Tunes for diesels vs gassers

[Enterko]

Ok, I started out my fullsize truck life with a Chevy 1500HD two years ago. (previously I drove lifted, heavily modified toyota trucks) It had a 6.0l gas motor, and I thought it was pretty fast from the factory.

I put on exhaust.....not a big change
I put re-programmed with a diablo sport.....not a big change
I re-programmed with a hypertech....not a big change

Overall it was faster and shifted better, but marginally, and not worth the $$$$. I got tired of the 10-12 mpg, so I started looking for a diesel.

Soon I found a F-350 with a 6.0L Powerstroke.
It wasn't crazy fast, but had more torque the the 1500HD, and I liked the increase to 13-14mpg. I was much happier with the more capable truck, and after I read a little on this forum I decided to try some upgrades

After I flushed the coolant to ELC, I thought I would try to increase the hp and mileage.

Deleted the cat and added a turbo back exhaust.....HUGE CHANGE
Tuned with and SCT X3 (canned tunes).....EVEN LARGER CHANGE
Tuned with custom tunes.....EVEN LARGER CHANGE

I know a fair amount about the mechanics involved with engines both gas and diesel, and I still don't understand why there is so much of a difference between modifying the two.

The best that I can tell is that a diesel's power potential is reduced form the factory in order to increase the longevity, hence the HUGE power increase from aftermarket "tuning".

But why wouldn't a gas engine's power potential be decreased from the factory? Or rather why are gas engines tuned to near max power from the factory and diesel's aren't?

Does anyone know the answer?.......

[Lilpooh]

No spark plugs!!! JK!!, I would like to know also.

[Tyler]

The big amount of compression and huge margin to add massive amounts of fuel to that large area of compression, then throw in 30+PSI of boost and you've got a nut bustin' power house.

[Enterko]

Originally Posted by Tyler

The big amount of compression and huge margin to add massive amounts of fuel to that large area of compression, then throw in 30+PSI of boost and you've got a nut bustin' power house.

I get that. The thing that I don't understand is this:

If the margin to add fuel exists from the factory, why don't they come from the factory that way. I know that 450hp and 750ft/lbs of torque is excessive from the factory, so why not create a motor that is smaller that produces more of it's potential power. (Not that I want a smaller engine, just using engineering logic)

I guess that the increase in power effects the longevity of our powerstroke's engine, and maybe that's the reason that they come from the factory with say 65% of their power being utilized(with tuning and exhaust alone). It's just curious that a gas engine doesn't come with the same percentage of potential power being utilized

[Enterko]

I also understand that towing with this much HP and Torque can damage the engine if not properly monitored, so I get how a factory vehicle wouldn't be set up in this manner.

What I don't understand is that a gas engine doesn't overheat or prematurely fail when towing, and it appears that they are using a larger portion of their potential power.

[adambomb]

i'm not sure either. it seems with a gas truck you put on a tuner they advertise 30hp and on a diesel it's like at least 100hp (talking about diesels within the last 10 years) and the newer can be like 300hp.

i always thought it was that you can just push way more fuel in a diesel motor and like what was said above about the compression and turbo boost

[Buffalo444]

more fuel always equals more power in a diesel, we're compression ignition. more fuel does not always equal more power in a gasser, they need the right combo of fuel air or it wont combust right. The reason diesels dont come from the factory with their full potential used is emissions, but thats something I'd argue another day. But bolt for bolt a diesel motor is FAR SUPERIOR to a gas motor, thats just how it is. not to mention us 7.3 guys are flex fuel stock

[Enterko]

What does "flex fuel stock" mean?

[Buffalo444]

Originally Posted by Enterko

What does "flex fuel stock" mean?

by that I mean a 7.3 has all the tolerances internally to run not just on diesel fuel, but waste veggie oil, waste motor oil, auto tranny fluid, hydraulic oil.... just about anything oily really. Wouldn't try that in a 6.0 though, they don't have very much acceptance for "alternative fuels"

[Enterko]

Gotcha.

I am not well versed in alternate fuels, but I don't see what would hinder a 6.0 and not a 7.3. Both utilize a HPOP, which is what I thought was a good thing for alternate fuels

With that being said I beleive what you say, but just want to know what specifically makes the 6.0 bad for those fuels.....I'm definitely not trying to start a pi$$ing contest, just curious.