cperna15 Posted April 2, 2009 Report Share Posted April 2, 2009 hello my grand prix has a 3100 and i was told if i put 3400 heads and intake in it will add a nice power increase, soo i went to harrys u-pull it in pa and i got the heads and intake, what else do i need to buy for it to run nice Quote Link to comment Share on other sites More sharing options...
MonteCarloDude Posted April 2, 2009 Report Share Posted April 2, 2009 First off, Welcome! If you are top swaping it, Then a bigger downpipe is a must, Maybe even headers. ( If you have $520 bucks.) Im not sure if the headers they make for the 3400 GA would fit a gen 1 W-body, I know they fit gen 1.5s but you have to grind ithe firewall and one of the mounts IIRC. Also, You would gain a lot from a good tune. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 2, 2009 Report Share Posted April 2, 2009 A) What year is your car? If it's a late model '95-'96, you won't have to swap heads at all. The intakes will bolt right onto your current heads. Not sure if there's an increase in flow on the newer heads, I didn't bother doing that on mine. Get the 3400 gaskets, obviously. You'll end up swapping the throttle cable bracket from the 3100 throttle body. You'll also want to swap the coolant outlet on the lower intake, if the one on the 3400 intake is screw-in and not pressed in. C) EGR - if the new intake is not a van intake you will have some issues. If it is from a minivan you can get a simple adapter from some online stores or people on this board (or even make one yourself). Some opt to block off the EGR completely, which will cause a SES light to come on when decellerating from highway speeds. This has no effect on drivability but might hit your gas mileage. I did this to my old '95 GP with help from a couple of members on this board. It wasn't terribly hard, just took quite a few hours. I think it's worth the effort getting a little more top-end from the 3100. If you have any more questions keep posting! Quote Link to comment Share on other sites More sharing options...
cperna15 Posted April 2, 2009 Author Report Share Posted April 2, 2009 well my car was made in december 1994, but it is a 1995 so im pretty sure im going to have to have to do a head swap. also i got the heads from a 2002 grand am gt with 18k miles the car got sideswiped by a tractor trailer the car was useless exept for the moter so i lucked i got everything for 22 dollers from harrys u-pull it, also im thinking of going back and buying a 3400 but i dont think i can do the swap cause this is my only car so i cant be without a car for a few days. is the 3100-3400 top end swap close to the actual 3400. also i have a cold air intake, not an autozone special i spent almost 300 for it and i have a 3"free flowing exhaust, no mufflers, no cat and no resanator so i really want headers lol Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 2, 2009 Report Share Posted April 2, 2009 i have a 3"free flowing exhaust, no mufflers, no cat and no resanator way excessive, if you're talking about the entire damn exhaust being 3" you are losing so much torque it isn't funny. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted April 3, 2009 Report Share Posted April 3, 2009 I have 2.5" exhaust on my swapped and modded 3400, sometimes I think thats still too big. Quote Link to comment Share on other sites More sharing options...
johnnymossville Posted April 3, 2009 Report Share Posted April 3, 2009 The early 3100s are small port intakes and heads and all 3400s have large ports so the 3400 intakes don't line up well with early 3100 heads. When you picked up the 2002 heads and intakes you actually got the better 3400 intake because the 2000 and later 3400 upper intake flows better than the '99 and earlier ones. All 3100s made 2000 and later are large port and use the same heads/intakes as the 3400s do. Put your new 3400 heads, intakes and throttle body on your engine with a 2.5" downpipe or a set of S&S headers and you shoud be happy with the performance improvement. As mentioned earlier a tune or a PCM from MILZY Motorsports will greatly enhance the head/intake/throttle body swap. Your 3" exh. is deffinitely hurting your low end torque, a 2.5" would be much better because you will not be make the 300 hp needed to take advantage of that 3" pipe. Good luck with your swap and I hope that you enjoy the performance increase. Quote Link to comment Share on other sites More sharing options...
jtwmechanic Posted April 3, 2009 Report Share Posted April 3, 2009 if your not going to use headers then you need the exhaust manifolds from the 3400 to benefit from the extra air flow. the 3100 to 3400 swap is a breeze. if you have two complete engines you can't go wrong. be sure to use 3100 injectors and all other electronic components from the already running 3100. lots of options along the way. 3500 top end? turbo requires special exhaust work and headers for the application. tuned prom? the only limit is that of your wallet. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 3, 2009 Report Share Posted April 3, 2009 The early 3100s are small port intakes and heads and all 3400s have large ports so the 3400 intakes don't line up well with early 3100 heads. What? On my '95 3100 that had notches for roller rockers on the heads, we bolted the 3400 intakes on no problem. I agree though, a full engine swap would be best. And if he's going to use the 3400 exhaust, he'll obviously need the 3400 heads. Quote Link to comment Share on other sites More sharing options...
