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Why are you guys running a 3" alternator pulley?
Mine is still the stock diameter but I haven't really wound it up yet as I'm still in the tuning phase.
Why are you guys running a 3" alternator pulley?
Mine is still the stock diameter but I haven't really wound it up yet as I'm still in the tuning phase.
Slow down the rotation/speed of the alt to its usable range at high rpm.
Yeah. These alternators pretty much quit working normal around 18,000 RPMs. So, if the stock crank balancer is 7.48" and the alternator pulley is 2.4", that means the alternator RPMs is a little over 3 times the engine RPMs. Any engine RPMs over around 5900 and the alternator is no long putting out "normal" voltage. I've seen it down to 12V. Ironically, unless you are logging BATT voltage and monitoring it, you would never know and wonder why the engine seems down on power at high RPMs. Not unheard of to have guys think they are out of pump or injectors or have weak coils. Switching to a 3" alternator pulley, you can go around 7200 RPMs before the alternator gets affected. Of course, you can also do an underdrive crank pulley or do both but you have to be careful so the alternator RPMs is not too low at idle, especially with stock-ish engines that idle low.
Yeah. These alternators pretty much quit working normal around 18,000 RPMs. So, if the stock crank balancer is 7.48" and the alternator pulley is 2.4", that means the alternator RPMs is a little over 3 times the engine RPMs. Any engine RPMs over around 5900 and the alternator is no long putting out "normal" voltage. I've seen it down to 12V. Ironically, unless you are logging BATT voltage and monitoring it, you would never know and wonder why the engine seems down on power at high RPMs. Not unheard of to have guys think they are out of pump or injectors or have weak coils. Switching to a 3" alternator pulley, you can go around 7200 RPMs before the alternator gets affected. Of course, you can also do an underdrive crank pulley or do both but you have to be careful so the alternator RPMs is not too low at idle, especially with stock-ish engines that idle low.
I have a customer that has a relatively mild engine, but he uses his car for autocrossing, and spends quite a bit of time at high RPMs. He also lives in Arizona and has AC and big cooling fans and drives the car on the street a lot. He installed a bigger alternator pulley to slow the alternator when he is racing, but that led to low voltage when idling with the AC on and the cooling fans running. To solve this, I made a simple 1D advanced table that would automatically raise his idle speed based on voltage. Works like a charm.
Wouldn't a late model car like my 1999 Camaro do this anyways at idle?
It will fire up and be at 14+ volts at idle but once driving around the voltage will drop to about 12+ and then bump up again as needed.
If I toss a 3" pulley on will it come automatically at idle if voltage gets low or is it the fact the alternator is not spinning fast enough?
*EDIT* Just confirmed I have the 7.48" ATI Balancer and the 2.24" alternator pulley so I'm thinking I'll order a 3" pulley soon.
Motion Raceworks has one I like and the price is good too.
Last edited by Black_Sunshine_99; Mar 8, 2022 at 12:07 PM.
Parts are trickiling in but making some progress. Will fab up the downpipe tomorrow and then all the tubing gets final TIG'd and manifolds get jet-hot coated.
Tranny cooler and the massive 5" I/C are in place. Radiator is being modified to move the lower pipe to the psss-side and build a shroud for dual SPALs. Need to do a little final welding on the crossover and the WG tubes and take the whole assembly down to be wrapped. Waiting on the TB adapter hose to finalize cold side. Already working on rewiring the car, so it won't be long before it makes some noise.
After numerous delays waiting on parts and sorting out a chassis wiring mess, it fired up with the 1st twist of the key and ran with no major issues. However, there are some minor ones to sort out. Cannot get the idle below 1450rpms. I suspect it's an IAC issue, either faulty or the wrong one. Ran it for about 20mins and will fire it up again today after a full heat cycle. Gonna check for a vacuum leak to make sure before I go chasing an IAC issue. I'm suspecting the IAC because I unplugged it while the engine was running, expecting a change in the idle speed and there was none. Don't know enough about how IACs operate, so gonna have to do some more research. There's some confusion on my part about what IAC should be used with a Holley 92mm Sniper TB and need to sort that out.
Also have a defective t-brake solenoid. It tested out fine 3 or 4 times but now is blowing the fuse. Had this same issue with 2 other builds where somehow the positive wire on the solenoid has ground on it causing a short when you put 12V to it. As expected the vendor wants to blame it on how it is wired but eventually replaced the 2 previous ones that have been working fllawlessly for years without changing how they were wired. Ironically, the fused circuit that was providing 12V (hot while cranking) to the t-brake relay was also proving the SW12V for the Holley and coil relays. Chased my tail figuring that one out until I isolated the t-brake.
NOTE: Andrew, if it ends not being a vacuum leak, I'm going to employ your expertise to help me sort out the IAC issue.
You can easily test the IAC without starting the engine. Pull the IAC, then with the key on, change the IAC Park position in the software. As you change the IAC Park position, you should see the IAC moving. Zero park will fully extend it's and 100% park should fully retract it.
Looks great, need some idle video when the IAC is sorted.
Just for reference on the 3" alternator pulley too, I put one on my 4th gen and have been street testing it and it doesn't seem to have affected my alternator charging little if at all.
I get 13-14 volts charging at 800-850 rpm idle and charging during low speed cruising so if you want steady voltage up to 7K rpm, I'd scoop one up, the Motion Raceworks unit is very nice.
Here is what I found and TBH, I'm still not 100% certain what the correct solution should be. Did the test as suggested..........DEAD. Moved the IAC over to the Volvo and got the same result. BTW, The Coronet is an HP and the Volvo is Terminator X. I then removed the IAC on the Volvo and tested it on the Coronet and it extended and retracted fully with the 0% & 100% IAC PARKED settings. The next logical step would have been to install the IAC from the Volvo on the Coronet and fire up the engine, but I didn't. It's not a Holley brand, just one I had laying around in my pile.
The IAC on the Coronet is a Holley 543-105 based on some research. One of the 2 screw holes didn't line up, so I dremeled it out like someone else said they had to. It wasn't until I pulled the IAC on the Volvo that it registered that the rubber cap on the end of the pintle was missing from the 543-105. Checked a couple of pics on the Internet and they all showed it without the cap. Did some more research today and found a post on the Terminator X forum discussing this very topic:
So, from what I've read so far: 543-105 might need to have pins swapped; Holley's documentation recommending 543-105 is incorrect; Danny believes the part # should be 543-34, suggested it to someone but never got feedback that it worked; someone tried to use an OEM IAC from a truck TB and couldn't get it to fit the 92mm TB without tearing up the o-ring.
******,
it has a big alt pulley. Voltage was 14.5 with a Powermaster alt but not really valid info since it was at 1450 rpms.
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