I was planning on putting an LT1 in my Formula next summer. I was at the junkyard today however, and I came across 3.4 DOHC out of a wrecked 92/93 Z34. Both engines have around 150,000 miles on them, so I'd have to rebuild either.

The LT1 is coming from a friend for only $150 with all the accessories.

The 3.4 will set me back $500.

Here's a pic of the 3.4

My brother is a member of a few Impala clubs and forums, and can get LT1 parts cheap if not free. Not to mention he just rebuilt and stroked one for his 96 Caddy Fleetwood. (sweet ride)

I don't know much about the 3.4, so I was hoping you guys could give me your opinion on these engines, and what you'd suggest I do. Are the cams reusable with that many miles or would they need to be replaced? Do these engines have roller rockers from the factory? Or are the valves actuated right off the cams? What does a typical rebuild on a 3.4 cost? Are performance parts readily available? Does Summit and jeg's have parts for them or is there a supplier you guys recommend? What would I need to take from the donor car? I assume I'll need the harness and computer (this particular Z34 has a Hypertech chip in it already), but what else? Exhaust manifolds, too, I'm guessing. It also had a solid upper motor mount too, so though I do not know the condition of the engine, if it's been rebuilt or not, but I can tell an enthuiast owned it...

I realize that the 3.4 swap is much simpler to do than the LT1, but as far as being the more cost effective, which would be the better of the two?

--Nick

[This message has been edited by Uniquekind (edited 07-28-2005).]

If you are after performance I'd say go with the LT, there's not much off the shelf for the 3.4 DOHC. In general I'd say the 3.4 is a pretty easy swap mechanically (even though mine is still not running right), cannot comment on the LT swap though. I'd guess electrics is an issue in just about any major swap.

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Dave E

www.ltlfrari.com

The 3.4 will be about 1/4 the price to install into a fiero, but is short 75-100hp. Its up to you, an LT-1 is a sweet motor, but so is a 3.4dohc. I traded my LT-1 for my 3.4dohc

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Buy a fiero, become a mechanic

Ouch, $500 for a 3.4 with 150k? I wouldn't even think about it. $150 though is a real nice deal, but I would weigh that carefully with the fact that you need an install kit, and I hear the LT1 takes a bit more work vs the regular SBC.

Here's Orville's LS1. It's not a LT1 but I have no issues with seeing one in the back of a Fiero

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Archie's Choptop conversion #11, #15, Redux & The Stealth

I believe the LT1 requires some frame modifications, the motor is 2" longer than a regular sbc due to the waterpump and distributor which is on the front of the motor (optispark) run directly off the cam. You will need custom axels, basically you need an Archie kit. He sells a kit specific for the LT1 which costs more than a regular install kit.

You can probibly find a 3.4 in a local yard with less miles for cheaper. Check this site, its handy.
www.car-part.com

quote I traded my LT-1 for my 3.4dohc

Are you enjoying the 3.4 more than the LT1?

Do you have any pictures of the LT1 installed?

Which was more fun for you to drive?

--Nick

Never installed the LT-1. I had it in my head that I could install and turbocharge the 3.4dohc for the same or less money then installing the LT-1. I had the 3.4dohc in and running, very nice and smooth motor. 100% better than a 2.8. It definitly made driving the car fun. I pulled the 3.4dohc out and now I'm installing a N*.

quote Originally posted by Uniquekind: I don't know much about the 3.4, so I was hoping you guys could give me your opinion on these engines, and what you'd suggest I do. Are the cams reusable with that many miles or would they need to be replaced? Do these engines have roller rockers from the factory? Or are the valves actuated right off the cams? What does a typical rebuild on a 3.4 cost? Are performance parts readily available? Does Summit and jeg's have parts for them or is there a supplier you guys recommend? What would I need to take from the donor car? I assume I'll need the harness and computer (this particular Z34 has a Hypertech chip in it already), but what else? Exhaust manifolds, too, I'm guessing. It also had a solid upper motor mount too, so though I do not know the condition of the engine, if it's been rebuilt or not, but I can tell an enthuiast owned it...

1) The cams are probably reusable. For some reason, the above motor looks VERY familiar. I am on every board remotely having to do with 3.4s, and I swear I've seen that motor before...At any rate, his car is slightly modded, see the FFP poly dogbone mount. Anyways, if he knew enough to get one of those (99% of FFP part holders are on message boards), he knew enough to run synthetic oils. Even if he didn't, I'd bet the cams are good. The motor would spin a bearing LONG before it harms the cams in any way. I spun a bearing in my Z34 at 127k, and the cams not only looked brand new, but when checked by a machine shop, came up perfectly within factory specs, showing minimal if any wear.

2) The valves are actuated right off the cams. The cam pushes down a lifter, like an inverted dish that fits over the valve, which in turn pushed down the valve/spring assembly.

3) A rebuild will run you anywhere from $500-$3000, depending on a lot of things. If the motor is 'good' when pulled, you should be able to escape under $1000.

