3100 vs 3400 | building for boost

[96gaGT]

Ok, so i plan on going junkyard hunting for ether a 3100 or 3400. The question is witch is a better base setup for boost? would a 3100 be better because of its shorter stroke to achieve higher rpms, or other specs? or is it not even worth it and go with the 3400?

[bszopi]

The 3100 and 3400 share the same stroke, just a different bore. 3400 will give you more displacement, which is always good. If you get a 3100, just make sure to get a 00+ one.

[rickykline]

i say 3400 with 3500 top end...

[96gaGT]

More Displacement is a beautiful thing but it also means a thinner engine wall. Would that limit how much boost i can get out of this thing? tho im prutty sure ill brake a rod before the block blows. just wanted to see if their was any advantages to the smaller displacement.

[AaronGTR]

More displacement is a beautiful thing but it also means a thinner engine wall. Would that limit how much boost i can get out of this thing? Though I'm pretty sure I'll brake a rod before the block blows. Just wanted to see if there was any advantages to the smaller displacement.

No. It's an iron block and plenty strong. Stock crank is also pretty strong, and rods aren't too bad. Weakest part is the piston, then rods, then crank. You can modify small journal chevy v8 rods to work with the 3400 crank though. Or you could shot peen/cryo treat the stock rods if on a budget. Get some forged pistons to go with 'em and you should have a durable boost setup.

[SappySE107]

3100 and 3400 are different cast blocks with the same nominal wall thickness. You aren't going to a thinner wall just by comparing 3100 to 3400. The larger bore deshroud the valves for better flow so I would use a 3400 without question. 3500 top end wont work with a 3100 either so that limits it without an overbore and 3400 head gaskets (if that works ok).

[96gaGT]

Looks like im getting a 3400 with the 3500 top end.
One more question. the 3500 TB is electric... would it be easier just to bore out the 3400 TB then it is to use the 3500?

[SappySE107]

I have (out of stock right now) 65mm billet throttle bodies and adapter plate to use on a 3500 upper intake. It would be easier to use a 3400 plenum on a 3500 lower and heads if you want to keep a 56mm TB. You can bore the 3400 plenum out for a larger throttle body but the 3500 plenum is more ideal for 65mm.

[96gaGT]

How hard would it be to wire up the 3500 TB on 3100 electrical? or are you saying i should replace the electrical parts from the 3500 TB with mechanical parts from the 3400 TB?

[IsaacHayes]

Your 96 computer cant control an electric throttle body. I dont know if you could make a controller with a pedal and have it directly control the electric from your pedal, that would be pointless to go to all that custom work though, when you can just get an adapter and bolt on a mechanical throttle body.

You can bolt on the 3400 56mm TB with the stores adapter, or get one of their 65mm billet units. Also I heard a 4.3l vortec bolts up but you gotta mod the linkage and IAC and stuff to get it to work /etc.

[96gaGT]

i thought that would be a pain in the ass. Anyway im trying to get my hands on a northstar throttle body from a member on the forum. i hope he still has one :-/