SVTPerformance Fueling the Fire : Gas Vs. Diesel Debate

[JTStreet]

Jealousy is an ugly color on you.

Hey everyone, look at me! :beer:

 

[REX-RACER]

Insurance cost is less on the gas trucks, but that's mostly due to their overall lower replacement costs if totaled. Whipple is supposed to be coming out with a blower for the 6.2L. Should be fun if you added some E85 to the mix.

DING, DING, DING! I know some will point out adding a f/i to a gas truck will necessitate the use of premium gas which costs on par w/ diesel or E85 which will lower gas mileage but I think those elevated fuel costs will still be off-set by regular maintenance costs for a diesel.

 

[DevilSun]

Since ford started making their own diesels the warranty is only 60k mile.

This is not true. It's 5 years/100k, see here. Don't mind that it says 6.4, I have the warranty book in my truck outside and it says the same...5 years, 100k.

 

[85FourEyedGT]

very good writeup!!

any chance you will do a comparison of the twin turbo v6 truck vs the the gas v8s? that would be awesome because i want a practical truck but 400+tq is enough for me

 

[SID297]

This is not true. It's 5 years/100k, see here. Don't mind that it says 6.4, I have the warranty book in my truck outside and it says the same...5 years, 100k.

Good news.

very good writeup!!

any chance you will do a comparison of the twin turbo v6 truck vs the the gas v8s? that would be awesome because i want a practical truck but 400+tq is enough for me

Thanks. That is something we'd like to do sometime in the future. We'd just have to set it up with Ford.

 

[DevilSun]

This was a very good write up, and had it been done before I got my truck I may have thought about it longer. In the end, so far, I absolutely love everything about this truck, engine included...but it only has just over 1,000 miles and has only towed a 21' Natique ski boat once. I have faith that Ford did this engine right, they're running out of "shots" to get it right, and from what they learned with EcoBoost development and the testing they did on this one, I have a lot of faith and I don't think it's ill-placed. Granted, the diesel may be overkill for me and my use in this day and age but truly only time will tell that as now all of this is pure speculation...but having it there when I need it is going to be great. Great write up and way to be extremely honest and unbiased.

 

[sneakysnake03]

It looks to me like the car manufactures are going toward 1 fuel source. Gas engines are going direct injection and are runing higher fuel rail pressure so you now have a high pressure fuel pump. They are getting turbos and making a lot more power per cubic inch. Diesels are being hit hard with emissions so they are getting redone. Ultra low sulfer fuel which is just like what happened to gas except it went unleaded. sulfer acted as a lubricant just like lead did in gas. With that being said because I'm getting off topic a little I think They should just go ahead and make the jump to clean diesel like they have in Europe because that is where we are headed slowly but surely.

 

[Great Asp]

You seem to fall into the "need a diesel" category. What killed the gassers you had? :

We bought a the 3 valve V10 in 2005 and 2006. We also got a great deal in 2006 for two old 2005 6.0 PS units (new not sold) that we bought. The V10's DRANK gas, which I suspect had something to do with my hot footed service techs.

But they stopped pulling at 110,000 miles (3 years), we still own both 6.0's. Both of the V10s needed rebuilding in the next 20,000 miles so we pulled the service bodies off and sold them.

Had our share for the EGR cooler on one of them, but cost of ownership when you factor in the cost of fuel gives the diesels the nod.

My DD is a 2005 6.0, I have 185,000 on it now.

E

 

[cottondoc]

I own a diesel truck which I absolutely love. I am one of the guys that just had to have a diesel because I wanted one. I definitely don't have a legitimate need for a diesel. I do love it and will probably always own a diesel truck as long as I can afford it. That being said, I bet 90% of diesel truck buyers could not justify purchasing a diesel based on financial reasons alone. This includes most commercial businesses. Unless you tow loads daily that a gasser had difficulty pulling, in most circumstances it would be cheaper and make economical sense to buy the gasser. Even most commerical truck users could buy a new gas truck every 2-3 years cheaper than buying a diesel less often. That's just my opinion.

