6.4 vs 6.7

getstuk · Sep 17, 2013

I've been saving up for the past 6 months for a 6.4L, I waited this long because I wanted extra cash to build her up to push 750ish rwhp. I am nearly ready to pull the trigger. The modding is highly unlikely to stop there just like what happened on my last truck, but I am curious what those who have already done this think. Would you do it again? How is the drivability? How is towing (I'll be towing a 42ft toy hauler)? (Specifically directed at those who are over 700rwhp (aftermarket turbos) on the 6.4L)

I've considered the 6.7L but it doesn't appear to make hp as easily, I strongly dislike the headlights and grill (what were they thinking), and the interior (at least in pictures) seems less attractive. The lariat interior in the 08-10 superduties was done tastefully and I was never in a position to afford it so I admired from afar...but not anymore. Just my opinions, would like to hear what the consensus is on the 6.7 body style compared to the 6.4?

01PSD · Sep 17, 2013

Everyone says once you sit inside a 6.7 and ride in it... your opinion will quickly switch away from the 6.4 interior being better.

WoodBoy · Sep 17, 2013

The body style and interior are substantially nicer in the 6.7 than the 6.4 in my opinion. They ride better also and are quieter (motor wise). I just installed an H&S with 5" DP back on my buddies 2013 6.7 and he is on a 6" lift with 37s and 22s. It moves pretty good. Not 6.4 fast but It does move good

If you are going to be towing much, I would say the 6.7 is the way to go. If you want a toy the 6.4 is the way to go. Don't get me wrong, I like my 6.4 and the power it has, but the 6.7 is just so nice to drive if you are going to be driving a truck everyday. I wish I had a 6.7 just because I drive my truck everyday and use it for everything. Honestly if you look at most of the guys who had the higher hp 6.4s and now have 6.7s, they haven't even programmed the 6.7 just because of how nice it is alone in stock form.

12stroker · Sep 17, 2013

Now if this is going to be a DD I would get a 6.7 hands down interior is a lot nicer then a 6.4.
Now if its power you are after get a 6.4.

getstuk · Sep 17, 2013

I'm glad I posted this question, because the last thing I want to have is buyers remorse when I'm sitting in a 6.4L and realize there is something better. I've driven a 6.7L a few years back and wasn't as attracted to the interior as much, but I'm worried that you are right and I'll come around.

12stroker, can you elaborate on what you like better about the Lariat interior in the 6.7L over the 6.4L? This is what I'm comparing to.

12stroker · Sep 17, 2013

Ok I like the full center console and ac vents in the back. Also having the information center it's nice being able to program your trailers. Having heated and cooled steats are a must I test drove a few without them and it was a option I am glad I got.

Corb@CorbinShipping · Sep 17, 2013

If you want a toy, that tows every now and again, get the 6.4. No doubt about how easy it is to make power. It also tows pretty well.

If you want a daily driver, that tows more than occasionally, get the 6.7... I own both, and as much as I love driving and playing with the 6.4, and it is a Harley Davidson Edition f250, loaded with everything that Ford makes, the 2013s updated their interior, and my 2013 350 DRW is only a Lariat, and makes my 2010 Harley 250's interior look like a 1987 toyota...

The 6.7 spools well, runs clean, and is much easier to drive in traffic. Just doesn't give you that rush from a 800+ HP engine...

sootie · Sep 17, 2013

you wont beat the power of the 6.4 with a 6.7 for a while yet. the interiors on the 6.7s are pretty nice. i'm partial to 6.4s myself

ncollins64 · Sep 17, 2013

I'm kinda with the other guys. I like the 6.7s but I like my 6.4 also. Mine is easy HP and will tow anything I need to. I like the interior in the newer ones I think a lil better and mine is a king ranch. I think the newer ones ride better also but they have have less rear leaf springs and squats real easy. Air bags would almost be a must IMO.

getstuk · Sep 17, 2013

well thought out responses from people with non-biased experience in both, just what I was looking for.

...is only a Lariat, and makes my 2010 Harley 250's interior look like a 1987 toyota...

Corb, your response speaks volumes considering you own the 6.4L Harley body style (beautiful btw) and a comparable 6.7. I can't believe it's that much of a difference, I think I'll need to go test drive the 6.7 again to find out what I'm missing. Bums me out to be honest, neither truck seems to have it all.

12stroker, the cooled seats are probably a great feature for this southern california heat.

The 6.4L will not be my daily driver, but it will tow occasionally (once a month).

sootie · Sep 17, 2013

getstuk said:
well thought out responses from people with non-biased experience in both, just what I was looking for.

Corb, your response speaks volumes considering you own the 6.4L Harley body style (beautiful btw) and a comparable 6.7. I can't believe it's that much of a difference, I think I'll need to go test drive the 6.7 again to find out what I'm missing. Bums me out to be honest, neither truck seems to have it all.

12stroker, the cooled seats are probably a great feature for this southern california heat.

