reverse polarity
Senior Member
Joined: Oct 2013
Posts: 2,152
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From: Orlando
Re: reverse polarity
Haven't measured the Crossfire but the GM spec is "less than 50 ma" when turned off. Reattae are 17-20 ma for the keep-alives. Back in the day I just used a battery disconnect on cars that sat but all they had for a drain was a kabang clock.
Today everything except the two Golf Cart batteries in my RV and the H6 in the Crossfire are AGM, either Optima or Duracell. Heep came with one.
Ones I do not drive often all have little 50 ma float chargers and all start quickly even if sitting for a month (I start everything and let idle until warm at least once a month).
Today everything except the two Golf Cart batteries in my RV and the H6 in the Crossfire are AGM, either Optima or Duracell. Heep came with one.
Ones I do not drive often all have little 50 ma float chargers and all start quickly even if sitting for a month (I start everything and let idle until warm at least once a month).
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
he new battery is say 6/8 months old but I am not convinced that is suitable for the SRT6 because it has 800 acc but only 50 ah
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
Haven't measured the Crossfire but the GM spec is "less than 50 ma" when turned off. Reattae are 17-20 ma for the keep-alives. Back in the day I just used a battery disconnect on cars that sat but all they had for a drain was a kabang clock.
Today everything except the two Golf Cart batteries in my RV and the H6 in the Crossfire are AGM, either Optima or Duracell. Heep came with one.
Ones I do not drive often all have little 50 ma float chargers and all start quickly even if sitting for a month (I start everything and let idle until warm at least once a month).
Today everything except the two Golf Cart batteries in my RV and the H6 in the Crossfire are AGM, either Optima or Duracell. Heep came with one.
Ones I do not drive often all have little 50 ma float chargers and all start quickly even if sitting for a month (I start everything and let idle until warm at least once a month).
Senior Member
Joined: Oct 2013
Posts: 2,152
Likes: 37
From: Orlando
Re: reverse polarity
Another thing that people know that just ain't so.
NA Crossfire has 10:1 compression, SRT has 9:1. Should be easier to spin.
Wish mine had 9:1, then I could run 87 PON and save 10% on gas.
BTW the idea of a lower compression ratio with a boosted engine, is not what you would think. The point is to have a larger combustion chamber packed to the same chamber pressure at TDC. This makes more power from the same swept volume.
What I do not understand is why a small bore engine at 10:1 needs 91 PON. 89 would seem plenty particularly with dual ignition.
Anyone know if both plugs fire at the same time or are they staggered like a hemi ?
NA Crossfire has 10:1 compression, SRT has 9:1. Should be easier to spin.
Wish mine had 9:1, then I could run 87 PON and save 10% on gas.
BTW the idea of a lower compression ratio with a boosted engine, is not what you would think. The point is to have a larger combustion chamber packed to the same chamber pressure at TDC. This makes more power from the same swept volume.
What I do not understand is why a small bore engine at 10:1 needs 91 PON. 89 would seem plenty particularly with dual ignition.
Anyone know if both plugs fire at the same time or are they staggered like a hemi ?
Senior Member
Joined: Dec 2010
Posts: 12,780
Likes: 184
From: Lineville, AL
Re: reverse polarity
The plugs fire at staggered intervals.
From the manual :
I have run 87 in mine, it seems to adjust fine without knock or detonation, seems to be about the same MPG also.
From the manual :
The ignition system for the 3.2L and the 3.2L SRT-6 engines utilize a Distributorless Ignition System design. The
ignition system uses a separate ignition coil pack for each cylinder. The one piece coil pack bolts directly to the
cylinder head cover. The coil packs are designed with two secondary towers for each spark plug wire. Rubber boots
seal the secondary terminal ends of the spark plug wires. A separate electrical connector is used for each coil pack.
The camshaft position sensor is a hall effect device, and the crankshaft position sensor is an inductive device. The
camshaft position sensor and crankshaft position sensor generate pulses that are inputs to the PCM. The PCM
determines engine position from these sensors. The PCM calculates injector sequence and ignition timing based on
crankshaft & camshaft position.
The two spark plugs per cylinder are fired slightly out of phase to prevent the cylinder pressures from rising too
quickly, which could cause knocking. To prevent one spark plug from eroding more quickly than the other, they
alternately lead each other. Under normal conditions, the timing is the same for all cylinders, but the timing can be
delayed in individual cylinders if knocking is present in one or more.
Two knock sensors are used to control spark knock. Highly sensitive knock sensors can distinguish knocking
ignition system uses a separate ignition coil pack for each cylinder. The one piece coil pack bolts directly to the
cylinder head cover. The coil packs are designed with two secondary towers for each spark plug wire. Rubber boots
seal the secondary terminal ends of the spark plug wires. A separate electrical connector is used for each coil pack.