My real reason for this post is the Ford 6.2L hurricane V8. This is a performance site, right? We all need to get together and beg Ford to build a real performance version of this motor and put it in a mustang or bring back the GT to put it in. Don't get me wrong, I am impressed with the new 5.0, but I want some cubic inches. Can you imagine what an over-square(4.125 borex4.00stroke) 7.0L, 32 valve DOHC version of the hurrican would do?!?! A friend of mine has a 6.2L Raptor and I love that motor! It screams for a truck motor! If Ford build a 7.0L version with 32 valves that would turn 7K rpms it would make 600hp, naturally aspirated with a conservative tune!! We can't let Ford squander the opportunity they have with this motor. They have to build a performance version and put it in something. Even if they bring back the GT(which I could never afford), eventually a crate version of the motor might be something I could buy. I really want a modern, big cube performance Ford V8. If Ford build a 7.0L supercharged version of that motor and put it in the GT with no changes other than minimal updating of the GT's chassis, that would be a world beating supercar. That car with 20 pounds of boost would make well over 1,000hp and embarass a Veyron. People would be pulling the supercharger, adding twin turbos and running 300mph in the standing mile!! Anyway, I am just trying to get as many people on board so we can convince Ford to build a performance version of the 6.2L or at least offer a performance version(bore capable of 4.125) of the block through FRPP.

 

[rip04ow]

i miss my 08 6.4 but it was the biggest pos ive owned and im only a ford guy. i have a powerstroke turbo blowing black smoke tattoo on my rib cage . < (true blue oval love)

i lost 70 days of work in the first year i owned it and it ended up forcing me to close my business and work at a factory job for $10.00 bucks a hr. ive always been diesels and always a ford guy but unfortunately i probably wont own another ford diesel unless the new ones are in fact so much better or if its an 03 7.3

anything after 07.5 whether its ford gm or dodge they will all have problems as they try to fight through all the emissions problems but hopefully fords new motor will bring back some hope for me.

If i had to buy a diesel today id buy a durmax

If i had to buy a gas definitely 3.5 ecoboost, 5.0 or 6.2 and i wouldnt buy any other gas truck besides a ford

 

[Jdaniel]

We bought a the 3 valve V10 in 2005 and 2006. We also got a great deal in 2006 for two old 2005 6.0 PS units (new not sold) that we bought. The V10's DRANK gas, which I suspect had something to do with my hot footed service techs.

But they stopped pulling at 110,000 miles (3 years), we still own both 6.0's. Both of the V10s needed rebuilding in the next 20,000 miles so we pulled the service bodies off and sold them.

Had our share for the EGR cooler on one of them, but cost of ownership when you factor in the cost of fuel gives the diesels the nod.

My DD is a 2005 6.0, I have 185,000 on it now.

E

My point exactly. In the end the gas engine will not be cost effective. My 2002 7.3L had over 200,000 miles on it when I traded it in for the new model and it was still going strong. Just had issues with loose steering. the 2002 7.3L was a two wheel drive crewcab and still got $10,500 for trade in and it wasnt in the absolute best condition either. LOL

 

[SID297]

My point exactly. In the end the gas engine will not be cost effective. My 2002 7.3L had over 200,000 miles on it when I traded it in for the new model and it was still going strong. Just had issues with loose steering. the 2002 7.3L was a two wheel drive crewcab and still got $10,500 for trade in and it wasnt in the absolute best condition either. LOL

You mean was not cost effective in that situation? What about in a situation where someone occasional tows a boat, camper, or car to the track?

 

[Jdaniel]

You mean was not cost effective in that situation? What about in a situation where someone occasional tows a boat, camper, or car to the track?

Well in most situations (like I mentioned before) the diesel will outlast the gas engine by double its life.

This gentleman just mentioned how they suck down gas. Very true. Fords (and Chevy as a matter of fact) get horrible gas mileage towing or not. So the extra .30 per gal for diesel fuel eventually isnt so much. Obvisously the diesel holds its value better. It costs me $55 to have my oil changed at the dealership and maintenance is quite a ways down the road with my 6 year 100,000 year warranty. The oil change on my corvette was double that. Anyhoo... ive mentioned all that. Just wanted to reiterate.

