| Author | Message | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 12 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
As part of my ongoing quest, I've been snooping around the bus market looking at a lot of MCI 9's lately, and I've noticed something. Most of the ones I find have either 6V92TA rated for 277HP at 2100 RPM, or 8V71 rated 280HP at 2100. Now again, please forgive this stupid newbie, but which one is best? Other than one being 6 cyl and the other 8, I see little difference in the power ratings. Then again, I know nothing.  Considering I want to get this right the first time without coming up underpowered, what is the right choice for a 9? Does the 6 get that much better mileage? Is it wimpy on hills? Please explain. Thanks Tom | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 988 Registered: 12-2000 Posted From: 71.195.113.23 Rating: |
What do you consider hills? The "Speed Bumps" back east or Rocky Top out west? A quick Detroit two-stroke primer, engine type ID: 6 or 8 = number of cylinders L or V = type of block, either inline (L) or V 71 or 92 = Cubic Inch displacement per cylinder T = Turbocharged A = Aftercooled So, an 8V71 = 568 cu.in. and a 6V92 = 552 cu.in. Now, the old hot-rodder's adage says "there's no substitute for cubic inches", BUT, in this case, the smaller engine also has a turbo on it, which boosts it's HP & torque output considerably. And that turbo makes a difference at 7,000 ft crossing the Sierras on I-80 into CA - the engine doesn't smoke nearly as bad, nor does the power fall off nearly as much. BUT - it only makes about a 5 minute difference on a 200 mile run, and the fuel mileage is statistically the same. OTOH, you can take a MUI (non-electronic) 6V92TA and easily pump it up to 350 hp by simply changing the injectors and turbo housing. To bump the 71, you've got to completely tear it down and rebuild it as a turbo - a LOT of work and $$$ for 75 hp. Better yet, find yourself an MCI 102C3 with the 8V92TA in it: 400 - 500 hp w/ the upgraded cooling system to match, plus an additional 6" of interior width - and you just know that Mama will like an extra six inches!! FWIW & HTH. . . | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 13 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
RJ, Thanks for a great answer that helps take some of the mystery out of it for me. Mainly, I will be travelling regularly up and down the East Coast, and as far west as Missouri and Indiana on occasion, but Atlanta-Nashville-Memphis or Atlanta-Chicago area will be a fairly regular journeys. Up, over and down the Appalacians a lot. I will, I'm sure be travelling westward over the big hills at some point, but not often. Not that I want to be a speed demon in a bus, I just want steady power with no strain. I hate the feeling of a severe loss of power up a hill in any vehicle. So I take it that a 6V92TA,especially at 350HP, would handle the East Coast hills with ease then? The 102C3 is a consideration, especially since I understand these also have higher interior roof height. I just see more 9's in my budget range. Thanks for sharing the knowledge, Tom | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 177 Registered: 9-2004 Posted From: 65.23.106.193 Rating: |
The east coast hills are of shorter duration so the slow down is not for long, usually. If slowing down on hills bothers you, get the highest HP you can. But that route will cost more now & every time you use it. How deep are your pockets? That is something only you (or a wife) can decide. I used to want to have 500+ hp, but now after pondering lots of other things, I think I'll be happier with a DD S50 with a 6 spd auto w/overdrive for my bus. I hear they can be tuned to 350 HP & get better fuel mileage than anything else in this application. | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 989 Registered: 12-2000 Posted From: 71.195.113.23 Rating: |
Kyle makes a very good point - Having a high HP engine sucking copious amounts of fuel EVERY time you drive it, just so you can climb a five mile grade 10 mph faster twice a year, makes great economic sense. . . NOT! Up until the S-60 became the most common hiway coach engine, Greyhound (for all their problems) stuck with the 275 hp rating on their engines, primarily for fuel economy reasons. And their drivers STILL managed to maintain relatively good on-time schedule performance - frequently better than the airlines! Reality check: Think of the children's fable of the Tortoise and the Hare. If you try to drive a bus like it's a Hare, you're going to be severely frustrated and disappointed. Drive it like it's a tortoise, and you'll be a happy camper! FWIW. . . | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 851 Registered: 12-2000 Posted From: 64.228.91.3 Rating: |
