GM 3.6 experts... Why the disparity between different LFX engines? (Page 2/7) lou_dias AUG 31, 08:58 AM One thing I can tell you is that it uses 3.7" diameter pistons and they look like the 3.4 DOHC pistons but slightly bigger (vs. 3.62"). When you bore a 3400 block to 3.7" bores you end up with a 3.5L engine... 88cryan AUG 31, 02:16 PM quote Originally posted by dobey: Which 3.6 are you talking about exactly? The earlier 3.6 timing chain issues were corrected in later revisions (ie, the LFX which is specifically the one asked about in this thread). Kinda like the corrected/revised lower intake gasket on the later 60* V6?, and I'm currently in the middle of a lower intake job on a 3500. The frequency may have went down with the revised chains but we still change them in newer cars at work for stretching (check engine light with cam/crank correlation codes). We have to reseal timing covers on low mileage 3.6 engines 1-2 a week and I've seen them with seepage at under 10k miles. Not to mention the other issues like misfires and carbon build up. I have zero faith in reliability in this engine but they do sound awesome at wot in any car/suv they are installed in. dobey AUG 31, 02:38 PM quote Originally posted by 88cryan: I have zero faith in reliability in this engine but they do sound awesome at wot in any car/suv they are installed in. Well, too much of the latter certainly has an effect on the former. But again, what engines exactly are you seeing this on mostly? There are many 3.6L DOHC V6 engines in the engine family. And what about other engines in the High Feature family? Most all the complaints I've seen have been about the 3.6, and see almost none about the 2.8, 3.0, 3.2, etc… versions. How many of these that you claim you are doing so often are the LLT engine? How many are LFX? How many LGX? LF3? LF4? LFR? 88cryan AUG 31, 05:00 PM I don't know which engine is installed in what cars...but by far the most are the gmc Acadia suv family, followed by the equinox family. Also I have seen several cts, srx, camaros, Malibu, and g6. The newest front cover reseal was on the new gmc canyon. We have re sealed the 3.0 before in the cts but I've never seen a 2.8 and our dealerships do not sell saab so I've never seen their version. Keep in mind we have most every make model but it's only a sampling of the gm market, we'd need agm technician to tell us their version. Joseph Upson AUG 31, 06:07 PM quote Originally posted by lou_dias: One thing I can tell you is that it uses 3.7" diameter pistons and they look like the 3.4 DOHC pistons but slightly bigger (vs. 3.62"). When you bore a 3400 block to 3.7" bores you end up with a 3.5L engine... No need to bore a 3400 to those specs to get a 3500 as the 3500 non VVT shares the same bore with the 3.6L and the pistons were considered by Superdave on the 60 degree forum as a means to bump the compression up in his built 3500 that I believe had reached 300 hp naturally aspirated with its stock compression ratio. Raydar AUG 31, 06:34 PM quote Originally posted by Joseph Upson: Interesting inquiry, I've been researching these specs since last week in consideration for buying an 08 or later Cadi CTS. I'm not sure what years the specs you posted cover but much of that diversity in performance output possibly addresses integral vs. traditional exhaust manifold arrangement and port vs. DI injection which apparently is still an option, along with the other differences you mentioned although I'm not sure about cam changes playing a big part from what I encountered in the past on that subject as they are usually the same throughout a particular engine nomenclature and often across. The Cadillac CTS received the first highest output 3.6L with DI and some fancy cylinder head work along with a compression ratio bump and some other stuff I don't recall and apparently the Camaro eventually received the same engine. There is a crate 3.6L upgrade for the 2016 ATS that produces more power than any of the engines you've posted, here; http://www.karlperformancep...Karl-Chevrolet/46462 As for the timing chain problem, I read a couple of days ago that a good bit of that problem appears to be the result of prolonged oil change intervals which an owner states a good faith recall was offered for, that would adjust the oil life monitor programming to require shorter oil change intervals. Another owner stated the real problem was not the chain but VVT module wear in conjunction with sensitive DTC programming that caused engine lights to come on and stay on, an issue that was also stated to have been addressed in the good faith recall with an adjustment to the programming