Crisp Acceleration......When Cold!!!

[Marauderjack]

Is it just me or do these cars have much more throttle response when the engine is cold?? :confused:

Mine seems much stronger just after start-up than when it is warmed up!! :bigcry:

Is this normal??

Marauderjack :)

[Petrograde]

of course..
engines love cold air. It's denser than warm air,... meaning more air... meaning more HP. :up:

[Marauderjack]

Same cold air after the engine is warmed up but the throttle is not near as crisp.....responsive!!

[rayjay]

Not a good idea to romp on a cold engine. I was always told by my head tech to keep it under 4K RPM until its warmed up. Those parade laps done before a NASCAR race are not just for show.

[Joe Walsh]

Not a good idea to romp on a cold engine. I was always told by my head tech to keep it under 4K RPM until its warmed up. Those parade laps done before a NASCAR race are not just for show.

I agree....On all the cars which I've owned that had a true oil temperature gauge, I am always suprised at how long it takes for the oil to get up to normal operating temperature. Don't "put the stirrups to 'er too hard" while she's cold.

[BillyGman]

What about drag cars? They stay cold in the staging lanes, then get started just before a burnout, then the burnout, and then it's 5 to 13 seconds or so of really hard throttle. In fact, really serious drag cars don't even have radiators since they never are allowed to get hot enough to have need for them. But anyway, my car has good throttle response cold or hot.

[Joe Walsh]

What about drag cars? They stay cold in the staging lanes, then get started just before a burnout, then the burnout, and then it's 5 to 13 seconds or so of really hard throttle. In fact, really serious drag cars don't even have radiators since they never are allowed to get hot enough to have need for them. But anyway, my car has good throttle response cold or hot.


Yeah....that's true, BUT a drag car gets its engine rebuilt often. (Top fuel cars get their engines 'rebuilt' EVERY run!)

[BillyGman]

Yeah....that's true, BUT a drag car gets its engine rebuilt often. (Top fuel cars get their engines 'rebuilt' EVERY run!)Yep, some do. such as the ones in the 5,6, and 7 second brackets. But not neccessarily the ones that run in the 9, 10, and 11 second brackets. I know of an 1,100 HP 9 second car that's been running for four years straight on the same engine without a rebuild. Howver, the guy doesn't drive it much on the street, so therefore it cannot have very many miles on the engine either. So I understand your point. :banana2:

[MENINBLK]

In fact, really serious drag cars don't even have radiators since they never are allowed to get hot enough to have need for them. But anyway, my car has good throttle response cold or hot.

Dragsters run the coolant through the dragster's frame rails, which are made of aluminum,
and can cool off the coolant just as fast as any radiator would.
Doing it this way also helps to distribute some of the engine's weight, over a larger area,
and it allows quick detection of cracks in the frame rails.

[BillyGman]

Dragsters run the coolant through the dragster's frame rails, which are made of aluminum,
and can cool off the coolant just as fast as any radiator would.
Doing it this way also helps to distribute some of the engine's weight, over a larger area,
and it allows quick detection of cracks in the frame rails.:rofl: Uhmm, you've got to be kidding.......

Topfuel dragsters and Funny cars do NOT have any coolant systems.

[tekguy]

An Engine is just a heat pump. You want the engine hot and the air to be cold. Cold air will expand more than hot air. The engine needs to be hot in order to have the gases expand the most. The expanding gases push your pistons. Most cars I have owned seem to respond better when cold because of enrichening circuits in the fuel system to compensate for low temperature. Also the transmission will tend to shift harder due to lower transmission fluid temperature causing thicker fluid and thus increased pressure in the valve body.

[Marauderjack]

Thanks tekguy....

That is more like what I expected to hear.....cold run condition is richer than after it is warmed up!! Makes sense. :beer:

Marauderjack :cool4:

[rayjay]

Thanks tekguy....

That is more like what I expected to hear.....cold run condition is richer than after it is warmed up!! Makes sense. :beer:

Marauderjack :cool4:
I just noticed your location. You probably have a little more lead way to play because your ambient temps never really get that cold. If I were to romp on mine after it sat out in -25 F temps, bye, bye engine at some point. I believe there is a thread here where that happened. The engine tossed a rod through the block at 5500rpm in cold weather.:rolleyes:

[Phil @ FLP]

Mod motors such as the Marauder are very prone to heat soak causing great amounts power loss. I have seen as much as a 40 hp drop on a hot Mustang GT with a procharger on our dyno compared to a cold run on our dyno and that car only made about 370 rwhp. Compared to a LS1 supercharged making 550 rwhp on a hot dyno run only lost about 20 hp.

[BillyGman]

Mod motors such as the Marauder are very prone to heat soak causing great amounts power loss. I have seen as much as a 40 hp drop on a hot Mustang GT with a procharger on our dyno compared to a cold run on our dyno and that car only made about 370 rwhp. Compared to a LS1 supercharged making 550 rwhp on a hot dyno run only lost about 20 hp.I wonder if that can possibly have anything to do with the fact that the Ford modular motors all have less displacement. :confused:

[metroplex]

Is it just me or do these cars have much more throttle response when the engine is cold?? :confused:

Mine seems much stronger just after start-up than when it is warmed up!! :bigcry:

Is this normal??

Marauderjack :)

My Vic runs the fastest when it is fully warmed up.

[metroplex]

What about drag cars? They stay cold in the staging lanes, then get started just before a burnout, then the burnout, and then it's 5 to 13 seconds or so of really hard throttle. In fact, really serious drag cars don't even have radiators since they never are allowed to get hot enough to have need for them. But anyway, my car has good throttle response cold or hot.

