. a small amount of heat "X" going into a large amount of air "Y" = air that's very, very slightly warmed up. a large amount of heat "X" (something like metal that's transfers easily) going into a large amount of air "Y" = warmer air than the first example

once again "heat soak" as discussed in our cars is a two part issue. one is the source of air. none of the standard intakes untilizing the stock position for the filter regardless of "shielding" or anything do a good job of pulling in outside air. they're are ultimately pulling from the same source.

the other type of "heat soak" is the sensor itself. first it's located in a....strangely enough.... METAL piece called the MAF on LS2s which is sitting in the engine bay just soaking in all that heat into it's very large mass and very efficiently transferring it to the IAT sensor. on a LS1 it is a separate piece that they conveniently put right in the blast of the radiator. in addition both use a fairly large mass sensor itself that being plastic (now it matters) gets rid of its heat slowly and that is what's supposed to be sensing the air temp. the best two prong approach is to have an intake that pulls all of it's air from outside the bay and having a smaller mass sensor that reacts more quickly to temperature changes and not be influenced by external heat that isn't in the air going in.

a few years ago i looked at (and logged) IATs using different intakes. the problems were pretty clear. i researched and found the Omega 44005 thermistor that replaces the stock sensor. it has a very small mass and thus reacts to air temp changes quickly. for a LS1 it's a pretty straight forward wire splice and install with a relocation to where it's not constantly heated up by external sources. on a LS2 it requires locating the 2 wires for the sensor portion going into the MAF and clipping those and splicing the new sensor into those with a relocation like the LS1.


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## LOWET (Oct 21, 2007)

You are correct when saying that stock intake filters or CAI filters are situated in a less then optimal position.They are more prone to injesting air contaminted with engine compartment heat then the unit you have. That is why I tried to position mine as close to the gap in the hood as possible. Most CAIs come with a sort of heat shield but their effectiveness is minimal at best. 
It just seems that this Heat Soak item is more of an issue with LS1 & LS2 owners then it is with owners of LT1, LT4 and earlier model engines. 
The Composite intakes do in fact repel heat much better then alloy, but it also will release the heat more slowly . I am just not convinced that the materials used in Composite or Alloy intakes are the main issue for heat soak. Either one can be a contributing factor but not the sole one. GM stated that part of the Heat Soak problems can be traced to the location of our fuel lines. Having them running across the sides of an intake manifold is not the best of locations . In years past our fuel lines ran across the fender wall and then directly to the intake T/B. Older models had the lines in the same position, ran to the engine mounted fuel pump and then to the carb. Back in my racing days we used to run COOL CANs. Fuel lines would connect to a can packed with ice and then routed back out and then connect to the Carb or other type of fuel intake. 

hhhmmmmmm. Maybe the location of our fuel rails is our main cause of our Heat Soak. I knew there was a reason why I hated those ugly FRCs so much. They do a great job of holding heat in that area. Mine have been off for a few years 

I guess the Heat Soak topic will go on forever. Maybe some day, someone will find a way to compleletly eliminate the problem.. Cars powered by fuel cells will be the ticket in the future


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## svede1212 (Nov 1, 2005)

LOWET said:


> You are correct when saying that stock intake filters or CAI filters are situated in a less then optimal position.They are more prone to injesting air contaminted with engine compartment heat then the unit you have. That is why I tried to position mine as close to the gap in the hood as possible. Most CAIs come with a sort of heat shield but their effectiveness is minimal at best.
> It just seems that this Heat Soak item is more of an issue with LS1 & LS2 owners then it is with owners of LT1, LT4 and earlier model engines.
> The Composite intakes do in fact repel heat much better then alloy, but it also will release the heat more slowly . I am just not convinced that the materials used in Composite or Alloy intakes are the main issue for heat soak. Either one can be a contributing factor but not the sole one. GM stated that part of the Heat Soak problems can be traced to the location of our fuel lines. Having them running across the sides of an intake manifold is not the best of locations . In years past our fuel lines ran across the fender wall and then directly to the intake T/B. Older models had the lines in the same position, ran to the engine mounted fuel pump and then to the carb. Back in my racing days we used to run COOL CANs. Fuel lines would connect to a can packed with ice and then routed back out and then connect to the Carb or other type of fuel intake.
> 
> ...


the "heat soaked" into the stock sensor is a bigger issue IMHO at least for cooling down to read actual intake temp air. because i have the software to log such stuff and messing with it is inexpensive, i've done a lot of research on intakes and temps. the shielding of intakes is only good in how they "wall off" air coming from the bay. the actual air inside the box is gone in a nanosecond when you floor it. it's where it gets its replacement air that's the problem. the gap in the hood, the tiniest of areas around the headlight, the two holes in the fender below the box, plus the gaps around the "shield" are the sources. only the first two are cool air and it probably makes for less than half the volume. at least getting the sensor reading right goes a long way to fixing the "heat soak" problem


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## LOWET (Oct 21, 2007)

svede1212 said:


> the "heat soaked" into the stock sensor is a bigger issue IMHO at least for cooling down to read actual intake temp air. because i have the software to log such stuff and messing with it is inexpensive, i've done a lot of research on intakes and temps. the shielding of intakes is only good in how they "wall off" air coming from the bay. the actual air inside the box is gone in a nanosecond when you floor it. it's where it gets its replacement air that's the problem. the gap in the hood, the tiniest of areas around the headlight, the two holes in the fender below the box, plus the gaps around the "shield" are the sources. only the first two are cool air and it probably makes for less than half the volume. at least getting the sensor reading right goes a long way to fixing the "heat soak" problem



I removed the rubber hood plugs a long time ago in an attempt to allow more outside air to get in to the engine bay under power and give the heated air a little more space to exit when shut down. Don't know if it helped at all. Also removed my FRCs, I thought they would do more harm then good when allowing the engine to cool down after shut down. Also thought that by removing them it would allow for better air circulation when under throttle.
Since I started to use my Dash Hawk [ prior to intake swap ] to check my IATs . I did notice that my IATs would climb after shut down and they would stay higher if I restarted in about 5 minutes or so. I don't remember how many degrees it would rise by but I think it was around 10 or 15 degrees hotter then when it was when the car was moving. The swapping and moving of the IAT sensor did show a big difference in how quickly the IATs would change. When I installed my Alloy intake the same thing would happen but the IATs did not seem to climb any higher after shut down then the stock intake. 
In my case, I added and insulated my CAI, installed a new sensor, removed the rubber hood plugs and removed the FRCs, insulated the plug wires and I am going to wrap the headers this Spring or sooner.


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