So what is the difference between the 3400 and the 3.4 as far as the block. Why does everyone get a 3.4 from a camaro and redrill the starter? Why wont the FWD 3400 bolt into the fiero? What did they change. I always thought the 3400 was built on the same block as the 3.4 iron head engine? No? Thanks Van
3400 has different oil pan + gasket setup, roller lifter-guides attached to block, starter holes on the correct side. The pistons have a larger dish so your compression ratio, without a piston swap is in the mid 7's... It will start but you'll have less power overall when used with iron heads.
You can rebuild with stock Camaro pistons for the 8.9-9.0 compression ratio or used the 3.4 DOHC pistons and get it up to 9.8-9.965 depending on which head gasket you use...
I'm not sure if a hole needs to be plugged in the Fiero timing cover when using the Camaro 3.4...
I think you mis understand. Why not put the whole 3400 engine into the fiero and scrap the fiero stuff altogether. wont it bolt right in? I know there are probably some things that will need changeing, but arnt they minor and worth it for the extra power a drivability. I may be way off, since Ihavnt done the swap. But I am trying to understand the advantage of using the 3.4 instead of the 3400 if you dont care about stock apperance. Thanks Van
Your topic headline asks for differences in the block, and now you are asking about engine swaps. There are dozens of threads here on PFF talking about the technical hurdles of swapping a 3400, or various parts of a 3400. There are many different opinions. You will learn a lot about the issues by reading those threads.....There is not a short answer, and the long answer is there for you to read.
[This message has been edited by Gall757 (edited 04-14-2014).]
I guess I am not very good with communicating my question. I am wondering why if the block for the 3.4 and the 3400 are the same, why is the 3.4 a direct bolt in and the 3400 a difficult swap.
I have read pages and pages of swap threads on this site, but they all deal with the challanges that particular builder faced from stuck bolts to frame rust. I havnt seen a comprehensive thread on the external differences of the 3400 vs the supposedly much easier 3.4.
Is it just that the Fiero acc. will fit on the 3.4 and not on the 3400? Was the block changed in such a way that it wont fit and custom mounts are needed? Does it not bolt up to the transmissions found in the fiero?
As someone recently involved in Fieros, but with many years of experiance modding vehicles I am just trying find out the difference between the two motors for a swap.
If you are a jackass who already has this info but think I havnt paid my dues enough to share it, and that i should spend days and days searching old threads looking for it then just move along. I was hopeing for a helpful individual who had done one of these swaps or both who could enlighten me so I can make an educated choice. All the thread I have read seem to be either a journey through the trials this builder or that builder has faced with very little real info. Or a pissing match as to what is better aluminum heads or cast iron. Not really interested in any of that. I already no how to make an engine make more HP and the advances the auto industry has made in general.
SO if any one can shed some light on the physical differences of 2 engines that seem to be externally virtually the same thing yet one has the reputation of being a direct bolt in and the other a "very difficult install" I would really be interested. Thanks Van
The block is basically the same, will bolt up perfect, the starter is on the proper side with a FWD block. The top end is different, aluminum heads and different intake. Front cover will swap over, but the accesories will not fit because of the different brackets do not fit between the aluminum and iron head engines. Larry
I guess I am not very good with communicating my question. I am wondering why if the block for the 3.4 and the 3400 are the same, why is the 3.4 a direct bolt in and the 3400 a difficult swap.
I have a hybrid in my 87 GT - 3400 roller cam block with Fiero top-end. At the time, seemed like a good idea. IF I were "doing over" I'd go 3800 S/C.
Yeah - the 3400 will bolt to the transmission and the starter is on the "correct" side. Other than that - everything else needs to be made to fit. Exhaust, front motor mount & dogbone, brackets for front accessories, cooling system connections and fill connection. Not sure about changes needed for A/C compressor, wiring differences, ECM swap wiring, compatibility to Fiero speedo/gauges etc.
The Camaro 3.4 - drill starter mount holes for the Fiero and swap it in. The engine is essentially the same as the 2.8 with more displacement. Every thing else "falls into place" with no modification. You can even run the stock ECM.
