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The Inevitable Comparison: GM 6.6 vs. Ford 7.3


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We don't know the whole story yet, but some of my observations so far:  Looks like GM simply when with an enlarged Gen. V version of the current L96.  Other than increased displacement, the only new features appear to be a forged crankshaft and direct injection.  The horsepower and torque figures are impressive and should be more than adequate even in a medium duty truck.  The engine has nothing in it that has not been in other LS engines for years, and should be completely reliable and as durable, if not more so, than the L96.  The Ford 7.3 is a completely new engine platform unrelated to any existing Ford engine.  Ford had to take this approach supposedly because the 6.2L was unsuited for medium duty truck use.  The 7.3 is not technically advanced and is strikingly similar in some regards to the LS.  It's bore spacing is a little larger than the LS.  Since Ford was not constrained using an existing engine's tooling, they probably figured what displacement they wanted and sized the block accordingly.  Ford has not released H.P. and torque figures yet.  I expect the 7.3 to have a little more H.P. and torque than the 6.6, but I think the 6.6's direct injection will largely make up for its smaller displacement.  I also think the 6.6 will be more fuel efficient.  And, I think GM spent a lot less money to develop their new engine.        

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I would not doubt 550 lb ft from the Ford... besting GMs setup by 100 lb ft should be no issue with 445 cubic inches.  Direct injection will not make up power.. The current 6.2 Ford is only a 34 lb ft deficit to the gm 6.6 so this 7.3 should be somewhere well above 500 lb ft.. possibly approaching 600 lb ft peak.  

 

Gm spent nothing to develop their engine.  They took a current gen V, cast the block in iron and did not add afm or dfm.Its nothing more than a stroked 6.2... same old 4.065" bore size with a 3.858" stroke crank.   I'm more excited to pull these 6.6s from these trucks and do performance oriented things with them in other vehicles.  That or even use the rods and crank in an LS block.

Edited by SierraHD17
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The 7.3 is definitely targeted to being a Triton V10 replacement, and I feel will probably the only gas option for F450 and F550, and then be the gas option for F650 and F750.  I think the 7.3 was really targeted for those trucks primarily and It just happens to fit into the F250 and F350. 

 

I think GM picked a good displacement size, and bumped the power rather well over the 6.0.  I did notice GM didn't claim any weight loss, and its 5 inches longer wheelbase over K2 HD, and longer overall, so more weight.  That has me slightly concerned.

 

I'm more bothered by the absence of the 10 speed with the 6.6.  I wonder if Ford had anything to do with that though.  Perhaps as part of the joint venture, they got first dibs for HD trucks?   

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  • 2 weeks later...

I have seen a little more of the 7.3L's insides, and have noticed a few things.  First, the head bolts are very short.  The pushrods, valve springs, and valve stems are quite long.  Not sure why they did this, it doesn't appear they needed to be that way to clear the intake ports.  Appears to have siamesed cylinder bores with open slots machined between them.  I understand the desire to get a little coolant flow between the cylinders, but I wonder if the slots will compromise head gasket sealing.  The L8T has siamesed cylinders too, but with bored coolant holes between the cylinders (GM has done this on hi-po crate engines).  Block deck surface between the cylinders uncompromised.  7.3L's exhaust ports and manifolds look very good.  7.3L block casting looks very thin in places, I am very curious to find out what it weighs.  Overall, the 7.3L looks like a good engine for larger trucks, but does not appear to have a lot of high performance potential.  I also see Ford is keeping the 6.2L around in the F-250 and 350.  I take that to mean the 7.3L will probably be a lot more common in the larger commercial trucks than pickups.   

 

The funniest thing about the 7.3L is after 20+ years of hearing how outdated the LS engines are compared to the Ford Modulars, the 7.3L has PUSHRODS!        

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  • 4 weeks later...
On 2/7/2019 at 2:20 PM, Sierra Dan said:

Weren't the Triton V10 engines a joke? Unreliable gas guzzler to say the least......

My neighbor had one and it spent more time in the shop than on the street from what I remember.

Only thing I’ve herd about ford v10 was they loved sucking ⛽️. Not very impressive on power but I thought they were fairly reliable and better overall engine than the dodge truck v10. 

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  • 2 weeks later...

I’m very interested in these motors, but the 6 speed in the GM trucks in really forcing me away. Direct Injection is not helping me to stay with GM either.  I don’t know why it bothers me given that both of my current vehicles are DI.  I’ve just read so many bad things that it causes me to hesitate a little, especially since I plan to order my next truck, exactly how I want it, and keep long term.

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16 hours ago, rjpoog1989 said:

I’m very interested in these motors, but the 6 speed in the GM trucks in really forcing me away. Direct Injection is not helping me to stay with GM either.  I don’t know why it bothers me given that both of my current vehicles are DI.  I’ve just read so many bad things that it causes me to hesitate a little, especially since I plan to order my next truck, exactly how I want it, and keep long term.

Direct Inj. is actually the way to go. About 5% more efficient and tremendous torque on the low end. I would NOT be scared of this engine. I have an LT1 in a 17' Camaro SS and the new 6.6 has more low end torque.

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  • 2 weeks later...

I will take the 6.6L when it is offered with the 10 speed auto. 

 

My 6.2 pulls our 4000lb enclosed trailer just fine. Now if I buy a 9klb loaded toy hauler in the future. May need to go HD

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The new 6.6L is not an LS engine. It is built on LT architecture. As far as DI far out performing port injection, not so much. The LS was port injected, we will use the 6.2L LS3 compared to the new LT1 for example. Same bore, same stroke, same overall displacement, essentially, GM changed upped the compression ratio and changed the fuel delivery method. With all that they only gained 20hp and 10lb-ft. If you took away the increase in compression, you would be talking 5hp, 2lb-ft gains from port injection to direct injection. Now, about the truck. Yes the new low end power increase would make the 2500 gasser and awesome unit and it wouldn't feel like such a dog. However, GM decided to change the final drive ratio from a 4.10 to a 3.73. This will likely take away and felt power increases available with the new gas mill. Pretty disappointing but it will lead to better interstate fuel economy, but what we were all after was to have a gas truck with some power, not take away the power increase through parasitic drivetrain loss. 

 

The 7.3L will be a beast, it is the engine we have been wanting Ford to build since the 302,351,460's went away, Injected, OHV, 6 bolt mains. Basically we wanted them to copy GM's LS because it was soooo good. We didn't want a SOHC or DOHC truck motor, save that crap for small engines and sports cars. I do find it a little disappointing it is technically a big block, but you will see guys in the aftermarket bolt on a big turbo on these things and make near 1,000hp on a stock motor if the connecting rods will hold. 

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