View Full Version : QUestion about ALternator pulley size and belt size
5ABI VT
11-17-2014, 04:16 PM
Im not sure if Im correct but the oem pulley seems to be a 2.75. Im considering an aftermarket alternator but they only have 2.5 and 2.9 inch pulleys. I would want the tensioner to have enough tension either way.
Can anyone tell me the oem belt length? If there are options for slightly bigger or smaller I can search it up and feel comfortable with either. I would guess the oem tensioner would still work on a 2.5 but I don't want it to not have full tension in case there is too much belt length etc.
Dynomite
11-17-2014, 05:14 PM
You can get longer or shorter serpentine belts. You are looking for 1/2 inch or more between the belt over the belt tensioner and the belt between the water pump pulley and alternator pulley.
geezer
11-17-2014, 05:39 PM
OEM length is 80.5 in.
WVZR-1
11-17-2014, 08:17 PM
Speak to "whoever" you're considering using as a source and investigate the use of the OE pulley and fan to keep the belt at OE length.
1978026 should be the correct "as built" fan and 10498550 should be a correct "as built" pulley. A competent reseller should be able to connect you with a tech person to address the issues. The OE belt is actually spec'd at 2037mm which is 80.1969.
You need to watch where you measure a pulley for diameter, what's considered a replacement for the 10498550 is mentioned to be 62mm which is 2.44 - you have your alternator measure it.
Use this to compare and to use as reference points for your measurements. It would be interesting for you to post your measurements vs. those referenced in the link. I've never measured an OE first hand, yours is original so it could be valuable information. Check the pitch dimension mentioned also.
http://store.alternatorparts.com/241250-6-groove-pulley-for-delco-10si-12si-15si-17si-cs130-cs144.aspx
-=Jeff=-
11-17-2014, 11:11 PM
Some info when I looked at this in the spring
http://www.zr1.net/forum/showthread.php?t=22894
5ABI VT
11-17-2014, 11:39 PM
I'll measure mine up and post. I originally measured from the outer edge on the face of te pulley. So 2.75 is definitely larger than the surface the belt rides on so 2.44 may actually be the right length. If that's the case 2.5 seems to be the choice to go with. The alternator is a billet unit and I'm told that it can handle quite a bit more rpm than a cs144 without even warming up.
WVZR-1
11-18-2014, 12:32 AM
You want to confirm before a purchase all of the dimensions and you might want to "circle" all of the mounting points on the rear housing(slip ring end) and send snapshots to the vendor to confirm the fitment before the purchase. Confirm also the mounting configuration for the forward housing(drive end frame) also, maybe they can confirm using your OE number.
You might mention in this thread the brand and part number before purchase also, maybe someone has experience with the product and can confirm fit or potential issues.
5ABI VT
11-18-2014, 01:50 AM
You want to confirm before a purchase all of the dimensions and you might want to "circle" all of the mounting points on the rear housing(slip ring end) and send snapshots to the vendor to confirm the fitment before the purchase. Confirm also the mounting configuration for the forward housing(drive end frame) also, maybe they can confirm using your OE number.
You might mention in this thread the brand and part number before purchase also, maybe someone has experience with the product and can confirm fit or potential issues.
Definitely no secret I've been posting on FB and cf I think I just forgot I never mentioned it on here. It's a mechman alternator and I've been in touch over the last several days and have sent numerous photos of the alt and other details. I do agree though I will try my best and confirm the mounting point dimensions and I'll ask them to reference the oe part number.
Does anyone know of the difference between the zr-1 and lt1/4 alternators? They didn't say they were the same at first they said they don't have anything for the z until I sent photos .. So I do have a slight feeling they may think it will work.
I'm going with a black anodized unit 170 amp.
WVZR-1
11-18-2014, 04:54 AM
Does anyone know of the difference between the zr-1 and lt1/4 alternators? They didn't say they were the same at first they said they don't have anything for the z until I sent photos .. So I do have a slight feeling they may think it will work.
I'm going with a black anodized unit 170 amp.
Comparing LT1/4 applications to the LT5, the forward housing is different, the fan is likely different and the pulley is different for OE applications. It depends which LT1/4 is compared, 124AMP or 140AMP.
According to their application charts there's certainly "hints" that they don't offer a fit. Their application charts don't cover what you mention buying. Can they build one? Only they can answer that. Of course their application chart is only for their 240AMP unit so any 170AMP that they did for you would be a "custom" build.
Your '94 would use these OE components, the forward housing 10470800, rear housing 1989706, the pulley 10498550 and the fan 1978026.
I didn't mean to "hint" there was a secret but there's not a specific model #/part number that they can supply you that would help someone mention it did or didn't work.
