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Thread: 3.4L/3400 Hybrid Build

  1. #1

    3.4L/3400 Hybrid Build

    Hey everyone!
    I'm a long time lurker on almost every v6-fbody site and I'm looking for some help with a new build. I've read a lot of threads about the 3x00 hybrid builds and I have some questions that I'm hoping you guys can help with. KoolCamaro, you did the 3500 top end swap if I remember correctly. I don't want to have to megasquirt at all and I have no experience with tuning at all and was wondering if there was any combination or swap where tuning wasn't involved. If I remember correctly Russ said that he did the 3400 top end swap and didn't need to tune at all? Can anyone else confirm this? From what I've gathered, I'd need 3400 heads, 3400 upper and lower intake manifolds, the 3400 fuel rails, 3400 injectors, and the water neck? What is the water neck? If anyone can help me out with this and kind of provide me with some answers or a kind of walk-through type deal? Any help is appreciated.
    Thanks,
    Johnny

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  3. #2
    Full Throttle SlasherVRGR's Avatar
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    You'd also need 3400 pistons or else compression will be ridiculously high.

    The 3500 heads allow you to keep the 3.4 pistons.
    No matter what you do however, you wont get all the potential gain without tuning.

    Sent from my ADR6300 using Tapatalk

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    Much nicer, better, cleaner, and most importantly faster than the old one

  4. #3
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    A top-swap might run without tuning, but you will need to tune to get the most out of the parts. The bigger 3400 injectors will also probably cause a rich idle without tuning even if they fuel properly under load.

    3.4 pistons with 3400 heads comes out somewhere between 12:1 and 13:1 IIRC. 3.4 pistons with 3500 heads comes out around 12:1 I think, maybe slightly lower

  5. #4
    What if I were to go with 3400 heads, 3100 intake manifolds, 19# fuel injectors, 2000 3400 throttle body? I just want something that'll push me to around the 200-220HP mark without having to tune a whole lot. I will eventually try and go with a bit more and tune but right now I'm just not ready for it.

  6. #5
    If John is around if you wouldn't mind pointing out any thing that would be wrong with that I'd greatly appreciate it!

  7. #6
    Full Throttle SlasherVRGR's Avatar
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    Im almost certain that 3500 heads put you lower than or around 11-1 dcr. I did quite a bit of research on this when i had my 3.4 bird. You can run the 3500 lower intake with 3400 heads and upper intake. If memory serves correct the 3500 LIM flows slightly better.

    If you go with 3100 or 3400 upper intake be sure to get the newer one. I forget what year, but i screwed up when i got my first one. The older ones have a big hump right inside the inlet that restricts flow quite a bit.

    There's a lot of small things to look out for. You need to tap the LIM near the thermostat housing for the coolant temp sensor.

    Sent from my ADR6300 using Tapatalk

    98 Maro
    5spd, Slp lid, Free ram air, Pacesetters, !egr, Slowmaster Cat-back, Founders Lcas, Founders relo brackets, 32mm front sway bar, 19mm rear sway bar, poly trans mount..
    Much nicer, better, cleaner, and most importantly faster than the old one

  8. #7
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    You cannot run a 3500 lower with 3400 heads as the ports won't line up. The 3500 heads flow better than 3400 heads though.

    You could be right on the CR being around 11:1. Either way 11:1 or 12:1 it should be possible to run it on high octane pump gas.

    If this is a 4th gen I'm pretty are the 3500 UIM won't fit under the cowl unless you lower the engine.

  9. #8
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    The top end swap will run without tuning. I ran a 3400 setup on my 3.4 for years without ever tuning the motor.

    The person to ask about this is ForcedFirebird - he has done a 3.4 with 3500 heads and intake - everything will line up as long as you get matching parts. What will be off - is the exhaust ports. They are 100% different IIRC, and I'm not sure how you would address that.

    The 3500 heads would give you between 9.5-10:1 CR if I remember stats, but only if you use the pistons designed for the 1997-2002 3400 (LA1 designation). You would want the 3500 upper if you can help it, the design is just so much better and you *can* run it under the cowl, you just have to drop the engine slightly or find another way to make room. Slasher is right, the 3400 upper from 2001 or 2002 (cant remember) is the best one before the 3500 intake. There is a double wire dual temp sensor (one for ECM one for Thermo) that the LT1 guys run that is in one of my threads somewhere (I have so many I can't remember offhand).

    There is a company out there (british car conversions dot com) that does 3400 engines into MGB cars, and they have a billet water neck (Bought one and tested it) - works like it was from the factory and straightens out the kink in the radiator hose (check out the pics, you'll see the kink).

    http://black34v6.wcfb.cc/modpics/
    Here is a link to pics I took after I did the intial swap (3.4 + 1998 3100 parts). It's the best I could dig into while the engine was in the car. There are a lot of changes so look carefully. The water heater hose had to be relocated under the coils with a part from Russell (hose manufacturer) and I had to make little "Brackets" that would raise the coils up enough to not sit on top of the heater hose. Also the alternator had to be moved ever so slightly (like an inch) with a special Z bracket I made out of a spare piece of metal (i think it was a used hinge) that I drilled out to make work. some of the braces for the alternator had to be modified to make everything line up properly too.

