L89 Question
Thread Starter
Drifting
Joined: Jul 2007
Posts: 1,712
Likes: 0
From: Tampa FL
L89 Question
I'm trying to update the engine configurations on my site based on the options sheets from year to year, can someone shed some light on what the "L89" designation stands for?
Isn't it just an L71 with aluminum heads?
Second question, were all L71's the Tri-Power setup?
Isn't it just an L71 with aluminum heads?
Second question, were all L71's the Tri-Power setup?
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Yes and yes.
The L89 was for all intents and purposes an L71 with aluminum heads. Same ratings, etc. Just a much rarer option.
L71's were all three deuce engines. So was the L68 427/400, but different heads, camshaft, intake and carbs, though visually they looked the same.
The L89 was for all intents and purposes an L71 with aluminum heads. Same ratings, etc. Just a much rarer option.
L71's were all three deuce engines. So was the L68 427/400, but different heads, camshaft, intake and carbs, though visually they looked the same.
Melting Slicks
Joined: Nov 2004
Posts: 2,672
Likes: 6
From: Nevada City California
Yes...and no. It's confusing, but technically the aluminum head option is exactly the same configuration as the iron head version, with one exception. The exhaust valve diameter is slightly larger at 1.84 inches versus the iron head version of 1.72. This slight difference should produce a bit more power. Both L71 and L71/L89 engines are rated the same.
The aluminum head that does make a big difference is the ZL-1, second design L-88, LS-6 unit. This head not only had an even bigger exhaust valve at 1.88 inches, it also had contoured intake port floors and contoured exhaust ports. Also with an open chamber design that unshrouded the spark plug area. It developed much more horsepower when configured with an open chambered piston with proper compression ratio design.
The aluminum head that does make a big difference is the ZL-1, second design L-88, LS-6 unit. This head not only had an even bigger exhaust valve at 1.88 inches, it also had contoured intake port floors and contoured exhaust ports. Also with an open chamber design that unshrouded the spark plug area. It developed much more horsepower when configured with an open chambered piston with proper compression ratio design.
Thread Starter
Drifting
Joined: Jul 2007
Posts: 1,712
Likes: 0
From: Tampa FL
Yes...and no. It's confusing, but technically the aluminum head option is exactly the same configuration as the iron head version, with one exception. The exhaust valve diameter is slightly larger at 1.84 inches versus the iron head version of 1.72. This slight difference should produce a bit more power. Both L71 and L71/L89 engines are rated the same.
The aluminum head that does make a big difference is the ZL-1, second design L-88, LS-6 unit. This head not only had an even bigger exhaust valve at 1.88 inches, it also had contoured intake port floors and contoured exhaust ports. Also with an open chamber design that unshrouded the spark plug area. It developed much more horsepower when configured with an open chambered piston with proper compression ratio design.
The aluminum head that does make a big difference is the ZL-1, second design L-88, LS-6 unit. This head not only had an even bigger exhaust valve at 1.88 inches, it also had contoured intake port floors and contoured exhaust ports. Also with an open chamber design that unshrouded the spark plug area. It developed much more horsepower when configured with an open chambered piston with proper compression ratio design.
So much detail, you should write for my site.
I guess what I'm getting at is, what was the advertised HP rating from the factory? Did they still sell it as a 435 HP car or something else?
Melting Slicks
Joined: Sep 2006
Posts: 3,377
Likes: 2,603
From: Burning Jet-A
The Rick Bizzoco book has the best information on this and it is definitive in my estimation.
The 1967 aluminum head 427's were 3904392 heads.
The 68 casting was 3919842 for aluminum versus 3919840 in Iron. I dont see any real difference in either closed chamber head, and the L-88 and L-89 used the same head all year, the additional power of the L-88 over the L-71 comes from the cam and rpm, not the valve.
The 69 L-89 used 3919842 for the entire run. There were no "L-88" head or more correctly "ZL-1" headed L-89's.
For 1969 L-88 cars the following applies. Any L-88 built after June 16, 1969 had the 3946074 "ZL-1" head.
In discussion then its easier to call the 392 head a 67 L88/89 head or "expensive"...
The 3919842 casting the "standard L-88 head"
The 3946074 casting the "ZL-1 head"
The 1967 aluminum head 427's were 3904392 heads.
The 68 casting was 3919842 for aluminum versus 3919840 in Iron. I dont see any real difference in either closed chamber head, and the L-88 and L-89 used the same head all year, the additional power of the L-88 over the L-71 comes from the cam and rpm, not the valve.
The 69 L-89 used 3919842 for the entire run. There were no "L-88" head or more correctly "ZL-1" headed L-89's.
For 1969 L-88 cars the following applies. Any L-88 built after June 16, 1969 had the 3946074 "ZL-1" head.
In discussion then its easier to call the 392 head a 67 L88/89 head or "expensive"...
The 3919842 casting the "standard L-88 head"
The 3946074 casting the "ZL-1 head"
Last edited by international blue; Jan 25, 2008 at 09:41 AM.
Melting Slicks
Joined: Nov 2004
Posts: 2,672
Likes: 6
From: Nevada City California
wfo76,
The '69 model L89 aluminum head option used a closed chamber piston design that mated with a closed chamber design in the head. This did not change at all during the entire model year.
The confusing part comes in, in that later L89 aluminum heads during the 1969 model year were reconfigured, these heads did not have the commonly seen pipe thread plug that most are seen with. They actually resemble the 3946074 aluminum head that was used on ZL-1 & LS-6 applications.
The 1969 L-88 engines actually used two different aluminum heads, early on the L89 head was used (same as on L71/L89), later on in the model year L-88 was redesigned using the ZL-1 head, which required using a open chambered piston to match the open chamber design in the head.
So the answer to your question is no and yes. The late '69 L89 did use the normal (early) L-88 head (one and the same) Late '69 L-88's did not use the same head, they used the ZL-1 head.
The '69 model L89 aluminum head option used a closed chamber piston design that mated with a closed chamber design in the head. This did not change at all during the entire model year.
The confusing part comes in, in that later L89 aluminum heads during the 1969 model year were reconfigured, these heads did not have the commonly seen pipe thread plug that most are seen with. They actually resemble the 3946074 aluminum head that was used on ZL-1 & LS-6 applications.
The 1969 L-88 engines actually used two different aluminum heads, early on the L89 head was used (same as on L71/L89), later on in the model year L-88 was redesigned using the ZL-1 head, which required using a open chambered piston to match the open chamber design in the head.
So the answer to your question is no and yes. The late '69 L89 did use the normal (early) L-88 head (one and the same) Late '69 L-88's did not use the same head, they used the ZL-1 head.
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