That's the short of it. You decide how much work you want to do.
I have a hybrid in my 87 GT - 3400 roller cam block with Fiero top-end. At the time, seemed like a good idea. IF I were "doing over" I'd go 3800 S/C.
Why? Is the power not what you expected? Is the 3800 an easier swap? What would make you choose a 3800 over the 3400 other than the displacement? If it is displacement, then why not a V-8? Thanks Van
The block is basically the same, will bolt up perfect, the starter is on the proper side with a FWD block. The top end is different, aluminum heads and different intake. Front cover will swap over, but the accesories will not fit because of the different brackets do not fit between the aluminum and iron head engines. Larry
If the accesories is the only issue, why not just keep the 3400 accesories and bolt it in and hook it up? I havnt done it, but it would seem to be an easy way to go. I must be missing something. Thanks Van
If the accesories is the only issue, why not just keep the 3400 accesories and bolt it in and hook it up? I havnt done it, but it would seem to be an easy way to go. I must be missing something. Thanks Van
you would need to loose the distributor and and the least goto the 7730 ecu, do some re-wiring for the ecu, or do alot of re-wiring to run an OBD2 ecu, not to mention change the fuel line setup, then the heads take different exhaust manifolds too, so need exhaust work done, and the coolant comes out at different area's so dont forget to re-work those lines....
if you mean why not just change out the blocks? well you can... change the blocks, use camaro or 3.4twin cam pistons, change over all the sheet metal, then get a custom cam setup to handle the rollor block on the iron heads as the old cams were flat tappet....
[This message has been edited by hookdonspeed (edited 04-15-2014).]
Why? Is the power not what you expected? Is the 3800 an easier swap? What would make you choose a 3800 over the 3400 other than the displacement? If it is displacement, then why not a V-8? Thanks Van
this question ive been pondering for a while... only thing i can comeup with is the 3800's have a larger aftermarket and were "done first" so they been proven, i myself did a 3500 swap that i plan on turbo'ing, im not going to "build it out" just a cam, and springs, i hope to be a bit over 300HP, but time will tell, guys over at 60degreev6.com have pushed the 34/3500's over 400 without problems, and TBH, the 3x00 swap is eaiser then the 3800 swap, and just a hair less power NA to NA outa the box. (201hp/221ft-lbs lbs for 3500, 185hp for 3400, 205hp/230ftlbs for 3800) the 3500 is 36lbs lighter from research despite what the wiki says of 22lbs (theres a huge writeup somewhere on 60degree)
Why? Is the power not what you expected? Is the 3800 an easier swap? What would make you choose a 3800 over the 3400 other than the displacement? If it is displacement, then why not a V-8? Thanks Van
I wanted the "stock look" but Fiero top-end cannot supply enough "air" for the increased displacement. Its seems the Pontiac engineers tuned it exactly for that displacement. The Supercharger solved the problem.
I should have gone 3800 S/C instead of going through all that.
Yeah - sure the 3400 bolts to the trans and the starter is in the right place. But that's about all you're seeing that makes it "easy". The 3800 does that too. It would be the same work as a complete 3400 install in your case.
[This message has been edited by fierosound (edited 04-15-2014).]
I have swapped in a 2005 3400 (but it was from a chevy equinox) and by far the easiest part of the swap was bolting the engine to my original trans, using the original Fiero V6 lower engine mount and bracket, and buying a performance Fiero specific exhaust with modified "D" port flanges.
Other then that, everything else needed a good amount of work. I wanted to run the OBDII computer from an early 3400 for simplicity but needed to add sensors to the engine that were since updated. Then all of the wiring was custom routed, same with fuel lines and coolant lines. The air intake hose didn't fit anymore so needed modification to use the stock air filter.
Lets compare to a 3.4L from a Camaro. Install the heads, intake manifolds, distributor, and timing cover with accessories from your already 2.8L V6 Fiero (everything bolts right on without modification). Drill the holes to move the starter to the stock Fiero side. Reinstall exactly the same as if you had an original V6 Fiero. Done.
The 3400 is a newer engine with enough advances in technology that it isn't as easy of an "unbolt and rebolt" process.
