I was just informed that my requested money for an after market alternator, and High Output battery was approved. So, I will soon have a 140amp alternator (I believe this was at 3k RPM) and an Optima Top 800 cold Cranking amp battery.
My question is, what type of wiring will I need from under the hood to the trunk for a Directed Audio D2400 (pushing 1,200wRMS @ 1 ohm) and a 4 channel Kenwood KAC-8452 pushing around 50wRMS per channel, so 200wRMS total?
Replies (3)
swez on 07/25/2007 08:17:49
That's a good thing to consider. It depends on how much current each amp draws at the listening levels you prefer.
At full power your amps will draw about 125 amps of current. This puts you at a minimum of #2 gage line from the BAT to D-block. The DA amp will be fine with a short #4 gage line from D-block to amp and your Kenwood is good w/ #8 wire.
Under the hood, #2 wire is very good, but #4 will work if you leave the stock wires in place too.
If this new H.O. ALT reaches full power at 3,000 RPM, you may need a smaller pulley on it to get more rotational speed at low engine RPM's. In most cases this is a good idea and should not be a problem for your new ALT. (H.O. & Racing ALT's are OK at 10,000 RPM)
In a nutshell, low engine speed RPM equals low ALT output power too. To compensate for this, we change the pulley ratios between the crankshaft pulley and ALT pulley to get that extra ALT RPM.
Do you understand this concept?
Swez
Ender2 on 07/25/2007 08:24:42
I think 125 amps of current is a bit shy, but close. The DA amp has 3 40Amp fuses in it, and the 4 channel has a single 35amp I think, I believe the total draw would be closer to 135amps, not that it makes a huge difference. :P
I do understand what you're saying, essentially we're speeding up the alternator so that it puts out the power I need at Low RPM's, but as far as changing the pulley ratio, I assume I'd just need to place a smaller pulley on the alternator, which would mean disassembling it?
swez on 07/25/2007 08:44:11
The amps may pull a tad more power than 125A's and is dependent on the voltage available. The higher the voltage, the less current draw needed to obtain the target output mentioned. (I used 13.5 volts to come up with the ~125A's) If your voltage is higher, the current draw will be under 125A's.
To change the ALT pulley, we only need to remove the original pulley and drop to a smaller diameter one. That just requires removing the locking nut that holds the pulley on the ALT shaft. That only requires an impact gun to loosen the locking nut, change pulley and reinstall the lock nut. (No need to disassemble the ALT body unless it needs to be "re-clocked")
FYI: You may need to use a shorter drive belt as well. That depends on how tight the present belt seats to all pulleys and how much play is available in the idler pulley tensioner.
Swez
My question is, what type of wiring will I need from under the hood to the trunk for a Directed Audio D2400 (pushing 1,200wRMS @ 1 ohm) and a 4 channel Kenwood KAC-8452 pushing around 50wRMS per channel, so 200wRMS total?
Replies (3)
swez on 07/25/2007 08:17:49
That's a good thing to consider. It depends on how much current each amp draws at the listening levels you prefer.
At full power your amps will draw about 125 amps of current. This puts you at a minimum of #2 gage line from the BAT to D-block. The DA amp will be fine with a short #4 gage line from D-block to amp and your Kenwood is good w/ #8 wire.
Under the hood, #2 wire is very good, but #4 will work if you leave the stock wires in place too.
If this new H.O. ALT reaches full power at 3,000 RPM, you may need a smaller pulley on it to get more rotational speed at low engine RPM's. In most cases this is a good idea and should not be a problem for your new ALT. (H.O. & Racing ALT's are OK at 10,000 RPM)
In a nutshell, low engine speed RPM equals low ALT output power too. To compensate for this, we change the pulley ratios between the crankshaft pulley and ALT pulley to get that extra ALT RPM.
Do you understand this concept?
Swez
Ender2 on 07/25/2007 08:24:42
I think 125 amps of current is a bit shy, but close. The DA amp has 3 40Amp fuses in it, and the 4 channel has a single 35amp I think, I believe the total draw would be closer to 135amps, not that it makes a huge difference. :P
I do understand what you're saying, essentially we're speeding up the alternator so that it puts out the power I need at Low RPM's, but as far as changing the pulley ratio, I assume I'd just need to place a smaller pulley on the alternator, which would mean disassembling it?
swez on 07/25/2007 08:44:11
The amps may pull a tad more power than 125A's and is dependent on the voltage available. The higher the voltage, the less current draw needed to obtain the target output mentioned. (I used 13.5 volts to come up with the ~125A's) If your voltage is higher, the current draw will be under 125A's.
To change the ALT pulley, we only need to remove the original pulley and drop to a smaller diameter one. That just requires removing the locking nut that holds the pulley on the ALT shaft. That only requires an impact gun to loosen the locking nut, change pulley and reinstall the lock nut. (No need to disassemble the ALT body unless it needs to be "re-clocked")
FYI: You may need to use a shorter drive belt as well. That depends on how tight the present belt seats to all pulleys and how much play is available in the idler pulley tensioner.
Swez
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