Ok, I think I have found the difference between these two engines! They are essentially the exact same engine, but in 96, it was switched to reverse-flow cooling and that got it up to 215HP, vs 210 for the previsous year. So, the 3.4DOHC should be a 96 model with reverse-flow cooling and the 3.4TDC is the same engine, but pre-96 with conventional flow cooling.

Anyone else heard this? I read this on one of the 3.4DOHC web sites.

Kind of interesting. They list some of the hop up and performance mods you can do to this engine. Now, I know the claimed gain from each of these mods is likely overrated, but:
Exhaust 20-30HP
Bored Throttlebody 8-10HP
Ceramic Coat manifolds 8-10HP
Cold Air Intake 9-10HP
Extrude Honed Intake with bored throttlebody 10.9HP (dyno tested?)
Underdrive Pulley 8HP
Port upper/lower intake 5-8HP

Yeah, I wouldn't expect these are all accurate, but if they are, lets see, starting with 215HP, that give you

215+20+8+9+10.9+8+5 = 275.9HP!!

Ok, so realistically, since most of us would do a lot of this anyway if we're gonna do a swap, even allowing for fudge factor, you should be able to get the 3.4DOHC close to 240-250HP without much trouble or too much money. Basically custom exchaust, big bore throttle body and cold air intake, underdrive pulley. Then add the ported manifolds if you want a bit more. You're really close to the output of a 3800SC, and it's normally aspirated and high revving - not to mention a lighter engine.

If my options were:
3800SC with SC pulley: 280HP
3.4DOHC with above mods: 250HP
LM1 350 with TPI: 275HP (according to some of Archie's customers)
Northstar: 300HP

Ok, so the N* wins in HP, but also in complexity. With that comparison, taking into consideration the weight advantage of the 3.4DOHC, it's looking more and more tempting. Don't forget, even though the 3800SC is more powerful, it's also a solid iron engine, so it's heavier.

If you want a SBC, nothing else will do, so it's hard to compare against that, but unless you go with a ZZ4, you won't have much more HP, but you will have more torque - and I would guess 100-150lbs extra over the 3.4DOHC.

N*'s biggest detraction, complexity and tranny. Once more have been done successfully with the 5-speed, it becomes a more attractive option, but for now it's sounding like the 3.4DOHC could be a winner.

Biggest advantage to the 3.4DOHC (IMO):
It's personality matches the Fiero. High revving, great sound, not a lot of low-end torque, so it's easier on drivetrain and clutch, light weight so it keeps the Fiero's balance. It's really looking like a great alternative from this perspective.

Biggest disadvantage to the 3.4DOHC:
Expensive to work on - high maintenance engine. Complex oiling system requires religious oil changes. Have to drop the cradle to change the front plugs. That amy not be so bad because it uses 100K mile platinum plugs. Not the gas-it-and-go type of reliability that you'd get from the 3800SC or N*, I'd wager.

quote Originally posted by Formula88: I read this on one of the 3.4DOHC web sites. Kind of interesting. They list some of the hop up and performance mods you can do to this engine. Now, I know the claimed gain from each of these mods is likely overrated, but: Exhaust 20-30HP Bored Throttlebody 8-10HP Ceramic Coat manifolds 8-10HP Cold Air Intake 9-10HP Extrude Honed Intake with bored throttlebody 10.9HP (dyno tested?) Underdrive Pulley 8HP Port upper/lower intake 5-8HP Yeah, I wouldn't expect these are all accurate, but if they are, lets see, starting with 215HP, that give you 215+20+8+9+10.9+8+5 = 275.9HP!!

Okay, but you forgot to mention that, if you're looking at the SAME sight I am, these additions to HP were dyno tested and were measured AT THE WHEELS.

275.9 + 17% = 322.803

Now, I have performed each and every mod on that list plus some valve work. Methematically, my numbers work out to within 1-2 HP of the ones you posted here but still, I need to Dyno to verify.

Kinda interesting to think about... 300+ HP from an NA engine

So... even if it IS exagerrated a bit, is 275 bad? Even 250? Get my point?

Neat huh?

DKOV -

In addition to the reverse flow, the '96 also got a revised intake, a slight head change, the C/R bumped to 9.7, OBD II and SFI. The purpose wasn't necessarily the HP improvement but were emissions related. One thing I'm not sure of if the pre '96 engines had the secondary air injection to help burn off hydrocarbons while the car is warming up. The '96 engines have it. Anyone with a pre '96 setup and at least one original exhaust manifold can look and see if the air pipes or air pipe connections are on it.

Another thing: people keep talking about 'no low-end torque' from these motors, that's a load of BS!

Both the 3.4TDC, and the Northstar make prodigious torque from idle right up to redline.

Yes, if you install overlapy cams you are going to change the torque curve from flat to peaky up high, and drop a few lb-ft at 800rpm, but who CARES!

The Northstar makes *over 220lb-ft at 1,000RPM* guys....

Both of these engines will yank your head off at any speed, and to my taste are far more suited to the Fiero than any pushrod motor ever made.

------------------

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

I dunno, every 3.4L DOHC I've driven felt like a 2.8L Fiero until about 3000 and then it was like the gates of heaven opened up. EEEEEEEEEEEEEEEEEEEEEEEEEE-HAAAAAA!

