3400 upper intake manifold worth it?

[Pimped Am GT]

hey i was wondering if a 3400 upper intake manifold would be worth my time putting on? will there be any gains at all and do i have to do any additional work while im doing that or will it all just bolt up, i got it for free and im gonna clean it out and make it look pretty lol , thanks

[Pimped Am GT]

please? lol

[VanishingImage]

no real gains. The engines even tho different but same in other ways,parts like that won't help much. You might as well port your 3.1 upper

[MantaGreen97]

I don't think there is much difference with just the upper. Plus I don't think the LA1 or LG8 UIM will fit the L82 lower properly. I.e. You have to get both the upper and lower to get it to work, and to see any gains.

As for porting the L82 manifolds, even ported L82 manifolds don't flow as well as stock LA1/LG8 manifolds, so you could just find a LIM to match and you're good to go...

[Colin]

Originally posted by MantaGreen97
I don't think there is much difference with just the upper. Plus I don't think the LA1 or LG8 UIM will fit the L82 lower properly. I.e. You have to get both the upper and lower to get it to work, and to see any gains. The ports in the heads are smaller in the earlier 3100 so they wouldn't match up well either . The later 3100 heads would be a good idea as well .

[voyager]

you can physically bolt the 3400 or late 3100 upper onto an older 3100 lower, but because the port sizes are different, you set up turbulent conditions and may actually get worse flow.

there's no way you'll ever port your older 3100 manifolds to the same flow that non-ported 3400/new 3100 manifolds will get. the new ones are just that much bigger. 3400 and newer 3100 manifolds are exactly the same except for which number (or blank like the minivan manifolds ) is stamped on the top.

so.. i don't think it's worth it unless you do upper and lower together ( and the TB of course ). at that point you'll probably want to do the heads as well since now they won't match (not as big a deal as the 2 manifolds being mismatched, but still.. ) and besides, you have half the engine apart replacing the LIM lol.

you do both manifolds, TB and heads and you've probably got 15 hp at the crank in the top end. no way porting your old stuff will get you that, no matter what internet advertisemens claim.

i did this with 3400 parts on my beretta. i definately think it's worth it, but it's no small job.. on the other hand it's not much more than replacing a headgasket and putting the 'wrong' parts back on. it took me whatever time to plan it all out and then an entire saturday afternoon to accomplish.

[Fastlanev6]

I'll add something...

If you use bigger ports on your upper IM than on your lower, the ridge on the lower (from having narrower ports) is going to create turbulence inside the runners and somewhat impede airflow. You'll probably notice a slight improvement, but not nearly as good as the real thing. I did a lot of research into this a few years ago when I ported my 2.8L V6 intake manifolds on my old Beretta. I knocked off .25 seconds in the 1/4 mile from doing it.

[SPECIALGAGT]

Fact and question. I ran a three-way test on the $o.99 "Radio-Shack" turbocharger we've all heard about. Bought and installed a triple-throw / double-pole switch. Had real Gizmo-the-geek wiring running outa the hood into the cabin, and hooked up this way: A. stock configuration right from the airbox. B. With the "supercharger" resistor in place of the stock airbox sensor. C. No connection to the sensor at all (1,000,000,000 ohms resistance.) Performance was noted on I-69 highway between Indy and Ft.Wayne, Indiana. Ambient temp about 70F. Car in 4-th gear, cruise on, air off, Metallica on, Radar-detector on. ABSOLUTELY no diff. in speed when switching between A., & B. & C. At 50MPH, no diff. At 60MPH, no diff. At 70MPH, no diff. At 80MPH, no diff. At 90MPH, no diff. At 100MPH, no diff. At 100MPH, no diff. At 110MPH, no diff At 120MPH, no diff. I chickened out then. I have run it with the resistor in place for weeks on end and noticed no change in mileage figures. But I "think" it adds power, so I drove it that way !! I have no way to measure performance in a Drag-race fashion, but think there would be no diff. I still have the set-up and will try it again at Zero-F weather. Now, the question: what is the largest TB that will easily (well, sorta easily) fit on the 3100 ~ 3400 engine and what HP might the increase be?? Thanks.

[Fastlanev6]

The important thing to note here is that the only "easy" TB to install would be one made specifically for your car....anything other than that, you'll have to fabricate yourself or make some sort of adapter plate. When it comes to the LARGEST TB you want to use, its like exhaust piping....larger is good, but you dont want to go too large or you'll lose some velocity in your incoming air. Along with that, you dont want much of a difference, if any, between the size of your TB and the size of the inlet on your plenum (Upper intake manifold).
With that said, if you're going to go custom, I would bore out your plenum first, then mesure, then determine how you'll make your TB as large as the plenum inlet. In other words, you'll want to work backwards. Make sense?