to increase the required thresh-hold to trip the light, which more frequent oil changes were also alleged would help by reducing wear. Thanks for that info. I specified the LFX, since it seems to have the most available power, without having to deal with DOD (cylinder deactivation.) It's just not something I am interested in. Of course, I may have missed some vital detail. I've just begun to research this. (This is all "pie in the sky" anyway. You may recall that I am also considering an LZ9/LGD for my swap, as an alternative. They all have their pros and cons.) quote Originally posted by dobey: The HP ratings are crank HP, not wheel HP, so what trans comes with is mostly irrelevant. ... I understand that. I'm merely considering the possibility that the "transverse automatic" engines may have been purposely detuned in order to ensure transaxle longevity, and reduce warranty claims for broken trannies. Will AUG 31, 07:46 PM quote Originally posted by cvxjet: I don't have any facts, but the usual reason for that large a HP difference would be different cams- The family car gets a "torque heavy" cam while the Camaro gets a cam that concentrates more power up high, including a high peak for bragging rights.....Different exhaust and even more restrictive intakes usually don't make that big a difference...usually only 5-15 hp. There also may be differences due to later model improvements. With variable cam phasing on a DOHC--meaning that intake and exhaust phase can be adjusted independently--the "torque cam" vs. "power cam" are all handled in the tune. Will AUG 31, 08:00 PM quote Originally posted by 88cryan: Kinda like the corrected/revised lower intake gasket on the later 60* V6?, and I'm currently in the middle of a lower intake job on a 3500. The frequency may have went down with the revised chains but we still change them in newer cars at work for stretching (check engine light with cam/crank correlation codes). We have to reseal timing covers on low mileage 3.6 engines 1-2 a week and I've seen them with seepage at under 10k miles. Not to mention the other issues like misfires and carbon build up. I have zero faith in reliability in this engine but they do sound awesome at wot in any car/suv they are installed in. That's an interesting timing drive. cmechmann AUG 31, 08:27 PM Yes the 3.6 we are seeing a lot of issues are the Arcadia, Equanox and Cadi clone. From about 08-11. The timing component issues would cause just enough "slop" in the timing chain to cause correlation codes. When you had scopes hooked up to look at the patterns, you could see the cam signals move around. You need a scope with 4 signal or 2 with 2 signal. You would dial in the patterns to get them even. Then slowly bring the rpms up and back down to see if the patterns would migrate around. You would normally see the patterns go off when the rpms came back down when the engine was under a decell condition. The timing between the front and rear cams would bounce around. Most of that was in the chain and the center guide. These were on engines, for the most part, were maintained and under 100,000. Yes we also seen phaser problems on those that had too few oil changes. The phasers would get "stuck" causing performance issues and correlation codes. We were seeing other issues on earlier 3.6s. These also were in the crossover type vehicles. It had to do with excessive oil usage to the point it would puke oil into the vacuum chamber right after the throttle body. This would cause oil to leech down into the vacuum booster. Then it would saturate the vacuum sensor in the booster causing an ABS code. The dealers also seemed to have plenty of the boosters in stock. The 2.8 56 degree engine in early 2000s CTS were known for burning oil. Odd the timing belt version of the 3.0 in older Saturns, seemed to be dependable as long as they didn't have a timing belt failure or they were over heated. dobey AUG 31, 09:04 PM quote Originally posted by Raydar: I understand that. I'm merely considering the possibility that the "transverse automatic" engines may have been purposely detuned in order to ensure transaxle longevity, and reduce warranty claims for broken trannies. I don't think much of the detuning is done for that. Torque management programming doesn't affect peak HP/TQ numbers, only how the torque is applied in certain conditions. Most of the tuning for dealing with transmission longevity and warranty concerns is done via the torque management. I think several of the transverse applications are also AWD, so there may be some tuning for that type of application which may result in slightly lower peak numbers.