3400 w/ 3500 Top End Swap Question

[surreal_awakening]

Ok, so new user here. First post. I've got a 1999 Olds Alero w/ a 3400. It was the first new car I ever bought. Got it in the fall of 1998, one of the early ones. Time, and perhaps more importantly life (i.e. kids, work, etc.) have taken their toll on it. It's got 250,000 miles on it, with a large portion of the car being original. The whole thing is in need of an overhaul, and I'm in a position where I can start devoting some attention (and money) to revitalizing it. With that said, I figure it's a good opportunity to step it up just a bit. So, I came here to look for the latest on ways to accomplish that. I haven't really kept up on the automotive world over the past few years, so the 3500 is news to me. So, this all leads me to my question.

I have 2 complete 3400 engines (one in the car, one I got from a donor 2000 GAGT that I stripped with 107k on it), so I'm pretty much set on sticking with a 3400 bottom end. If I stick with the stock 3400 bottom end, and go with the 3500 top end swap listed in the store, what kind of realistic hp/tq numbers can I expect? I'm not looking to break any records at the track, but I'd definitely like to step things up a bit from stock. I have no plans for any forced induction or NOS. All engine. I'm looking for something in the range of 225hp. Will the 3500 top end alone get me there with tuning? Or would I need to also do a cam? Larger TB? Any input is appreciated.

[discostu]

The 3500 bone stock motor has 200hp/220tq at the flywheel. Doing the 3500 top end swap you'd be looking at about bone stock 190hp/215tq with a 3400 bottom end.

Now if you tuned it for a little more juice and still going with 87 octane (yay gas prices) you could probably squeak that back up to 200hp/220tq. Using 91 octane and careful tuning could probably yield you another 10hp, maybe more.

Headers would give you some decent gains, along with a good exhaust system, high flow cat and muffler. A good cold air intake (re: not warm air intake) would give you better breathing, probably a couple of ponies. Some 1.6 double roller rockers would give you a little more valve lift and a little less friction (stock rockers are only fulcrum-rollers), and that wouldn't set you back that much. Even switching all your fluids to synthetic has been documented to free up a couple of lost horsepower vs conventional oils. I don't think you'd have to change your cam to see 225hp with this engine, there's other places you can find the power you're looking for, at a decent price...

Now if you wanted to have a little fun, you could do a port/gasket match on the plenum to the LIM and on the LIM to the heads, and get your valves backcut, you could realize some gains there. Depending on your budget you could have some minor port work done, and the combustion chamber cleaned up, and the valves unshrouded. You could probably see 250hp with that done.

[SappySE107]

They are ported from the store for that swap. The only thing I would recommend above that is the 65mm TB. I will open up the plenum to match it for free with the top end swap kit if you buy the TB as well.

1.6:1 rockers are stock for the 3400 and 3500. The 3500 rockers are 8mm studs though, not 10 like your 3400 so you will need new rockers. They are the only part not in the kit that you will have to find. 03+ 3400 use them as well.

With tuning, phil saw a 5 mpg increase using the 3500 top end (but with 3500 plenum instead of 3400.. I don't expect that to be the deal breaker on better gas milage). He also had a better powerband and a very noticable increase in power. Im sure george will chime in with his thoughts since he swapped phil's old setup onto his grand am as well.

I won't make any claims without dyno numbers but the simulation says well past 225 with or without the larger TB.

[3400-95-Modified]

Ben what do you think I'm going to yeild with my setup...

Its a 3400 lower, stage 1 cam, 3500 heads 3 angle, 3500 lower, and 3400 upper... All gasket matched to 3500 gaskets, and stock 3400 TB for now.

Also tuning capabilities.

[black05gt]

My VE/MAF tuning is about a week away from completion, so I should have the "before" and "after" dyno numbers in about two weeks. My butt dyno says the 3400 with 3500 heads, LS1 springs, ported LIM, and ported UIM with phenolic spacers and 65mm TB pulls harder from 2500 rpm up, but ...
And, the swap was straight-forward for my '05 GAGT - the only real 'mod' was to extend the ECT sensor cable several inches to accommodate the relocated ECT sensor into the right (firewall side) head. I also chose to drill the four holes to accommodate the locator pins on the 3500's orange 'valley' gaskets. Ben's FPR adapter made it a LOT easier, too. The rocker arms and studs were a direct swap from the '05 3400 heads onto the 3500 heads.

Dyno numbers will tell the tale....stay tuned , film at eleven <g>

[3400-95-Modified]

Sweet...

What were your before numbers? and those are Before 3500 heads and intakes, but tuned? And are you using the 3500 upper or are you using a 3400 one like I will be?

[black05gt]

I don't have the "before" numbers handy - but they were with stock 3400 heads, ported 3400 LIM, ported 3400 UIM with phenolic spacers and the 65mm TB.
I'm now running with a ported 3500 plenum.

[3400-95-Modified]

My best WHP numbers on a OBD1.5 3400 with a 4t60e stock, was 144hp and 168tq.

[IsaacHayes]

I'd go for the 3500 plenum and 65mm TB since that's what the 3500 runs stock. The plenum is a nice design over the 3400. Just my 2cents.

Or you could just throw a whole 3500 in there with the external crank adapter for probably less money than porting and swapping heads by the time you add up gasket costs...

You did say you wanted a boost but nothing crazy. So a whole 3500 makes sense to me

EDIT: I just realized that the 3500 doesn't have the 24x sensor either. So that scratches that idea for a whole 3500 in a ODBII car.. Would be nice though since 200hp stock..