As for the NS I can't imagine anyone saying they don't have low end torque. I say we kill the infidel!

But, Terry, that could be a GOOD thing. Like I said, that gets you off the line with less clutch and drivetrain stress, then once you're moving, you unleash the gates of HELL on the world!

I was being conservative. Some of those mods I listed are dyno tested (RamAir Tech) and some aren't. So I took the lower of the estimates, then cut that down some too. Still, 250HP seems very easy to get.

Ferraris aren't known for their brutal low end torque. Very docile in normal driving, but if you DRIVE the car, the power's ready and waiting.

I've had a 72 Trans Am (455HO) and a 87 Grand National. Both were fast as hell, but the turbo lag on the GN made it easier to race. Just mash the go pedal, and the turbo lag go the car moving without blowing the tires away, then the turbo came in and laid waste! The TA had to be very carefully launched, or it's monster torque would just have the car sitting still spinning the tires (and not holding the brakes, like most people have to do).

Yeah, you can only use as much *off-idle* low rpm torque as you need to spin the wheels through first gear, no more (because by then the engine is spinning, and you're making insane power because you're making *torque* at 7grand and torque * speed = bhp)

I guess it boils down to a taste thing in street vehicles, what do you want the car to do well?

A *fairly* high strung motor will be drivable withought accidentally putting you into the ditch (maybe between 1-2kRPM. At least you'd have a chance. Then the real kick in the pants starts above there and keeps going and going and pulling and dareing you to give it more!!!

Best!
Ben.

PS: I'm not talking about some guttless motor here, more like something *just* strong enough to smoke the tyres off the line at idle withought a clutch dump, and then rappidly building to a tire-smoking freenzy above 3krpm or so.

------------------

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

Formula 88,

You're right. The launches are easier. Although the DOHC isn't as fast the SC swaps, I like the DOHC more. It just fits the car better (performance and personality).

I disabled the rev limiter on Mike Smith's and we were buzzing around hitting nearly 8000 RPM. He said the valves were floating (and I was whincing), but that engine sounded so goooooood other than the resonance of the intake. This is before he did the custom intake, but it did have some cam timing changes. It was a bit bucky in the lowend.

quote Originally posted by artherd: The Northstar makes *over 220lb-ft at 1,000RPM* guys.... Both of these engines will yank your head off at any speed, and to my taste are far more suited to the Fiero than any pushrod motor ever made.

Well, Mr Ben, I invite you to ride in my 3400. I suggest you hold on to your head.

I Love engines that pull hard right to the top end. Nothing beats the feeling that the next 1000 rpm will be better than the last. But that's just me.

quote Originally posted by terryk: Formula 88, You're right. The launches are easier. Although the DOHC isn't as fast the SC swaps, I like the DOHC more. It just fits the car better (performance and personality).

I agree with that. I'm more interested in how much fun the car is rather than how fast it is. Besides, I could always turbo the 3.4DOHC, if I wanted to go 3800SC or N* hunting.

I think 7000-7500 rpm's and 250HP would keep me happy for a while. Maybe add a small N20 setup in case I run into a V8 Fiero...

I can make 350 horsepower at the crank of a 3800 sc, no nitrous, very easily.

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Well, I could make over 400HP out of a 3.4DOHC without nitrous - just throw on a turbo charger.

Speed costs money - how fast do you want to go? The dude with the bigger wallet can have the faster car. Period.

Hi Joe, you're on! If I remenber right, you have a 3400 with the genIII aluminum heads and a custom intake, right? When the northstar car is done, let's swap for a few laps

Best!
Ben.

quote Originally posted by Joe Torma: Well, Mr Ben, I invite you to ride in my 3400. I suggest you hold on to your head.

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

Yup...but stock intake(just ported)

Sounds like fun to me!
Hey...what happened to your head, Ben...in your sig? I see your torso, but no head?! A ride in a Northstar perhaps?

Joe

quote Originally posted by artherd: Hi Joe, you're on! If I remenber right, you have a 3400 with the genIII aluminum heads and a custom intake, right? When the northstar car is done, let's swap for a few laps Best! Ben.

[This message has been edited by Joe Torma (edited 11-30-2001).]

The later engines had sequential injection up until 3,000rpm also,a little crisper response maybe?
My engine was supposed to have come from a '97 model year car,the sticker on the door said 12/96,am thinking the "GM only" junkyard, just outside of Detroit may have gotten a bunch of company cars from GM's motorpool or something;there was absolutely nothing obviously wrong with this car,had 30K on it,wierd(?).
The easiest engine swap I've ever encountered,engine has enough torque to have nearly dis-membered the crossmember where the engine mount is,had to have some creative reinforcing done there after awhile,think maybe the guys at the bodyshop did that though,since I never do burnouts in the car,but if it's just the torque of the motor doing that,not the monkeys at that shop,then wow!
I can't believe how good it fits the engine compartment;the huge intake manifold goes right between the structure on the underside of the rear hatch,slick.The original throttle cable even worked out with a little work.The only wires from the new ECM that were connected to the Fiero wires were even the same colors.Nearly all the work to physically install the motor was accomplished by me with an angle grinder(Makita),backyard engineering at it's best IMO.