How much power can you get out of a 304?

[Commo64]

We all know that the LS engines can hold a crazy amounts of power but I've always wondered how much power a 304 can take with stock internals?

 

[keith reed]

We all know that the LS engines are known to hold a crazy amount of power but I've always wondered how much power a 304 can take with stock internals?

Raptor superchargers claim well over 500 rwhp. However I think most people would be using a stroker kit.

 

[someguy360]

They can take a fair bit. But thats all relative, I consider a fair bit for a car that made 165kw at the flywheel to be say 200rwkw, thats a substantial gain. But you have to think about these differently to LS engines, you can't just throw a cam at them and double your power etc.

They have very low compression in stock form (around 8.4) which means a good cam, roller rockers, good intake, tune etc might net you say an additional 20rwkw. LS's compression straight out the box is in the 10s before you even make any mods so the skies really the limit straight off the bat.

Bubba from all race in Vic has a Holden block running about 2000hp, but thats an aftermarket billet holden block, with all the fruit.

Stock internals can make around 400hp with boost if the normal holden oiling mods are done. Thats the biggest thing is making sure the oiling system is up to scratch. the 2 bolt mains are also pretty limiting factor of the longevity of the engine under high stress. Just because you can make 400hp in stock form, doesn't mean it will last.

Naturally aspirated with super high compression, all the bolt ons etc I wouldn't expect it to hit more than say 230rwkw in 304 form. Even then your probably pushing the boundaries of the 2 bolt mains.


At the end of the day the ONLY way to make power from these is either utilise the low compression and boost it or raise the compression significantly to get more NA power.

But most that have done either compression or boost on stock bottom end 304's seem to find their safe limit between 220-250rwkw.

Stay tuned on my thread when funds have recovered from the fire. I'll be sending 2 bolt mains on a 355 with around a 150 shot of nitrous down the strip.....could be interesting....for science.

 

[Immortality]

Holden quote the stock CR to be 8.4:1 but others think it's lower. COME worked out it's closer to 8:1 because Holden didn't factor in the thickness of the head gaskets. Stock CR is the limiting factor to making good power as mentioned earlier.

in NZ the NZV8 category made about 420hp on a 304 with only a bit of compression and a baby solid FT cam using a carburettor and Harrop DP manifold (heads could only be skimmed to achieve compression, no porting what so ever, not even to clean up factory casting marks). Not sure what piston they used though.

 

[someguy360]

Holden quote the stock CR to be 8.4:1 but others think it's lower. COME worked out it's closer to 8:1 because Holden didn't factor in the thickness of the head gaskets. Stock CR is the limiting factor to making good power as mentioned earlier.

Interesting, I could believe that especially with how unresponsive these engines are to even mild camshaft alterations.

When I put my modified heads on my engine I shopped around to get the thinnest headgasket I could for that reason. I went with a 0.039" felpro which was significantly thinner than the OEM spec gaskets, I've got a permaseal one sitting here from a gasket kit which weighs in at around 0.068" which is a massive difference when you factor in that I had 0.040" shaved off the heads. So people when building their engines if not checking gasket thickness could be pulling significantly more potential power off the table just from the brand of composite headgasket they go.

My machinist estimated with the headgasket and head combination I have I'd probably be at around the 9-9.1 mark and boy was the change noticable. Best $300 I've ever spent.

The only reason I didn't go MLS and remove a layer of the gasket was I was worried about sealing on a block surface that was still in the car and hadn't been machined. The 355 will likely be MLS to handle nitrous.

 

[Immortality]

I thought stock gaskets were .040" thick?

I too have considered the MLS gaskets, they are also available in .029" thick I believe but probably cheaper to get the .040" and remove one layer as you suggested. Copper coat gasket sealer?

 

[someguy360]

I thought stock gaskets were .040" thick?

I too have considered the MLS gaskets, they are also available in .029" thick I believe but probably cheaper to get the .040" and remove one layer as you suggested. Copper coat gasket sealer?

I’ve heard all sorts of varying reports of oem gasket thicknesses over the years so I went for the thinnest aftermarket one I could find on the market.

Some say they were 0.050 some say 0.040 some even say 0.060 I don’t think we’ll ever truely know unless someone has a new old stock one they can measure.

Different years could have had different gasket manufacturers too there’s so many variables.

Most aftermarket ones I’ve seen in gasket kits seem to lean more towards the thicker end of the scale.

And yeah I agree get the 0.040 mls and remove a layer that seems to be what most do.

Copper coat is a must regardless.

I was just worried about my deck surface this time around as it has done 250,000km and I only hit it with a knife stone to smooth it out, there’s bound to be imperfections there and sometimes even copper coat on mls struggles with that.

The new engine will have a machined deck surface as it will be going zero deck and I’ll still copper coat the mls at that point for added protection.

 

[Immortality]

If going zero deck then .040" gaskets will be fine.

 

[Commo64]

They can take a fair bit. But thats all relative, I consider a fair bit for a car that made 165kw at the flywheel to be say 200rwkw, thats a substantial gain. But you have to think about these differently to LS engines, you can't just throw a cam at them and double your power etc.

They have very low compression in stock form (around 8.4) which means a good cam, roller rockers, good intake, tune etc might net you say an additional 20rwkw. LS's compression straight out the box is in the 10s before you even make any mods so the skies really the limit straight off the bat.

Bubba from all race in Vic has a Holden block running about 2000hp, but thats an aftermarket billet holden block, with all the fruit.

Stock internals can make around 400hp with boost if the normal holden oiling mods are done. Thats the biggest thing is making sure the oiling system is up to scratch. the 2 bolt mains are also pretty limiting factor of the longevity of the engine under high stress. Just because you can make 400hp in stock form, doesn't mean it will last.

Naturally aspirated with super high compression, all the bolt ons etc I wouldn't expect it to hit more than say 230rwkw in 304 form. Even then your probably pushing the boundaries of the 2 bolt mains.


At the end of the day the ONLY way to make power from these is either utilise the low compression and boost it or raise the compression significantly to get more NA power.

But most that have done either compression or boost on stock bottom end 304's seem to find their safe limit between 220-250rwkw.

Thanks for the detailed write-up though in other words, you will just be throwing a whole lot of money for nothing if you wanted to make a 304 a lot more powerful...

Stay tuned on my thread when funds have recovered from the fire. I'll be sending 2 bolt mains on a 355 with around a 150 shot of nitrous down the strip.....could be interesting....for science.

Sorry for your loss, but post the link here when you've made the thread...

 

[Immortality]

Thanks for the detailed write-up though in other words, you will just be throwing a whole lot of money for nothing if you wanted to make a 304 a lot more powerful...

Not at all. 304's can make good power for not a huge amount of money. It also depends on how much work you can do. If someone else does all the work it will cost considerably more.