JPR
Full Access Member
Is much difference between Delco Remy and Leece-Neville alternators? (Looking at 31si or 34si) Or is this a Ford vs Chevy question?
Thanks John
Thanks John
Difference in alternator brands
- Thread starter JPR
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Mr_Roboto
Full Access Member
I've seen both make very small and very large alternators. Probably no real advantage of one brand over the other, although there may be advantages of particular models.
JPR
Full Access Member
Thanks for the reply. I bought a Delco Remy 20 series, instead of the more expensive 34si that I wanted.
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VALKYRIES
Registered User
alternators
I was wander sometime ago do they rate a duty cycle on them at all. If so a higher duty cycle for one might be farrrrr better then a highter output of another?
I was wander sometime ago do they rate a duty cycle on them at all. If so a higher duty cycle for one might be farrrrr better then a highter output of another?
JPR
Full Access Member
I believe they are all rated at 100% duty cycle. However, there are temperature limits that can be exceeding if pulling large loads at an idle.
Delco recommends that the output be 50% more than the vehicle load requirements.
Delco recommends that the output be 50% more than the vehicle load requirements.
I've had it explained to me this way.....
Keep in mind, my biggest concern is if the alternator is working at idle speeds. Why? Towtrucks often have a full light load at idle for long periods. So do EMS vehicles. My rebulder has modified the Ford 7078 series to have a faster cut-over around 900rpm. That's the lowest he can get it to happen. The next step is the Lecce-Neville unit that does put out full output at idle. Bad part is that it tends to overcharge at high rpm. He said that I'm going to get one or the other but not both. If you would like to talk to him I can PM you his phone num. He's been building alternators and starters since the earth cooled.
Keep in mind, my biggest concern is if the alternator is working at idle speeds. Why? Towtrucks often have a full light load at idle for long periods. So do EMS vehicles. My rebulder has modified the Ford 7078 series to have a faster cut-over around 900rpm. That's the lowest he can get it to happen. The next step is the Lecce-Neville unit that does put out full output at idle. Bad part is that it tends to overcharge at high rpm. He said that I'm going to get one or the other but not both. If you would like to talk to him I can PM you his phone num. He's been building alternators and starters since the earth cooled.
VALKYRIES
Registered User
Alternators
Thank You JPR and Towcat! It was one day going to work that the question occured to me? JPR it sounds like Delco recommends a 50% duty cycle on them. For with better heat sinking they could/ would be able to run at 100% you would only need a heatsink the size of ??? run in cool air with ??? That is fair enought although. Yes Towcat I did know of the different operations of diesels and gas engines where they usually ran rpm wise but the vehicles that operated out of that peramiter, is a very good point. Interesting that they wouldn't regulate properly at higher rpm's.Sounds like the cct's aren't quit sensitive enought? Thank You. In moments of bordom I learn something.
Thank You JPR and Towcat! It was one day going to work that the question occured to me? JPR it sounds like Delco recommends a 50% duty cycle on them. For with better heat sinking they could/ would be able to run at 100% you would only need a heatsink the size of ??? run in cool air with ??? That is fair enought although. Yes Towcat I did know of the different operations of diesels and gas engines where they usually ran rpm wise but the vehicles that operated out of that peramiter, is a very good point. Interesting that they wouldn't regulate properly at higher rpm's.Sounds like the cct's aren't quit sensitive enought? Thank You. In moments of bordom I learn something.
JPR
Full Access Member
Delco is saying the duty cycle is 100%, but if you have 100 amps of load, you need 150 amp alternator to be safe and not over load it.
One thing that Towcat mentioned is amperage at and idle vs running rpm.
Some alternators do not charge much at an idle, ie 1G Ford alternator. Other alternators are designed for high loads at an idle such as Leece Neville 7711JA which came on some of the Ford 7.3L IDI ambulances.
The Leece Neville 7711JA should deliver 135 amps at 3000 rpm (alternator speed, not engine) with a max amperage of 160 amps. So the idea is to size the pulley so at an idle the alternator is turning at 3000 rpm. However, you still have to verify that at max engine rpm the alternator is not above it's rated rpm.
One thing that Towcat mentioned is amperage at and idle vs running rpm.
Some alternators do not charge much at an idle, ie 1G Ford alternator. Other alternators are designed for high loads at an idle such as Leece Neville 7711JA which came on some of the Ford 7.3L IDI ambulances.
The Leece Neville 7711JA should deliver 135 amps at 3000 rpm (alternator speed, not engine) with a max amperage of 160 amps. So the idea is to size the pulley so at an idle the alternator is turning at 3000 rpm. However, you still have to verify that at max engine rpm the alternator is not above it's rated rpm.
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VALKYRIES
Registered User
Alternators
If Delco recommends the 150 Amp to do the output of 100 Amps. It sounds like a 66% duty cycle to me? But the rpm that you get that at I will agree with you.
If Delco recommends the 150 Amp to do the output of 100 Amps. It sounds like a 66% duty cycle to me? But the rpm that you get that at I will agree with you.
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