3400 sfi and 3500 ports

[SwiftDrift]

can someone post a side-by-side pic of the bottom of the plenums or the top of the manifolds?

edit: or seperate pics.... anyone have any?

[carbon]

Why? The 3400 plenum can be ported to match the 3500 runners and vice versa... The real difference is internal to the plenum... volume, total runner length and air distribution.

3400 LIM


3500 LIM

[SwiftDrift]

people are telling me i should just stick with the 3500 intake with the larger tb and adapter... but i dont have that kind of money so i figured i would just use the 3400 intake, i just wanted to see if its a major difference almost like a 3100 small port and large port

edit: i knew they were close but people make the 3500 out to be 10x better :/

[1988GTU]

a 3500 uim should not be that expensive??

[SwiftDrift]

yeah it will come on the 3500, what im saying is i cant afford a tb and to make an adapter to use it

[caffeine]

How expensive do you expect the TB to be??

[sassyness77]

yeah it will come on the 3500, what im saying is i cant afford a tb and to make an adapter to use it

Well you would need the ~$50 adapter and either your stock TB or the lx5 TB (which around here are about $30 65mm) for the lx9 upper. They do sell adapters for the TB, just in case you haven't seen them yet....

[SwiftDrift]

so 80 bucks? if 80 opposed to 10 is well worth the power than thats not so bad

[stargaazer7467]

im using the 3400 upper on teh 350 lower. Just because i dont like the looks of the 3500 upper tho.

[SwiftDrift]

got dyno numbers? or flow data? i wish there was a way for me to know exactly whats different about them.

[caffeine]

Well it's easy to tell right away that a 3400 plenum has longer runners. Longer runners generally are better for low end power and are not as good at higher rpms. Then there's the TB opening that's smaller. Superdave has said that the smaller throttle alone will cause a 3500 to pull a vacuum at WOT (atmospheric pressure is desired with N/A). The fact that it's pulling a vacuum means its a restriction.

Intake port size is surely different as well but I don't know what the size difference is.

[SwiftDrift]

i do plan on having an @$$ load of torque. however, my hp will need to be over 300-350

[SwiftDrift]

would it be worth modifying the 3400 intake to take the larger tb? horsepower is important but the torque would be what really ignites the tires

[caffeine]

The shorter runners on the 3500 plenum don't restrict bottom end power though. I think they help more up top. When I dynoed my Fiero with a totally stock 3500 it made >200 ft lbs at just 2000 rpm.

[SwiftDrift]

how much can you cam out a 3500 without touching the ports?