C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Maximum alternator rpm?

Thread Tools
 
Search this Thread
 
Old Jul 12, 2018 | 10:26 PM
  #1  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default Maximum alternator rpm?

What is it I have read it as 18000 at the alternator. I have a rebuilt alternator and taking off under drive crank pulley to install a stock one(L98) that is 7 1/8 diameter and the alternator one is 2 inch. Assuming the rev limit on a L98 is 5600 That comes out to 19950 at the alternator. Has anyone run this combination and made out ok? Doing air pump eliminator at the same time and sure seems a lot simpler than what I have seen done.
Reply
Old Jul 12, 2018 | 11:11 PM
  #2  
Patsgarage's Avatar
Patsgarage
Team Owner
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Dec 2012
Posts: 30,427
Likes: 1,609
From: Outside the Quick Stop N.J.
Default

Check to see if the internal cooling fan is metal or plastic. The plastic ones do not like high RPM, after one blew apart on me I had my rebuilder put a metal one in.
Reply
Old Jul 12, 2018 | 11:21 PM
  #3  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

There is an internal fan too? How do you see it from outside through the case?
Reply
Old Jul 12, 2018 | 11:26 PM
  #4  
Patsgarage's Avatar
Patsgarage
Team Owner
10 Year Member
Liked
Loved
Community Favorite
 
Joined: Dec 2012
Posts: 30,427
Likes: 1,609
From: Outside the Quick Stop N.J.
Default

Originally Posted by ddahlgren
There is an internal fan too? How do you see it from outside through the case?
IIRC there should be holes in the front of the case.
I am assuming () that most of the late 80s early 90s GM alternators were built the same way, the one I had was off of a 1500 pickup.

Last edited by Patsgarage; Jul 12, 2018 at 11:28 PM.
Reply
Old Jul 12, 2018 | 11:51 PM
  #5  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

Big metal fan on the outside behind the pulley
Reply
Old Jul 13, 2018 | 08:25 AM
  #6  
C409's Avatar
C409
Le Mans Master
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2005
Posts: 6,475
Likes: 564
From: Clearwater Florida
Default

….. My set-up is as stock as far as pullies are concerned and this combo has been north of 8000 rpm with no ill consequences …..
Reply
Old Jul 13, 2018 | 01:04 PM
  #7  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

Originally Posted by C409
….. My set-up is as stock as far as pullies are concerned and this combo has been north of 8000 rpm with no ill consequences …..
71/8 crank pulley and 2 inch alternator? Even if you have the 21/4 alternator one still well past anything I would do. With that combo you would still be over 25000 rpm at alternator. I get it I am worrying too much about it.
Reply
Old Jul 13, 2018 | 03:12 PM
  #8  
WVZR-1's Avatar
WVZR-1
Team Owner
20 Year Member
Veteran: Army
Active Streak: 30 Days
Liked
 
Joined: Sep 2003
Posts: 25,344
Likes: 2,727
Default

Originally Posted by ddahlgren
71/8 crank pulley and 2 inch alternator? Even if you have the 21/4 alternator one still well past anything I would do. With that combo you would still be over 25000 rpm at alternator. I get it I am worrying too much about it.
Is the pulley on the alternator stock or actually measured as 2"? The CS130 stock for that car is 2.2 (56mm) so I thought maybe it was the way you took your dimensions.7 1/8 and 2.2+ is something right at the 18000 (18064 maybe). I did the math earlier in the day and best I recall.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

 Michael S. Palmer
story-1

2027 Corvette vs The World: Every C8 vs Its Closest Competitor

 Joe Kucinski
story-2

10 Most Common Corvette Problems of the Last 20 Years!

 Joe Kucinski
story-3

5 MOST and 5 LEAST Popular Corvette Model Years in History!

 Joe Kucinski
story-4

2027 Corvette Buyer's Guide: Everything You Need to Know!

 Joe Kucinski
story-5

10 Things C8 Corvette Owners Hate (But Won't Tell You)

 Joe Kucinski
story-6

10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!

