Ok, I've been searching for engine swap candidate and found a few of each, 3.4DOHC and 3800SC engines. I know the 3800SC is more powerful stock, and can get up to 300HP pretty easily. The 3.4DOHC has about 215HP, and should be able to get up to about 250HP without a lot of trouble.

I know it's been discussed before, but now I can talk money, too. The 3.4DOHC engines I've found range from $750 to $1000. The 3800SC engines are typically $1200-1600. So, do you think the 3800SC is worth the extra money? I really love the idea of a high winding engine and the 3.4DOHC is supposed to sound MEAN as HE11! The 3800SC should be more powerful, and heavier.

How difficult is the swap for each? The 3800SC swap doesn't sound too hard, just the wiring being the hard part. The 3.4DOHC has those huge heads and intake you have to make room for, but other than that, shouldn't it be almost a drop in since it's the same 60* V6 block (externally, I mean)?

I'm not looking for an "answer." I'm looking for people's opinions. Then I'll decide which way to go. That is unless I find a "good" LT1 for cheap.

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"We will always remember. We will always be proud. We will always be prepared, so we may always be free" -- Ronald Reagan

Did you do a search? I think we beat this bloody a few weeks ago.

I've done both swaps and prefer the DOHC. Less power but I think it fits the car's personality better. In fact I prefer the DOHC to the V8's. H*ll I prefer it to the Pratt and Whitney Radial!

The DOHC's sound very "Indy car".

The effort. depends on the trans. The effort is about the same. You just trade one issue for another. A manual trans 3800 adds a little due to the flywheel issue (which is currently being beaten bloody in another thread).

IMHO.

[This message has been edited by terryk (edited 01-18-2002).]

Well I think you know what I want, 3.8SC. You help me with my decision with some of your post to me. Why, well a V6 blowing the doors off V8 (non modified or slightly) is a great feeling. The Fiero wieghs 900 lbs less than a new Camaro or Firebird and with a 3.8SC with slight modifications will put out almost the same HP @ 300. A Mustang wieghs 400 lbs more with less 40-50 less HP. Now if anyone wants to check those specs you can find them at GM.com & Ford.com. Vettes, I couldn't find the wieght although I'm sure someone has it. I think it wieghs about 3500 with 405 hp. That could be interesting if you could get 350 hp out of a 3.8SC. Someone suggested a small boost NOS. Viper-forget it. It's just to good.

before pics

Present being repainted

[This message has been edited by FieroGT87 (edited 01-18-2002).]

Vettes are roughly 3100 I believe? but I rode in a SC Grand Prix today (my friends moms car) that things got some balls

wouldn't mind having a GP for a winter car

I would have gone 3.8 SC but its to much work for me besides I like the 5 spd, sure you can do a 5spd, but custom flywheel yada, yada, yada.. but you were looking to do the different 3.4 setup.

I'm doing a rebuild on a 3.4 out of a camaro, but it should be pumpin some pony's out after I'm done, then I'll break her in and NOS her up.

If I get a hold of a fastback for a reasonable price I'm all about the 3.8 SC!

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-KC

1988 Formula, 3.4
LoW Key's Red Bullet

Yeah, we did go over this before. I guess what surprised me was that the 3.4DOHC can be had for $500 or so less than the 3800SC. I'm just wondering if I should let the price be a deciding factor. I didn't realize I could find them that cheap. I was all theoretical until I actually found some engines.

A mechianic I know said that if a 3.4 makes any unusual noise it serious. I don't know how true it is. I do know since he works at a GM dealership service dept he sees alot of engines. He also said thats why they went to the 3.5.

I've driven both 3400dohc and 3800II powered cars. Neither in a fiero yet .

I think the 3.4DOHC is much better suited to the fiero. It's an engine that likes to rev and be wound out. The 3800 is more of a typical torque lover American engine. Its nice, but I think it more suited to a sedan then a little sports car. The 3800 is probably a bit more reliable. The 3.4DOHC did have its share of problems.