I occasionally tow a car to the track... and then I sold the Corvette. Now I have an F350 for a daily commuter. Actually my wife driving it till she arrives here in Abu Dhabi with me and then it will go into storage till we decide to return stateside. I believe its falls mostly under personal preference. I will NEVER own another gas powered truck because of all the issues I had out of the F150 I owned. Two engine rebuilds, three tranny rebuilds and god only knows what else because I had tons of issues with that POS. So my preference is diesel.

 

[SecondhandSnake]

Very interesting writeup. I figure that I'd throw my 2 cents in as well.

As an engineer for a massive diesel engine company, but one who actually works in the spark ignited natural gas division, I've got a unique perspective into both gas and diesel worlds. Of course I'm also not as familiar with the Ford 6.7 line, I'm familiar with another, more prolific 6.7. :-D

For all intents and purposes, a spark ignited natural gas engine behaves the same as a gasoline engine. The only difference is that you're using a gaseous fuel instead of a liquid one. You can readily convert a NG engine to gasoline, and vice versa.

Now I would have to say that in general, a diesel is a wise investment but only for those that need the power, and will hold onto it for a significant amount of time. Now let's break it down into their strengths and weaknesses.

Fuel Economy-
This is somewhat of a toss up, and there's various ways to skew the result. What I will say is that in terms of BSFC (brake specific fuel consumption) the diesel will beat the gas, hands down, every time. Notice I don't say fuel consumption period. I'll get to that later. The diesel cycle is just more efficient than the otto cycle, no way around that. This is true even with the extensive aftertreatment equipment, including the DPF regenerations that essentially dump fuel into the exhaust, and pricey DEF fluid. Note: Cummins ISB engines DO NOT require DEF and DO NOT have an SCR system like the Duramax and Powerstroke.
Of course if you're comparing the diesel to the gas, or worse still the Ecoboost, the gas will win. You also won't have the same power/torque band of the diesel, but you will use less fuel. If you compared a gas engine to a diesel engine with the exact same power/torque curve, you will see the diesel gets better economy every time. And yes, this is accurate, we use gas and diesel engines with the same base parts, and the exact same power rating. However in this case we're comparing apples to oranges. The 6.2 is not close to the same as the 6.7, and the ISB is not the same as the 5.7.

Of course if you're unethical you can remove the emissions equipment and create massive gains for the diesel, furthering the gap. Tuners for fuel economy are readily available for diesel as well, as diesel allows leaner mixtures than gas.

Outcome: If you don't need the power of a diesel, you'll save coin on gas. If you do need the power, diesel will save you money.

Reliability:
This very well may be engine dependant. Gasoline engines are not designed for an extended life, and generally are well designed, but not intended to go hundreds of thousands of miles. On the other hand diesels are intentionally designed to go possibly over a million miles. They make their money racking up millions of miles in tractor trailers, and that know-how gets carried over. Looking at the robustness of a straight six ISB will make most gasoline engines blush. This can be shown in tests of the natural gas engines that use diesel components, and can take abuse most gasoline engines could never dream of. Engine wise, particularly the simplistic ISB is a rock solid platform.

Where the achille's heel of diesels are is the emissions control equipment. These are the most frequent failures. EGR coolers, DPF's, and SCR's top the list. Again, an unethical person could remove them. However these are not typically huge problems, irritating at best.

Outcome:
Over the long haul, diesel is the way to go. In the short term you may see less problems with the gas, but when the gas is on its last leg, diesel still has a ways until its first overhaul.

Cost:
Obviously you pay the $7-8k up front for the diesel. There's only one way to make that back. Time. If you're the kind that trades in every 3 years, diesel i s not for you. If you drive it into the ground, you'll want a diesel. Diesel's also boast a much higher residual value than gas if you do opt to sell.

Outcome:
Short term buyer, gas. Long term owner, diesel.

Hopefully that will shed some light on the topic.