A lot of what is mentioned here is why I went the hybrid approach with a rebuild. The 3400 block + cam is better than the 3.4, yet when you swap in Camaro or 3.4 TDC pistons you can still run he Fiero ECM right away and optionally do a '7730 conversion later and even lose the distributor. People complain about the Fiero intake but a DAWG neck mod and bigger throttle body fixes it just fine for a 3.4 as a flowbench has proven.
A lot of what is mentioned here is why I went the hybrid approach with a rebuild. The 3400 block + cam is better than the 3.4, yet when you swap in Camaro or 3.4 TDC pistons you can still run he Fiero ECM right away and optionally do a '7730 conversion later and even lose the distributor. People complain about the Fiero intake but a DAWG neck mod and bigger throttle body fixes it just fine for a 3.4 as a flowbench has proven.
yes, but doesn't the 3x00 heads flow ALOT more then the old iron heads? even more then highly ported iron heads? have you have that hybrid dyno'd? id be curious to howmuch your loosing via going iron.
yes, but doesn't the 3x00 heads flow ALOT more then the old iron heads? even more then highly ported iron heads? have you have that hybrid dyno'd? id be curious to howmuch your loosing via going iron.
This has been an arguement here for a long time. If I were you I wouldnt get into this debate here, it would be better for you to inquire over at 60*v6, Mars made 220ish WHP with his 3400 fiero.
Originally posted by hookdonspeed: yes, but doesn't the 3x00 heads flow ALOT more then the old iron heads? even more then highly ported iron heads? have you have that hybrid dyno'd? id be curious to howmuch your loosing via going iron.
I dyno'd at 187 @ 4100 and 249 ft*lbs at 3600 on a Mustang dyno when I had the intake neck restriction. It would have been about 196/261 on a dynojet this was on a Fiero ECM and still running a little rich. I converted to the Trueleo intake + '7730 + DIS but my crank position sensor wires and knock sensor wire are sitting against the block and close to the header and have been getting burned and I haven't had good timing signals since then so I only posted 172 @4900 / 220 @4000 with that build but I hope to have those issues resolved by the end of May. But with the restricted intake I basically made 4.9 power. My 4.9 + Allante intake dynod ~175 rwhp and 265 ft*lbs...
The better question is how much flow does a 3.4L motor need. La Fiera's CNC ported iron heads flowed 185 cfm which is what 3400 Gen3 heads flow stock. Oreif's 3.4 heads flowed [a mere] 165cfm and he still put down 204 rwhp on iron heads. Velocity is as important as capacity and why flow #'s aren't the whole story especially when the test is done with more vacuum than your motor can actually produce...
Probably the most limiting thing on the iron heads is the combustion chamber delsign, and there is not a lot you can do to fix that. Straight valves just don't get it. The aluminum heads are just a better design, and a lot less prone to detonation and other bad things. Put a nice valve train and cam in a 3100 and it will turn over 7,000 freely, which alone makes the car a lot more fun to drive. Where the engine makes power has at least as much to do with the performance of the car as simple hp, you could put a tractor engine in that makes 300 hp at 2,500 rpm but it would not be much fun to drive. Larry
Probably the most limiting thing on the iron heads is the combustion chamber delsign, and there is not a lot you can do to fix that. Straight valves just don't get it. The aluminum heads are just a better design, and a lot less prone to detonation and other bad things. Put a nice valve train and cam in a 3100 and it will turn over 7,000 freely, which alone makes the car a lot more fun to drive. Where the engine makes power has at least as much to do with the performance of the car as simple hp, you could put a tractor engine in that makes 300 hp at 2,500 rpm but it would not be much fun to drive. Larry
Is that why LS3 heads use straight valves? Or did they switch to splayed to lower the height of the valve covers since those motors were going into FWD cars?
Here's a tidbit I just read: " For iron heads applications it is possible to install valve guides to allow the use of 8MM valve stems from late model engines. The less valve stem in the port the less of an obstruction they present. Viton valve stem seals from a Small block Chevy can be installed on iron heads with 11/32 valve stems on both the intake and exhaust valves to improve oil control on the exhaust valves which normally do not use any seals. The oil shedders under the valve spring retainer should be discarded." So taking this into account, the shark vane in the intake can be narrowed slightly since its purpose is to deflect air equally around the valve stem on iron heads further increasing airflow...
