| Author | Message | ||
| Alan Lindsey (Arl)
Registered Member Username: Arl Post Number: 6 Registered: 6-2009 Posted From: 64.130.185.5 Rating: N/A |
Howdy everyone. I'm quite sure you've answered this question many times, but my searches through the archives aren't getting my the answers I'm looking for. If you know of an exhaustive post already done, please point me to it. If you have ideas, please let me know. I am desperately seeking a solution to the repowering of my existing 8V71 and Fuller 5spd manual to something else. ANything else. I hate that engine. It's loud and sucks fuel and pukes oil. It has no turbo, the tranny has no overdrive. It's killing me one mile at a time and I want to upgrade. It's burned four valves in a year, uses a gallon of oil every 400 miles, and just badly needs an overhaul (which the previous owner said it already had). I'd rather spend the money on some improvements. SO... what's the optimal engine/tranny combo for repowering an MCI-9 with 8V71? I'm a guy that just wants to get me and my family from point A to point B reliably and as efficiently as possible. I don't need extra horsepower, I don't need fancy anything - well... cruise and jakes would be nice if easily incorporated. I'd like the engine to have turbo and the tranny to be either autoshift or automatic, though this is not essential as me and my kids have learned on this Eaton Fuller 5spd and are comfortable with manual. Many many many thanks in advance for your expert and thoughtful help getting me back in service. | ||
| Don Fairchild (Don_fairchild)
Registered Member Username: Don_fairchild Post Number: 42 Registered: 3-2007 Posted From: 76.83.97.36 Rating: N/A |
Alan; Your lowest cost would be to rebuild and turbo the engine you have and change to a 7 sp with overdrive. There are several people that can help you out. One of them is Dallas down in Texas. I am further away in Cal. There are probley a few shops around you that can help. Hope this helps Don | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 392 Registered: 3-2006 Posted From: 216.198.139.38  Rating: N/A |
Alan The options are endless depending on your mechanical ability. I have seen MCI's with almost any engine/tranny combination but it can be very expensive to replace your existing combination with a four stroke and automatic. Like Don says rebuild your engine in a turbo version and find an automatic in good shape and go for it. There was an artical in Bus Conversions magazine a while ago about engine swaps and why do we bus nuts do it. The answer was "because it can't be done". Good luck on which ever route you go and enjoy it. Bill | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1336 Registered: 10-2006 Posted From: 99.12.242.128  Rating: N/A |
A pre EGR engine (2003) of any make is always the best choice. We went with a DD series 50 as the new toy is only 25,000 lbs road ready. 300+hp The extra 10,000 or 15,000 if the MCI would work nice with the Ser 60.450hp You MUST get a tranny with OD (or a new rear axle) as the 4 strokes love to cruise 1200 to 1400rpm , not the 1900-2100 the 2 strokes run at speed . 10 mpg should be an easy goal . FF | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 155 Registered: 3-2004 Posted From: 75.206.39.217 Rating: N/A |
I installed a 8-71TA, rated 375, West bound from Pa. to Az. 65-70mph, 5.5-6.5, than East bound 6-7, same speed, total oil used/ one small leak, less than 2 gallons in nearly 6K miles. AND I did get it hot, the TA is not as noisy as the old plain 8-71 and it had 70 injectors. First I would call Sam Caylor in Kansas, he has 4 cycle powered buses in his scrap yard. I had considered getting a cradle and parts and doing a Series 60, but I need to DRIVE 100,000 miles just to brake even. I am to old for that. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1124 Registered: 8-2006 Posted From: 99.172.180.11 Rating: N/A |
Alan, A practical conversion would be a 6V92TA, and a 740 Allison auto. Many of the later MC9s came that way, and you will be able to find lots of used-rebuilt parts easily. The upside of this conversion is that it will give you 350 hp, and you won't have to enlarge your radiators. The 92 series are all turbo, so they get better mileage, and have all of the auxiliary drive connections on the 'rear' of the engine. The adapters on the rear of your 71 will fit, so you won't need to make a bunch of brackets for your air compressor and alternator, etc. The down side is that it is still a Detroit, not quite as noisy, not as smoky, and doesn't leak as much oil. Consider Ralph's post immediately above. Some of the advice above hasn't been driven yet, and IMNSHO that final drive ratio will make a sluggish bus in traffic, and on hills. It will also be very hard on the torque converter, and the trans will spend a lot of time in the lower gears. I'm absolutely NOT suggesting a high numerical ratio that will result in the engine running 2000 RPM at 65 mph, but if the bus mfrs could get 12-14 mpg by running an engine at 1200 rpm cruise, they would have years ago. Consider increasing your tire size as a way of lowering your final drive ratio, which will increase your fuel mileage. All of the mfrs publish a fuel consumption curve, which you can Google. The 71 and 92 series are most efficient around 1700 RPM, if I remember correctly. HTH G | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1340 Registered: 5-2001 Posted From: 65.74.72.213 Rating: N/A |
George, you're right about the manufacturers publishing their fuel consumption curve, but I have yet to see one that covers part throttle operation. Since our fuel mileage is mostly determined by the partial throttle efficiency, we almost never have enough information to get the best out of these engines. The 4106 with the VS2 and the transit rear axle are an example of what I am writing about. I saw a report that a fellow was running 65-70 with the engine running only 1650 RPM, and I saw another that reported getting better than 10 mpg with his. None of that is in the cards for V730 setups, and their performance shows it. They run hot and get poorer fuel mileage. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1985 Registered: 10-2003 Posted From: 71.58.71.157  Rating: |
For the engine change you are talking about and the total ending cost, plus windows that have screens, why don't you just find another conversion that already has these things? There are fantastic bargains out there now and if fuel prices keep climbing like they have done in the last few months, there will be even more. |
