304 Stock intake limitations

[Immortality]

Stock intake with the front cut off and modified for a bigger TB.

The banana's with the top cut off and a plenum welded on with twin TB's is the Walker manifold.

 

[gtrboyy]

They chop elbow section off where accelerator cable bracket bolts to & weld in new section with larger opening & 90mm throttle body(?) looked factory at first glance.

Similar results with ls1 throttle body & new flange but better results taking elbow out & having throttle body facing forward...whatever you do will be some sort of limitation with bananas

 

[shane_3800]

I measured the elbow and it's 70mm at the narrowest point like I mentioned earlier my calculations suggest the runners will never need more than 70mm of TB.

 

[Immortality]

Theoretical calculations are great but they don't trump real world experience and there are plenty of people who have thrown a lot of money at these manifolds chasing small gains.

The Starr manifold was popular on 215i cars and gave a good improvement on the stroker motors.

 

[shane_3800]

Theoretical calculations are great but they don't trump real world experience and there are plenty of people who have thrown a lot of money at these manifolds chasing small gains.

The Starr manifold was popular on 215i cars and gave a good improvement on the stroker motors.

The calculations are based off flow tested TB's from the list I linked, I'll link it again.

https://accufabracing.com/cfm-air-flow
these guy's are one of the biggest and most well renowned engine builders in the US btw.

 

[Immortality]

That's really nice, how much experience do those guys have with the 304 banana's manifold?

 

[shane_3800]

That's really nice, how much experience do those guys have with the 304 banana's manifold?

If a 70mm TB can flow enough air to make 550 to 600hp how exactly is it a restriction?

 

[Immortality]

If a 70mm TB can flow enough air to make 550 to 600hp how exactly is it a restriction?

You can't take a single component as a guide to what an engine will make, you need to consider the entire intake system from filter to intake valve.

But what do I know, I can only tell you what I have seen.

If you want to prove what has been achieved before is wrong go right ahead, I await your results eagerly.

 

[shane_3800]

You can't take a single component as a guide to what an engine will make, you need to consider the entire intake system from filter to intake valve.

But what do I know, I can only tell you what I have seen.

If you want to prove what has been achieved before is wrong go right ahead, I await your results eagerly.

What I'm trying to alude to is if the intake runners are the biggest restriction there's not much point in increasing the TB size.
I bet if the plenum was enlarged with a 70mm TB it would out perform the Starr manifold.
My theory is that the Starr simply is slowing the air speed at the plenum entrance helping the first two runners.

 

[losh1971]

What I'm trying to alude to is if the intake runners are the biggest restriction there's not much point in increasing the TB size.
I bet if the plenum was enlarged with a 70mm TB it would out perform the Starr manifold.
My theory is that the Starr simply is slowing the air speed at the plenum entrance helping the first two runners.

Less talk, more action..... Keen to see dyno results before and after.