[This message has been edited by lou_dias (edited 04-16-2014).]
Is that why LS3 heads use straight valves? Or did they switch to splayed to lower the height of the valve covers since those motors were going into FWD cars?
Here's a tidbit I just read: " For iron heads applications it is possible to install valve guides to allow the use of 8MM valve stems from late model engines. The less valve stem in the port the less of an obstruction they present. Viton valve stem seals from a Small block Chevy can be installed on iron heads with 11/32 valve stems on both the intake and exhaust valves to improve oil control on the exhaust valves which normally do not use any seals. The oil shedders under the valve spring retainer should be discarded." So taking this into account, the shark vane in the intake can be narrowed slightly since its purpose is to deflect air equally around the valve stem on iron heads further increasing airflow...
yes, but doesn't the 3x00 heads flow ALOT more then the old iron heads? even more then highly ported iron heads? have you have that hybrid dyno'd? id be curious to howmuch your loosing via going iron.
Is that why LS3 heads use straight valves? Or did they switch to splayed to lower the height of the valve covers since those motors were going into FWD cars?
Here's a tidbit I just read: " For iron heads applications it is possible to install valve guides to allow the use of 8MM valve stems from late model engines. The less valve stem in the port the less of an obstruction they present. Viton valve stem seals from a Small block Chevy can be installed on iron heads with 11/32 valve stems on both the intake and exhaust valves to improve oil control on the exhaust valves which normally do not use any seals. The oil shedders under the valve spring retainer should be discarded." So taking this into account, the shark vane in the intake can be narrowed slightly since its purpose is to deflect air equally around the valve stem on iron heads further increasing airflow...
and LS3's also have alot more bore to work with compared to the tiny V6 bore...what's to say the LS3 wouldn't make gains by going with canted valves? oh and maybe the LS3 has straight valves to better fit between the strut towers of a 'vette...
you talk about gaining airflow, the 3x00 heads flow more stock then the iron heads flow ported. this has been shown to you multiple times, and then you say flow numbers don't matter? now they somehow matter again???
the 3x00 heads are better out of the box then max effort iron heads in every catagory, chamber size/shape, port flow, material, weight ect... the only aspect the iron heads win when compared to the aluminum heads is that the iron heads can maintain a stock look, but even that isn't worth anything IMO, these aren't valuable cars stock/stock appearing.(or modified for that matter)
I will say again, lou back up your claims that the iron heads are so much better, I've posted data proving my points many times, you still have yet to post something to prove anything substantial, just some circle track times that are meaningless when talking engines performance alone, and a couple of mediocre dynos.
------------------ 1st class A**hole.
we're in desperate need of a little more religion to nurse your god-like point of view...
boost is just a measure of resistance to flow, it doesn't really solve anything, a head that flows better will make more power then another head at the same boost pressure because more air is making it into the cylinder.
Also the iron head chambers suck compared to the aluminum head chambers when it comes to knock resistance.
If were betting on an iron head or an aluminum head Fiero running side by side I know which one I would put money on. The iron heads just plain suck, but plenty of people try to make a Silk Purse out of a Sowse's ear and all they end up with is looks and getting their butts kicked by stock aluminum. If iron was so hot they would have never built aluminum heads. Larry
and LS3's also have alot more bore to work with compared to the tiny V6 bore...what's to say the LS3 wouldn't make gains by going with canted valves? oh and maybe the LS3 has straight valves to better fit between the strut towers of a 'vette...
you talk about gaining airflow, the 3x00 heads flow more stock then the iron heads flow ported. this has been shown to you multiple times, and then you say flow numbers don't matter? now they somehow matter again???
the 3x00 heads are better out of the box then max effort iron heads in every catagory, chamber size/shape, port flow, material, weight ect... the only aspect the iron heads win when compared to the aluminum heads is that the iron heads can maintain a stock look, but even that isn't worth anything IMO, these aren't valuable cars stock/stock appearing.(or modified for that matter)
I will say again, lou back up your claims that the iron heads are so much better, I've posted data proving my points many times, you still have yet to post something to prove anything substantial, just some circle track times that are meaningless when talking engines performance alone, and a couple of mediocre dynos.
