3400 vs 3500 [Archive] - GrandAmGT.com Forum


View Full Version : 3400 vs 3500

09-21-2011, 10:25 PM
iv heard alot of talk that the 3500 takes the 3400 out to lunch but my question is is it true? does the lx9 make THAT much of a difference?

also if it does, are things like headers, intakes, etc the same or different? could i just pick up a 3500 and drop it in or would it take heavy modifications like new wiring harness etc etc etc... not saying im taking this route just curious what you guys think

09-21-2011, 10:29 PM
or is it just more worth it to do the top swap?

09-22-2011, 05:15 AM
If you are comparing apples to apples, a 3500 will always rank higher than a 3400.
But swapping the entire motor does present some challenges. You don't need a completely new wiring harness, but the 3500 uses a different MAP sensor (you can get the pigtail to splice it in for a few bucks), and the CTS (coolant temperature sensor) is relocated to the rear cylinder head (instead of the lower intake manifold). You also need to get a 7x trigger wheel and sensor mount from TCE to bolt to the harmonic balancer - the 3500 crank has a different trigger wheel built onto the crank, so your normal 7x sensor won't work.
With either option, uou need to use a 3400 throttle body with a TCE adapter - the 3500 TB is drive-by-wire. Also the 3400 fuel rail and pressure regulator must remain, as 3500 cars used a returnless fuel delivery system. Some grinding of the 3500 UIM and a FPR relocation bracket are needed for clearance. You cannot mount your coil packs to the 3500 UIM, but you can still use the standofffs in the rear head.

Top-swap is easier, but you don't get the small bump in displacement and compression ratio goes down a bit. But most engine builders agree that the heads are more condusive to power than the bottom-end.
Either solution needs tuning to run it's best.

09-22-2011, 09:28 AM
Most of the compatibility issues are taken care of if you get the Milzy MMS 3500 swap kit from Milzy Motorsports that has almost every part you will need in one kit. Yes... you can buy some of the parts separately from others, but having everything you need in a kit form is very convenient. Do some research both here and over on 60degreeV6 forum since every aspect of doing either the 3500 top swap or complete engine swap is covered.

Here is my Milzy MMS 3500 swap kit. I have a 1999 GA, so my kit has a few extra parts you may not need.


09-22-2011, 11:45 AM
it kind of seems like all the modifications are made to the top end tho no? meaning that any sort of modifying of the bottom end would be minor in comparison. iv looked at some pictures of the engine itself and it looks as tho they are fairly identical in size and where everything is mounted. fairly. things like the oil filter tho i see are located on the bottom as opposed to the front. but are the stock transmissions strong enough to handle the 3500 or do they need some sort of.. beefing up?

and Starglow i too have a 99 so i would need all of the extras too lol. its nice that you took a pic of that so i can look at the kit and say, well that goes there, and that goes on that.. thanks i appreciate that. i see you went with the 65mm TB, how are you liking it?