Suppose your gas-diesel engine has to be replaced, should one consider > what??
Diesels give better mileage
but cost more to keep up...
Gas give worse mileage
but parts cost less....
....So what is a good alternative??
Gas V-10? Hybrid? Steam? Horses?
...or just a newer used diesel??

quote:

Originally posted by Doug Smiley:
Suppose your gas-diesel engine has to be replaced, should one consider > what??

One should consider...
1) What is in there now. This would determine your ultimate cost with conversion and parts interchangeability.
2) Intended use. If you have a gas motor and you put on low mileage and short trips, stick with another gas motor.
3) What you have as a donor vehicle. Lets say you have a Dodge pickup or other suitable truck. Then you have a complete drivetrain to do your swap with all the little extras one might need.

The only problem now is how you plan on using an emergency brake. My, Former Commercial, Oshkosh coach has a C-6 Ford Transmission with a Hydraulic Operated Transmission Prop Brake. If the donor truck engine and transmission was so equipped, it would be a no-brainer to use the diesel.

If not, one would then have to consider if there is an available, alternative, tailshaft housing conversion.

If the coach is a P30, the crossmember would interfere the deeper sumps of most diesels (except the GM 6.2/6.5).

Most of the attention would go toward the drive line, engine support system. Diesel engines develop their power at lower RPM so if gas equipped now, the diff ratio probably would need to be changed. If carburetor is used now, probably wouldn't have the required fuel return line for either fuel injected or diesel applications. If front engine, a diesel would be hard to noise-insulate. The list goes on and on.

Most any conversion can be done but at what cost? If you throw enough money at anything, sure but is it worth it? If you have the skills and are doing the work yourself, could be a fun project, otherwise, a money pit!

Rusty, do you know the diff ratio on yours?

Where is the driving range on your tach?

To review, mine is an AMG 6.5L TD built-to-spec, all-mechanical (the only computer is on the tranny), by Peninsular Diesel in MI. The stock AMG is rated at 190 HP/360 lb.-ft.; mine is uprated to 230 HP/420 lb.-ft. Additionally, the compression ratio is lowered from 21.1: to 18:1, a marine IP and hi-pop injectors were installed, as were a larger non-wastegated turbo and a camshaft gear drive instead of the stock timing chain. Boost is increased from stock 6-7 psi to max 17 psi (@ sea level), where the turbo runs out of breath.

Fuel economy went from an average with the OEM GM 6.5L TD of 9.1 mpg to 10.5+ mpg in hilly/mountainous country, 11+ mpg straight-and-level, with the AMG.

My engine was spec'ed to max torque at 2600 RPM (max efficiency); I cruise at 60 mph, 2700 RPM, ~4 psi boost, 600°F EGT (pre-turbo). I think the diffy ratio is 4.73. Engine yellow line is 3500 RPM; the red band goes from 4-5000 RPM.

One feature I like is that I can run a 6% downgrade in 2nd gear @~50 mph, 1700 RPM, rarely touching the brakes. I tested on an 8% down in first, and it held at 40 mph, 1900 RPM. No need for an exhaust brake. Tranny temp never exceeded 160°F.

I think the engine package was around $9,500 delivered, including an external engine oil cooler (the AMG block uses 1/2" lines as opposed to the GM 3/8", so I went to a 1/2" cooler instead of reducers on the radiator); I installed a fan on the oil cooler. Blocking off the radiator oil cooler makes a noticeable (but not dramatic) difference in engine and tranny temp.

I have to do some wallowing around under the coach next week, and can check the diffy tag; I never wrote it down. The tranny, BTW, is a GM 4L80E with an exteme-duty rebuild.

I highly recommend Peninsular Diesel! Another alternative would be Kennedy Diesel; he's a very small shop, and very particualr in his rebuilds. Peninsular sells all-new engines; base prices start around $8K for long short blocks, with the AMG-designed, Navistar cast blocks, about 25% stronger than the OEM GM blocks due to structural and metallurgical improvements. The decrease in CR also contributes to extreme durability and longevity.