The 6.4L will not be my daily driver, but it will tow occasionally (once a month).

if the truck is not a DD and is mainly a toy-go with a 6.4...there is a TON of aftermarket support and the ability to make BIG power.

uga33 · Sep 17, 2013

Just went from a tuned and deleted '09 KR 6.4 to a stock '12 6.7 KR. Power was fun. It towed okay. Once on the interstate it was a monster, but the way it had to get the loads started annoyed me. Leaf springs were soft on the 6.4, but the 6.7s springs are softer. Power comes on quick and strong with the 6.7. Love the manual shift option and being able to lock out gears on the 6.7. Love the cooled seats and flow through console. My biggest complaint about the leather (King Ranch) between the two is that the '12 leather scratches way too easy compared to the '09. LOVE the way the 6.7 tows!!

Matt · Sep 17, 2013

If they didn't cost so much, and if I drove my crew cab more often, I would trade it for a 6.7 in a heart beat. For the small amount of driving I do, and the price tag, I just can't justify it right now.

Dzchey21 · Sep 17, 2013

First off... dream on with a 700 hp truck that can tow a 42 foot anything... and be reliable

Corbin said it best as well as others

towing a trailer with a 6.7 is much better than with a 6.4, my 6.7 is stock and is keeping me plenty happy but it sees alot of trailer time

cory151 · Sep 18, 2013

Theres always gonna be something better, its much better to want what you have instead of always trying to get yourself in debt with the latest and greatest. Besides these trucks do exactly the same thing, your in fact opting for a slightly less powerful potential engine.

getstuk · Sep 18, 2013

Dzchey21 said:
First off... dream on with a 700 hp truck that can tow a 42 foot anything... and be reliable

Corbin said it best as well as others

towing a trailer with a 6.7 is much better than with a 6.4, my 6.7 is stock and is keeping me plenty happy but it sees alot of trailer time

I was hoping someone with your experience would chime in. Couple questions, there are products like the Elite Tow Power setup to help in that area. But before we talk about that, many seem to tow often with the spartan 310 tunes (we're almost to 600rwhp) without issue. Is the additional 100-150hp the difference between reliable and non-reliable towing? For the record, I would like to have the throw you back in your seat top end power (I'm sure this eliminates the tow power setup), but would like to maintain some level of occasional heavy towing ability.

By the way thanks for chiming in guys, it's surprising to me that nobody regards their 6.4's as very good at towing in comparison to the 6.7. What can we attribute that to, low end torque on the 6.7, better turbo setup? I'm starting to worry about whether the 6.4L will tow the trailer well at all, we're talking 15k~ lbs.

Dzchey21 · Sep 18, 2013

Its not so much that there arent products that are towing capable at 700 or even 800 hp. Its just really difficult to make that kind of power, with as little displacement as we have live very long.

The heavier things get the harder it is on input shafts, transmission parts, torque converters ect. OF course you can always back the tune down to run say 550-600 hp while towing but not allot of people stick with that.

If you want good top end you will need a bigger atmo charger. but stay small with the high pressure. I think elite is offering a raw power compound set up thats like a 59mm vgt with an 82? Atmosphere turbo, its supposed to be inexpensive. Personally i think this would be the closest thing to do what you want. good low end, the atmo is still going to make good boost cruising and towing.

To cover the rest of the engine i would have IH pistons that are coated. I would run a 60% nozzle and back the pw down for towing, that should help it run cooler egt wise. The trans will have to be pretty well built stage 4 i would say with a good converter.

Its not IMPOSSIBLE but it will be hard to do and will probably need baby sat as far as towing a driving with someone who knows to watch all temps ect

6.4strokin · Sep 19, 2013

There's a reason why tow tunes are only around 50 hp. It's not all about horsepower when it comes to towing. 6.7s are great stock motors I think ford really did a beautiful job with them. They're quiet got good power and a lot of torque from factory. 6.4s could possibly be the worse stock Diesel engine to be put in a ford. Mainly because dpf. Obviously tuned and deleted its a different story. Interiors u can't even compare I love the 6.7 interior compared to my 6.4s. I do love my 6.4 mainly because it has compounds from factory and the bottom end can hold some power. Since it has compounds it runs super cool. But at the end of the day 6.7s are more reliable then a 6.4.

Sent from my iPhone using Tapatalk - now Free

swinky · Sep 19, 2013

700hp 6.4 that tows will most likely have some major issues. Tuned 6.7 gets my vote.

getstuk · Sep 19, 2013

Are there any shops you'd recommend I talk to? Elite, Rudy's, Spartan...? I'm in Southern California so local would be preferable but I'm going to be doing business with the vendors.

I know my desires are somewhat unusual but detuning it for towing should hopefully be enough to keep reliability up. I'd really like to have a larger atmospheric turbo, something like the Gtx4508r (inspired by user younger19931) but run it with a high pressure that is capable of spooling at towing RPM's as well. I know there needs to be a decent boost mapping relationship between the two turbos but that is where I'm still doing research. I think I've ruled the 6.7 out at this point, as aftermarket power is of high importance to me.

I just looked but have not seen anything about the Raw Power setup from Elite yet. I'm impressed people are still making modifications for this engine, is this the case?

When you say "back the pw down for towing", I'm assuming you are referring to pulse width?

Beyond that, I'm going to take care of this truck pretty well, she'll have a lot of downtime so I'll have to buy her some toys to keep her entertained...