Hello Tom Between the 6V92 and 8V71 in stock trim, the choice depends on what you want it to do. The 6V92 can breath better up high, because of the turbo and makes a bit more torque than the 8V71. The 8V71 is snappier off the line, if squirting out into traffic from a stop is a concern. The 6V92 needs a little time to get the turbo pressure up to make big power. There were a few stock 8V92 in MC9.... The real numbers you want to pay more attention to in a heavy unit is the torque. Torque is what pulls you up the hill, horsepower is often thought of as another word for fuel consumption. One of those MC9 8V92 with the 5 speed stick shift would be a dream machine..... well, for me, until my left knee goes....fun until it did....! If it has 8V92, be very sure it is stock, or there may be problems if the swap was done poorly. happy coaching! buswarrior | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 14 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
RJ, your right, both you and Kyle make a load of sense on that, and fuel economy is an important factor. It's not speed up a hill so much with me as it is not having to floor it to do 45 and still feel like I need more, like I've had to do on some cars. Buswarrior, thanks for pointing out the differences off the line also, as this too is very important to me. Far be it from me to question the judgement of professional transit companies, but having never driven and not knowing the "feel" of one yet, I'm just trying to quell my newbie paranoia by soliciting the opinions of drivers as to which engine offers the best overall performance across the range of real world conditions. I think that would have probably been a more correct manner in which to have posed the original question, but I hear so many coach drivers talking of being underpowered, and I know what that feels like in a car. Just don't want to make that same mistake in a bus. Thanks again Tom | ||
| Kyle Pesely (Kylexisxrad)
Registered Member Username: Kylexisxrad Post Number: 39 Registered: 12-2005 Posted From: 216.220.208.232 Rating: |
my Eagle 10 has a 6v92TA that has been bumped up to 350HP through the method RJ talked about, and although it DOES take a bit longer off the line to pick up speed(especially if there's a sudden slowdown in traffic on the freeway and I lose my momentum), it performs EXTREMELY well in the mountains, especially on that horrendous climb up eastbound HWY-50 towards donner pass(RJ knows what I'm talking about). and, so far I'm getting 10 mpg highway if I drive it sensibly. FWIW. kyle in norcal Eagle 10 #30223 | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 64 Registered: 10-2004 Posted From: 71.125.20.202 Rating: |
Tom, get yourself to some bus get togethers ( they post here and elsewhere, chapters in FMCA etc)and ASK ?'s, most people will be very helpfull. I remember when I first got my bus how i was gonna do this and that to cure the slow top end and the lag from 3rd gear to 4th. We were decent off the line till we shifted to 4th and it seemed for ever to hit 60 from 40. I was complaning about this when 3-4 old timers laughed and said welcome to the club. the kicker was we had a 4-71 and they all had 8V-71's. its all relative to weight also. If you can keep your rig light that will help alot. Its a small group with the hi HP engines and the resulting bragging rights. Steady does it. | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 15 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
Thanks David, I've been watching the board trying to find some bus events near me that I can work around my crazy schedule. You can bet I'm going to go do this several times at least before I write the big check. Your advice on minimizing weight is also something which I am already incorporating in my planning. Thanks Tom | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 990 Registered: 12-2000 Posted From: 71.195.113.23 Rating: N/A |
