Hey guys, I am brand new to this Forum, infact just today I got my registration done. I have been on the site for some time but just got an 86' fastback that was made in March of 86' (Apparently one of the first to leave the dealer ship.)

None the less I want to do an engine swap and considering I don't have $3,000 to spend on a 3.8SC I want a 3.4 because of the money/performance. I realize there are a few topics about the 3.4 PR vs 3.4 DOHC but I can't find much on price. Another engine I can't find much info on is the 3.4SFI is there anyone out there that could recommend one more out of the three?

I am looking to just do the swap and not change much as far as adding turbo's or anything crazy, just more power so I can burn some of these "Street racing" ricers on the street

One of the big things im after is reliability, I read that the 3.4PR is more reliable than the DOHC but doesn't have the performance, but what about the SFI as far as performance/Reliabilty.

Any help would be great, Thanks for your time

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The wetter the better

I would go 3400 or 3500 and never look back.

I say 3400. Make sure it has the updated lower intake gasket and it's as reliable as anything else on the planet that is taken care of.

You should really check out 60 Degree V6 if you are interested in these motors and what they are capable of...

You CLEARLY stated you want to do as little work as possible...
The 3.4 SFI is from a 93-95 Camaro/Firebird. This is your best bet.
The 3400 [SFI] uses aluminum heads and requires about as much work as any completely different engine swap except for custom flywheel and mounts...so you can probably rule this out. It also involves a new ECM and lots of rewiring.

It would help to know what you are capable of doing yourself.

Keep in mind with a 3.4 swap, you will make anywhere from 135 rwhp (no mods, period) to 204 rwhp depending on the level of extra mods you put into it base on what people have posted for dynos on this forum over the years...

With a 3400, since you have to build a new exhaust for it, you're looking at 170 rwhp as a base. In one extreme case a 3500 has done 275 rwhp in another car, heavily modded, of course.

For a little more work (not much) you can have a 3800SC and start with 240 rwhp with a lot more potential. For the minor difference in work, I'd select this over any 3100/3400/3500 swap.

Keep in mind your 2.8 in perfect stock and new condition makes 115 rwhp.

A lot of the mods you'd do to the 3.4, you can do to your 2.8 and get it up to 130+rwhp fairly easily now. (1.6 roller rockers, ported exhaust manifolds, ported cross-over pipe, DAWG intake mod, 56/57 mm throttle body).

quote Originally posted by lou_dias: For a little more work (not much) you can have a 3800SC and start with 240 rwhp with a lot more potential. For the minor difference in work, I'd select this over any 3100/3400/3500 swap.

I think a 3400 would be quite a bit easier than a 3800SC. It can use the stock motor mounts and the stock transmission (the stock transmission wouldn't last long behind a 3800SC). Also, a 3400 is 185 flywheel hp, a 3800SC is 240 flywheel hp, not 240 rwhp. Doesn't the trunk need to be cut for the 3800SC exhaust?

quote Originally posted by masospaghetti: Doesn't the trunk need to be cut for the 3800SC exhaust?

Depends on how you do it... the easiest way is to cut the trunk.

quote Originally posted by lou_dias: A lot of the mods you'd do to the 3.4, you can do to your 2.8 and get it up to 130+rwhp fairly easily now. (1.6 roller rockers, ported exhaust manifolds, ported cross-over pipe, DAWG intake mod, 56/57 mm throttle body).

I did all that stuff to my old 2.8 V6... ported intake, Trueleo headers, mildly ported heads, camshaft upgrade, etc, and got 140 RWHP on a chassis dyno. When that engine blew up, I replaced it with a 3.4 V6 crate engine. The 3.4 V6 crate engine, right out of the box, performed as well as the modified 2.8 V6. I honestly wish I had gone for the 3.4 crate engine to begin with, because the money spent modding the 2.8 V6 was basically wasted.

To answer the original question, out of the 3 engines listed, I'd pick the 3400 SFI. It's lighter than the other two engines, has the best fuel economy (in stock form), and performance is about halfway between the 3.4 V6 and 3.4 TDC. With a cam swap and some headers, you'll have performance similar to the 3.4 TDC in an engine that weighs about 100 lb less. The drawback is that the 3400 SFI is an OBD-2 engine. So you'll need to do some rewiring.

quote Originally posted by Blacktree: The drawback is that the 3400 SFI is an OBD-2 engine. So you'll need to do some rewiring.

Or slap an OBD-1 '7730 on it and deal with the loss of SFI.

Yeah, I guess that's an option.

