lightweight and smallish diesel for Fox Body Ford

yldouright

Registered User
Joined
Jan 11, 2019
Posts
7
Reaction score
0
Location
New York
Money is always a factor. An 8.8" rear is about the beefiest you can use on a Fox. When you factor in the cost, weight and headache of fitting a more adequate drivetrain, a higher revving diesel seems like a better idea. I may be mistaken but even a 3.23 final gear drive with >500ft/lbs will have trouble matching the top speed of a more conventional rear with higher revs. What combination of torque and drivetrain do you suggest for the Fox?
 
Last edited:

Kiwif150

Full Access Member
Joined
Apr 6, 2017
Posts
161
Reaction score
81
Location
Waimate New Zealand
Money is always a factor. An 8.8" rear is about the beefiest you can use on a Fox. When you factor in the cost, weight and headache of fitting a more adequate drivetrain, a higher revving diesel seems like a better idea. I may be mistaken but even a 3.23 final gear drive with >500ft/lbs will have trouble matching the top speed of a more conventional rear with higher revs. What combination of torque and drivetrain do you suggest for the Fox?

If it was me and i wanted to keep it diesel i'd look at something like this from copart ...... all wiring computers , driveline etc to drop in the fox.

https://www.copart.com/lot/54166628

These are the performance specs for it in the e90 series ..... fox is going to weigh less than one of those.

Engine In-line six-cyl, 2993cc, bi-turbo
Max power 282bhp @ 4400rpm
Max torque 428lb ft @ 1750-2250rpm
0-60 6.1sec (claimed)
Top speed 155mph (limited)
 

yldouright

Registered User
Joined
Jan 11, 2019
Posts
7
Reaction score
0
Location
New York
I don't want an inline 6. A shorter engine is preferable. I'll make up any power difference with boost and my handling will be better with less weight in front of the rack. Remember my modest needs. I've asked this before but I'll repeat the question, what, if anything, prevents diesels from spinning like gas engines?
 

Thewespaul

Supporting Member
Supporting Member
Joined
Jul 27, 2015
Posts
8,796
Reaction score
8,058
Location
Bulverde, Texas
I think you would benefit from reading up on how Diesel engines differ from gassers, there’s some very good YouTube videos on the subject. Basically, diesels run a lot more compression ratio, this makes a lot of cylinder pressure. To hold up to this amount of pressure, the rotating assembly needs to be very stout. The bottom end of a stock medium/heavy duty diesel is what similar in design and engineering as what you would see in a 1000+ hp big block gasser. The diesels’ bottom end are too heavy to spin the rpms a gasser would without stretching rod bolts and breaking rods. 4000 rpms is a lot in most diesels. I used to work on a 2000 hp cat diesel, that was limited to 1800 rpms. 16 cylinders and 8 turbos sounds like ten times the rpm that it’s really spinning.
 

Oledirtypearl86

Full Access Member
Joined
Sep 17, 2018
Posts
1,673
Reaction score
949
Location
Whitehall MT
Like Wes said that rotating mass on. Diesel bottom end is a huge limit iv Never been into a 1000hp gas engine but I'd imagine it being stout like a diesel and yes Wes at the mine we got a bunch of 240 ton cat haul trucks with v16s an they are quad turbo and when you hear one going by on the haul road it sounds like it's running about 8k rpm I got to see one run away at the garage one day and the noise and vibration was beyond belief
 

Kiwif150

Full Access Member
Joined
Apr 6, 2017
Posts
161
Reaction score
81
Location
Waimate New Zealand
I don't want an inline 6. A shorter engine is preferable. I'll make up any power difference with boost and my handling will be better with less weight in front of the rack. Remember my modest needs. I've asked this before but I'll repeat the question, what, if anything, prevents diesels from spinning like gas engines?

Wes explained it pretty well.

I was involved a few years ago with building an LD28 nissan diesel up to run in a jet boat ..... we turboed it, made up a water to air intercooler for it , decompressioned it and replaced the flywheel with a beefed up flexplate. Blew up 3 engines before we got it semi reliable - it would run at 4-4300 rpm all day long but just get it over 4500 and things would get rather noisy and exciting before it got deathly silent.

Not saying it can't be done especially with recent advances in fuelling and better metallurgy in engine construction ...... i hope you have deep pockets because you are going to need them when you get into this kind of territory with machining costs plus "one off" parts.

I know it's not what you want to hear but you are going to find that as was suggested earlier in the thread , build a 5.0 gasser and call it done ..... less cost less weight and a guaranteed result.

