3.4 DOHC baffled

[scottwhite98]

I've done some poking around about the DOHC 3.4L GM V-6 and I am baffled that there aren't more mods for it. I've read the story about how GM designed it to produce 275+ HP but it was limitations from the Hydra-matic division that de-tuned it to a 210hp engine. I believe this is complete hogwash.

 

The Hydra-Matic division of GM had been building FWD transmissions since 1966, first for the Oldsmobile Toronado. It was a TH-425...kind of a TH-400 with the tail end bent sideways. It sat behind a HC Olds 425CID with 385HP and 480lb/ft of torque. Twenty-some years later they couldn't build one to even handle 210hp? Not only that... but over the entire production of this engine to 1997, HP only increased by 5? So, Hydra-Matic couldn't improve on their best FWD transmission to accept any more than 5 additional HP over another 6 years? 1994 saw the introduction of the supercharged 3800, capable of 225hp in front of a 4T60E HD. 1996 saw the introduction of the Series II Supercharged 3800 with 240hp. If the DOHC 3.4 was detuned so much, it certainly should have been unreigned by then!

 

Still... after all these years, and all the potential of all that natural aspiration, there are so few mods? Swap it out or add turbo is about all I read.

 

So, for the shadetree mechanic, what's there to do?

 

-modified airbox

-bigger TB

-TB coolant bypass

-exhaust

- engine mount wishbone

 

Very depressed that an engine with such potential gets tosse aside. Very sad.

 

Scotty

[l67ss]

Thers a dude that installed an m90 and 284 in his 96 z34

I've done some poking around about the DOHC 3.4L GM V-6 and I am baffled that there aren't more mods for it. I've read the story about how GM designed it to produce 275+ HP but it was limitations from the Hydra-matic division that de-tuned it to a 210hp engine. I believe this is complete hogwash.

 

The Hydra-Matic division of GM had been building FWD transmissions since 1966, first for the Oldsmobile Toronado. It was a TH-425...kind of a TH-400 with the tail end bent sideways. It sat behind a HC Olds 425CID with 385HP and 480lb/ft of torque. Twenty-some years later they couldn't build one to even handle 210hp? Not only that... but over the entire production of this engine to 1997, HP only increased by 5? So, Hydra-Matic couldn't improve on their best FWD transmission to accept any more than 5 additional HP over another 6 years? 1994 saw the introduction of the supercharged 3800, capable of 225hp in front of a 4T60E HD. 1996 saw the introduction of the Series II Supercharged 3800 with 240hp. If the DOHC 3.4 was detuned so much, it certainly should have been unreigned by then!

 

Still... after all these years, and all the potential of all that natural aspiration, there are so few mods? Swap it out or add turbo is about all I read.

 

So, for the shadetree mechanic, what's there to do?

 

-modified airbox

-bigger TB

-TB coolant bypass

-exhaust

- engine mount wishbone

 

Very depressed that an engine with such potential gets tosse aside. Very sad.

 

Scotty

[Galaxie500XL]

I suspect the reason there are so few mods for the LQ1 is there were very few LQ1's actually produced, relative to other engines GM used in the same car lines at the time. IIRC, the LQ1 was a $1700.00 option on my '95...which would be awfully close to 10% of the base price for the entire vehicle...not exactly a winning strategy to encourage widespread use.

[Nas Escobar]

I thought the LQ1 was the "high performance" engine for the W bodies, and was found in more than half of W bodies produced... moreso in Cutlass and Grand Prix versions of the W. How is it that no one wanted to make performance parts for these cars?

[19Cutlass94]

These cars are not what you would call 'popular'. There is no market for these cars, and what there is, is very small. Thus the reason for so few , aka WOT-Tech and only a couple others make/offer performance parts for these cars.

 

For 99.8% of the population, these cars are beaters.

[RobertISaar]

the whole "story" behind the 270-300HP LQ1 is nothing but a fanboy fabrication using extrapolated quad4 numbers. that being said, the 4T60E and most 4T65s really do not take well to a lot of torque without stuffing in upgraded parts. even then, the heftiest engine a 4T65 ever dealt with was the LS4 making ~320 lb/ft and they're notorious for killing them in short order.

 

if you want to build up a LQ1, there are options out there, depending on if you want to stay N/A or boost it. the 96-97 heads were improvements over the 91-95, as were the intakes. the 94-95 cams seem to be the best stock grind cam available. getting any reground is kind of a difficult(and potentially expensive) process, though IIRC, CHRFab may still be willing to do them....

 

there are a few boosted builds out there putting down up to 400WHP without any really special attention needed, generally the trans will be the weak link before anything else IF the calibration is well taken care of.

 

realistically, you could build a N/A LQ1 up to the 270 crank HP range.... but you're going to cause a lot of stuff to suffer along the way, especially your wallet.

[Galaxie500XL]

Far fewer than 50%. IIRC, the '95 Cutlass had the LQ1 in only around 9% of the entire model year run. Considering that Oldsmobile made just over 100,000 Cutlasses in '95, that would translate to fewer than 9,000 LQ1's found in Cutlasses in that model year. When you stop and consider the LQ1 was exclusively offered in W-bodies, there just aren't that many out there.

 

I thought the LQ1 was the "high performance" engine for the W bodies, and was found in more than half of W bodies produced... moreso in Cutlass and Grand Prix versions of the W. How is it that no one wanted to make performance parts for these cars?

