The 3.4DOHC engine (Also known as the LQ1) is a 60° V6 engine built from 91-97.
This engine made 200-210 hp (150-160 kW) at 5200 rpm and 215 lb·ft (292 N·m) of torque at 4000 rpm. From 1994 to 1997, it used sequential port fuel injection, making 210 hp (157 kW) at 5200 rpm and 215 lb·ft (292 N·m) of torque at 4000 rpm.
Car's it was put in:
-1991–1994 Chevrolet Lumina Z34 and the Euro 3.4 sedan -1991–1996 Oldsmobile Cutlass Supreme -1991–1996 Pontiac Grand Prix -1995–1997 Chevrolet Monte Carlo Z34 -1995–1997 Chevrolet Lumina LS -1997 Chevrolet Lumina LTZ
So is there advantage of this 3.4 over the 3800NA? Probably has been asked several time. A forum member told me the 3800 is an easier install.
Advantages? Well, people like this engine because of the RPM range. You can go up to 7k before having to shift again. The 3.8N/A has similar HP/torque numbers as this engine. The 3.8SC engine however, has plenty of after market support and would cost about the same.
DOHC engines tend to all have the same issue, head gaskets. Remember, that layout means more parts are moving, thus the cost of repairs is going to increase.
I like to stick to OHV or SOHC because they are more reliable and have less parts moving. Just my .2 tho
DOHC engines tend to all have the same issue, head gaskets. Remember, that layout means more parts are moving, thus the cost of repairs is going to increase.
I like to stick to OHV or SOHC because they are more reliable and have less parts moving. Just my .2 tho
I have NEVER heard of LQ1's having head gasket issues. only complaints I hear are timing belts and oil pump drive o-rings.
Have been googling this engine, this looks like the best one out there. Looks better than the 3800 IMHO but I guess the 3800 is more reliable. Then again there were a few engine fires with the 3800 also.
I have one in my car and LOVE it. 7000 RPM of DOHC noise is just right for the Fiero. That's why it was supposed to be the GT engine for the 1990 Fiero. The 1990 prototype has an early prototype version of this engine. After they cancelled the Fiero, the engine showed up in the 1991 W-bodies.
------------------ 1986 SE Aero coupe.
3.4 DOHC swap is complete and running, now just have to finish the rest of the car...
Originally posted by tesmith66: I have one in my car and LOVE it. 7000 RPM of DOHC noise is just right for the Fiero. That's why it was supposed to be the GT engine for the 1990 Fiero. The 1990 prototype has an early prototype version of this engine. After they cancelled the Fiero, the engine showed up in the 1991 W-bodies.
I think the engine in the prototype was actually a 3.1 or 3.2. Not sure what all other differences it might have had with the final 3.4 production engine.
Originally posted by zzzhuh: Personal experience with DOHC engines such as the 4.6L Northstar engine.
I've also seen it happen on a 2.5L DOHC 97 Subaru as well.
As dobey said, the engine is top heavy and sucks to work on.
The Northstar didn't have gasket problems either. It had problems with the threads on the head bolts, which is a completely different issue, and which is also a solved problem with the tech bulletin GM put out on it.
And any engine can develop a head gasket issue, especially when you get up in the XXX,XXX mileage range.
The Northstar didn't have gasket problems either. It had problems with the threads on the head bolts, which is a completely different issue, and which is also a solved problem with the tech bulletin GM put out on it.
And any engine can develop a head gasket issue, especially when you get up in the XXX,XXX mileage range.
Are you sure? Go on craigslist and look up any cadillac that had the 4.6L Northstar.... You know what you'll find?
$1000-2500 range will be filled with a description like:
"Car over heats / head gaskets are blown."
I promise you, these engines are prone to head gasket failure. and so are the Subaru's.
I've never had a good engine that was DOHC, OHV is a comfort zone that is less complicated and has stayed true for over 60 years.