The camshaft position sensor is a hall effect device, and the crankshaft position sensor is an inductive device. The
camshaft position sensor and crankshaft position sensor generate pulses that are inputs to the PCM. The PCM
determines engine position from these sensors. The PCM calculates injector sequence and ignition timing based on
crankshaft & camshaft position.
The two spark plugs per cylinder are fired slightly out of phase to prevent the cylinder pressures from rising too
quickly, which could cause knocking. To prevent one spark plug from eroding more quickly than the other, they
alternately lead each other. Under normal conditions, the timing is the same for all cylinders, but the timing can be
delayed in individual cylinders if knocking is present in one or more.
Two knock sensors are used to control spark knock. Highly sensitive knock sensors can distinguish knocking
Senior Member
Joined: Aug 2012
Posts: 1,709
Likes: 10
Re: reverse polarity
Another thing that people know that just ain't so.
NA Crossfire has 10:1 compression, SRT has 9:1. Should be easier to spin.
Wish mine had 9:1, then I could run 87 PON and save 10% on gas.
BTW the idea of a lower compression ratio with a boosted engine, is not what you would think. The point is to have a larger combustion chamber packed to the same chamber pressure at TDC. This makes more power from the same swept volume.
What I do not understand is why a small bore engine at 10:1 needs 91 PON. 89 would seem plenty particularly with dual ignition.
Anyone know if both plugs fire at the same time or are they staggered like a hemi ?
NA Crossfire has 10:1 compression, SRT has 9:1. Should be easier to spin.
Wish mine had 9:1, then I could run 87 PON and save 10% on gas.
BTW the idea of a lower compression ratio with a boosted engine, is not what you would think. The point is to have a larger combustion chamber packed to the same chamber pressure at TDC. This makes more power from the same swept volume.
What I do not understand is why a small bore engine at 10:1 needs 91 PON. 89 would seem plenty particularly with dual ignition.
Anyone know if both plugs fire at the same time or are they staggered like a hemi ?
Senior Member
Joined: Dec 2010
Posts: 12,780
Likes: 184
From: Lineville, AL
Re: reverse polarity
Afraid you lost me on that one .......
Senior Member
Joined: Oct 2013
Posts: 2,152
Likes: 37
From: Orlando
Re: reverse polarity
Drop under 9-10v and no computer car is reliable.
That said DO NOT ever ever ever start a computer car with a charger attached unless designed for computer systems (none from HF). If you need a boost use a jump box and not a charger.
Most do not put out 12v but rather a half wave rectified mess at sorta approximates 13 or 15v DC & the noise will drive a computer stark raving bonkers.
I have seen cars not start or start and run very rough with even a 10A charger attached.
Also many of the Clover Trail (last year's Windows tablets) run on 12v and people ask about connecting directly. I tell than that unless they want to chance a brick to get a 150-180w cigarette lighter inverter and use the wall wart that came with the computer. They have internal switchers and filters that provide what sensitive electronics need.
That said DO NOT ever ever ever start a computer car with a charger attached unless designed for computer systems (none from HF). If you need a boost use a jump box and not a charger.
Most do not put out 12v but rather a half wave rectified mess at sorta approximates 13 or 15v DC & the noise will drive a computer stark raving bonkers.
I have seen cars not start or start and run very rough with even a 10A charger attached.
Also many of the Clover Trail (last year's Windows tablets) run on 12v and people ask about connecting directly. I tell than that unless they want to chance a brick to get a 150-180w cigarette lighter inverter and use the wall wart that came with the computer. They have internal switchers and filters that provide what sensitive electronics need.
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
Drop under 9-10v and no computer car is reliable.
That said DO NOT ever ever ever start a computer car with a charger attached unless designed for computer systems (none from HF). If you need a boost use a jump box and not a charger.
Most do not put out 12v but rather a half wave rectified mess at sorta approximates 13 or 15v DC & the noise will drive a computer stark raving bonkers.
I have seen cars not start or start and run very rough with even a 10A charger attached.
Also many of the Clover Trail (last year's Windows tablets) run on 12v and people ask about connecting directly. I tell than that unless they want to chance a brick to get a 150-180w cigarette lighter inverter and use the wall wart that came with the computer. They have internal switchers and filters that provide what sensitive electronics need.
That said DO NOT ever ever ever start a computer car with a charger attached unless designed for computer systems (none from HF). If you need a boost use a jump box and not a charger.
Most do not put out 12v but rather a half wave rectified mess at sorta approximates 13 or 15v DC & the noise will drive a computer stark raving bonkers.
I have seen cars not start or start and run very rough with even a 10A charger attached.