On a more personal opinion though, even as a spark-ignited guy, my next pickup will certainly be a diesel. I may not need the power all the time, but I hang onto vehicles as long as possible, and I appreciate the dependability of the ISB.

Of course you can probably guess I won't be getting a Scorpion powered truck anytime soon. I'll have to stick with the tried and true straight six.

 

[Jdaniel]

Very interesting writeup. I figure that I'd throw my 2 cents in as well.

As an engineer for a massive diesel engine company, but one who actually works in the spark ignited natural gas division, I've got a unique perspective into both gas and diesel worlds. Of course I'm also not as familiar with the Ford 6.7 line, I'm familiar with another, more prolific 6.7. :-D

For all intents and purposes, a spark ignited natural gas engine behaves the same as a gasoline engine. The only difference is that you're using a gaseous fuel instead of a liquid one. You can readily convert a NG engine to gasoline, and vice versa.

Now I would have to say that in general, a diesel is a wise investment but only for those that need the power, and will hold onto it for a significant amount of time. Now let's break it down into their strengths and weaknesses.

Fuel Economy-
This is somewhat of a toss up, and there's various ways to skew the result. What I will say is that in terms of BSFC (brake specific fuel consumption) the diesel will beat the gas, hands down, every time. Notice I don't say fuel consumption period. I'll get to that later. The diesel cycle is just more efficient than the otto cycle, no way around that. This is true even with the extensive aftertreatment equipment, including the DPF regenerations that essentially dump fuel into the exhaust, and pricey DEF fluid. Note: Cummins ISB engines DO NOT require DEF and DO NOT have an SCR system like the Duramax and Powerstroke.
Of course if you're comparing the diesel to the gas, or worse still the Ecoboost, the gas will win. You also won't have the same power/torque band of the diesel, but you will use less fuel. If you compared a gas engine to a diesel engine with the exact same power/torque curve, you will see the diesel gets better economy every time. And yes, this is accurate, we use gas and diesel engines with the same base parts, and the exact same power rating. However in this case we're comparing apples to oranges. The 6.2 is not close to the same as the 6.7, and the ISB is not the same as the 5.7.

Of course if you're unethical you can remove the emissions equipment and create massive gains for the diesel, furthering the gap. Tuners for fuel economy are readily available for diesel as well, as diesel allows leaner mixtures than gas.

Outcome: If you don't need the power of a diesel, you'll save coin on gas. If you do need the power, diesel will save you money.

Reliability:
This very well may be engine dependant. Gasoline engines are not designed for an extended life, and generally are well designed, but not intended to go hundreds of thousands of miles. On the other hand diesels are intentionally designed to go possibly over a million miles. They make their money racking up millions of miles in tractor trailers, and that know-how gets carried over. Looking at the robustness of a straight six ISB will make most gasoline engines blush. This can be shown in tests of the natural gas engines that use diesel components, and can take abuse most gasoline engines could never dream of. Engine wise, particularly the simplistic ISB is a rock solid platform.

Where the achille's heel of diesels are is the emissions control equipment. These are the most frequent failures. EGR coolers, DPF's, and SCR's top the list. Again, an unethical person could remove them. However these are not typically huge problems, irritating at best.

Outcome:
Over the long haul, diesel is the way to go. In the short term you may see less problems with the gas, but when the gas is on its last leg, diesel still has a ways until its first overhaul.

Cost:
Obviously you pay the $7-8k up front for the diesel. There's only one way to make that back. Time. If you're the kind that trades in every 3 years, diesel i s not for you. If you drive it into the ground, you'll want a diesel. Diesel's also boast a much higher residual value than gas if you do opt to sell.

Outcome:
Short term buyer, gas. Long term owner, diesel.

Hopefully that will shed some light on the topic.

On a more personal opinion though, even as a spark-ignited guy, my next pickup will certainly be a diesel. I may not need the power all the time, but I hang onto vehicles as long as possible, and I appreciate the dependability of the ISB.

Of course you can probably guess I won't be getting a Scorpion powered truck anytime soon. I'll have to stick with the tried and true straight six.

You just took everything from my head and put it in a cleaner format! Thank you.