What claims? Why do you troll most threads I post in? Why have you appointed yourself defender of the honor of aluminum head engines?
I guess I am not very good with communicating my question. I am wondering why if the block for the 3.4 and the 3400 are the same, why is the 3.4 a direct bolt in and the 3400 a difficult swap.
The 3400 installation is not difficult at all. It's just not bolt-in.
The iron head 3.4 is bolt in. It uses the Fiero exhaust manifolds and can use the Fiero intake manifold and distributor. I don't think that the reasons people use the Fiero dist & intake are... worthwhile, but that's my opinion and I'm pretty results-oriented.
The 3400 bolts directly to the same engine mount and transmission as the 2.8. It has a high mount alternator which interferes with the decklid. Exhaust, coolant, heater and fuel plumbing (and an intake tube, most likely) all need to be built when swapping from a 2.8 to a 3400. In addition, there is wiring work to make a nice neat harness to run the 3400 DIS in the Fiero body.
However, the 3500 and 3900 require very little more work and bring 30-60 more HP to the table than the 3400, while costing essentially the same. I don't see why to bother with the 3400 anymore.
The 3400 installation is not difficult at all. It's just not bolt-in.
The iron head 3.4 is bolt in. It uses the Fiero exhaust manifolds and can use the Fiero intake manifold and distributor. I don't think that the reasons people use the Fiero dist & intake are... worthwhile, but that's my opinion and I'm pretty results-oriented.
As someone who just completed my first engine swap ever and did the 3500 swap, I wouldn't say that its easy. It took me about six months and I'm still working on the tune. I'm sure its easy compared to some other swaps but it's still a lot of work and a lot of parts to get together, where a 3.4 swap seems like it would be doable in a weekend.
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However, the 3500 and 3900 require very little more work and bring 30-60 more HP to the table than the 3400, while costing essentially the same. I don't see why to bother with the 3400 anymore.
The 3500 requires an external crank trigger for the 7x signal (the 3400 has an internal one); It also requires a different throttle body, coil pack, and fuel rail since it uses a returnless system. The 3500 also came with "header" style manifolds, I have no idea if these can be made to fit, but I had to use 3100/3400 crossover manifolds. Perhaps not dealbreakers, but still extra work.
I adapted my Fiero accessories to fit my aluminum head 3500 but it required fabrication to do so.
The VVT 3500 and 3900 require some provisions to deal with the cam phaser and are significantly different than the early LX9 3500. Has anyone successfully swapped one of these into a Fiero?
[This message has been edited by masospaghetti (edited 04-17-2014).]
The 3500 requires an external crank trigger for the 7x signal (the 3400 has an internal one); It also requires a different throttle body, coil pack, and fuel rail since it uses a returnless system. Perhaps not dealbreakers, but still extra work.
The VVT 3500 and 3900 require some provisions to deal with the cam phaser and are significantly different than the early LX9 3500. Has anyone successfully swapped one of these into a Fiero?
my 3500 is still a return less fuel rail... i used a fpr down need the filter to keep things simple and neat, the module and coils are just standard 3400 setup, as alot of yard engine wont come with these to begin with, i dont see it being `extra`, also the 7x sensor can be pressed onto the crank inplace of the 52x(i think its 52) sensor, and the 24x for obd2 SFI is just a simple balancer change. my 3500 swap (minus exhaust) took 4 days.
I consider them "extra" because they don't bolt on, Milzy sells adapters to get them to fit, or you have to make little brackets. Same with the throttle body.
To press the 7x sensor onto the crank means disassembling the bottom end. I'm sure to someone whos done it before its no big deal, for someone that hasn't touched a bottom end before this is not trivial.
What did you do about the wiring? Did you use the donor harness or did you modify the original one? It took some time for me to modify the Fiero harness to work with the 7730 computer and different sensor locations.