Those engines are made with special low friction components. They rebuild them after each race so longevity is NOT a concern for them.

Standard commercial engines, OTOH, are not the same.

If you look at the rule of thumb brake specific fuel consumption factors, pro drag racing and racing engines are rated at about 0.40-0.44 while naturally aspirated street motors are around 0.50-0.55, and forced induction (blower) is 0.6-0.7

translation: pro racing engines have less friction, the supercharged engines are losing about 10-15% horsepower to the blower itself, while our commercial engines are in the middle.

Typically a street engine will perform the best with a steady flow of cool air into the intake stream with the engine itself at optimum operating temperature so all of the rotating surfaces and components are expanded enough with the right clearances.

[Phil @ FLP]

I wonder if that can possibly have anything to do with the fact that the Ford modular motors all have less displacement. :confused:
Most likely its assoiciated with the cooling system of the engines not the displacement though LS1 engines are aluminum blocks which helps with heat discipation.

[metroplex]

Most likely its assoiciated with the cooling system of the engines not the displacement though LS1 engines are aluminum blocks which helps with heat discipation.

And what do you think your Marauders have? Iron blocks? :D (you have aluminum blocks).

BTW the LS1/Chevy 5.7 V8s use a different reverse cooling system. I had the luxury of being explained this by a GM powertrain engineer...

Basically the coolant enters the combustion chamber jackets FIRST and then going through the rest of the system. This reduces the combustion chamber temperatures (which is what you want) and they can jack the timing way high. The rest of your engine only needs coolant to prevent excessive wear, damage, scoring, etc... the comb. chamber needs to be cool to prevent detonation.

I'm not sure what your quad-cam V8s have, but IIRC the dual-cam mod motors have a conventional cooling system...

[woaface]

Cold, dense air is good for engines because it keeps things cold...you know, down with the friction? Common sense...that's why Billy G has times listed with temperatures.

Many/most drag cars also have oil pumps that get turned on before the engine is engaged. You can't really compare drag cars to street/consumer cars.

Also, there's a thread here somewhere that someone was going in to get an oil change and found another Marauder in a bay where a guy took off reall quick on a cold day late for work and blew one of his pistons clean out of the bottom of the block.

[metroplex]

Cold, dense air is good for engines because it keeps things cold...you know, down with the friction? Common sense...that's why Billy G has times listed with temperatures.

Many/most drag cars also have oil pumps that get turned on before the engine is engaged. You can't really compare drag cars to street/consumer cars.

Also, there's a thread here somewhere that someone was going in to get an oil change and found another Marauder in a bay where a guy took off reall quick on a cold day late for work and blew one of his pistons clean out of the bottom of the block.

BillGman's times listed with temp confirms the fact that its the COLD DENSE AIR that is good for the engine, NOT because his engine is kept much colder.

Like I said before, what you want is the cold air intake charge with the engine at optimum temperature. At optimum temperature (whether its 170F-190F) your engine oil is flowing FAST, providing lubrication and reducing friction on the rotating surfaces. Your metal parts have expanded "properly" and everything is running smoothly like a well oiled machine.

A lot of people think because the ambient temp is low, their engines (after driving to the drag strip) are freezing cold. The only way its going to really cool down that much is if you left it there for at least 5-6 hours in very cold ambient temperature.

At -10*F, starting up my vic in the garage in the morning results in a groggy and sluggish Vic. After it warms up, the throttle response is back, the tranny is shifting better, and the engine is revving normally.

Heat soak is your enemy.

[woaface]

Indeed! I agree, and great website BTW...I just finished looking around a bit!

Keeping oil cool isn't a bad idea either...along with the engine, which is done by cold ambient temps that flow well into a nice intake and into your engine. Hot humid crappy yucky SC summer air sucks...but my Marquis runs killer in the spring, fall, winter and on summer nights.


BillGman's times listed with temp confirms the fact that its the COLD DENSE AIR that is good for the engine, NOT because his engine is kept much colder.

Like I said before, what you want is the cold air intake charge with the engine at optimum temperature. At optimum temperature (whether its 170F-190F) your engine oil is flowing FAST, providing lubrication and reducing friction on the rotating surfaces. Your metal parts have expanded "properly" and everything is running smoothly like a well oiled machine.

A lot of people think because the ambient temp is low, their engines (after driving to the drag strip) are freezing cold. The only way its going to really cool down that much is if you left it there for at least 5-6 hours in very cold ambient temperature.

At -10*F, starting up my vic in the garage in the morning results in a groggy and sluggish Vic. After it warms up, the throttle response is back, the tranny is shifting better, and the engine is revving normally.

Heat soak is your enemy.

[jjaguda]

Cold, dense air is good for engines because it keeps things cold...you know, down with the friction? Common sense...that's why Billy G has times listed with temperatures.

Many/most drag cars also have oil pumps that get turned on before the engine is engaged. You can't really compare drag cars to street/consumer cars.

Also, there's a thread here somewhere that someone was going in to get an oil change and found another Marauder in a bay where a guy took off reall quick on a cold day late for work and blew one of his pistons clean out of the bottom of the block.
I just talked to my Ford Dealer shop foreman who told me that he just replaced a motor in an '04 COBRA with 1200 miles on it. Cylinders were extremely fubar'd. He believed that the motor was started cold and slammed IMMEDIATELY, but had no proof.

As an aside, he notified FORD of his suspicions, so, if the same car shows up again with extreme damage/wear . . . .