 

[DougT]

Well this is one of the best threads yet !! I work as a Rep / Distributor for Miller Industries America's Best and Largest Wrecker Manufactuer. I can tell you a few years ago I started to pay more attention to the Diesel Issues Mostly the 6.0L Diesel and 6.4L diesel.

In the Commercial Field the Gas Engine has taken off in the last 3 years or so. We have went back the gas engine more than the Diesel as the Inception price is alot cheaper, Gas is cheaper , Maintaining a gas engine is alot cheaper and most of all the gas powered units are way more reliable Period and last longer than Todays Diesels. When the ordering bank opens up for the F-650 w/ V10 gas we will be the first to have at least 6 units build for stock.

I have one customer that has 325k on his 2008 F550 V-10 carrier and all it has ever Needed is Plugs,Filters and coil packs and still on the Original Torque shift trans . I have another customer that has a 2010 F550 Diesel w/ 75k on it and it has 3 blocks,Multiple water pumps,2 transmissions and so on. These above examples play out all over in any Business and many more of my customer that have switched to Gas trucks could not be happier!

Now throw in the New 6.7L diesel (2011+) they have been way more reliable and have better fuel economy than the 6.4L, But most are still leary and again Gas is just way Cheaper. Think Diesels have better resale ?? Really ?? I cant keep a Good used GAS truck in stock for more than a few weeks and diesels sit around 5 times longer.

My Current demo is this F350 XCAB 4X4 with a service body and wheel lift and this 6.2L pulls the house down and still gets 12 mpg hwy. Yesterdays thinking about how diesels are the only way is over for the savy Business man.

When it comes to light duty /Medium duty the gas choice for a business is a good option.

 

[Great Asp]

You mean was not cost effective in that situation? What about in a situation where someone occasional tows a boat, camper, or car to the track?

From the stat's it looks like you will ge the $7,000 upcharge for the diesel back, then it is just the cost of fuel and maintenance.

I think the edge goes to the "have to" truck. I have pulled my trailer with the old Expedition (5.4) in Illinois and Indiana, no problem. But I bought my 6.0 when I knew I would be pulling to VIR and we planned some trips to Colorado. The 5.4 would have been over matched for those trips.

Because we always have the service bodies on and tools (I think my guys carry too many tools ) it is a no brainer.

Note: We now are faced with retiring our Econoline service bodies early because the Church of the Blue Oval is no longer making diesels in E-chassis...

E

 

[utfan98]

Living in the Rust Belt, I see many Diesels (mainly pick ups) that are rust buckets. The engine does last longer as stated but they are eye sores and would never past a safety inspection if the state of MI had one. One thing to consider is how with the rest of the vehicle hold up.

 

[Quicktime_GT]

I own a 6.7 cummins.. all the emisison deletes and a smarty programmer.. the truck gets a solid 20mpg (hand calcuatlated) and would likely put down a reliable 400rwhp and 800rwtq.

If you can get over the initial cost of a diesel, it's hard to argue with their efficiency and power output.

A 7.3 has about half (maybe less) as many parts as a 6.7L and has economies of scale on its side with parts prices. The days of buying a new diesel engine like that are long gone.

6.7 Cummins still rocks the same basic proven 24v cummins design. In terms of simplicity cummins is at the top. In terms of stock vs stock power, I feel like this simple I6 design is only going to become farther and farther behind.

 

[SID297]

I own a 6.7 cummins.. all the emisison deletes and a smarty programmer.. the truck gets a solid 20mpg (hand calcuatlated) and would likely put down a reliable 400rwhp and 800rwtq.

If you can get over the initial cost of a diesel, it's hard to argue with their efficiency and power output.




6.7 Cummins still rocks the same basic proven 24v cummins design. In terms of simplicity cummins is at the top. In terms of stock vs stock power, I feel like this simple I6 design is only going to become farther and farther behind.

The ISB is beautiful in its simplicity. Unfortunately, it's not in a Ford (not counting the F-650 or F-750) and still is packed with emissions crap. I'd like to see Cummins convert it to DOHC and make it all aluminum.