What can I expect?

[ZeeTwentyFour]

Hello I am new to the forum, but a little seasoned in the 60* V6 area. Hypothetically speaking, If I got a 3400 and bought the 3500 top end swap from the store, what kind of HP numbers could I expect? and also would there be much difference if I got the same top end swap (ported heads and manifolds) and put it on a 3500 bottom end?

[MY91GT(Z)]

not sure on hp difference would be but pending what ur putting it in can make the swap much easier to use 3400 lower end, w/ the setup in my sig ive heard of some1 gettin around 225whp w/o headers so im thinkin its around 255-270 chp. not sure if this helps but the best person to ask would be ben (sappyse07) for ur answers

[ZeeTwentyFour]

Thats what I was thinking, I have a 93 cavalier id like to swap it into eventually, and the ease of fitting a 3400 bottom end might be worth it.

[SappySE107]

The 3500 bottom end would be best but its more work. I would do it if the budget allows for it. If you want to have an easier time finding pistons, the 3400 bottom end would be the way to go. It all depends on your goals and what all you plan on doing.

The 3500 top end swap is ported but uses the 3400 upper. This is the easiest method. I will have some options available on the new site/store once I have everything done.

I have simulated the stock 3500 heads/manifolds (so its the 3500 upper, not 3400). +33hp over stock. Ported its +62hp. This includes the 56mm vs 65mm throttle body being used as well. Crank HP, not wheel hp.

Either bottom end, I recommend the 3500 top end for NA applications. 3400 or 3500 upper, its going to be worthwhile

[silvergtjrad]

I have a 3500 top end I swapped on in the spring. With stock heads, ported 3500 LIM and ported 3400 uim, I took off three tenths in the quarter mile. There was definitely an increase in power at the top end of the powerband too. This is in an 02' grand am, but I dont see why you wouldnt experience the same gain in power.

[Superdave]

I have the whole 3500 in my 91, all you need is a sledge hammer and saw-zall to fit it in, i have a whole writeup on the swap at V6Z24.com

Here: http://www.v6z24.com/jbodyforum/3500...ls-t98567.html

[ZeeTwentyFour]

The 3500 bottom end would be best but its more work. I would do it if the budget allows for it. If you want to have an easier time finding pistons, the 3400 bottom end would be the way to go. It all depends on your goals and what all you plan on doing.

The 3500 top end swap is ported but uses the 3400 upper. This is the easiest method. I will have some options available on the new site/store once I have everything done.

I have simulated the stock 3500 heads/manifolds (so its the 3500 upper, not 3400). +33hp over stock. Ported its +62hp. This includes the 56mm vs 65mm throttle body being used as well. Crank HP, not wheel hp.

Either bottom end, I recommend the 3500 top end for NA applications. 3400 or 3500 upper, its going to be worthwhile

WOW I didn't know just using a stock 3500 top end would yield that much, I was expecting that ported. I would definitely like to do that swap eventually when I get the funds. What kind of bottom end work would be needed if you put the ported heads/manifolds on? and what kind of tuning work to tie it all together?

[SappySE107]

No bottom end work unless you consider a cam bottom end. Then its up to your powerband. I would run the 00+ rail and injectors off a 3400 minimum, or trailblazer injectors. Tuning will be necessary. Not sure who could help you with that local but I don't have anything for this setup yet to allow you to just drop a chip in.

[ZeeTwentyFour]

No bottom end work unless you consider a cam bottom end. Then its up to your powerband. I would run the 00+ rail and injectors off a 3400 minimum, or trailblazer injectors. Tuning will be necessary. Not sure who could help you with that local but I don't have anything for this setup yet to allow you to just drop a chip in.

thats great! I don't plan on changing the cam, I still want this as a daily driver. My last question would be can you do anything with exhaust manifolds? I figure porting them would be the best idea because I don't think I could fab headers and the cost of having some one do it would be A LOT. I appreciate your time to answer my questions.

[Sidewinder]

I've looked into exhaust manis for my engine before. Someone on here made note that you can get manifolds from 2005 impala (edit) from a 3400 that have the same port size as the 3500 heads. This style of manifold is also the design as the regular 3400 manifolds. The other option is to either get headers or get 3500 manifolds and have an exhaust shop hook them up. I will have a look and see if I can find that thread.

Not to thread highjack. I know those numbers are just sims, but that means that unported the swap should make 213hp, and 242hp ported? So how much less (if anything) would it make with a 3400 UIM? The 3400 mani basically make it a drop in swap like the 3400 right?

Edit: I found the thread.

Look for exhaust manifolds from an 05 Impala with the 3400. They were originally designed for 3500's and have significantly larger ports and internal diameter but still maintain the old log-style design. Should be more effective than Milzy's ported older ones and cheaper to boot. I'm currently looking for a set of these for myself.

3400-95-modified was using them for awhile. You can see them at this thread: http://www.60degreev6.com/showthread.php?t=36268
You just need to make sure you use 3500 exhaust manifold gaskets with them.

I'm not sure if its my browser or if the pictures are no longer up. Milzy at www.milzymotorsports.com does sell ported exhaust manifolds for 3100/3400 if you wanted to look them up, although I think the 05 impala manifolds would be a better option.

[SappySE107]

I don't like porting exhaust manifolds because its labor intensive (expensive), destroys bits (expensive), weakens the cast iron manifolds (can cause cracks if you go too thin), and doesn't show a significant gain (tried it on a 3.4 DOHC). The 3500 manifolds (crossover type) would be better in my opinion, though I haven't seen if the downpipe works.

I am working on a better exhaust option for us, since I would rather make something with a better design than modify something that I don't believe is worth modifying.

[Superdave]

In a 2nd gen Jbody it is possible to use 2 "front" 3500 header style manifolds on gen3 heads. As long as you get the flanges with the manifolds you are set.

We're doing this setup on a 92 Sunbird with a 3400 swap, i believe i'm going to try to get a nice 2" mandrel U bend and bring the front one back up and over the tranny like the stock setup was. If you go under the pan ground clearance becomes an issue. Either way the header style ones will make tons more power than the stock logs.

[ZeeTwentyFour]

So lets say I get the 3400 with a 3500 ported top end, the header style 3400 manifolds would suffice? I would also get a new down pipe and full 2.5 inch piping, I already have 2.5 after the cat.