    The EGR system was completely removed because none of it lined up - I had planned to go back over with a MAP torch and some copper pipe and make a slick hardline, but that never happened. the EGR eventually fell off (yes fell off) the RKSport headers that I had attached up there

    Basically its like this - if you want this to go smoothly and do what I did, here is *another* list of parts:
    2002 3400 Upper Plenum
    2002 3400 Lower Plenum
    2002 3400 Throttle Body
    2002 3400 fuel rail + regulator
    Fuel lines from a 2002 3400 car (bought those brand new and "unkinked" them to run more straight. Then I "attached them" to the lines in the car with some rubber tubing. Look at the pics - you'll see how I made it happen.

    3.4 Water Neck from british car conversions
    2002 3400 heads / covers
    RKSport Headers
    spark plugs designed for 3400 heads (they are different. stock 3.4 is 1/4 long and 3400 is over 1/2 inch long)
    Dual wire Temperature sensor installed on top of where the thermostat goes on the 3400 lower

    I used rubber tubing to get all the vacuum connections to line up and then tapped the holes that were left on the plenum and installed set screws with loctite on the threads to keep the whole thing air-tight. The fuel rail was pretty plug and play. the injectors on the 3400 are 19# and the injectors that come with the 3.4 are 17# - so that helped. The fuel harness was removed from the 3400 (same ports but I wanted to make sure that the fuel worked) and i unwound the tape from the stock 3.4 harness, made the wires go to where they needed to - and re-taped it. That's it.

    There were other little brackets made here and there, and little bits of playing around - the serpentine belt needs to be changed, I never got a part number on that and I haven't needed to (its also worn off) so I'm not sure about that one. Just have to play with the size until you get one that is a good tightness but doesn't slip off (had that problem).

    I'll answer any questions about the build that I can - being that it seems that my 3.4/3400 has the longest running history of anyone that's done it "shade-tree" style.

    But really, ForcedFirebird can do more than I can - he knows a lot more and really finessed this whole thing down to a science.

    Hope he shows up here

    Good Luck

  10. #9
    But even after doing that Russ, did it still need a real good tune up or did it run alright? And did that dyno at?

  11. #10
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    Robindehood are you planning on swapping the heads and leaving stock pistons? If so then compression will be high and the stock tune won't be ideal if it will even be ok to run.

    If you're swapping pistons then compression ratio will be much more normal and a stock tune would be ok. However you will never reach the full potential without a proper tune. There's no disputing that.

    Something else to consider; Tunercats just came out with support for the 3.4L PCM in Winflash. That means that for $20 + whatever you ALDL costs + a laptop for tuning, you can be tuning yourself. Since a stock tune should be close to begin with, it would be a really good learning experience to teach yourself tuning, and cost next to nothing. There's no excuse lol.

    RWD exhaust manifolds will bolt up if you slot the lower holes. However the ports in the stock manifolds and probably also aftermarket headers will be too small. Port match as much as you can to the 3500 gaskets.

  12. #11
    Caffeine, I was planning on swapping the pistons with the heads. What's ALDL? And I just don't feel confident to spend hundreds of dollars on megasquirt or something that I wouldn't be able to use confidently :/ But I guess I have to start somewhere right? Haha. A lot of people have been telling me to just leave the stock heads and cam it and what not but I don't want to put a bunch of money in for such minimal gains. I've always been drawn to this swap but the tuning is what discourages me every time.

    Would it make any difference for headers? Because I was planning on ordering a set of pacesetters no matter which route I go :/

  13. #12
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    3.4L/3400 Hybrid Build

    Headers will be better of course but the issue is the 3x00 heads use D ports as opposed to the iron head round ports. As I mentioned just port match as much as possible.

    What makes you think Megasquirt is the only way lol? You can tune the stock PCM and since the tune will already be close its a great opportunity to learn.

    If you made your own ALDL cable (cable that goes from your diagnostic port to your laptop) you could be tuning for under $50. Even if you buy a ready made cable you could still be tuning for under $100. No megasquirt or other standalone necessary.

  14. #13
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    One more thing is that even with the head swap the stock cam will be the limiting factor. After the hybrid conversion the next best mod would be an aftermarket cam. The aluminum heads will easily make power to 7k with the right cam.

  15. #14
    When you say port match, does that have to do with the kind of headers or with just lining it up? haha. And I know there's megasquirt or hptuners and ones like that. The plan is definitely to cam while I have the engine all apart, so if I do go ahead with this build I'll be diving into the cam research and go for the best one.

  16. #15
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    When I say port match I mean place the 3500 exhaust gaskets over the ports on the headers and enlarge them as much as possible to match. Also if possibly try to blend the D-shape into the ports on the headers.

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