johnnymossville Posted April 3, 2009 Report Share Posted April 3, 2009 The bolt holes do line up it's just that the ports don't match. All 3400s have larger ports than any 3100 before 2000. If I am not mistaken the early 3100s actually have a smaller intake valve as well. The 2000 plus upper intakes on the 3100s and 3400s are identical except the script on them identifying the engine size. Another interesting note is that the 3100/3400/3500s all use the same camshaft. The 3500 combustion chamber has a larger dia. than the 3100 bore and this would cause issues if you tried a 3500 top swap on a 3100. A 3500 top swap on a 3400 is good for a 20 hp increase even though the cr would drop from 9.6:1 to around 9:1 due to the larger combustion chamber. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 4, 2009 Report Share Posted April 4, 2009 A 3500 top swap on a 3400 is good for a 20 hp increase even though the cr would drop from 9.6:1 to around 9:1 due to the larger combustion chamber. so 3400 block + 3500 heads/intakes = recipe for reliable boost? Quote Link to comment Share on other sites More sharing options...
GP1138 Posted April 4, 2009 Report Share Posted April 4, 2009 The bolt holes do line up it's just that the ports don't match. Totally aware of the intake port sizes... we're talking LOWER AND UPPER intakes here. Bolting to the heads. I ran my '95 3100/3400 hybrid for 2 years like this. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted April 4, 2009 Report Share Posted April 4, 2009 I see a few mixed (or unclear) facts here. I believe the intake port size on the 3100 and 3400 are the same. (but yes, you could port them) the major difference in the heads is that the 3400 and large intake 3100s have exhaust ports that are larger (basically ported) and "D" shaped, the loss of the port for the single wire temp sensor, and 94 and early 95 heads are not roller rocker compatible with no guide slots cut in the head. their is an upper and lower intake that have larger bores, and several different versions. lower intake could have a threaded or unthreaded feed port for the heater core. (but you can thread and tap it) as well as an earlier version or the intake which flows worse than the newer version, which has an two digit number visible to ID it. Later ones are preferable (2000+?) and the upper could be blank, say 3100, or 3400, \ and could have a horizontal or vertical EGR (adapter for either are available) and the earlier ones have a restricting choke in their neck.... Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted April 4, 2009 Report Share Posted April 4, 2009 A 3500 top swap on a 3400 is good for a 20 hp increase even though the cr would drop from 9.6:1 to around 9:1 due to the larger combustion chamber. so 3400 block + 3500 heads/intakes = recipe for reliable boost? 3400 heads are better for boost because 3400 heads lower the compression. 3500 heads are better for NA applications due to increasing the compression. Read about it over on 60* Quote Link to comment Share on other sites More sharing options...
johnnymossville Posted April 4, 2009 Report Share Posted April 4, 2009 Been there for 1.5 years. 3400 heads when ported are better for boost because of the runner design and the 3500 heads are better for N/A engines because of the raised intake runners and the D shaped exh. ports, you are correct on that. The 3500 heads have larger cc combustion chambers (32.4cc) than the 3400 heads (28.6cc). With my '93-'95 3.4 iron head pistons and 3500 heads my cr is 11.56:1. The same set-up with 3400 heads and smaller chambers would be over 12:1. Check it out. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted April 4, 2009 Report Share Posted April 4, 2009 Your right I had the compression backwards on them Quote Link to comment Share on other sites More sharing options...
jtwmechanic Posted April 4, 2009 Report Share Posted April 4, 2009 back to the original ? since you already have bought your parts for a 3400 topend swap then i would recommend using the 3400 exhaust manifolds also since their inside diameter is larger than 3100. if you got a complete top end then other than gaskets (get improved design by fel-pro) good platinum plugs (nothing fancy) general tune-up and such and you should be pleased for now. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 4, 2009 Report Share Posted April 4, 2009 A 3500 top swap on a 3400 is good for a 20 hp increase even though the cr would drop from 9.6:1 to around 9:1 due to the larger combustion chamber. so 3400 block + 3500 heads/intakes = recipe for reliable boost? 3400 heads are better for boost because 3400 heads lower the compression. 3500 heads are better for NA applications due to increasing the compression. Read about it over on 60* i think 9:1 is plenty low for boost, but i'm assuming a lot of other factors as well. Quote Link to comment Share on other sites More sharing options...
SappySE107 Posted April 14, 2009 Report Share Posted April 14, 2009 It takes $700 in port work to make 3400 heads better than 3500 heads for boost. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.