That would still require some wiring mods, but not as much as an OBD-2 swap. I was able to do the 7730 swap, and I'm not exactly an electronics guru.

quote Originally posted by carbon: Or slap an OBD-1 '7730 on it and deal with the loss of SFI.

I've ran my 3400 off of a '7730 OBD1 batch fire and an OBD2 sfi ecu and noticed almost no difference in fuel economy at all. It ran noticeably smoother on the OBD2 setup.


Here is some info on what's involved in doing a 3400 swap.
https://www.fiero.nl/forum/Forum1/HTML/091261.html

Thank you Blacktree for a straight answer. From what I understand it's kinda like this

3.4PR:
Easiest swap, less expensive, high reliability, but only has about 20 more HP than stock

3.4DOHC:
Hardest swap, most expensive, reliability is questionable, but has the most power (and maybe the most aftermarket?)

3.4SFI:
Hard swap (wiring) semi-expensive, reliability is high, weighs almost nothing, and has medium power but can be upgraded to be similar to the DOHC.

Now this 3.5 I haven't heard of this engine but I checked out Bridgetown's link and found it rather interesting, what is the cost on a 3.5 swap?

I don't think the 3400 is any easier than the 3.4 DOHC, nor is it cheaper. They both require much the same things. I've had good luck with all of my 3.4 DOHC's, of the 10 or so I've had I only had problems with my first, which I spun a bearing on.

quote Originally posted by RobertGT: I don't think the 3400 is any easier than the 3.4 DOHC, nor is it cheaper. They both require much the same things. I've had good luck with all of my 3.4 DOHC's, of the 10 or so I've had I only had problems with my first, which I spun a bearing on.

3.4 DOHC is definitely no harder than a 3400 swap, and it's probably still better documented. Here's a good place to start.

I also wouldn't say that it would cost any more than a 3400, but it's certainly getting harder to find a good running, low mileage example these days. (Unless you happen to find 23 crate engines on some random Michigan auction site last month)

I enjoy the DOHC in my car, but if I were doing a swap these days.... out of your 3 choices? The 3400 because they are plentiful, simple, reliable and lightweight. Out of any choice? The 3500 because it is all of that, with more power. It is a bit more work than the 3400 though.

[This message has been edited by Silicoan86 (edited 01-11-2014).]

I'm sure yours was not a deliberate attempt to confuse the new guy, zzzhuh, with your statement:

quote Originally posted by lou_dias: You CLEARLY stated you want to do as little work as possible... The 3.4 SFI is from a 93-95 Camaro/Firebird. This is your best bet.

Let's not inadvertently confuse the new guy, or anyone else reading this thread.

More specifically --- instead of the "3.4 SFI" you'd mentioned --- I assume you meant instead to reference the first of the engines named in the title of zzzhuh's thread, the "3.4 PR" (with "PR" referencing its "pushrod" construction)?

The "3.4 PR" engine --- not the SFI --- is the one which can be sourced from `93 through `95, V6-equipped, Camaros and Firebirds --- or, for that matter, from the "3.4 V6 crate engine" which Blacktree mentioned in this thread.

By the way, zzzhuh, welcome to this forum.

quote Originally posted by masospaghetti: I think a 3400 would be quite a bit easier than a 3800SC. It can use the stock motor mounts and the stock transmission (the stock transmission wouldn't last long behind a 3800SC). Also, a 3400 is 185 flywheel hp, a 3800SC is 240 flywheel hp, not 240 rwhp. Doesn't the trunk need to be cut for the 3800SC exhaust?

You have to build a custom exhaust for both.
185 flywheel = 160 rwhp
240 flywheel = 215 rwhp
That's stock for stock. When you have to build a custom exhaust for both, that's why you can't make a direct comparison.
In the cars that 3400's came in, they came in automatics and with obviously stock exhausts and dyno between 150 rwhp and 155 rwhp. In a 'swap', the custom exhaust is more free flowing than the original stock exhaust and they dyno higher.
Same applies to 3800/3800SC swaps.

Change a pulley and the 3800SC gains more power.
3800[SC] mounts are available in the mall...
3800SC flywheel if going manual is available on ebay...
3800[SC] swap harness is available in the mall

I don't see how a 3400 is not much less "work" than a full engine swap to a completely different platform with much more potential...

If you're going to go thru that much effort, the 3800SC gives you both a higher base and a higher potential. To argue otherwise is madness.

lou_dias I see your point here but the big difference between a 3.4 and a 3.8 is almost $2,000. For that much money I could probably get a really nice looking car along with a rather quick car. I wasn't aware that the 3.4 SFI had the starter on the correct side though, that is good info. If my fiero is an 86 GT how much modification are we talking about for the 3.4 SFI? I want my car to look rather stock, meaning there are no huge pipes sticking out the front or anything. I guess im going for a "Sleeper" look but want good performance, Any good links you could provide?