Has anyone used or considered a Mechman alternator build?
http://www.mechman.com/
5ABI VT
11-18-2014, 09:40 AM
There was a post a while ago on corvette forum Ill try and search it. I cant remember how long ago but I didn't have my zr-1 but I saw the post in the z section on cf and inquired about it for my 93 non z car because of the improvements at higher rpm. From what I can remember its a billet unit but they offered a LT5 specific fitment. ALso from googling all night Ive come across several vendors that pretty much all market the mechman alternators and rebrand them.
-=Jeff=-
11-18-2014, 09:51 AM
the LT1s at some point when to the later style CS-144, it is a larger case ans will not fit in the LT5. I have tried a couple times.
Basically you need the Early style CS-144 not the late style
-=Jeff=-
11-18-2014, 09:52 AM
Billet Alt on CF
http://www.corvetteforum.com/forums/c4-zr-1-discussion/3266144-is-there-any-interest-in-a-group-buy-for-machined-billet-aluminum-alternator.html
5ABI VT
11-18-2014, 11:15 AM
found it easy search http://www.corvetteforum.com/forums/c4-zr-1-discussion/3266144-is-there-any-interest-in-a-group-buy-for-machined-billet-aluminum-alternator.html
5ABI VT
11-18-2014, 11:17 AM
Billet Alt on CF
http://www.corvetteforum.com/forums/c4-zr-1-discussion/3266144-is-there-any-interest-in-a-group-buy-for-machined-billet-aluminum-alternator.html
lol beat me to it :) :)
5ABI VT
11-18-2014, 11:23 AM
the LT1s at some point when to the later style CS-144, it is a larger case ans will not fit in the LT5. I have tried a couple times.
Basically you need the Early style CS-144 not the late style
Interesting info there. Ill relay that to mechman. I sent an email and will call the above guys as well. I was in touch with them quite a bit last year and funny only a few months later I ended up with a zr-1 :) It sounds like the same alt at mechman to me, same internal description etc.
WVZR-1
11-18-2014, 11:58 AM
That billet unit looks like it's based on a CS130-D with an "internal fan". There would need to be lots of documentation I'd think done and also with the CS130-D you would need to maybe fabricate a rear brace mount. Here's the LT5 mounting that I believe is consistent for all.
3901
Once the mounting was confirmed a CS130-D would be probably a very good service replacement. They're known for very high and consistent output at lower RPMs for newer electronics where the older CS144 often wasn't sufficient or effective.
Did Craig or no one else ever attempt the one from the CF thread? Seems like maybe a good bit of effort to accomplish what?
5ABI VT
11-18-2014, 04:20 PM
Good question but Im guessing that he didn't have many people lined up for it for a group buy. my motor got delayed.. and now delayed again thanks to my z last year :) .. but I'll be buying one for that car as well. I contacted quality power and have been trading emails with them the last few hours. They have one that is a direct fit for the z they say. My last question was about alternator pulley size options or if I could use my oem pulley. I will measure my pulley tonight. The quality power is a nipponDenso unit with the hairpin wire technology which I believe is the same as the mechman units. It has a dual rectifier and twice the diodes for durability and their amperage claims are in line with mechmans. The outer design however does differ as the quality power unit looks to have a traditional casing with the stator sandwiched in between while the mechman has a solid housing out of billet. There isn't too much of a price difference I think. ($500 vs 580)
btw anyone know how to measure a pulley correctly? ie. measure outer diameter.. use a wire around the top of the ribs? bottom of the grooves etc? the difference may be minuscule but Id sure like to know
Its funny though that digging into alternators.. I cant help but feel the same way about engine parts. Im actually excited for my stereo system, and exlectronics in the car. now the grounds are beefed up and with this alt anything that needs power should be happy. I will however fire up my current alternator to ensure it works and make some videos of it being tested etc while running. I may just sell it cheap or keep it as a spare not sure just yet.
WVZR-1
11-18-2014, 07:02 PM
The links I posted explain the "how to measure" and the pitch dimension is critical for belt alignment BUT changing the manufacturer is going to change the style of pulley available. Everything other than the diameter and the width is worthless, you'll need to use mounting points to bracket(s) to calculate what's required OR send your alternator to the source for them to determine what's actually needed for pulley alignment.
Dynomite
11-18-2014, 08:30 PM
Tech Info - Calculating Alternator Pulley Diameter (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3117790-tech-info-lt5-zr-1-technical-calculations.html#post1581660593)
WVZR-1
11-18-2014, 11:00 PM
I believe that GM always tried to maintain a ratio of something near 2.8:1 for the CS144 alternators and that would result in an alternator RPM of 2240@ 800 crankshaft RPM.