4) Performance parts aren't readily available, but they are out there. That is a 91-93 motor, so a 96 intake swap with a bigger throttle body will help, www.60degreev6.com/store sells a chip that helps a lot, they also sell lightened lifters and he does headwork, there are also many bolt ons that can be done, to include intakes, exhausts, plug wires, etc. Basically anything you want done can be done. I'm in the process of building my own intake manifold and headers. I plan on selling 3.4 DOHC headers when I get around to doing my swap, expect to see them in about 6 months to a year.

5) Take the complete engine, every accessory, and the complete wiring harness and ECU. If you think you need it, get it. Definately get the intake and exhaust manifolds, and the exhaust crossover.

If I can be of any more help, let me know. Although, looking at my all important ratings bar, I may not be around long enough to help...

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No offense to Ben over at 60 degre dot com intended but, you can get a better deal on a chip for the TDC from Darth Fiero here on this forum. He's got a lot of experience with the chips for these engines and does some nice work with them. He's the only one, so far, who's working on ther 94-5 chips too. He's got a ocuple beta testers out now on those. One is a friend of mine and we're both impressed with Darths work.
His chips are only like $30 too which I have yet to see beat. He also works with you on the chip and will keep working with you until it's right.
Again, no disrespect intended towards Ben over at 60 degree, he's a sharp guy too with these engines, but I've seen Darths work firsthand and I'm impressed with it.

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I agree Darth does know his stuff, but let me defend Ben for a little here, which i don't know why I'd do considering how much of a dick he's been to me int he past. Oh well, I'm sure I deserved it...

Ben is not only working on the 94-95 chips, but he can tune them as it is right now. The only thing he is waiting on is more info so that he can make the chips even better, he is waiting on some stuff for shift points right now. But he said he has the performance side of the 94-95 chip down. He also really likes the 94-95 setup. Factory he says it is pretty good, only needs minor adjustments, whereas the 91-93 needed a bit more.

The most positive side of Ben's chips are that he has tested them through and through on the DOHC, on dynos, with wideband O2s and exhaust monitoring, EVERYTHING. So they will give the maximum gain possible. He also offers free updates so long as you own the car. $30 is cheap tho, I think Ben does them for $100 or so.

But I trust Darth's opinion, and he may be the lucky one that gets to tune my highly modded 94-95 Fiero, if I ever get it done....

Something about those cams. I still have yet to see a set with any real noticable wear. Honestly, what would you have to do to rebuild the 3.4 DOHC? Pull the heads clean and have them decked slightly. Dismantle, bore and clean the block, change the pistons, rings and bearings. I imagine this would cost somewhere between $800-1200 If you don't decide to do anything beyond that... Such as a crank, cams and valvetrain. Just a basic refresher on the wear parts. As far as the valvetrain goes, I would pull all the valves, check the guides (they tend to move) and correct as necessary, and change the valve seals. It is a good idea to have a valve job done, but thats more $$$.

But If I could, I'd much rather have a LT1 back there if I didn't care that the frame would need to be modified. It's just WAY more powerful. The LT1 is scary fast while the 3.4 DOHC is just a lot of fun. But the LT1 will cost more.

Cryzone - are you still planning on doing a N* swap in your GT? Got to tell you man, you have one of the nicest GT's on the forum - very tastefully done. If you are ever considering selling it, let me know!

BTW - my friends from WhiteCourt are coming into town tongith - I'll ask them if they have seen your car tearing up the streets.

Everybody talks about cutting the frame on the LT1 swap. As you can tell by my PFF name, I have that eng and yes my frame was notched. It was not hacked up in order to get the eng to work, it was notched and a plate was weled in to regain support. No big deal, no cracks, no problem. Would I do it all over again-----------in a heart beat.

But the 3.4 DOHC is by far a much easier swap.

And after owning a 1994 Z28 6-speed, I wouldn't call it scary fast. In fact, it wasn't even fast. It was quick at best. I really wasn't impressed with it though. Yes it was faster than the Z34 (My stock one, not the modded one), but it didn't feel it. The only thing I liked about it was how it sounded, it was a sweet sounding car with the stock exhaust. Other than that, let's just put it this way, we owned the white Z34 for much longer, and just rebuilt another Z34 for our use, whereas the Camaro was sold within 8 months of buying it.

I suspect the 3.4tdc will cost about 3x what a LT1 does for the rebuild... might want to price out that part of the job. It's also a much more complicated engine to assemble.

Hey guys, how does the 3.4 DOHC sound? Can you describe it to me? I saw a clip with 3800s, 4.9 and Northstar but no clue what the 3.4 sounds like.

Send me an email address that will accept a file that is about 10 megs, and I will send you a video. Granted it is of a turbocharged 3.4 DOHC, but you can't really hear the turbo at all in the video. Its a nearly 4 minute video of the car tearing up some california winding mountain road. I can't host it.

