| Author |
Message |
Peter (Sdibaja) (200.56.111.119)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 27, 2002 - 11:48 am: | |
I have a normal 8v71 in great shape; it will outlive me if I don't screw it up.
Like everyone else (almost) I would like a few more horsepower.
Has anyone out there turboed an 8v71?
1. Notable difference?
2. Cost?
3. Jakes?
Thanks, Peter |
RJ Long (Rjlong) (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 27, 2002 - 2:27 pm: | |
Peter -
This has been covered several times before, and the answer is yes, BUT:
You cannot install a turbo on an non-turbo 8V71 (or ANY other non-turboed diesels) and expect it to live, any more than you can install a turbo on a gas engine and expect it to live.
There are a number of changes that must be made to the engine, such as different cams, pistons, oil supply & drain for turbo, injectors, the correctly sized turbo, etc., just for starters.
Best results are obtained when using a block designed for the turbo, especially the later models set up for an aftercooler. (8V71TA models, which are out there, altho somewhat rare.)
You don't mention which model coach you have, but if it's a GMC, you cannot slap a truck 8V71TA in it as is, or you'll end up with four speeds in reverse and one go-forward.
A stock 8V71N with N60 injectors set to standard timing will put out about 275 hp. The turbocharged, aftercooled 8V71TA, using 7C75 injectors, pumps out 370, roughly 100 more. Fuel mileage suffers a little when you bury your foot in it.
Heat rejection also becomes an issue - you've got to cool the beast! So paying close attention to the cooling system is a must, and, depending on your coach model, modifications to increase capacity may be required.
IBME, that over a 300 mile run, having the extra 100 HP makes a FIVE minute difference in arrival times after pulling 70 miles of 4, 5 & 6% grades.
Some grades that used to require the top end of second gear, for example, now can be pulled in the middle of third. Whoopie, a whole 7-10 mph faster, and a whole lot more fuel burned, too.
The big question is whether or not the cost to bump the HP is worth the extra time savings - and is almost a moot point if you never get into the mountains (and I don't mean those speed bumps they call mountains east of the Mississippi).
Finally, IMHO, if you're doing a lot of mountain work (west of the Mississippi!), installing a jake brake is a far better investment than bumping the HP.
OTOH, if it's rebuild time, then it's time to do a lot of serious thinking, and this would include the possibility of using a 6V92TA out of a donor transit, which can easily be bumped to 350 hp with simple injector and turbo swaps (MUI engines - DDECs require a little more "massaging". . .)
Decisions, decisions, decisions. . .
HTH,
RJ
PD4106-2784
Fresno CA |
Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 30, 2002 - 5:37 pm: | |
Yea, you can turbo your present Detroit, but as already said, it will be $expensive$. To do it correctly one should change out the....
Pistons to lower compression versions, using either the late model 2-piece turbo type or the older, pre "N" pistons which would be less expensive.
Then you need (I think...may be wrong here) to ADVANCE the timing (?) to the "A" position, change/modify the blower, (bypass do-hicky)
Go to a four (4) valve head if not already, then install bigger injectors (anywhere from 75's to 90's) somehow get a properly sized intercooler to fit....
In front of the radiator, add the proper turbo, open up your exhaust and intake system, install the reguired extra dash gauges, larger fuel lines, fuel pumps....
Figure out all the extra piping and plumbing to mate everything up properly, then dealing with the extra compartment engine heat....
Then hoping the radiator(s) will handle the extra load from the extra HP heat rejection, then figuring out how someway to ?pay? for all of this.
Are we having fun yet? Anyway, you get the idea----it can be done, it HAS been done, it IS fun, but to do it requires time, money and lots of patience.
Anyway, I am facing the same thing kinda with my Crown Coach conversion. Now have the non turbo big cam Cummins 250 and I really want to open it up into a 400 or a 444.
Same thing basically with the Cummins applys with the Detroit. Lots of stuff inside the mill needs to be changed out. I may have to settle for only a Jake Brake with is a necessity. Good luck. |
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