That funky intake on SEFI models... why?

[King_V]

Alright, I know the theory, the extra-long runners help boost torque way down low. Same theory was used on the Chrysler 413 Cross-Ram back in the 60s, and I know the theory is generally sound.

HOWEVER... does it really have that much of an effect? The reason I ask is because of my experience and what (little) I know of the 231 from GM (later the 3800).

Basically, GM started using SEFI on the 3.8L V6 in 1986, and by 1988 that evolved into the 3800. However, both have a more, I guess "typical" inverted V shape - a plenum at the top center, and relatively short runners going down to the intake ports.

I'm going to do this in terms of power-per-cylinder, since technically slapping two more cylinders on a 231/3.8 would result in 308 cubic inches.

So, anyway, with single exhaust on the lo-po 5.0, we get:

150 hp @ 3200 - 18.75 hp/cyl
270 ft-lbs @ 2000 - 33.75 ft-lbs/cyl

The SEFI 3.8 (1986, 1987, and some models in 1988)
150 hp @ 4400 - 25 hp/cyl
200 ft-lbs @ 2000 - 33.33 ft-lbs/cyl

The 3800 (some 1988 models, 1989 to 1991)
165 hp @ 5200 - 27.5 hp/cyl
215 ft-lbs @ 2000 - 35.83 ft-lbs/cyl

I'm not really all that concerned with the horsepower numbers, although they're interesting that the GM engines in this case have a wider peak-torque to peak-horsepower spread in their respective RPMs. I also realize that I'm sort of comparing apples to oranges.

But, I suppose I'm just wondering if going to a manifold more or less shaped like the ones on the Buick V6 engines would not lose any torque on the 5.0, and at the same time make accessing certain parts underhood (injectors, valve cover, etc) on the passenger side WAY easier.

Thoughts?

[Pesty351]

It has a lot to do with the cam profiles as well.

[Lincolnmania]

look at the torque numbers
the lopo only has 20 ft lbs of torque less than the ho

[85crownHPP]

Upgrading to that type of intake sure gave me buku low end torque... but other things were upgraded too at the same time.

[mrltd]

bore and stroke, head design and a lot of other factors come into play

[mrltd]

oh ,and a lot of the other intakes have a huge plenum under the runners and changing the TB location simplifies the intake design. Most newer GM motors are like that, and the ford mod motors too.

[Mercracer]

But, I suppose I'm just wondering if going to a manifold more or less shaped like the ones on the Buick V6 engines would not lose any torque on the 5.0, and at the same time make accessing certain parts underhood (injectors, valve cover, etc) on the passenger side WAY easier.

Thoughts?

If you switch to one of the currently available box plenum style uppers you will give up some amount of torque but may not necessarily miss it depending on your cam and heads, etc...
You most certainly will gain a pile of space under hood..

[King_V]

Ah, well, I was just thinking along the lines of an otherwise bone-stock lo-po... I sort of thought that the tame cam and E6 heads would make that big, long-runner upper intake unnecessary for producing the bottom-end torque that the 5.0 does.

[85crownHPP]

I drove some type of weird Caddy coupe a costumer has... its has an upper shaped just like ours, and it has a lot more low end balls than any other Caddy Ive driven...