Also many of the Clover Trail (last year's Windows tablets) run on 12v and people ask about connecting directly. I tell than that unless they want to chance a brick to get a 150-180w cigarette lighter inverter and use the wall wart that came with the computer. They have internal switchers and filters that provide what sensitive electronics need.
Administrator
Joined: Jun 2009
Posts: 13,952
Likes: 1,278
From: Fort Worth, Texas
Re: reverse polarity
Clean battery posts and terminals are important.
A healthy, strong battery is important.
Senior Member
Joined: Oct 2013
Posts: 2,152
Likes: 37
From: Orlando
ANFSCD - the spark
Making this separate since is completely different.
The nice thing about a straight 6 or a 60 degree bent six is that you fire one cyl every 120 crank degrees which makes a single intake plenum and exhaust very good for scavenging (if you really want to know see http://en.wikipedia.org/wiki/Helmholtz_resonance ). Can also be used to create a quiet exhaust without mufflers or restriction. Doesn't work if you have really wild cams but for the street is very nice.
Can treat a V-12 as two sixes for best tune.
A 90 degree V-8 fires every 90 degrees so is best to treat as two four cyl engines which prevents overlap. There have been a number of attempts to smooth out an 8 (or 10) but flat cranks really vibrate and the Ford "bundle of snakes" exhaust only works for individual intakes and makes for a wide engine.
Still unless you have VVT preferably on both I and E which requires a DOHC (see Chrysler Pentastar) you are going to have a torque curve with a peak and taper.
For the Crossfire this is at 3,000 rpm unlike my 3800s which peak at 2000. This may be the reason for such a short 6th but that is another matter.
In the early 60's Buick needed an "economy" engine which became the 231 V6 (several other sizes but this is the most common) and to further reduce startup costs and simplify tooling, it was a 90 degree V6 so it could use the same tooling as a V8.
From day one it vibrated. Soft engine mounts could not completely hide but big cars could absorb A Lot.
In the end the 231/3.8/3800 had a 40 year life and was the base of some of the fastest cars GM had built but in smaller chassis the vibration was too much so in 1978 they came up with the "evenfire" engine by using offset crank journals. In 1988 they added a balance shaft and my Reattae are very smooth. These are the basis of the L67 supercharged engine of drag fame.
An iron engine in an aluminum time it was replaced in 2004 by a more modern engine.
My point is that the 3.2 Crossfire engine is also a 90 degree V6 but I have seen no mention of an offset crank, just a balance shaft. I suspect this is why it is really being treated as two three cyl engines from an exhaust standpoint with separate pipes and catalysts & 240 degree separation instead of 150-90-150-90-150-90.
I have not taken a close look at the intake but suspect it is staggered. This uneven pulsing would also explain why people have had success with very large throttle bodies.
So meanwhile back at the ignition. That 150-90 business is easy for a computer but there are only six coils for 12 plugs amd firing is staggered so it is not a pure "lost spark" like Honda and Buick used.
Which makes me curious, just how many times do the plugs fire in a complete cycle and in what order ? YWTK (Suppose I'll need to rig up a scope to the ignition and see for myself but is an interesting problem.)
ps know this is long but putting down helps me to think about it and might find out if anyone has been here first, am still a newbie to Crossfires.
The nice thing about a straight 6 or a 60 degree bent six is that you fire one cyl every 120 crank degrees which makes a single intake plenum and exhaust very good for scavenging (if you really want to know see http://en.wikipedia.org/wiki/Helmholtz_resonance ). Can also be used to create a quiet exhaust without mufflers or restriction. Doesn't work if you have really wild cams but for the street is very nice.
Can treat a V-12 as two sixes for best tune.
A 90 degree V-8 fires every 90 degrees so is best to treat as two four cyl engines which prevents overlap. There have been a number of attempts to smooth out an 8 (or 10) but flat cranks really vibrate and the Ford "bundle of snakes" exhaust only works for individual intakes and makes for a wide engine.
Still unless you have VVT preferably on both I and E which requires a DOHC (see Chrysler Pentastar) you are going to have a torque curve with a peak and taper.
For the Crossfire this is at 3,000 rpm unlike my 3800s which peak at 2000. This may be the reason for such a short 6th but that is another matter.
In the early 60's Buick needed an "economy" engine which became the 231 V6 (several other sizes but this is the most common) and to further reduce startup costs and simplify tooling, it was a 90 degree V6 so it could use the same tooling as a V8.
From day one it vibrated. Soft engine mounts could not completely hide but big cars could absorb A Lot.
In the end the 231/3.8/3800 had a 40 year life and was the base of some of the fastest cars GM had built but in smaller chassis the vibration was too much so in 1978 they came up with the "evenfire" engine by using offset crank journals. In 1988 they added a balance shaft and my Reattae are very smooth. These are the basis of the L67 supercharged engine of drag fame.
