my dirt cheap 454 build

[68post]

All of the bigblocks have a poor combustion chamber design except the vortec design. 35 years ago you could find higher octane fuel than you can now , and I battled spark-knock constantly with a factory rated 10.25 or 10.5 compression 396 which was in a lighter vehicle , had a larger solid cam than you're proposing , and lower gears too.

My tuning could've been way off , I was pretty young, but I think you'll find the same problem.

You can always try it , and if more octane is needed you can run 10% up to 20% toluene with your pump premium and tune accordingly.

 

[rumblebox]

I've decided to forego the domes due to detonation risk after some research.

Using flat tops, decking the block and heads so it's at least 8.4:1.

850 double-pumper with annular boosters
Air gap knock-off
1.75" headers
3" mandrel bends
X-pipe behind the T-case
Custom Lunati solid flat cam, 2/3 4/7 swap
Big valves if i have any money left
3.08's
NV4500 swap (if i sell my bike)

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[68post]

Sounds ok. But 2 1/2" pipe is plenty.

 

[rumblebox]

Sounds ok. But 2 1/2" pipe is plenty.

Not for the cam I'm running.

 

[68post]

Not for the cam I'm running.

Your headers are too tiny for a large engine at high RPM, and your compression is too low for a big cam. Gearing doesn't match anything but a torquey engine.

??

An 8.4 compression engine wouldn't warrant an 3" exhaust even with a hit of nitrous. The 1.75" headers would be the bottleneck !

 

[rumblebox]

Your headers are too tiny for a large engine at high RPM, and your compression is too low for a big cam. Gearing doesn't match anything but a torquey engine.

??

An 8.4 compression engine wouldn't warrant an 3" exhaust even with a hit of nitrous. The 1.75" headers would be the bottleneck !

That is partially true about the headers, but since this is such a budget build, 1.75 are the only ones I could get for a decent price.

I'm not building for only right now. I'm anticipating better heads, higher compression, and bigger headers later on without having to rebuild my exhaust again.

BUT, even for the time being, the crazy cam I'm having cut is specifically meant to raise DC to make it act like it has higher SC.

...and just because you have small headers doesn't mean you can't atill benefit from larger post-primary exhaust, because science.