Here are three videos of my 3.4l DOHCs. The first is stock, this is my red Z34 on the dyno, making 178whp/186wtq. The second/third are of my white Z34, which was pretty highly modded. It made 218whp (No excuses, but we had a lot of issues, and the dyno was f-ed up), and the other is it racing a friend's highly modded TSi Talon. I compare the sound to a Ferrari. It just screams, with a nice growl. On the low end, it can be sorta raspy, but pretty much sounds like a 3.1. It's after 3500 when people are like, "WTF is making that noise?!?!?!"

http://lukez34.com/galleries/video/dynoday/
^The video is aarondyno, bone stock 1992 Z34 5-speed with a brand new crate engine

http://mfmllc.com/kenny/MVI_0195.avi
^That is my modded white Z34 on the dyno

http://www.mfmllc.com/kenny/MOV00001.MPG
^Crappy video, but you can hear the 3.4l REALLY well (It is the loud one)

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quote Originally posted by LT188GT: Everybody talks about cutting the frame on the LT1 swap. As you can tell by my PFF name, I have that eng and yes my frame was notched. It was not hacked up in order to get the eng to work, it was notched and a plate was weled in to regain support. No big deal, no cracks, no problem. Would I do it all over again-----------in a heart beat.

Gots to agree with you on this one.

AaronZ34--Thanks for all the info. VERY helpful.

LT188GT--Could you tell me a little bit about your swap? Did you do it yourself? Pictures? Cost?

I'd like to thank everyone for their knowledge here. I know I'm beating a dead horse with a stick, the whole V8 vs V6 thing, but I don't recall reading about many LT1 swaps, especially compaired to the 3.4.

I'm pretty sure my heart is set on the LT1, I'm just afraid that once I start it, I'll never finish. I've checked V8 Archie's site a few times looking over his products, and he states no frame modification is necessary for his kits--Anyone know if that's true for the LT1 as well? Every other source says the frame has to be modified to fit the LT1.

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quote Originally posted by loafer87gt: Cryzone - are you still planning on doing a N* swap in your GT? Got to tell you man, you have one of the nicest GT's on the forum - very tastefully done. If you are ever considering selling it, let me know! BTW - my friends from WhiteCourt are coming into town tongith - I'll ask them if they have seen your car tearing up the streets.

Thanks for the compliment. It would be cool if your friends seen my car around town. I am in the process of installing my N*. Its a 2003 engine, 30k kilometers on it. You can see progress pictures of it here
https://www.fiero.nl/forum/Forum2/HTML/060639.html

My car hasn't been on the road since spring, so you might have to refresh their memory with a pic

quote Originally posted by Uniquekind: AaronZ34--Thanks for all the info. VERY helpful.

My pleasure, just ask if you have any more questions!

quote Originally posted by AaronZ34: It's after 3500 when people are like, "WTF is making that noise?!?!?!"

I love that sound. It does sound like a stock v6 upto that point though...... so you gotta try to keep it above

http://60degreev6.com/Sappy/0-70.wav

Uniquekind----You have a PM

quote Originally posted by Uniquekind: I'm pretty sure my heart is set on the LT1, I'm just afraid that once I start it, I'll never finish. I've checked V8 Archie's site a few times looking over his products, and he states no frame modification is necessary for his kits--Anyone know if that's true for the LT1 as well? Every other source says the frame has to be modified to fit the LT1.

The V-8 kit for a "normal" SBC is designed to where it shouldn't need any frame modifications. The LT1 wasn't even built when the V-8 kit was originally designed. And the LT1 is not a "normal" SBC, it has the distributor on the end of the engine & had an internally driven W/P making the completed engine block a few inches longer than the traditional "normal" SBC.

Archie

quote Originally posted by Archie: The V-8 kit for a "normal" SBC is designed to where it shouldn't need any frame modifications. The LT1 wasn't even built when the V-8 kit was originally designed. And the LT1 is not a "normal" SBC, it has the distributor on the end of the engine & had an internally driven W/P making the completed engine block a few inches longer than the traditional "normal" SBC. Archie

A "normal" LT1 is a "normal" SBC ..well it is as far as layout anyway. Remember the 70 1/2 Z28 or the LT1 Sting Ray? I know you do Archie but younger generations probably dont

[This message has been edited by Erik (edited 07-29-2005).]

The early LT's were LT-1

The late LT's are LT1

They are not the same.

I had a 70 1/2 LT-1 Z28 that turned 12.20 in the 1/4 after doing a lot of work to it and still drive it to work everyday.

quote Originally posted by LT188GT: The early LT's were LT-1 The late LT's are LT1 They are not the same. I had a 70 1/2 LT-1 Z28 that turned 12.20 in the 1/4 after doing a lot of work to it and still drive it to work everyday.

Sounds the same, I believe GM intended it to ride on the first generation LT1's notariety

I would love to have my 70 1/2 LT-1 in the Fiero as that eng had solid lifters and I shifted at 7500 to 8000 rpm with no problem. Now this was not a bone stock engine.

quote Originally posted by LT188GT: I would love to have my 70 1/2 LT-1 in the Fiero as that eng had solid lifters and I shifted at 7500 to 8000 rpm with no problem. Now this was not a bone stock engine.

I'll take the 302 DZ with the cross ram thank you

quote Originally posted by Erik: I'll take the 302 DZ with the cross ram thank you

Crossram ain't $h!t when I'm breathing through 32 valves in my Arao-Head small block, neither is your LT-whatever

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