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The wetter the better

quote Originally posted by lou_dias: You have to build a custom exhaust for both... I don't see how a 3400 is not much less "work" than a full engine swap to a completely different platform with much more potential... If you're going to go thru that much effort, the 3800SC gives you both a higher base and a higher potential. To argue otherwise is madness.

Granted, I haven't done a 3800 swap but the 3x00 swap seems to have some advantages that make it easier:

1) It's easy to keep a full trunk even with a custom exhaust
2) Use stock motor mounts
3) Use stock transmission
4) Cheap - especially the 3500
5) Lighter weight than the original 2.8 - doesn't the 3800 weigh significantly more than the 2.8?

IMO the 3x00 has a much better exhaust note too.

My point is not that a 3x00 is a "better" swap than a 3800SC and it's obviously going to be less powerful, but the OP specifically said he/she is on a tight budget.

quote Originally posted by masospaghetti: The 3.4 SFI does NOT have the starter bolts on the correct side, you will need a drill jig to do this properly. Rodney sells them. The 3400 has the starter bolts on the correct side, but the 3400 is not a bolt-in replacement like the 3.4 SFI. Other than the starter bolts, the 3.4 SFI is a literal bolt-in replacement, and you can even keep your Fiero intake plenum. It will look completely stock. These are easy to find in wrecked 93-95 F-bodies or you can get a new 3.4 GM crate engine.

What you've said about what you're calling the "3.4 SFI" is identical to what I would say about the "3.4 PR" engine.

Did the originator of this thread, zzzhuh, use within the title of his thread two different nomenclatures (specifically, "3.4 PR" and "3.4SFI") , to reference the same engine twice?

quote Originally posted by zzzhuh: Thank you Blacktree for a straight answer. From what I understand it's kinda like this 3.4PR: Easiest swap, less expensive, high reliability, but only has about 20 more HP than stock

Keep in mind that while the 3.4 only has 20 horsepower over stock, you can fairly easily add another 20 horsepower to that with basic modifications including underdrive pulleys, headers, better flowing exhaust, larger throttle body, 1.6:1 roller rockers, and a few other odds and ends. You can still get even more power if you go with a better camshaft. You're limited really by the intake plenum... specifically at the neck between the throttle body and the rest of the plenum.

But, with a well tuned vehicle with a 3.4 and a manual transmission... mid/high 14s are pretty easily attainable.

240 HP from the 3800 SC ? I thought that was only the earlier stuff. They went to 265 HP didn't they?

quote Originally posted by weaselbeak: 240 HP from the 3800 SC ? I thought that was only the earlier stuff. They went to 265 HP didn't they?

Series III was higher than II, I forget the exact #'s...

OK for us newbie fiero guys... sorry but this thread did get a LITTLE confusing about what 3.4 is what. I just picked up a 3.4 SFI last night. Is the sfi the one that will interchange with the 2.8 other then having to drill the starter bolts?

I'm making a truleo type intake so any thoughts on how that will affect hp coupled with all the supporting mods such as headers, cam, rockers, etc. ?

good thread guys, thanks for sharing your knowledge

Sorry to keep switching names.

The 3.4 PR (pushrod) is the same as the 3.4 SFI, both which are essentially a 2.8 with larger displacement and some internal upgrades. This is different than the 3400 SFI which has aluminum heads and requires a different computer.

quote I just picked up a 3.4 SFI last night. Is the sfi the one that will interchange with the 2.8 other then having to drill the starter bolts?

Yes, the 3.4 SFI (from a 93-95 f-body) requires starter bolts to be drilled, but otherwise will interchange with the 2.8.

[This message has been edited by masospaghetti (edited 01-13-2014).]

quote Originally posted by masospaghetti: Sorry to keep switching names. The 3.4 PR (pushrod) is the same as the 3.4 SFI, both which are essentially a 2.8 with larger displacement and some internal upgrades. This is different than the 3400 SFI which has aluminum heads and requires a different computer. Yes, the 3.4 SFI (from a 93-95 f-body) requires starter bolts to be drilled, but otherwise will interchange with the 2.8.

cool cuz i was looking for that one lol I'm just building a fun work car and not worried about making big hp. the 3.4 lower end swap seemed like a cheap, quick upgrade since i already have my motor out.

quote Originally posted by ttt123: cool cuz i was looking for that one lol I'm just building a fun work car and not worried about making big hp. the 3.4 lower end swap seemed like a cheap, quick upgrade since i already have my motor out.