Kyle - You talking about going over Echo Summit into Tahoe, or over Donner into Reno? OR both? What the hey, they're both 7,000+ ft passes thru the Sierras - and you can see the benefit of the turbocharger in your Eagle. FWIW. . . PS: Are you in Sacratomato?? | ||
| Kyle Pesely (Kylexisxrad)
Registered Member Username: Kylexisxrad Post Number: 40 Registered: 12-2005 Posted From: 216.220.208.232 Rating: N/A |
rj- I was thinking echo and typed donner. ha. and yeah, I'm up here in good ol' sacratomato. if you're up here before I have a chance to get down there(don't you have family around these parts?), the pepsi's on me. I have a cold 24 pack in my fridge as we speak. kyle in norcal | ||
| Bob Wies (Ncbob)
Registered Member Username: Ncbob Post Number: 181 Registered: 2-2006 Posted From: 72.71.65.233 Rating: N/A |
Hi Tom...we're neighbors (almost) and I sent you an E-mail to introduce you to some of the busnuts in our area. Hope to hear from you soon. Bob | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 16 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
Thanks NCBob! I sent you an e-mail back as well. If you have trouble recieving it, let me know. Thanks Tom | ||
| Greg Peterson Unregistered guest Posted From: 71.228.18.37 Rating: |
The engine question is a frequently reoccurring question. I will give you the “Peterson’s laws of bus engine power” for help. I give no guarantee that the laws are correct and do not want to offend anyone that does not agree with them. Use them at your own risk. First law is a diesel engine in a bus must have a turbo charger. Some of the reasons have already been stated but there are also additional benefits as well. This eliminates the 8v-71 and now you have Series 60, Series 50, 8v-92ta, 6v-92ta, and maybe a Cat engine as options. Law 2 is more torque and horsepower is always better. Make sure you look at the Cat RV site. It has a very good article on power requirements to climb hills at different speed. Law 3 is don’t spend more than you can afford. This law will help you pick which turbo engine you will buy. Law 4 is the cost to convert the bus will be more than you originally estimated. This is a good law for building houses or anything that is complex and expensive that you have never completely done before. Law 4 can influence law 3 because the more expensive bus will leave less cash remaining to finish the conversion part. Law 5 is do not believe guys with 4-71, 6v-71, or 8v-71 when they say, “ I don’t need any more power”. These guys bought their bus back when a MCI 9 was out of their law 3 ranges. They bought a MCI 8 or less that only had 6v-71 or 8v-71 engines. They could also say “ I like to go up hills at 20 mph with everybody passing me… I even get out of the way of the guys on bikes” or “ I like all that black smoke I am blowing out because I think it keeps the bugs under control.” Good Luck | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 17 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
Thanks Greg, sounds like a well thought out theory to me. Tom | ||
| Pete P
Unregistered guest Posted From: 24.222.131.9 Rating: |
Well I have to agreee. I have a '06 with an 8V71 that has an urban v92 blower on it and N71 injectors coupled to a V730. Yep, I can climb hills, pull 13-15PSI on the turbo, the pyro gets into the 1100s and the mileage I manage about 6.5, weight of the unit is 28K lbs. A manual with smaller injectors and not turbo gets about 8 mpg so the trade off isn't that bad. Now 'm headed into a '9 with a 6V92 because we want that extra 6 inches. I guess that's why we're busnuts | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 857 Registered: 12-2000 Posted From: 70.48.193.36 Rating: |
Excellent work, Greg! I'll add the bus driver's addiction: There ain't no such thing as too much power. Once you've driven a 475HP Series 60 that has all the correct settings for flank speed blast off... And got used to it.... You start wishing you had just a little more.... engine power is like a heroin addiction. more isn't enough! happy coaching! buswarrior | ||
| Thomas Weeks (Buscrazytom)
Registered Member Username: Buscrazytom Post Number: 20 Registered: 7-2006 Posted From: 66.188.77.156 Rating: N/A |
Hmmm, suffice it to say I guess that like a heroin addiction, engine power can kill you as well.... Tom | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 860 Registered: 12-2000 Posted From: 64.228.91.147 Rating: N/A |
Yup!! happy coaching! buswarrior |
