CR for 87 octane?
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
I know of some guys running 9.5 on 87. but the timing cant be advanced more then 12*. aluminum heads allow you to run more compression then cast heads before you get detonation. make sure your wires are routed properly and are good quality wires. also becarful what plugs you run as well. whats this motor in?
Thread Starter
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New User
Joined: Nov 2002
Posts: 14
Likes: 0
From: El Cajon, CA
The motor is in a go-fast baja prerunner bronco. Right now it's a stock motor
(351 iron heads) and it runs on 87 octane. The motor is old and tired and I'd
like to rebuild it. I'd like to build a strong high rpm motor but I must still burn
87 octane.
I want to build a 408 stroker with some good aluminum heads but I need to
decide how much CR I can handle with 87 octane so I can select heads and
determine how much dish the pistons will need.
(351 iron heads) and it runs on 87 octane. The motor is old and tired and I'd
like to rebuild it. I'd like to build a strong high rpm motor but I must still burn
87 octane.
I want to build a 408 stroker with some good aluminum heads but I need to
decide how much CR I can handle with 87 octane so I can select heads and
determine how much dish the pistons will need.
Elder User
Joined: May 2002
Posts: 627
Likes: 0
From: Claremore, Ok 74017
I seen some running 9.5 on 87, low power and poor milage, they swapped to 92 in the same engine and better milage and more power. I would agree with sticking around 9.0. I'm running 9.5 and 89 octane easy with plenty of power, haven't tried octane swaps to see a difference though.
Thread Starter
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New User
Joined: Nov 2002
Posts: 14
Likes: 0
From: El Cajon, CA
Thx for the info. I don't mind paying for higher octane but a few times a
year I end up in remote areas of baja where they only have 87 octane.
Ford has a 351 crate motor listed with the Z304A high flow heads, 9.0:1,
410hp, 417 ft-lbs. Part M-6007-Z351. Looks perfect except I'd want to
use it with factory EFI. Seems like that motor should run on low octane
as long as the timing is not too advanced?
year I end up in remote areas of baja where they only have 87 octane.
Ford has a 351 crate motor listed with the Z304A high flow heads, 9.0:1,
410hp, 417 ft-lbs. Part M-6007-Z351. Looks perfect except I'd want to
use it with factory EFI. Seems like that motor should run on low octane
as long as the timing is not too advanced?
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Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
good motor. factory mass air efi would work. run an a9l or a9p ecu but may still need some dyno time to get it perfect
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