Either will make an incredible fiero!

Can you email me info on where you're finding these 3.4s? I'm looking to do this swap later this year, and will need sources for the motors.

The prices you're finding are lower than I expected, as well.

I'm thinking a 3.4 DOHC with a low-pressure SC would be completely awesome in our cars.

Thanks!

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Project MR1 ~ triadtuning@hotmail.com
AIM ~ Michael Blue 72

I'd go with the 3800sc just for ease of installation. See this website, it explains things down go the nitty gritty http://www.ipass.net/~fieroman/terranexus/fieroman/3800shrt.htm. Hope this helps,.

phil

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GTDude 87 Fiero GT 3.4
25 years GM experience

Id say when you can make an engine look this cool, go with it

dont worry the valve covers were switched when the engine was installed. I put them on there for the pics and didnt even think of putting them on the right heads.
3 days and counting...

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http://www.fieroX.com
coming soon L67 powered 87 notchback to smoke you with!

Wow, FieroX, that looks GREAT. I've been following your buildup on your site, too.

Ok, so which swap is more difficult? Correct me if I'm wrong, but since the 3.4DOHC is based on the 60* V6, would it use the same engine mounts as our 2.8? I know the 3800 required fabricated mounts. Wiring is probably a similar pain for each - but which one is easier to physically install in the vehicle?

I also keep thinking of the 3.4DOHC, maybe with Nitrous or a turbo in the future. The simplicity of just dropping in a bone stock 3800SC is pretty good, too. All that OEM reliability, etc. I really have no idea which one I want to go with.

BTW, I found these engines on a junk yard search engine, so I haven't visually inspected them, but there seems to be plenty of each to choose from in my area. Check out http://www.car-part.com for free searches.

Damn, Fiero X, are those your headers? Nice! Hopefully 'm not folling myself, but they look relatively straight forward to fab, as compared to some other header projects.

The headers took me about 9 hours to make. I had the flanges CNC plasma cut, then I machined the mounting holes, and did a little port work to them for a nice fit with the pipe installed. Those are 1.75" primary tubes, mandrel bent. I just bought a bunch of bends from a header company, and started cutting and fitting. The first one took me a long time, but the second one went well. Kind of like Mr. Mikes seats! I may sell a few sets if there is demand enough, our prices are the best in the business.

Well the reason the motors are different in price is probably because of age. The 3800Sc cars came on around 97- present so they are newer. And as reliabilty? The 3800 is hard to beat. And for sound? Have any of you heard a supercharger whining at full throttle only about a foot behind your right shoulder?

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Earl Sessions
1985 Fiero w/ 1998 Supercharged 3.8 V-6
Best ET: 13.232 @ 101.24 mph

As far as reliablity goesm the 3.4L is a good engine. The timing belt is a big problem. The power steering lines are also. The engines eat alternators for breakfast, lunch, and dinner. But I hear if you run it low on oil, you will be screwed.

The 3.4L is a good engine IF taken car of. It is in this sense as reliable as the 3.8, but NOT as rugged. When the 3.4L came out it made 275+ hp. Becuase of automatic tranny issues of that day, they cut the power to 200hp. The engine is easy to mod to make 240hp. But anything really more is going to take some money. There are not a whole lot a performance parts or info on this engine. It seems that GM wants to forget about this engine.

The 3.8 S/C has MUCH more capabilities. There is also a lot a z34 guys that are taking out there 3.4L and putting in a 3.8 S/C (L67 i think it is called)

Yeah, the 3800SC is a really awesome engine. I think I like the personality of the DOHC, high winding, etc... but I'm really torn between these two. I've been following FieroX's buildup and read about a few other 3800SC swaps. Can some people who've done 3.4DOHC swaps give some info on how hard they are to do? How about replacement parts? Rebuild parts? 3800SC has the clear advantage here, because it's still in production. Are 3.4DOHC parts getting hard to come by?