[l67ss]

Theres bunch in the jy around here. sorry had to

Far fewer than 50%. IIRC, the '95 Cutlass had the LQ1 in only around 9% of the entire model year run. Considering that Oldsmobile made just over 100,000 Cutlasses in '95, that would translate to fewer than 9,000 LQ1's found in Cutlasses in that model year. When you stop and consider the LQ1 was exclusively offered in W-bodies, there just aren't that many out there.

[RobertISaar]

probably people that changed the timing belt once and when it went again, scrapped the car.... that seems to be how it happens around here anyways.

[l67ss]

Yeah some are pretty decent cars. Kinda tempting to buy and build a lq1 just for the hell of it. i am gonna use an lq1 radiator in my 3.8 s/c build though.

probably people that changed the timing belt once and when it went again, scrapped the car.... that seems to be how it happens around here anyways.

[Psych0matt]

lots of little things you can do. I didn't know that the 94-95 cams were better, I may try to get a hold of some of those for when/ I do my intake swap, since I'll most likely do the timing belt at the same time.

[l67ss]

Theres three 95 monte z34 dohc in the jy i go to

lots of little things you can do. I didn't know that the 94-95 cams were better, I may try to get a hold of some of those for when/ I do my intake swap, since I'll most likely do the timing belt at the same time.

[Nas Escobar]

probably people that changed the timing belt once and when it went again, scrapped the car.... that seems to be how it happens around here anyways.

 

I've noticed most people junk GM cars because they don't want to be bothered with fixing some of the rather off problems like the belt/chain, the gaskets, or because they mixed dexcool with green coolant. As far as the LQ1, most I see at the yard have relative low miles (130K - 160K) and are in ok condition. A to B type cars. I tend to notice most people just get rid of them when something on em is wrong and it is expensive to fix.

[1988PhantomFE3]

LQ1 or QUAD4 Build? Which one should I choose to do? I always assumed the stock '94 LQ1 had unlimited aftermarket parts available...guess I was wrong...

 

Thinking either one is going to run me some Green Backs, especially those new $100 ones with that center strip thing that makes me feel drunk when I stare at it...

[RobertISaar]

there really aren't aftermarket parts for either of them..... the quad4(in L and N bodies) has a header available and a cam or two out there..... but not much else.

[Galaxie500XL]

If I were determined to build a V-6 with at least some aftermarket support, I'd suppose the L67 would be at the top of that list. Most everything else that fits in a W would be pretty much spotty at best--unless you're thinking of putting a V8 in the car. After all, at the end of the day, it's pretty hard to beat cubic inches.

[l67ss]

Id build one just to build it, not to run it

[rich_e777]

Yeah some are pretty decent cars. Kinda tempting to buy and build a lq1 just for the hell of it. i am gonna use an lq1 radiator in my 3.8 s/c build though.

Grab some washers to space the fans out a bit. Walking a klick and a half round trip to replace a radiator is only fun if you have a clever message on the box. Vegas?

[l67ss]

gonna have to do some work with the fans anyway, im gonna swap to gen 2 fans at the same time

Grab some washers to space the fans out a bit. Walking a klick and a half round trip to replace a radiator is only fun if you have a clever message on the box. Vegas?

[scottwhite98]

I know this engine is perticularly rare in Cutlass W-Bodies. I used to pay a lot of attention to these cars and just saw my first CS SEDAN with a 3.4DOHC. With a moonroof, no less, but very very rough shape...sad for what a rare car it is.

 

As for the 3.4DOHC, I figured there'd be aftermarket cams for them at least... I've read that most chips are just fancy governor eliminators. There's just so much potential with all that air flow. Too bad it's so expensive to utilize it.

 

It's true that a lot of people don't realize/appreciate what they have and scrap cars that really ought to be saved.

 

Scotty

[RobertISaar]

I've read that most chips are just fancy governor eliminators.

 

not really.... with a couple of keystrokes, the 10HP advantage that the 91-93 manuals have over the 91-93 automatics is back, if not more. i've done a premium fuel tune for someone running a 95 and they picked up ~5MPH at the end of a roughly 1/4 mile distance.

[scottwhite98]

What chip is most recommended?

[RobertISaar]

Ben does good work with the LQ1. WOT-Tech.com would be his store, or you could contact him on 60degreev6 or even here, assuming he still checks his PMs.

[crazyd]

not really.... with a couple of keystrokes, the 10HP advantage that the 91-93 manuals have over the 91-93 automatics is back, if not more. i've done a premium fuel tune for someone running a 95 and they picked up ~5MPH at the end of a roughly 1/4 mile distance.

 

So, hold on. Does this mean that the 10hp difference between 91-93 autos vs manuals is in the computer rather than the heads?

[RobertISaar]

there is no head difference from auto to manual. the theory for the 10HP difference since forever was that there was a .5(or was it .25?) difference in compression from auto to manual due to pistons.... well, the pistons are identical from auto to manual, along with the heads and headgaskets, so no possible change in compression there.the 10HP difference is done through a combination of two items: the manual having RDSC spark allowed and the auto having a LOT of torque management built into the calibration. during rapid acceleration, RDSC(RPM derivative spark control) will add up to x amount of spark depending on how quickly RPMs are building and is referenced by gear. torque management will remove spark based on a couple of situations.