An iron engine in an aluminum time it was replaced in 2004 by a more modern engine.
My point is that the 3.2 Crossfire engine is also a 90 degree V6 but I have seen no mention of an offset crank, just a balance shaft. I suspect this is why it is really being treated as two three cyl engines from an exhaust standpoint with separate pipes and catalysts & 240 degree separation instead of 150-90-150-90-150-90.
I have not taken a close look at the intake but suspect it is staggered. This uneven pulsing would also explain why people have had success with very large throttle bodies.
So meanwhile back at the ignition. That 150-90 business is easy for a computer but there are only six coils for 12 plugs amd firing is staggered so it is not a pure "lost spark" like Honda and Buick used.
Which makes me curious, just how many times do the plugs fire in a complete cycle and in what order ? YWTK (Suppose I'll need to rig up a scope to the ignition and see for myself but is an interesting problem.)
ps know this is long but putting down helps me to think about it and might find out if anyone has been here first, am still a newbie to Crossfires.
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
I think it's a problem with the battery optima red even though it has 800 acc 50 ha are just starting to SRT6, any of you have a optima red on the srt 6? and how is it?
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Joined: Jun 2009
Posts: 13,952
Likes: 1,278
From: Fort Worth, Texas
Re: reverse polarity
The optima red is not popular over here.
My battery is rated at 875 cca (cold cranking amps) I think that is MORE than enough, but it is what they sold me.
My battery is not available in Italy.
My battery is rated at 875 cca (cold cranking amps) I think that is MORE than enough, but it is what they sold me.
My battery is not available in Italy.
Senior Member
Joined: Oct 2013
Posts: 2,152
Likes: 37
From: Orlando
Re: reverse polarity
I just bought the Crossfire a month ago and it has a MOPAR H7 from 2011. When it needs replacement, I'll go to an AGM but see no need before then.
If having a starting issue I'd connect a voltmeter to the big starter connection and crank. If it goes under 9-10v and cranks slow it is one of three things:
1) Bad battery (can check with a load meter.(Mostly use one of these ).
2) Bad wiring - will see a drop between the battery terminals and the starter - will generally get hot after a few seconds creaking - can spot with an IR meter)
3) Bad starter - pulling too much current.
However what I said earlier still stands, the lower compression should make a SRT easier to crank than a N/A, not harder.
If having a starting issue I'd connect a voltmeter to the big starter connection and crank. If it goes under 9-10v and cranks slow it is one of three things:
1) Bad battery (can check with a load meter.(Mostly use one of these ).
2) Bad wiring - will see a drop between the battery terminals and the starter - will generally get hot after a few seconds creaking - can spot with an IR meter)
3) Bad starter - pulling too much current.
However what I said earlier still stands, the lower compression should make a SRT easier to crank than a N/A, not harder.
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
875 acc but how many amps? 70, 80, 90 or 100?
Administrator
Joined: Jun 2009
Posts: 13,952
Likes: 1,278
From: Fort Worth, Texas
Re: reverse polarity
We have two major ratings in the USA:
1) acc and cca are the same. Both tell us the number of amps the battery can deliver to the starter when cold.
This will be hard to translate.
2) RC (Reserve capacity) The number of minutes the battery can deliver 25 amps at 80 degree C. My battery is rated at 90 minutes.
Your amps rating is the same as RC but stated in a different way. Your rating tells us how many amps the battery can deliver for 60 minutes.
I hope this helps.
acc or cca is the most important rating.
Thread Starter
Joined: Jul 2010
Posts: 157
Likes: 1
From: italy
Re: reverse polarity
OPTIMA REDTOP : BATTERIA OPTIMA RT U 4.2 REDTOP ROSSA 50Ah SUV SIGILLATA FURGONI AUTO CHRYSLER DODGE JEEP 4X4 ALTA POTENZA RTU4.2
We have two major ratings in the USA:
1) acc and cca are the same. Both tell us the number of amps the battery can deliver to the starter when cold.
This will be hard to translate.
2) RC (Reserve capacity) The number of minutes the battery can deliver 25 amps at 80 degree C. My battery is rated at 90 minutes.
Your amps rating is the same as RC but stated in a different way. Your rating tells us how many amps the battery can deliver for 60 minutes.
I hope this helps.
acc or cca is the most important rating.
1) acc and cca are the same. Both tell us the number of amps the battery can deliver to the starter when cold.
This will be hard to translate.
2) RC (Reserve capacity) The number of minutes the battery can deliver 25 amps at 80 degree C. My battery is rated at 90 minutes.
Your amps rating is the same as RC but stated in a different way. Your rating tells us how many amps the battery can deliver for 60 minutes.
I hope this helps.
acc or cca is the most important rating.