Whats the Difference between 91-93 and 94-97 DOHC

[Acid_Burn]

Well I would like to know the difference between the 91-93 and the 94-97 3.4 DOHC engines. Like whats the hp rating on the engines, is there deffernt mounting locations for any thing like the a/c pump, alt, etc... And just anything that is deffernt between the years. And would one of the newer 94-97 engines bolt right up and plug right in? Or would I have have to swap some stuff out on my 92' Z34 5speed? And what are some of the negitves and positves of the DOHC engines? Well any into will be greatful.

[jeffglitman]

I can tell you that I am just finishing up putting a 1997 3.4L DOHC engine into my 1995 Grand Prix GTP. The lower end block is pretty much the same with the same with a few minor changes. The 94/95 block had only 1 knock sensor and the 96/97 block had 2. Heads changed for 96/97 engine. Lower Intake and Plenum also changed which uses a different EGR valve as well. I used my 95 Intake and it bolted up fine to the 97 motor using 95 gasket set. Everything else that I can thing of bolted right up. A/C, Power Steering Pump, Alternator, Starter etc. Vacumm lines are different as well with 96/96 Intake but since I used my 95 Intake, all my 95 vacumm lines worked. If I think of anything else I'll let you know.

I don't know much about the 91-93 engines but I don't think they had any knock sensor at all. Here is some data I can share.

The LQ1 (also called the Twin Dual Cam) was a special DOHC version of the 3.1 L LH0 V6. It was built from 1991 to 1997. From 1991 to 1993, it used tuned multi-port fuel injection, made 200-210 hp (150-160 kW) @ 5200 rpm and 215 ft-lb (290 Nm) of torque @ 4000 r/min. From 1994 to 1997, it used sequential port fuel injection, making 215 hp (160 kW) @ 5200 rpm and 225 ft-lb (300 Nm) of torque @ 4000 rpm. It had four large valves per cylinder. The 3.4 L engine used a cogged belt to drive the four overhead camshafts. Adapting a pushrod block for the LQ1 was difficult, and the 60° angle made this a very tall engine, but power output was impressive.
Bore was increased to 92 mm, but the 3.1 L engine's 84 mm stroke was retained. There are only a few interchangeable parts between this DOHC engine and other members of the 60° family, namely the connecting rods and crankshaft.
The heads and intake manifolds were redesigned for the 1996 model year, incorporating a larger throttle body and plenum area, slightly shorter intake runners, cloverleaf combustion chambers, and larger "square"-shaped exhaust ports. Camshafts and cam timing were also revised for the new, higher RPM powerband.
Applications:
1991-1994 Chevrolet Lumina Z34 and the Euro 3.4 sedan
1991-1995 Oldsmobile Cutlass Supreme
1991-1996 Pontiac Grand Prix
1995-1997 Chevrolet Monte Carlo Z34
1995-1997 Chevrolet Lumina LS
1997 Chevrolet Lumina LTZ


Jeff

[91DOHC284]

only thing i am aware of is the injector timing was different. not sure why but the 91-93 injectors would fire when the intake valves were closed so the fuel would pool ontop of the valves and the 95-97 engines would fire the injectors when the intake valves were open shooting the fuel directly into the cylinder with no pooling. so i'd imagin you would need to change the comp to get the newer style of injection if you so choose to have it... or you could just keep your 92 top end on the newer motor.

[dohcfiend]

to be more accurate you'd have to split it into 3 groups.

91-93
94-95
96-97

there are quite a few differences. some well known and some not so well known but all of which can be found by using the search.

without getting into the technicals b/c i am about to go to sleep.

putting a newer engine into an older car-easy

putting an older engine into a newer car-not so easy.

[RedZMonte]

I know the 1996/7 has different heads with larger intake/exhaust ports, SFI vs MPFI, Upper intake man., lower intake manifold and different cams. If i remember correctly the older cams are more agressive (slightly) then the 1996/7 cams.

[dohcfiend]

alright i am feeling gracious. i haven't read any1 elses threads so some of it may be duplicate.

known differences between 91-93 to 94-95.