Yes, the 3.4 Sfi pr will be good, quick swap. It'll take you longer to strip the camaro crap off the motor then to install it. I've also done this swap before.

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quote Originally posted by Custom2M4: Yes, the 3.4 Sfi pr will be good, quick swap. It'll take you longer to strip the camaro crap off the motor then to install it. I've also done this swap before.

Great to hear. i got an awesome deal and it sounds like this motor with some mods will be just fine for a quick little fiero as a work car

A 3800 swap would raise the value of the car much more than any of these but only cost a slight amount more

quote Originally posted by darkhorizon: A 3800 swap would raise the value of the car much more than any of these but only cost a slight amount more

for me not a worry as i just bought this for something to tinker with as my buddy builds his 3.8sc in my barn. i have $600 for the car(85 with 90k original miles that ran great) and $200 for the 3.4 and I'll maybe sink $1000 into this build and use it for work only. i have my eye on a 930 slantnose to purchase this spring so ya this is just to have a little fun with.

Hey guys I guess my initial post was rather confusing. I didn't realize the 3.4 SFI is different than an 3.4SFI Aluminum (No idea what to call it to distinguish the difference ) None the less I appreciate all of the replies and the support. One thing im still confused about is a 3.5L V6, is this swap much different, and is it more complex than a 3.4SFI or a 3.4DOHC?

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The wetter the better

In general people refer to the 1rst and second gen 60 degree engines as 2.8 and 3.4 and the 3rd gen and up engines as 3400, 3500 etc to avoid confusion (GM refers to them this way as well)

quote Originally posted by gtjoe: In general people refer to the 1rst and second gen 60 degree engines as 2.8 and 3.4 and the 3rd gen and up engines as 3400, 3500 etc to avoid confusion (GM refers to them this way as well)

That's not true.
GEN1 used iron heads (2.8, 3.4 in Camaro/Firebird) up until 1995 for 3.4, hydraulic cam (There were some gen1 style aluminum heads available through Potter Heads years ago. They are very rare.)
GEN2 used aluminum heads, splayed valves (2.8, 3.1 in FWD cars) started in 1987 until 1996, hydraulic cam
GEN3 started in 1993 with the roller cam, but then around 1997 the ports on the heads got bigger when the 3400 debuted.
changed naming to 3100, 3400 (and some smaller displacements) and the ports were much larger than GEN2 heads but otherwise the same (exhaust has D shape ports)
In 2004, China started making V6/60 motors (including the 3500 LX9, not the be confused the 3500 LZ4) but I think they are still considered GEN3...so it seems GEN3 had a revision or two...

I'm ignoring the 3.4 TDC...

[This message has been edited by lou_dias (edited 01-14-2014).]

quote Originally posted by lou_dias: That's not true.

It is true, and you didn't post anything that conflicted with it. What you wrote is correct also.

I used to want to play with one of the Chinese 2500 SFI cranks with 66.7mm stroke... but those are hard to get here.

[This message has been edited by Will (edited 01-15-2014).]

quote Originally posted by Will: It is true, and you didn't post anything that conflicted with it. What you wrote is correct also. I used to want to play with one of the Chinese 2500 SFI cranks with 66.7mm stroke... but those are hard to get here.

There was no "factory" GEN2 3.4 and no GEN1 3.1. Perhaps it's how we read the statement.

quote Originally posted by lou_dias: There was no "factory" GEN2 3.4 and no GEN1 3.1. Perhaps it's how we read the statement.

nowhere in my statement did I imply either of these things I was just simply stating that gen 1 and 2 engines are refered to as x.x and gen 3+ are refereed to as 3x00. And when people stick to that it makes discussions less confusing.

quote Originally posted by lou_dias: There was no "factory" GEN1 3.1. Perhaps it's how we read the statement.

Not true. GM produced the F-body with a GEN1 iron-head, 60 deg, 3.1L MFI V6 from 1990-1992. They also produced FWD minivans with essentially the same 3.1L engine (exc it only had TBI fuel injection) from 1990-1995.

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OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

Anyways,

I am going to be getting an 02 Chevy Impala 3.4 engine in a few months, It must be the newer version and probably will need the OBD-2 system installed on it, can anyone send me a link to a thread that has this engine in it? Im still trying to figure out this site unfortunately and can't seem to find one.

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The wetter the better

You wont need the OBDII PCM to operate that 3400, a '7730 ECM will work just fine