If you find a low miles 3.4 get it, otherwise go for the 3.8. There is a lot of info on the 3.8. There is next to none on the 3.4. the 3.4L is VERY expensive to work on too. Lifters are $25 each, and you need 24 of them!!! There will be one more web site on the 3.4 when I have completed mine. I've only found 3 sites with swap info on them.

How about sharing those websites?

A gent that goes by the name of 'DKOV' here on the fourm has probally the most extreme 3.4DOHC motor... I belive he's over the 300hp mark. (about 320?) with extensive mods.

The engines have *very* different personalities... The 3800SC is a typical american engine. low-speed, rumble, torquey. (booring IMO.)

The 3.4 is an Indy car motor At least in personality and sound (the Northstar/Aurora V8 *are* basically Indy car motors, and they're very similar to the 3.4TDC/DOHC.)

There is about 250hp or so that you can get out of a stock 3.4DOHC with little to no work.

It's internals are all fordged, and if taken care of (OF COURSE AN ENGINE WILL GO BAD IF IT HAS NO FAGGING OIL!!! :P) it will rev to 7grand all day long.

Musclecar Fiero, or Exotic Fiero, your choice!

PS: Beware, the 3.4DOHC will have you grinning like an idoit, and you'll want to upgrade the rest of the car (13" 4-pot brakes, coilovers, etc.)

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

See, Ben, you've got the right idea, there. I love the 3800SC, but the personality of the engine is very important. Obviously, the N* is the way to go, but that's outta my reach right now.

250HP out of a 3.4DOHC would be about as fast as a stock 3800SC. The SC does have better reliability, I would imagine.

Now the next question, how hard is the swap? I know the 3800 is pretty straight forward, except for wiring. How about the 3.4DOHC? Other than the decklid hinge, any major install issued to worry about?

I'm gonna check some websites I've found, but any extra info or sites people want to post here would be appreciated. for either engine.

I went back and forth between these for a while too. I finally decide on the DOHC for the reasons mentioned above plus I want to keep my 5 speed. The DOHC has a couple of advantages here; 1. my factory 88 flywheel or an off the shelf DOHC flywheel will work, 2. I should be able to run a stock DOHC ECM with a 5 speed.

So far all I've done is buy a high mile 3.4 DOHC cheap with the plan being to rebuild it.

What needs to be modified to connect a 86 GT 5 speed Tranny to then 3.4 DOHC? Exaust, Someone told me that the dohc block and the 2.8 block were basically the same - would exaust from 2.8 fit (manifoldas, crossover...) what needs to be made up, whats the hardest part of the swap? how hard is the wiring to convert, do you need to piggyback?

Kyle

Ok I'm getting into this one too... Found an older model 3.4 think its an 89 or 90??? anyways what all do I need for the swap into a 4cyl auto???

I'll chime in with what little I know.

Formula88: I've got a '96 29K mile DOHC V6 for sale. It includes the ECU, manifolds, harness, all sensors, compressor, EVERYTHING you would need from the donor car for $1500, I paid $1700. I had to back out of my swap due to going back to school. I'm down just north of Atlanta too.

KRMFiero: All you need is a neutrally balanced flywheel from an 88 GT or 91-93 Lumina, Grand-Prix.

The blocks are somewhat different although from the same block heritage. Several people have simply used the front manifold on the rear and fabbed a simple y-pipe and then used the stock exhaust layout from the down pipe on. The '96-'97 DOHC engines have SFI, redesigned heads, manifold ports(HUGE!!), Intake runners, and reversed flow cooling(probably really good for Turbo or SC).

They can rev to 8K with the rev limiter removed, talk to TerryK about it. The 91-95 DOHC's are gruntier down low but don't have the top end of the '96-97 blocks.

You can use a 93 stickshift ECM to control all DOHC models.

Dude, jump on this!

It's a mini Northstar, very good stuff!

Neither swap is very hard, if you're able to fab up your own engine mount (ie, have a welder or a friend who does) and not too afriad of a little soldering iron...

