305 rebuild with performance parts

[Hipster]

I can't believe nobody has asked this yet: why does the OP feel the need to rebuild the engine? Did it throw a rod through the block? Does it burn a quart of oil per tank of gas? Or does he simply perceive that it's worn out because it's slow because it's a truck?

I think in another thread it was mentioned as low mileage. I'd leave it alone and just drive it while I saved up some 350 money. The same tricks on bigger displacement bring bigger gains.

 

[CRF450R]

I think in another thread it was mentioned as low mileage. I'd leave it alone and just drive it while I saved up some 350 money. The same tricks on bigger displacement bring bigger gains.

That's what I'd do aswell. Now I did own a 90 GMC Sierra regular cab Long box 2wd with a 305 was gutless but dam great on gas like 26 mpg at 110km/h felt like driving a 6.2 gutless diesel though I did have over half a million on that 305 and believe it or not the 700r4 aswell. I'd definitely swap in 5.7 if I was going through the work of pulling the motor though. I'm litterly trying to give my old 5.0 vortec engine away for free and still can't get anyone interested in it so might make another V8 coffee table out of it.

 

[CRF450R]

Your best bet is to just buy a set of 305 Vortec heads. They outflow any other 305 head, really any stock chevy heads other than 350 Vortecs or maybe 2.02/1.6 heads like the 492s I have in my garage. They are basically Tbi heads done correctly. 305 Vortecs make more hp than 350 Tbis. With those heads you will also need an intake like GMs Vortec Carb intake, plus an adapter for Tbi like the one GM used on big block Tbis that had spread bore intakes. Lunati's smallest Voodoo cam was made for small bore engines or Tbi engines go with that too. Then tune.

I have a free 98 305 vortec engine if anyone want I'm in Saskatchewan Canada ran great but got a good deal on a high torque cammed 5.7 vortec so if anyone is from Saskatchewan and wants a free 305 vortec hit me up she's all yours.

 

[badco]

Ive built lots of 305 nhra stock eliminator engines and we made 440+ hp with stock heads, stock valve size, stock Lift cam, stock cast intake and qjet. Cant change piston design, rod length or stroke. In the camaros they run 10.8s qtr.

 

[RichLo]

^ Wow

Any more details on how you made that happen? Basically the only things left that I can see are tons of porting in the heads + intake and an insanely high rpm cam.

 

[Erik the Awful]

For some reason this thread popped back into my head. Back in the corners of my mind are nuggets such as "nitrous doesn't care what size the ports are", which got me to wondering...

If you had a 305 and a 350 that were both built identically, the 305 is 87% of the displacement of the 350. If the power is proportional to the size (just for hypothetical questioning), and the 350 is built to 300 hp, the 305 should put out around 261 hp. What makes the 305 such a dog is that if you go all-out and build a 350 with its maximum of 2.08 valves, the 305 can't hang. Not only are you at 87% of the displacement, but now you're also limited by the valve size. Interestingly, the area of a 1.94 valve is also 87% of the area of a 2.08 valve. 87% of 87% is 76%, so in hypothetical math, with no flow bench, a 305 is limited to 76% of the potential of a 350.

...BUT...

If you built a 350 with a big cam and 2.08 valves, could you build a 305 with 1.94 valves and nitrous it to the same level? Absolutely.

So what's the upper limit for nitrousing a wild 350, and can a 305 make 87% of that by dumping more nitrous in it? The blocks have the same architecture, so it even though it's 87% of the displacement and 87% of the valve size, it should be 100% of the structural integrity.

Anybody have any experience spraying the crap out of a 305 until the block broke? I'm not asking about nitrous mixture mishaps, I'm asking about overpowering the block.

 

[Supercharged111]

Isn't the block itself good for around 500whp?

 

[Hipster]

[/QUOTE]

Isn't the block itself good for around 500whp?

That's about where you start to see Dart and World blocks creeping into the scene

 

[Hipster]

Ive built lots of 305 nhra stock eliminator engines and we made 440+ hp with stock heads, stock valve size, stock Lift cam, stock cast intake and qjet. Cant change piston design, rod length or stroke. In the camaros they run 10.8s qtr.

Me thinks Brzezinski was involved. lol You stock eliminator guys definitely have some tricks up your sleeve.

 

[RichLo]

Check out 'engine masters' on youtube, they sprayed a junkyard SBC (forgot if it was 305 or 350) until the rings cracked. If they would have gapped the rings for nitrous it would have handled more. I want to say it was around 200hp NA and over 600hp before the rings cracked.