1994 Diesel Suburban Build

[cRiPpLe_rOoStEr]

Originally Posted by oldtamiyaphile

possibly do a chrome wrap

Much like those aluminium foils used for roofing thermal insulation. They might be not so bad at all, are even used to seal gaps in firewalls of second-hand Japanese imports converted from RHD to LHD in Chile and Paraguay.

[oil pan 4]

Also put a bigger turbo on there, unless you are going to be doing nothing but pure city driving.
Highway and towing the bigger turbo always wins.

[aardvarcus]

Oil Pan,
Yeah I wouldn't buy anything that wasn't from a major manufacturer. I was looking at the GE Nighthawks, but I will delay that purchase as long as possible to hopefully let the options increase and the prices decrease.

Cripple Rooster,
To hit my MPG goals, I will either have to change the body or fabricate an add on tail. I like the rear doors, but I would rather lose the doors than increase the length. Honestly as the Suburban is set to replace a truck, a tailgate style rear cargo area would be a better fit for carrying large and long cargo.

Oldtamiyaphile,
Yeah Rustoleum gloss white was my initial thought, unless I can find something that has published reflectivity and emissivity numbers that are both significantly better. I also plan on putting some self adhesive foam insulation on the underside of as well to help cut the heat transfer to the cabin. I know bare metals usually have terrible emissivity compared to painted surfaces.


Speaking of firewall seals I would also like to find a good foil faced high temperature insulation product for the engine firewall. I noticed today the stock stuff which has a black liner is starting to fall apart.

[aardvarcus]

With regards to the turbo, I know this is counter to popular opinions on the subject, but the BSFC numbers I have been able to find in some published military papers between turbocharged and naturally aspirated 6.5L show better BSFC numbers at peak levels but not across the spectrum. The numbers I have seen at low to moderate power outputs weren't significantly different.

Doing the modifications listed should greatly reduce the steady state power requirements to roll down the road so most driving time should be at low levels of fueling, which in a 6.5L engine would result in very high air to fuel ratios. In this scenario, I don't think extra air will help increase efficiency since the air to fuel ratios should already be very high.

If I was using a lower displacement engine thus decreasing the air volume or did not do any load reduction thus using more fuel where the typical air to fuel ratios were lower, I think the turbo would be a better fit. Anyway if I end up dissatisfied with natural aspiration, I can always add a turbo and do a real A-B comparison.

Edit: To be clear I am not making blanket statements above, I understand how a turbocharger typically increases efficiency and how a smaller diesel engine with turbocharger would be more efficient than a larger naturally aspirated engine to make the same power. I would rather have a 3.25L engine running 14 psi boost than my 6.5L (3.25L at two atmospheres ingests the same air as 6.5L at one atmosphere). However since I want to use the 6.5L platform but reduce the load required, I don't think the turbo will benefit that scenario.

[aardvarcus]

Attached is a chart I made to compare between a turbo and non-turbo engine BSFC numbers. Both of these data sets are from freely available publications on military 6.5L engines, and are both done on JP-8 fuel. These are comparing BSFC numbers at specific torque outputs for two RPM levels. As you can see, the efficiency results are very similar at the 2000 RPM level.

Part of me wants to add a turbo to increase maximum torque at low RPMs. The other part of me wants to leave it N/A to reduce weight and complexity.

[rmay635703]

Originally Posted by aardvarcus

Attached is a chart I made to compare between a turbo and non-turbo engine BSFC numbers.

I am glad you posted this, just goes to show how sad it is that inexpensive NA diesels aren't sold in the US.

Reality is NA is just as efficient and only 20% more for the motor than a gasser. (As compared to exponentially more for turbo)

Hope this shuts up the turbo folks.

Diesels don't have to be 600 hp monsters, I guess that is why I own a 6.2

[me and my metro]

I am very happy with my 6.5 na pickup. It has 4.56 gears and a 700r4, it tows my 10,000 lb Avion just fine. I have three different brands of turbos for it, I have a Banks, an ATS and a factory set. My 6.5 is piston cooled with the improved main bearing caps. I have run GM diesels since the Oldsmobile days, yes they have their problems. I will never hurt my 6.5 if I don't install a turbo! The 700r4 is the fuse that limits the horsepower in my truck.

[oil pan 4]

Put a turbo on it.
If you live in the mountainous part of TN you will really need the turbo.

When I put a turbo on my 6.5 fuel economy increased 10% to 12%.

[aardvarcus]

Rmay and Metro,
Glad to hear your 6.2 and 6.5 are working for you naturally aspirated.

Oil Pan,
There’s a non-mountainous part of TN? Your input on the turbo is duly noted. (I mean that seriously, not sarcastically, I am taking note of your input.) I have seen lots of conflicting accounts on this subject, so I surmise there are other factors than just the turbo that come into play with this (driving style?). I am strongly considering starting the project off naturally aspirated (assuming I can round up manifolds and a downpipe) just to get the project going and testing out a turbo for myself at a later time.

Current Update:
Four longer 10MMx1.5 bolts from TSC got my optimizer engine off the floor and up on my engine stand yesterday. I am going to start pulling the accessories and other items I am not going to use off of it to get it ready for the brackets off of the 1994. Then I can start mounting up the new accessories as well as getting a handle on any other small parts I may need to source.

[oil pan 4]

Yeah you can add a turbo later, that is exactly what I did.
I live in a very flat part of NM but really do like having a turbo. I wish it would have been one of the first mods I did.
My fuel economy improvement happened while in NM.

I think GM did a disservice to the entire US diesel market by offering a non turbo diesel truck. When you start trying to do actual truck stuff with them especially in thinner air, really anything above 3000 feet above sea level they really suffer.