Originally posted by zzzhuh: Are you sure? Go on craigslist and look up any cadillac that had the 4.6L Northstar.... You know what you'll find?
$1000-2500 range will be filled with a description like:
"Car over heats / head gaskets are blown."
I promise you, these engines are prone to head gasket failure. and so are the Subaru's.
I've never had a good engine that was DOHC, OHV is a comfort zone that is less complicated and has stayed true for over 60 years.
Uhm. OHC has been around for over a hundred years.
And the people selling the Northstars for cheap with complaints of overheating and blown head gaskets are exactly due to the well known bolt thread problem. Those cars all probably have around 100-120K miles on them, and were never fixed, simply because whoever is selling it has no idea there is a problem, and doesn't take proper care of the car. The bolt thread issue is well known and any GM dealer should know about it and be able to fix it.
Head gaskets are wear items. They will not last forever in any engine. Boosting will of course increase cylinder pressure, which also increases the possibility of blowing a head gasket. Improper maintenance of coolant level can also increase the probability of failure.
I've had three Subarus, and the only time I had a head gasket issue was when I overheated my '99 Forester and warped the hell out of the heads, and I suspect that car had some serious cooling system issues when I bought it. Not a single problem from the other two.
...and the Northstar head gasket issue is a well known problem with that motor. Just need to install steel inserts or studs in the block to fix the problem forever. That's an aluminum block issue, not a DOHC issue.
Also to keep this LQ1 related, I'd like to reinforce that the LQ1 is just a modified 60V6 motor. Look at the majority of bottom-up DOHC motor designs, such as Subaru EJxx series motors and Northstars and you'll see open deck blocks. Look at the LQ1 and you'll find a GM 60V6 closed deck block with some provisions for a timing belt. I mean, the drive sprocket for the timing belt rides on what is essentially a cam blank in the center of the block.
Every motor needs maintenance eventually. It's just a matter of how much and when. You can't realistically expect to shove any 100,000+ mile motor in your Fiero and have it last forever.
LQ1's are indeed a special kind of bastard to work on. Stuffing one into a Fiero's engine bay would probably result in EVERYTHING being harder to access. Maybe someone who owns one can elaborate? On the flipside, the 7000 RPM redline sounds amazing and for an early 90's V6 engine it shoots out a sick amount of power. Plus, they CAN be turbo'd and react to the boost quite nicely. That being said, they also eat the auto transmissions that came mated to them, right up. "I don't think any GM automatic transmission can stand up to 7k RM ***** slaps for very long." LOL. It's all preference, I suppose.
Uhm. OHC has been around for over a hundred years.
And the people selling the Northstars for cheap with complaints of overheating and blown head gaskets are exactly due to the well known bolt thread problem. Those cars all probably have around 100-120K miles on them, and were never fixed, simply because whoever is selling it has no idea there is a problem, and doesn't take proper care of the car. The bolt thread issue is well known and any GM dealer should know about it and be able to fix it.
Head gaskets are wear items. They will not last forever in any engine. Boosting will of course increase cylinder pressure, which also increases the possibility of blowing a head gasket. Improper maintenance of coolant level can also increase the probability of failure.
You are right, but im my case I've never had good luck with them and they always seem to be prone to the same issue. If you would rather work on an engine that has more moving parts and cost's more to fix, be my guest.
I was trying to explain to the O.P. that the 3.8SC is going to be a better option.
As a side note, late '90s/early '00s Subarus do tend to have head gasket problems. Like the Northstar bolt thread problem, the EJ25s tend to suffer head gasket failures at around 120k. Doing a HG on these cars is a pain due to clearance issues, but smart folks will just pull the whole engine and do it on the bench. It's a 6-10 hour operation, not all that different from any split bank type of engine. After the early '00s, Subaru largely got the issue under control, just in time to start having oil pump/turbo issues instead. IMHO, the EJ25 was a cursed motor.
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