| Author | Message | ||
| Jason Simons (Bigblock01)
Registered Member Username: Bigblock01 Post Number: 18 Registered: 6-2008 Posted From: 209.164.238.7  Rating: N/A |
How hard and costly would it be to take an 8v71n and rebuild to an 8v71t. I understand that the pistons are different. Just thought that it would be something I might like to do have access to a spare 8v71n that needs rebuilding has cracked head and busted piston so I thought I would try to get into it myself. I have never built a diesel before only old chevys. Any ideas? I have MC-9 with 8v71n runs good now no heat problems. If I build to the t motor do you think I might run into heat problems? | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 248 Registered: 10-2003 Posted From: 66.165.176.60  Rating: N/A |
I asked a similar question ont he detroit yahoo board a while back and there was a whole host of other parts including injectors and a different bypass blower. Can it be done yes but concensus was just to find a good turbo model and swap the whole powerplant. It would be worth joining the detroit group as there is a wealth of info in the group http://autos.groups.yahoo.com/group/DetroitDiesel/ | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 616 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
Jason, they are not that hard to build, the pistons and liners are about the same price,and you can do without the bypass blower they were for fuel saving I can not see much difference in that changing from a non bypass (factory) on my 8v92TA to a bypass type.One thing if your block will not accept the after cooler you will need to go air to air and that can be costly so check your serial number on the block before you start,and most will not produce anymore heat because they burn all the fuel with enough air to make it work a 325 HP 8v71 is a nice setup with good fuel mileage ,power and no smoke good luck | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1277 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
One suggestion that was offered some time back, was to go with std. pistons and use lower boost to get almost all the benefit at lower cost. Anything that is done to increase horsepower is going to create more heat. Why not find a good or rebuildable 8-92 TA and go with it. As far as cooling, I think you can upgrade to the 92 series cooling system from one that already had the larger engine. Just keep in mind that a loaded coach of 30 to 36 thousand pounds or more isn't going to see as much improvement as you might think on the hills with just turboing the 8-71. Oh, it'll run better, but are you going to be satisfied with what you get for what you need to spend? We had a friend that converted an MC-9 several years ago when they were still relatively new. He wasn't happy with the power it had, so he upgraded with larger injectors, which didn't help much. He then had it upgraded to a 425 horse 8-92. It really flew up the hills then, but then he was unhappy with how much the fuel consumption increased. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 617 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
Jason, heat and HP do not always go together if you build a clean burning engine it won't produce more heat 2 strokes produce heat from to much fuel and not enough air.I can increase my 8v92 to 500 HP and it shows no more heat increase than it does at 445 HP.the 325 HP 8v71 is a good engine I had 1 for years in a MCI 8 with a side mounted turbo with no problems good luck | ||
| Jason Simons (Bigblock01)
Registered Member Username: Bigblock01 Post Number: 19 Registered: 6-2008 Posted From: 209.164.238.7 Rating: |
Ok thanks for the thoughts. I am not dissatisfied with my 8v71n it is doing a good job. I can handle the speed to stay with it I was just tossing the idea. I have a friend that has given me an 8v71n that he pulled from as '68 Eagle he said the head was cracked and has a busted piston. I am going to build it myself just to learn how to work on the internals of it and then I'll have a spare. I was not sure about the turbo. The 8v92ta has a nice ring to me because of the 450-500 hp because my truck has a 550 Cat but the ol 318 does fair. I wieghed the bus the other day and it came out at 33000# still have a few things to go but it pull the hills around Cherokee NC alright and did not get to 190* it stayed alittle below 185*. If I go with the turbo do I need to go with N75 injectors. The motor I'm running now I'm not sure what is in it the guy I bought it from said it most likey had the fuel squeezer in it I guess that would be N60's. My 4104 has 6-71 with N65 brown tag in it and it does a good job pulled the same hills about the same maybe alittle faster (I think that was my fault thought I let the auto do the work in the MC9 have changed now I shift it if I hit a hill that pulls it down.) I have enjoyed reading on this forum and have got alot of great pointers here so Thanks to everyone that posts here because sometimes you can find answers to ? that you what to know but don't want to ask be cause someone else has ask it for you. Because we are all work on our deams and it helps to hear what to do are to look for from someone that is there are has been there and done that. Check out my groups site we are a gospel group and use our bus to travel. www.thedixiesonlighters.com Thanks and God bless BigBlock01 (Message edited by bigblock01 on January 10, 2009) | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1278 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
smaller injectors= less heat and less horsepower, but the turbo will make an improvement even with smaller injectors. Same with an 8-92. They had models with only 350 horsepower and small injectors that would last about forever in a coach and still provide outstanding performance compared to the engine you have.They also generate less heat than the higher horsepower versions. The spec sheets call it heat rejection. Keep in mind that as the years go by, the parts for upgrading these engines will be more difficult (not impossible) to obtain, even with the internet. The torque increase is what you'll appreciate. Also those small injector version models will cruise at lower rpm's, probably saving fuel if geared properly and run in their torque/power band. That's why those small injectored 8-71's would work with the vs2-8's and run at lower rpm's in overdrive without damage to the engine. ( and get great fuel mileage ) Using a turbo with smaller injectors will greatly reduce smoke output in either engine model, which will be a benefit in many areas traveled nowadays. | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 53 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
I did exactly this job to my 8V-71N with brown tag 65N. It now has 9C75 injectors, puts out 375hp and 1125lb/ft torque with air to air intercooling, bypass blower. Don Fairchild in Bakersfield did the conversion-we kept the high compression pistons since they had transit bus style compression rings that can take the pressure (I don't burn anymore oil than I did before). I cost about $9,500.00 to do. Well worth the cost as it REALLY wakes up the 8V-71. For our usage, I would stay with the 8V-71 with its' dry cylinder liners, rather then the 92 series with its' wet cylinder liners that can leak into the crankcase (again call Don Fairchild and ask how he knows about that personally). Good Luck, TomC |