 Brett Foote
story-7

Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)

 Joe Kucinski
story-8

Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!

 Michael S. Palmer
story-9

5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!

 Joe Kucinski
Old Jul 13, 2018 | 03:17 PM
  #9  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

Measures to the top of the ribs on the pulley
Reply
Old Jul 14, 2018 | 02:33 PM
  #10  
383vett's Avatar
383vett
Race Director
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Default

I wouldn't worry about an alternator blowing up. I've seen hundreds of motors blow at the track and have never seen or heard of an alternator blowing.
Reply
Old Jul 14, 2018 | 06:55 PM
  #11  
JackDidley's Avatar
JackDidley
Race Director
20 Year Member
Active Streak: 30 Days
Liked
Loved
 
Joined: Sep 2003
Posts: 16,835
Likes: 337
From: Database Error Indiana
Default

Originally Posted by Patsgarage
Check to see if the internal cooling fan is metal or plastic. The plastic ones do not like high RPM, after one blew apart on me I had my rebuilder put a metal one in.
First time I went to 6000 RPM my plastic fan exploded. Replace alternator. Second time at 6000 it exploded. Bought a new, not rebuilt alt at the Autozone with a steel fan and fixed the problem.
Reply
Old Jul 14, 2018 | 09:22 PM
  #12  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

Originally Posted by JackDidley
First time I went to 6000 RPM my plastic fan exploded. Replace alternator. Second time at 6000 it exploded. Bought a new, not rebuilt alt at the Autozone with a steel fan and fixed the problem.
Does it have an internal and external fan?
Reply
Old Jul 14, 2018 | 11:32 PM
  #13  
JackDidley's Avatar
JackDidley
Race Director
20 Year Member
Active Streak: 30 Days
Liked
Loved
 
Joined: Sep 2003
Posts: 16,835
Likes: 337
From: Database Error Indiana
Default

Originally Posted by ddahlgren
Does it have an internal and external fan?
Internal fan blew apart.

Reply
Old Jul 15, 2018 | 03:57 PM
  #14  
ddahlgren's Avatar
ddahlgren
Thread Starter
Melting Slicks
10 Year Member
 
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Default

Found the internal fan, can see it through the last radial vent holes by electrical connectors, it is metal so screw it no worries there. Gave the pulley a spin and has a slight high pitched squeak. Is this car ever going to surrender?It it makes noise we have a local rebuilder that is real good and a friend will just have him put some bearings in it if needed.
Reply

Get notified of new replies

To Maximum alternator rpm?





All times are GMT -4. The time now is 11:10 PM.

story-0
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-1
2027 Corvette vs The World: Every C8 vs Its Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-24 16:12:42


VIEW MORE
story-2
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE
story-3
5 MOST and 5 LEAST Popular Corvette Model Years in History!

Slideshow: 5 most and least popular Corvette model years.

By Joe Kucinski | 2026-04-08 13:25:01


VIEW MORE
story-4
2027 Corvette Buyer's Guide: Everything You Need to Know!

Slideshow: 2027 Corvette buyer's guide

By Joe Kucinski | 2026-04-17 16:41:08


VIEW MORE
story-5
10 Things C8 Corvette Owners Hate (But Won't Tell You)

Slideshow: 10 things C8 Corvette owners hate, but won't tell you.

By Joe Kucinski | 2026-04-01 18:36:07


VIEW MORE
story-6
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!

Slideshow: Should you add one of these incredible Corvettes to your garage?

By Brett Foote | 2026-04-01 18:14:05


VIEW MORE
story-7
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)

Slideshow: Every Corvette Grand Sport explained

By Joe Kucinski | 2026-03-26 07:13:44


VIEW MORE
story-8
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!

Slideshow: Breaking down the 2027 Grand Sport, Grand Sport X, Stingray, and LS6 V8.

By Michael S. Palmer | 2026-03-26 13:48:45


VIEW MORE
story-9
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!

Slideshow: 5 reasons bad drivers crash sports cars & 5 ways to avoid a costly shame!

By Joe Kucinski | 2026-03-25 16:32:55


VIEW MORE