new to the polished plenum clan

[extreme1ont]

yes takes alot of patience i noticed once i started lol. i need to get more paper, im doing this one to put on my gf's 99 lumina 3100. the 3400 throttle body is much larger, hopping the ports that meet the lower plenum are the same size to mate up.

Also used my dremel a little where the seams are and sanded off the little lip around it. eventually i will finish it, not in a rush since her car is still sitting waiting to re insure it.

[3X00-Modified]

is it a small port 3100 upper intake? 2 bolts per port? If so then stop wasting your time it wont fit unless you want to do the Lower intake as well. that would be a standard 3400 top end swap minus the heads which is possible, the 3100 heads will line up with the 3400 lower intake ports.

[beretta]

umm the car i want to put it on is a 99 lumina 3100.. the top intake is from a 99 as well and 3400. would they not be the same where they mount on ?

If not i will just throw the throttle body on it instead of changing the top intake, figured would be best to swap the whole thing since the opening in the 3100 would be smaller then the 3400 TB. unless i bore it out to match up like i did on my beretta 3.1

[3X00-Modified]

No they wont be the same... 3100's did not go to large port till 2000 all 99's were the same small port design that the beretta originally came with. Just look at it, they look nothing alike and the 3400 is missing 4 bolt holes to even bolt up.

94-99 3100


See how there are two bolts per port... Now look at the 00+ 3100



The same design as the 3400's... These are the 3100 large port engine, the intakes and runners changed drastically.

So really if your current engine has the 3100 with the lines on the upper intake then you can not use the plenum your starting to polish.

[beretta]

well. that sucks lol. i assumed the 3100 and 3400 were the same size ports until a certain year. looks like i will be either just putting the throttle body on or swap the lower intake as well. how much of a performance increase would i get out of it with the 3400 lower and upper +TB on a stock 3100 ?

Is it worth doing if i can get the lower intake cheap ? it will cost me maybe 15.00. 20 tops to get the lower and prob the upper along with it from the JY.

So this plus gaskets to swap it, probably $50 for all the parts, plus my time. thats if i can talk my gf into letting me strip her engine down that far, dont think she wants me to put this on but i said well i think it will just bolt right on. maybe i just wont tell her and just do it LOL.

[3X00-Modified]

If you have the roller rockers its close to a bolt on, but you also need to thread the coolant output port behind the thermostat to accept the threaded one we use. 3400's are pressed in with an O-Ring.

As far as power, well roughly I gained 25 or so HP from the swap... Granted two different dyno's and two different days, but I had 124HP with a stock 3100 and then I got 144-150hp with the 3100 with the 3400 top end.