Using Cliff's 6.875 (crankshaft pulley diameter) and the 2.44 (62mm often mentioned stock alternator pulley diameter) the ratio would be 2.818(6.875/2.44) so that seems to be in the vicinity. I believe I've seen that the later CS144's will do 75AMP/14V at that alternator RPM. You could of course check the output of the alternator on the car at various engine RPMs to evaluate or confirm.
If you decided that you're using another alternator of some sort because of "electronics" you need to evaluate the equipment's needs and then ask the vendor of the alternator what ratio is going to be required to supply the required power at what ever RPMs that you choose. Vendors I believe often stretch the performance quotations of their product so you might want to be cautious. Now you just need to hope that there's a pulley diameter available with the correct belt routing to accomplish your needs.
Are there any specs from either of your vendors that mention the AMP/RPM outputs of these alternators. Alternators get pretty testy, we did some fleets and emergency equipment that had rather outrageous requirements and in many cases a single alternator wouldn't accomplish it or they were some very unusual configurations.
Your situation is that it also needs to FIT a rather restricted install space. I believe if I were you I'd just consider a build of yours to a MAX AMP from off the shelf parts, pretty it up by "blasting" the case halves as "JEFFZ51" mentioned someplace in your discussions.
-=Jeff=-
11-18-2014, 11:42 PM
Yep.. you can use a later stator but rotor is a limit due to the style change.
Scratch that.. I would want the AD244 NOT THE CS130, If I Swapped
HMMM
5ABI VT
11-21-2014, 07:23 PM
From what I can gather .. ALL of the alternator options are using a Denso hairpin stator with a billet housing machined for any fitment application. One told me this is the same alt that the c7 uses, and the hairpin stator allows it to be much more efficient, run cooler with less parasitic loss while providing much more amperage at idle and at speed. Not to forget much better long term durability. In my eyes it's an all win-win scenario moving to this option. It also looks cooler although I can't decide what finish to go with just yet. I should have my plenum and top end coming together in the next few days and I'll be using the oem one for now.
I measured the pulley using my caliper at the tip of the ridges and I get 2.78" 2.44 might be measured with a string at the bottom of the belt grooves ? Still don't know if there's a general standard for measuring pulley diameter.
-=Jeff=-
11-22-2014, 09:58 AM
What is the cost for that alternator you are talking of? Dkd you dind out if you can use the OEM pulley with it?
5ABI VT
11-22-2014, 10:55 AM
I'll double check my emails the range is $480-580 give or take depending on finish (most offer pc and anodizing) . The stock pulley won't work. I've been given reccomendations for pulley sizes from 2.2 to 2.9 and several in between. I'll most likely stock with close to stock sizes at 2.5 (measured at the 'peak' of the belt ribs)
Make sure your electrical connections are also in the proper locations. Purchased a Powermaster Alt that was advertised to fit with ZR1 and the pulley was too small and the harness connection was 90 degrees out of phase. I was not happy. I was able to get the stock unit working, cleaned and tightened the hot wire connection. Also, the upper connection that requires the through bolt was helicoiled and would only allow a short bolt to thread into it which is clearly not how that upper bracket is designed to work. The only way the direct fit powermaster will work is removal of the helicoil, swapping the pulleys and re-clocking the rear of the housing (if possible) to allow for the harness to reach the connector. I am not looking forward to once again navigating through the aftermarket "Direct fit" misinformation gauntlet. What a joke.
5ABI VT
11-22-2014, 01:54 PM
Make sure your electrical connections are also in the proper locations. Purchased a Powermaster Alt that was advertised to fit with ZR1 and the pulley was too small and the harness connection was 90 degrees out of phase. I was not happy. I was able to get the stock unit working, cleaned and tightened the hot wire connection. Also, the upper connection that requires the through bolt was helicoiled and would only allow a short bolt to thread into it which is clearly not how that upper bracket is designed to work. The only way the direct fit powermaster will work is removal of the helicoil, swapping the pulleys and re-clocking the rear of the housing (if possible) to allow for the harness to reach the connector. I am not looking forward to once again navigating through the aftermarket "Direct fit" misinformation gauntlet. What a joke.
Appreciate the input that's definitely something I'll ask about next. 2 vendors have told me that they will provide adapters to plug and play for the harness connection those being quality power and Dc power. Mechman said it would be straight fit but they also said at first it was a one wire race alternator and a side post for the 12v which I expressed I didn't want.
WVZR-1
11-22-2014, 09:34 PM
I can't imagine attempting this install without sending the vendor of your choice a correct alternator to use for modeling. There's way to many things to go wrong. You supply the correct "fitment" and they either can or can't replicate the fit. Using billet "one of" I actually can't imagine a vendor assuring you of "a fit" without having the correct fitment available to model from.
Where do you go with this if the product "as shipped" in a "NO FIT"?
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