There are several very knowledgable 3.4DOHC swappers on here who can give you the low-down via PM/Email. It's also a swap you can take to almost any level you want. Just toss in the stock motor now (7grand redline STOCK!) and then in a few years, pull the motor, do DKOV's mods, and have over 300hp and still sound like a Ferrari!

Basically, if you're considering the DOHC engine, if it's giving you pause... then you HAVE to do it man! It's the engine for you, You'll love it!!

Belive me, the first big step to a swap is just getting the motor sitting in your garage.

From there, the rest just kind of falls into place!

Does anyone have any sound clips of a 3.4DOHC in a Fiero really breathing to entice him?

Best!
Ben.

quote Originally posted by msweldon: Formula88: I've got a '96 29K mile DOHC V6 for sale. It includes the ECU, manifolds, harness, all sensors, compressor, EVERYTHING you would need from the donor car for $1500, I paid $1700.

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

I want to some sound clips too. I kinda wanted to be suprised when i first start mine up, but i can't wait any longer.

I need this. I've decided to go with the DOHC, even though it's about 30HP weaker than the 3800SC in stock form. It's just got the personality the Fiero needs. And it's obviously got hop up potential. I can' imagine not being happy with 250-300HP, so I'm sure this will do fine. Now all I have to do is find $1500 to jump on the engine deal. That's exactly what I'm looking for!

Formula88:

If you want to see some pics of the DOHC V6 sitting in my garage look here:
http://www.mindspring.com/~msweldon/Fiero/

Also, take a look at the beaut of a fiero I was going to put it in as well. I was building her up for a monster engine swap before I decided to go back and get my masters. It's still for sale too. anyone,..anyone...

Geeze, hearing all you fellas talk about the DOHC has got me wanting to start the swap. Nah...just kidding. I've heard one wind up before and it just keeps winding winding winding. It rev's like a 4 but growls like gm v6.

Personally, I think its one of the best hotrod v6's out there. No VTECH, no variable intake, no vvti, just 3.4L with huge intake and exhaust ports. The CR on the 96 is 9.7:1 but with the reverse cooling and proper intercooling, 10-12psi on a Garrett T4 is well within reason putting out around 300-400hp with little stress. I was originally seeking to extract the rumored 270+ hp out of it in NA form, but Micheal Smith beat me to it before I even got started.
http://fiero.cc/fiero-tdc/members/mws/intake/index.html

great guy, he sold his fiero to a board member but still knows a ton about it.

If your really interested(I've had alot of welchers), let me know and email me at msweldon@hotmail.com and we'll talk more.

sincerely,
m weldon

I belive Chris West's Turbo 3.4DOHC car is making in excess of 400bhp... (with lots of time into the engine management of course, but that's the potential of this motor

Nice car, I got a chance to see it in person at this year's West Fest.

Engine really looks like it belongs in there. Sounded like it too!

If you want big numbers, get a booring 4500rpm redlining v8, if you want exotic and performance, and HUGE GRIN FACTOR, the 3.4DOHC is hard to beat!

You'll go really fast, but more than that, you really won't care exactly how fast you're going because you'll be having such a darn good time!

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

Would the same apply to the new 3500 n* engine? It would seem it is the new version of the 3.4tdc or 3400 dohc. You could get one crate for around $3500. It is the a brand new engine. Would those ecm for manual work for this engine too?
You know the ones from 91-93 I think it was mentioned above. Now this is a true
N* v6!!!!!!!

That engine will require the same stuff that a N* requires for a manual tranny. Namely, a $1300 customised aftermarket fuel management system (ecm.) forget adapting 'stock' electronics to it.

It would make a hell of a Fiero motor though. Even more kick than the 3.4TDC. And N* performance valve springs at least would fit. Cams can be ground...