As to donor 6.5L TD engines, one should look for the 599 blocks (the strongest) and plan on, at the least, upgrading to the 130 GPM pump and the dual-thermostat kit. Any donor engine should have the heads pulled and inspected for undesirable cracks (some minor ones are insignificant) and the condition of the rear four cylinders (5-8), which are susceptible to scuffing and worse. I do have the original engine (cannibalized to short-short block status) here if someone wants to do a rebuild; heads have been inspected, magnafluxed, and trued, and the turbo also tested and found OK (prior owner replaced it - has around 30K miles), and the 130 gph water pump and dual thermostats installed. It would need new manifolds, crankshaft damper, pulley, etc., and accessories.

In any event, StaRV II's Peninsular Diesel engine blows (or is it "sucks"?) the doors off the stock GM engine. Merging on the Interstate is no longer an adventure - it's kinda fun to blow onto the highway and acclerate away from oncoming traffic!

Based on lots of experience building hotrod big block engnes we have found the most effective and least costly process is to replace with the same 454. You have an truck 454, not a car and they are very different in the web thickness, journal dimensions and head design. Consider (for what it is worth) the following - pull the engine and take it to a dyno equipped shop. You can make significant improvements by replacing the heads with current ones and by modifying the torque and timing with a new distributor and electronic ignition. New pistons with balanced and blueprinted internals and roller tappets can improve your low end response and increase your mileage at the sacrifice of high end speed (usually not an issue with a motorhome). Change to larger headers, increase tailpipe and muffler sizes to improve the breathing and get the engine set up with a new tuned carb on the dyno. They can modify and adjust for best torque and a flatter power band that will optimize your performance in your usual speed and weight range. All 454 P-30's were built for torque and reliability in a wide range of weight and vehicle types from step vans and Surburban's up to dump trucks. If you find the right shop you can watch and work with them on the blueprinting and setup and see the results directly on the dyno. It is not unusual to see 15% gains in HP and 20% in torque, although you want to be very careful on the range of rpm you want it built to be most efficient. This approach should not exceed Rusty's estimate of cost. The last improvement is whether or not you plan to use an overdrive unit - that has a significant impact on the torque demands at highway speeds so be sure you work with them on the entire drive train to get the best results.

I second Tom K's opinion, though I would add this: A crate engine as El Segundo Bill has installed in his Barth is effective, modestly priced (relatively speaking - modest cost is not the handmaiden of any hobby) easier, but lots less fun if your thing is building engines.

Engine conversions are fun to contemplate, and, as MWrench said, almost anything is possible if you throw enough money at it. Going either way between gas and diesel is complicated by the need to change rear axle ratios, as most diesels develop their torque at half the RPM of the typical gasser.

I just discovered that MWrench already said all of that. Blame it on age. It's my birthday. Today I hit the big 8-0.

Hey, Happy Birthday Roy!!! Hope you have many more.

quote:

Originally posted by olroy:
A crate engine as El Segundo Bill has installed in his Barth is effective, modestly priced (relatively speaking.

I love engine swaps, and still drive a Jag with a Vette engine, but for my Barth, I went with the 502. . I am very happy with it, combined with a Wieand manifold and Thorleys. I have built a number of 454s and a stroked 454 was about the most cost effective, but still not as nice as the 502. There is something about the 502 that just makes everything snap together. The Chevy engineers knew what they were doing.

I have a super duper rumprump 502 in the ski boat, too, and it is a great engine, too. My wife even likes the open exhausts, a situation that never occurred with previous engines.

However, a full roller 454 stroker would still be at least a grand under a 502, so it would be a good project, as Tom says. When the truck 454 gets tired, I will probably cheap out and just give it a stroker crank and a little more cam. Or maybe I'll move the 502 from the Barth to the truck and put a 572 in the Barth.

And Happy Birthday! I will miss you again at Quartzsite.