Here's a link to a news article that features a banks 3.0 diesel combo package that would work for you ..... not cheap i would imagine.

https://www.dieselarmy.com/news/3-0l-diesel-engine-option-for-your-diesel-engine-conversion/
 

Comptech

Full Access Member
Joined
Dec 17, 2018
Posts
145
Reaction score
56
Location
Ohio
Simply put, it's the the entire design of the diesel engine that you will be forced to build around. My father was a blown alcohol truck puller for many years. I've been inside K Blacks,JP1 and Alan Johnson hemis. My 4bt is built heavier internally than those engines. check out the pressure spike and length of that Spike of diesel vs gasoline and you will see another reason why diesel does not spin like gasoline. Simply adding boost will not make more power unless you have the fuel to burn. Then you start getting into drive pressure spikes and inconsistencies throughout the power band.in alcohol and gasoline applications you are building an engine to withstand detonation. Blowers such as the 8 and 14-71 do not produce linear boost per given RPM/load just as a turbocharger on a diesel.for the parameters that you have laid out you would have to have one heck of a fuel control system to cover such a wide RPM range. Otherwise you would just be one of those over fueled/under aired guys that fog out an intersection until they get their way too large of a turbocharger making any air. Do that with a gasoline or alky engine and it will detonate to pieces quite quickly. We lost blower belts a couple times and it blew the heads literally off the block with the unburned fuel.Just trying to throw some design differences in there to show a comparison of the two engines
 
Last edited:

u2slow

bilge rat
Joined
May 8, 2007
Posts
1,815
Reaction score
812
Location
PNW
I would be looking at Mercedes, Volvo, or Datsun/Nissan pickup for a donor. There's a reasonable chance of a manual trans then, and its already a RWD setup.
 

compressionignitionrules

Full Access Member
Joined
May 1, 2016
Posts
840
Reaction score
286
Location
Bluevale ON
OM 617 3.0 5cyl has lots of aftermarket stuff now and lots of guys building them big boost bigger injectors but on the other side of the atlantic., you need to do some surfing around europe. company in PA makes an adapter kit to a small block Ford bell...............................
 

BrandonMag

Dana 50 rebuilder
Supporting Member
Joined
Oct 20, 2009
Posts
1,185
Reaction score
99
Location
Oregon east
Last edited:

lotzagoodstuff

Supporting Member
Supporting Member
Joined
May 19, 2007
Posts
2,724
Reaction score
666
Location
Carmel, IN
I'm sure they're fantastic engines that have excellent response, low vibration and are very durable, but that's just too much scratch for me.

"Prices start from $28,985"

Put me in the "that's just too much scratch" category as well Brandon :p

I'm up in Maple Valley now, stop on by if and when you get up Seattle way for any reason.
 

Oledirtypearl86

Full Access Member
Joined
Sep 17, 2018
Posts
1,673
Reaction score
949
Location
Whitehall MT
So please don't think I'm trying to troll but a high revving diesels are way more than a gas motor when they was in highschool I worked for a concrete company to buy a 89 fox body my brother and I pulled the motor and built a 333 stroker with a powerdyne supercharger and as a 17 year old dummy I could run 10s all day for less than 2500 is this a comp car or a passion project
 

yldouright

Registered User
Joined
Jan 11, 2019
Posts
7
Reaction score
0
Location
New York
Guys, I appreciate the discouraging and sobering input but I think I've found a tack that might lead to a solution. Nissan makes an under square 3 cylinder 1.2L that has VVT and is direct injected (see HR12Dxx). With some rigid bolts, SS gasket and precision facing, it should hold together with 2 bar of boost so I'm not terribly concerned about the pressure spikes. The motor is well balanced and spins well without any balance shafts. Mating this engine to a Garrett T3 should get me a wide band torque around 285ft/lbs. If I can get it to spin to 7500, I should meet my 400whp goal. By my calculation, the piston speed will be under 50mph. Will that be enough time for all the fuel to burn completely? Obviously, the fuel delivery would need a substantial upgrade. Injectors >100lbs/hr with wide dispersion and pumps that can hold 60psi. I've heard of these engines running 2 bar at 8800rpm on E85 without issues so I'm hopeful that a diesel setup might work here. Looking forward to more input.
 

Thewespaul

Supporting Member
Supporting Member
Joined
Jul 27, 2015
Posts
8,796
Reaction score
8,058
Location
Bulverde, Texas
Is this engine a diesel? Your typical 100lb/hr injectors will not work in a DI Diesel.

You’re looking at making over 150hp per cylinder, so I would look into piston, connecting rod and cylinder wall upgrades. Typically at that power level the cylinder pressure is enough to destroy any oem bottom end. Imagine you were making the same power per cylinder in a V8, you are going to be at over 1200hp, you’re not going to get there with many oem parts at all.

Another thing to look into is the valvetrain, 2 bar (about 30psi boost right?) Is going to need valve spring upgrades to keep from floating valves. The increased seat pressure may require upgraded valves if the oem valves are too soft and wrinkle under the tension.

Next I would look at is driveline, make sure before you spend any money that there’s clutch or transmission options for that engine that can handle the power. You can make all the power in the world but if you can’t use it then it’s worthless. That’s where the Honda’s were at in the 90s, people were making tons of power for that time but the transmission tech wasn’t there to really use it.
 

Forum statistics

Threads
91,198
Posts
1,128,134
Members
24,024
Latest member
Bugoo

Members online

Top