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Discussion Starter · #1 · (Edited)
This engine seems really sensitive to heat soak. More so than any other engine I have owned. Maybe my opinion is due to the 0-60 timer we have, whereas all my other cars have not had such a tool/reference point to judge this by, but wow the difference in performance.

When the motor is freshly warmed, I am getting roughly .2x to .3x better 0-60 times vs when it's highly driven/warm/heat soaked. This creates more of a performance difference than any mod I've done. The best mod I've seen for our cars is an engine with about 5 minutes warm up time vs driven all day. It hates heat! I even installed a water/meth injection kit (running 80/20 meth to water, as this has given best results) in an attempt to mitigate the heat soak to no avail. Being able to manage this heat soak seems to be a worthwhile mod for this engine.

As a note, I just installed a srv 392 intake manifold, which is the best mod I have done so far, but 0-60 times range from [email protected] 80 degree ambient temp to a heat soaked 4.9x at same temp.

Any ideas on how to reduce heat soak?
Any thoughts?
 

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Can you post a thread about the 392 intake I'm interested in that mod or can you share where you read about it
 

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Discussion Starter · #5 ·
Yes I have a home made CAI. Below the factory box, I have a 5in tube coming up from a ram air scoop under the car to the triangle opening at the base of the box with a k&n filter inside. Intake temp is on average 10 degrees above ambient when cruising around town at 30-40 mph. When activated, the injection drops it another 30 degrees. It can be in the mid 80s outside and I'll have intake air in the 50s.

The sensor is about 5" downstream of the nozzle, so the water/meth affects it quickly. However, I question how much air is being displaced when the water/meth evaporates.
 

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This engine seems really sensitive to heat soak. More so than any other engine I have owned. Maybe my opinion is due to the 0-60 timer we have, whereas all my other cars have not had such a tool/reference point to judge this by, but wow the difference in performance.

When the motor is freshly warmed, I am getting roughly .2x to .3x better 0-60 times vs when it's highly driven/warm/heat soaked. This creates more of a performance difference than any mod I've done. The best mod I've seen for our cars is an engine with about 5 minutes warm up time vs driven all day. It hates heat! I even installed a water/meth injection kit (running 80/20 meth to water, as this has given best results) in an attempt to mitigate the heat soak to no avail. Being able to manage this heat soak seems to be a worthwhile mod for this engine.

As a note, I just installed a srv 392 intake manifold, which is the best mod I have done so far, but 0-60 times range from [email protected] 80 degree ambient temp to a heat soaked 4.9x at same temp.

Any ideas on how to reduce heat soak?
Any thoughts?
180 T stat and adjust the fan settings Did wonders for my 06 300c 5.7 1/4 mile times.
 

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Discussion Starter · #8 ·
Funny, people get all bent about air temp. Not really much of an issue, add a blower and intercooler if you want more air.
Yes actually air temp is very important. I would be making more power with straight air at 50+ degrees vs evaporated methanol fuel and air at the same temp. The evaporated fuel is displacing oxygen, as evidenced with a sharp increase in the air/fuel ratio. I'm still playing with this some, but my trinity is freezing up on me preventing me from logging.

I am just amazed how much output drops when the hemi is heat soaked. I wonder if a lot of dyno discrepancies are due to engine heat soak. Next time I dyno, I might test this. Let the car cool for several hours outside the dyno shop, then put it on the rollers freshly warmed and compare it to being heat soaked.
 
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Discussion Starter · #9 ·
Can you post a thread about the 392 intake I'm interested in that mod or can you share where you read about it
I'm not sure if I can post links to other forums on here. Do an internet search for 6.4 srv intake swap cirkit boss. You will pull up a thread elsewhere from JS1977 I think. He posted instructions.

I bought the intake from another member who is putting a supercharger on his car. He had the harness already made up. I bought the intake, harness, intake elbow, msd rpm switch, and cirkit boss. It is an easy mod and probably the best single one so far. The first one I could actually feel. Repaired the low end torque destruction due to the Modern Muscle NA cam.
 