I consider them "extra" because they don't bolt on, Milzy sells adapters to get them to fit, or you have to make little brackets. Same with the throttle body.
To press the 7x sensor onto the crank means disassembling the bottom end. I'm sure to someone whos done it before its no big deal, for someone that hasn't touched a bottom end before this is not trivial.
What did you do about the wiring? Did you use the donor harness or did you modify the original one? It took some time for me to modify the Fiero harness to work with the 7730 computer and different sensor locations.
i made a custom obd2 wiring harness (i.e. why i needed the 24x sensor) and the coil packs, i used the 3500 mounting place and drilled a few holes in it with some bolts, took all of 10minues to do that, yes you need a TB adapter, and who installs a yard engine without pulling the crank etc and changing the bearings? i personally didnt change the sensor ring, was just stating it can be done.
i made a custom obd2 wiring harness (i.e. why i needed the 24x sensor) and the coil packs, i used the 3500 mounting place and drilled a few holes in it with some bolts, took all of 10minues to do that, yes you need a TB adapter, and who installs a yard engine without pulling the crank etc and changing the bearings?
Maybe I got lucky but I didn't pull the crank on my motor and change the bearings.
Clearly you're well experienced with swaps. I still think the things that may take you "10 minutes" are a much bigger deal to someone who's used to doing maintenance but not fabrication (and I think this is a big reason why people choose the 3.4, since it essentially requires no fabrication).
Other than a few posts debateing which is better iron or aluminum, this is the info I was looking for! So the engines both bolt in, what make the 3x00 engines more work is acessories and wiring.
How much wiring is involved? swapping motors and fabricateing is second nature to me, BUT from the old school. Computers and wiring are all Greek to me. It sounds like the problems people have with the 3x00s in swaps is the tuning rather than the actual swap.
Will the fiero computer do a good job of running the 3.4? What about the 3x00? What if you ad a turbo (I own 7 turbo vehicles now so the Fiero is just a matter of time) do you have to change to a different computer to run the turbo? If so then wouldnt it be smart to change from the get go and have the ability to turbo down the road? How do the engines respond to turbo chargeing, does the forced induction make up for the flaws in the iron heads? Thanks for the help guys. Van
If you do a *full* 3400 swap, it's ECM can be reprogrammed for a turbo. If you go hybrid or just 3.4, it's highly recommended to convert to the '7730 You can also downgrade the 3400 install to the '7730.
I've used a stock 87 Fiero ECU with a Buick ESC module and MSD ignition to control a turbo but it's not recommended. An 85 V6 ECU can be modded to control a turbo as well.
Its a common GM computer from the early 90's, OBD1. It's more sophisticated than the Fiero computer.
You can run the 3.4 with the original Fiero computer, wiring, and distributor. You could also upgrade to the 7730 and run the distributor OR a distributorless ignition - The 7730 can be configured to use either. If you use the 3x00, you have to use a 7730 or a newer OBD2 computer.
I used the 7730 on my 3500 swap. Whether it was easier or harder than using an OBD2 computer, I have no idea.
Maybe I got lucky but I didn't pull the crank on my motor and change the bearings.
Clearly you're well experienced with swaps. I still think the things that may take you "10 minutes" are a much bigger deal to someone who's used to doing maintenance but not fabrication (and I think this is a big reason why people choose the 3.4, since it essentially requires no fabrication).
was my first swap... anywho, i did *ALOT* OF reading first and mapped everything out i had to do before i started.
i used a 98 venture van 3400 ECU on my 3500 swap, i had darth re-program it.
wiring is *EASY* (in my opinion), i took a 3400 harness, and i 100% stripped it down (also had the 3500 harness as i needed a few things from it.)
took each sensors wire, lableed it, wrapped it up neatly and put to the side, when the engine was in the car i pluged them in 1 by 1, mounted my ECU, and ran the wires to the ecu and cut them to length and all, spliced inthe fiero C205 and 500 connectors from the ECU, ran wire and grounds, and added in the fuel pump relay circuit of my own (relay, direct from the battery, controlled via the ecu)
