ls4,ls5,ls6
Thread Starter
1st Gear
Joined: Sep 2005
Posts: 1
Likes: 0
ls4,ls5,ls6
hi ever one i have a 74 vette big block (manual) i understand that this engine is a ls4 270 hp my question is why the big deffrence in hp between my engine and ls5 and the ls6 .
is this due to the cams valves or what and what can i do to make my engine more like the ls5 and 6
is this due to the cams valves or what and what can i do to make my engine more like the ls5 and 6
Racer
Joined: Sep 2005
Posts: 262
Likes: 0
From: Kissimmee Fl
Everything is different, from the crank to the cam, heads, pistons, rod bolts, etc. when compared to an LS6. On the other hand, the LS5 is also an oval port motor so I would think that upgrade would be feasible for you. I am not knowledgeable of the difference between these 2 motors but I am between the LS6 and those below it in regards to performance. Chevrolet used to sell LS6 crate motors and I was lucky enough to buy one. If that were still the case, you could have just bought one in the crate and swapped it out, saving your LS4 for originality in the process.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
The difference is not as much as you'd think. 1971 was the first year for the new SAE NET power rating. Before 1971 power was rated to a standard that enabled some "creative" measurements. The '71 LS-5 was 365 hp SAE Gross and 275 hp SAE NET. So your Ls-4 is only 5 hp less than a LS-5! I forget the LS-6 SAE NET rating it was in the low 300.
Advanced
Joined: Jul 2005
Posts: 54
Likes: 0
From: Southampton PA
zwede
I went to you link and was fascinated as I am headed down the same path you went down. I think You could really shed some light on where I'm going.
I don't want to hi-jack this thread so I will send you an e-mail. Hope that's o.k.
Funny when I came back in the link on your post was gone??
I'm still trying to figure this thing out.
I went to you link and was fascinated as I am headed down the same path you went down. I think You could really shed some light on where I'm going.
I don't want to hi-jack this thread so I will send you an e-mail. Hope that's o.k.
Funny when I came back in the link on your post was gone??
I'm still trying to figure this thing out.
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Safety Car
Joined: Aug 1999
Posts: 4,862
Likes: 118
From: Texas
Originally Posted by BigBlockk
The '70 LS5 had 10.25/1 compression. In '71 that was dropped to 8.25/1 if I remember correctly and it became the LS4. The '71 LS6 had 9/1 compression.
BigBlockk
Later.....
BigBlockk
Later.....
Pro
Joined: Aug 2004
Posts: 538
Likes: 1
From: ATLANTA GA
I want to go more at hole shot will a 3/4 cam do it? can I use my springs. I have good heads I know it I can feel what it wants to do, I refuse to change the intake and the carb, I have had a SB OK A FORD that was faster than KRYPT and krypt weghhs a 1000lbs less and she crawls. Tell ME what I need Everyone says its a CAM.
