AndrewD

I don't know if anyone has posted this before, but has anyone rebuilt a 5.4L 3V to be at a higher compression ratio than factory? Factory specs say the engines only came with a 9.8:1 ratio and I'm curious how it would run with at say 10.5:1, with stock cams or aftermarket.

jkenprice1

I'm not an expert, but the first thing that comes to mind is will you be able to use pump gas without detonation.

jsav05150

He will have to use premium gas

Eric Kleven

The stock engine already needs 93 octane and a tune to make max power. The only reason I'd see for going with higher compression is if you have a good steady available local supply of e50 or e85 gasoline and want to make max power on that.

Good luck finding the right domed pistons for these 3v heads, they're flat-tops stock...

650NutKase

Best thing to do is a stroker setup. The stock cams and heads are going to be the restriction

Eric Kleven

It's already swinging a 4.16" stroke, how much more do you need?

If you're looking to spend a pile of money for more power, you're backed into a corner. Everything points to forced induction and/or nitrous to hit any sort of reasonable doller-per-added-horsepower mark.

Eric Kleven

I found some Wiseco dome pistons on a speed shop site yesterday, but it was about a 2cc dome, and 10.5:1 compression on a 5.4. That's probably *just* enough compression that you won't be able to find gas to run it... maybe it would go on 93, but is that worth it?

AndrewD

So far it's looking about like I imagined, not worth the effort. To be honest i was mostly curious to see if anyone had built one and what the results were.

Eric Kleven

I'd be willing to say that anyone looking to change out parts in the bottom of the engine would be doing so to support some form of forced induction. The dollar/horsepower has you backed into a corner.

A generation ago, it was worth the payout to go from a 150hp engine to a 300hp engine, emissions tuning and state of the art was leaving that 150hp on the table.. Now we're starting with a 300hp engine that's not leaving much on the table. For what the returns are, camshafts are stupid expensive, porting is stupid expensive, headers are stupid expensive. You could drop several thousand dollars and maybe pick up 100hp on a naturally aspirated combo. Granted, it would be fun to drive, but you can drop that same several thousand dollars on a turbo/blower/nitrous combo & tune and pick up 200+ at the wheels without breaking into the engine or breaking parts.

A $500 tuner will get you nearly 100ft/lb below 3,200RPM (Computer flat-limits the torque curve to about 265ft/lb below 3,200) and shape up the trans shifting. That would feel like a whole new truck.

There's not much classical hot-rodding left in the modern automobile.