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I agree with all the posts about air and coolant temp, i just have to add that not alot of ppl know/realize how important fuel temp is. When your fuel rails are competely heat soaked, and that fuel is being misted at super high temps, your differences in air temp really are mitigated. Gasoline doesnt cool off like water or ethanol does when its vaporized (much lower vapor pressure at same temp) so whenever you atomize fuel into the intake gases, it can actually heat them up if the fuel is boiling hot. Having said that, i don't really know of a way to minimize the effect, other than insulating your fuel rails, or upgrading to a thinner aluminum rail.
 
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Discussion Starter · #11 ·
I agree with all the posts about air and coolant temp, i just have to add that not alot of ppl know/realize how important fuel temp is. When your fuel rails are competely heat soaked, and that fuel is being misted at super high temps, your differences in air temp really are mitigated. Gasoline doesnt cool off like water or ethanol does when its vaporized (much lower vapor pressure at same temp) so whenever you atomize fuel into the intake gases, it can actually heat them up if the fuel is boiling hot. Having said that, i don't really know of a way to minimize the effect, other than insulating your fuel rails, or upgrading to a thinner aluminum rail.
I completely forgot about this. I almost bought a cool can for my 400 sbc, but it's not very practical for driving around in the street.

Very good point, this has to be the main reason for hemi heat soak.
 

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I completely forgot about this. I almost bought a cool can for my 400 sbc, but it's not very practical for driving around in the street.

Very good point, this has to be the main reason for hemi heat soak.
You should see how hot your fuel is in the tank. Real hot. And if you have dual pumps turning. LOL LOL you have heat issue. One reason I run pump # 2 on a hobbs switch set to come in at 2psi of blower air.
At 58 to 62psi fuel like anything being compressed, it makes heat. It deadheads at the rails and bypasses in the take through a return line. All in the tank.
FT











32 on a hobbs set at 2psi boost to turn on.
With 58 to 62psi fuel dead heading at the rail and bypassing in the tank where alot of heat comes from.
 

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I installed a set of fuel rail insulators from my buddy's 6.4. Not sure if they help keep fuel temps down or not, but I figured they couldn't hurt.

 

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Nice point about hot fuel rails! I never would even have thought to look there for heatsoak improvements.

My usual comment for this kind of topic is usually to look into ways to insulate your intake tube and shield your airbox away from the rest of the engine bay. Got to be smart about this, too, because you don't want stuff falling off into your fan belt or stuff catching on fire from the intense heat.
 

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Intake heat is indeed the enemy of horsepower. has anyone thought about the heat

introduced to the intake manifold by the PCV system. Have you touched the catch

can lately? Keeping the oil out is a great idea but what about the heat ? Has anyone

vented the PCV to the atmosphere ? I know its important to vent crankcase pressure

but is atmosphere venting a problem on these new vehicles ?
 

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FlatTop vents to the atmosphere from what I've read. I would like to, but have to pass emissions. The whole pcv system just sucks, pulling oil and heat.
 

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Ive seen catch cans that had a mini conical filter mounted to them? Like this
 

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Ive seen catch cans that had a mini conical filter mounted to them? Like this
I have too, Cpl, and am curious how they would work with our system. I wonder if it would throw a code from a change in pressure.
 

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I have too, Cpl, and am curious how they would work with our system. I wonder if it would throw a code from a change in pressure.
Now you've peaked my interest... It seems it would mimick a vacuum leak and make the car idle rough, no?
 

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Intake heat is indeed the enemy of horsepower. has anyone thought about the heat

introduced to the intake manifold by the PCV system. Have you touched the catch

can lately? Keeping the oil out is a great idea but what about the heat ? Has anyone

vented the PCV to the atmosphere ? I know its important to vent crankcase pressure

but is atmosphere venting a problem on these new vehicles ?
Good point. One reason I run a vac pump and vent to open air. Being FI theres a diffrence.
FT
 
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