91-93 has an oil cooler and 94-97 does not.
91-93 has external tranny cooler and 94-97 does not.
91-93 is MPFI and 94-95 is SFI until 3000 then switches to MPFI. Note 94-97 is backwards compatible to 91-93.
91-93 cam carriers do not have a cam position sensor and 94-97 do.
91-93 use a MAP, 94-95 use a MAF and 96-97 use both.
91-95 use 1 knock sensor and 96-97 use 2.
91-95 pcv system goes to both Valve covers and 96-97 only goes to 1.
91-95 use fixed fuel pressure regulators and 96-97 use an adjustable one.
91-93 cam carriers use this annoying lock ring in them for adjustment and 94-97 cams do not have this.
there are revisions to the oil passages in the block spanning the life of the lq1.
from word of mouth, the 94-95 cams are most aggressive and the 96-97 are least aggressive.
91-96 cam carriers use 35mm lifters and 33mm lifters came in 97 only.
91-96 used 4t60e trannies for auto's but 97 used 4t65e trannies.
manual trannies came in 91-93 only.
91-93 use obd1, 94-95 uses a more advanced version of obd1 and 96-97 use obd2.
91-95 auto tranny exhaust manifolds are bare, 91-93 manual tranny exhaust manifolds use evap on them as well as the 96-97.
compression ratio for 91-95 auto trannies is 9.25:1, 91-93 manual tranny is 9.5:1 and 96-97 is 9.7:1.
91-95 the oil pressure sensor is located on a spin on adapter behind the oil filter, the 96-97's are screwed into the block.
91-95 use "hemi" style combustion chambers and 96-97 use cloverleaf chambers.
91-95 use the same style sparkplug wires, 96-97's are different.
91-95 use the same style manifolds and exhaust ports in the heads, 96-97 uses different style manifolds with larger exhaust ports.
91-95 use the same exhaust valves, the 96-97 uses canted and raised exhaust valves in their heads.
the cooling system on the 91-95 is the same, 96-97 uses a different routing for the cooling on the upper half of the engine.
the 91-95 valvesprings are slightly stiffer than the 96-97 springs.
91-95 use the same valve covers but the 96-97 use different valve covers.
91-95 have the coilpacks located underneath the exhaust manifold and the 96-97 have them located next to the intake manifold.
91-95 use the same egr system, 96-97 uses a different egr system.
91-93 uses a 1 wire upstream o2, 94-95 uses a 4 wire upstream o2 and 96-97 uses a 4 wire upstream and downstream o2.
the intake manifold is the same for 91-95 but was completely redesigned for 96-97.
94-97 the alternators are the same and 91-93 the plug locations are different but the newer alts are backwards compatible.
the harmonic damper is the same for 94-97 but different for 91-93. the newers ones are backwards compatible.

think that's it. enjoy.

p.s. there is a differncr in injector flow rates on the 91-95 versus the 96-97 but i forget what they are. i know the 96-97s are 24lbs. the 91-95 are either22 or 23 iirc.

[jeffglitman]

Along those lines, I am putting a 1997 3.4L DOHC motor in a 1995 Pontiac Grand Prix. I'm using the 97 spark plugs but I am using the 95 coil pack location. Can I use 95 plug wires? Everything on the 97 motor is using my 95 sensor and ECM. I know the heads are different and cams for 97 so which plugs, wires and coils would work best. I would prefer to use the 95 wires and coil pack location to make wiring back up easier. Is the wires just different lengths but same resistance?

Thanks,
Jeff

[dohcfiend]

first you'll have to use whatever wires that go with whatever valve covers you are running. the 91-95 valve covers stick up a little higher and the 91-95wires are deeper.

next there is no way you could use 96-97 wires with a 91-95 location. the 91-95 wires are much longer.

[91LQ1Lumina]

Compression Question

I think the motor in my Lumina may have been change before I bought it, and was wondering is it possible to tell if it is the 9.25:1 or the 9.50:1. The reason that I ask is because my exhaust manifolds have the evap lines plumbed to them but they are capped off. So I think this motor may have come out of a car with the manual trany.

[series8217]

I have seen early Luminas with automatic transmissions that had the AIR lines in them but plugged from the factory.

[dohcfiend]

interesting, as far as i know the evap manifolds is the only significator of a 5 spd engine.

other than that check to see if it is a 96-97 engine.

[gpse3400]

Evaporative emission control has nothing to do with the exhaust manifolds....

Those bosses in the manifolds are for the AIR Pump. Air Injection Reaction. To light of the catalyst faster.

Evaporative system pull fuel vapor from the charcoal canister in the back of the car that absorbs vapors from the fuel tank. AKA Canister Purge. Related part; canister purge soleniod.

[dohcfiend]

oh yea, the 91-93 rads are a little smaller than the 94-97 ones.