But for $3500 I can find a slightly used N* for $2k, then dump 1.5k into the heads/cams/springs/valves and make 450+bhp. at 9,000RPM+

Best!
Ben.

quote Originally posted by dourain86gt: Would the same apply to the new 3500 n* engine? It would seem it is the new version of the 3.4tdc or 3400 dohc. You could get one crate for around $3500. It is the a brand new engine. Would those ecm for manual work for this engine too? You know the ones from 91-93 I think it was mentioned above. Now this is a true N* v6!!!!!!!

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

I don't know much about the 3.5L DOHC other than its all aluminum, based on the N*, has a great torque curve, and GM has had a few problems with the crank and main bearings I believe. We all know the teeth cutting period for new GM engines.

I know everyone tells me a v8 would be cheaper, but IMO I just don't think that it really suits the fiero's personality. the 3500 is a good match... light weight... high rev ... it just would sound like it would "fit" better. The on;y V8 that I like are small ones like ones below the 4l mark. I love the N* 4l v8 in the aurora, but that I think would be HUGE bucks to put in. Then again I really don't know as I have never researched it....hmmmm. I also hear theres a Rover v8 that is a 3.5l all alluinium.... him a V8 .... Well those engine I might be interested in.

quote Originally posted by msweldon: We all know the teeth cutting period for new GM engines.

That is one thing I like about the 3800, it has been around for years, and the technology has really been refined. We all know the reliability of the 3800, and if we look back to the GN's and T-types the performance heritage is there big time. The series II engine has only been around for 6 years, and just now the aftermarket is starting to take off. Give it another 12 years or so and we will be where the GN's are now.

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http://www.fieroX.com
L67 powered 87 notchback to smoke you with!

quote Originally posted by msweldon: I was originally seeking to extract the rumored 270+ hp out of it in NA form, but Micheal Smith beat me to it before I even got started. http://fiero.cc/fiero-tdc/members/mws/intake/index.html great guy, he sold his fiero to a board member but still knows a ton about it.

That member would be me. Although I wasn't a member until after buying his fiero. Originally I was eventually going to drop a v8 into the fiero I did own at the time. Then Mike decided to sell his car, so I bought his, swapped what custom suspension stuff I had onto it, returned it to stock and sold it. Over the course of Mike building his car (now mine), I have helped him numerious times. If you want an engine that you can sit there and just smoke your tires all day, then this engine is not for you. That is about my only complaint about the engine (96-97 vintage), but once you reach 3k rpm, you forget all about that.

Hopefully if I get off my lazy bum, I am wanting to mount a super charger on it. That should take care of the low end torque, and give me more upper end HP as well. It should be more then enough to make me happy. Not that I am unhappy with it at the moment, mind you. But as the saying goes: You can never have too much power!

[This message has been edited by 88-DOHC (edited 01-22-2002).]

Can we get DKOV in here? I would like to know about his Black 88 Fiero GT, 3.4L TDC, 322.84 NA HP. His car must be insane.

Not to discredit DKOV's claims but without a new set of cams and a dyno chart to prove it, I find it hard to believe any DOHC in more or less stock form could put down 322.84.

Correct me if I'm wrong, but I think I remember he said that 322.84hp was the theoretical limit of the engine, since that number is parallel to my rudimentary calculations as well. Possible, but it would take some HIGH overlap cams and serious revs to get there.

88-DOHC, you wound up with Smith's Fiero? I drove that thing once when he was just messing with the cam timing.

Yes, I have Mike Smiths old car. There is still alot of things I want to do to the car, but time and money are always a premium (well, mostly time). When he sold me the car, we had to put it back into smog legal condition, so we had to put the cat back on, smog pump, re-cam it, remove the headers, etc.. I havn't bothered putting it back the way he had it just because its alot of work (I am not quite as fanitical about things as Mike is).

John, if I were you (and I'm not, so that's why I'm sugesting this), I would buy a VW diesel, convert it to run on Corn oil and slap it in the Formula! Think of it, you would never run out of fuel as long as there is a McDonalds near by!

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hoop
Red 86 GT 5 speed
Black 86 SE Automatic