300hp 4.3

[IBuryyou]

I ran across this article about a 300hp 4.3. 9:1 compression and stock heads. built for $3000 including machine work. Not a turbo but intresting reading anyway. Article was probably posted here before but I couldn,t find it.


http://www.compcams.com/Community/Articles/Details.asp?ID=232019365

 

[kessler]

Re: 350hp 4.3

Re: 350hp 4.3

Interesting Find, Althoe according to the Dyno #s it produced 301HP at 5500rpm
But for an all motor 4.3 its still impressive.

 

[IBuryyou]

Re: 350hp 4.3

Re: 350hp 4.3

my mistake, but 350 got you're attention

 

[dgoodhue]

Re: 350hp 4.3

Re: 350hp 4.3

The article say 300hp, but anyways its like building up a 400hp 350 Chevy. I am surprise they used stock heads vs a later 96 up vortec heads. Right out of the box vortec flow enough to do a little over 300hp N/A. I did find interesting how they mention about pushrod angles.

One thing I always hate about these article is how never factor in labor, you would be hard pressed to do $3000 with an engine rebuild and iron cylinder head porting, come on. They even sent out the heads, so its not like DIY job :roll:

For our applications, if you want to use good components, it would be hard to be able to build up a DIY block for $3000. I have spreadsheet that I have done, without any machine work for 4 bolt, it was $2600 with valvetrain (no heads either).

 

[HotRodV6]

Re: 300hp 4.3

Well the reason they didnt use vortec heads on that engine was becasue that was done about 5 years ago IIRC, and edelbrock or anybody else didnt make a carb intake for the vortec heads yet.

I did see a follow up on that engine in HotRod that said they were going to re dyno the engine with a set of stock and then ported vortecs and use the new edelbrock intake that had come out, but never see the actual article.

But with that cam and even stock vortecs with the same 2.02/2/60 valves would pick up almost 30-40 HP pretty easy, and maybe close to 60-70 on a fully ported head. That would be a stout little motor.

I also seen the article where they bolted on the vortec carb blower running like 5psi and made something like 450 HP, it was very impressive.

 

[dgoodhue]

Re: 300hp 4.3

Well the reason they didnt use vortec heads on that engine was becasue that was done about 5 years ago IIRC, and edelbrock or anybody else didnt make a carb intake for the vortec heads yet.

That would make sense.

But with that cam and even stock vortecs with the same 2.02/2/60 valves would pick up almost 30-40 HP pretty easy, and maybe close to 60-70 on a fully ported head. That would be a stout little motor.

I pretty sure with that cam, there is now way it would make 360-370hp with ported vortec, it would need more RPM and/or more cubic inches to make that power. (using the 3/4 rule) it pretty hard to get 480-495 hp out of 350 SBC with out being radical, especially spinning it to less than 6000rpm. Essentially this and many other articles like, they modify the motor with parts to provide enough air flow for the displacement such that it get all the easy HP out of the engine. Additional mods will get diminshing returns.

Stock vortecs only flow a litle bit better than the article ported stock head numbers (less than 10cfm) I am not sure how 2.02/1.6 valves would affect that. Most of the gain going to vortecs would be probably through additional timing. I would be surprised to see only 25-30 hp out of a good set of ported Vortec's (it probably wouldn't make difference whether it flow 250cfm or 300cfm.) That cam isn't that radical and the power band isn't high enough. To really to take advantage of the cylinder head flow it would need higher RPM and/or more cubic to move the air.

 

[canadian]

Re: 300hp 4.3

That was originally a Car Craft or Hot Rod article from only a few years ago, but you are right, the 2114 hadn't been made yet. They could have done the intake mods like everybody else does since it's not rocket science, but they wanted an off the shelf solution.