I have been researching this quite a while and have a couple of takeaways with not having done this mod as of yet.
1. Many comments from others state that after adding a pyro on even a non-turbo'ed NHC250 that the exhaust temperature is way higher than they ever expected and after viewing it they think they may have already done damage to their motor with the "stock" config and their old driving styles. Because the exhaust temps are now being viewed,they modify their driving style to protect their unmodified motor.
2. Many comments from other state that after adding their turbo their exhaust temps actually drop. Now this possible due to the added air being pushed into the engine, however, if your adding more air.... you would like to add more fuel (power) to match. This pushes the temps back up, but even so most have reported better than stock temps even under loads or climbing hills. Even with this "caution" most users having added the turbo are very happy with the bump in power. In my opinion if you are going to add a turbo on the non-piston oilier squirter style NHC250 you should without question add an after-cooler to the intake. This is to me a little added insurance to the already questionable motive of adding a turbo that does not have piston squirters. But to each their own as many have not gone this route.
3. Prior to the Turbo mod, most MVrs add the Dual fuel mod. I did mine and it added maybe some power... Not very noticeable but it is there.
Well like the title says I did a duel fuel line mod on my m818. I did some reading on a combine forum that some guys do this to there big tractors and there is a noticeable difference with it running smoother at idle and having more guts while pulling. I haven’t run it yet so I cant tell you if...
4. The HT3B or HT60 seem to be the choices of a turbo. Most of the comments of those who have had both is they are both an impressive improvement but the HT60 gives better more noticeable lower end power in the range of 1000 to 1600 rpm. So from the comments of others, the HT60 was the one I was holding out for if I choose to go this way.
5. You will need to be touching several other items on your motor, like a new fuel button, Most have a 21, or a 17 and some go as low as a 15. However all of these increase fuel rail pressure which has adverse affects on the cam to injector stress. The lower the number the higher the stress. My rig has stock about 150 PSI fuel rail pressure. For some reason this pressure jumped to 160 when I did the dual fuel mod. Some feel you can safely run up to 200, others feel 220 psi but others feel anything above stock is looking for trouble. To get around changing the fuel button which increases the fuel rail pressure and puts you into this questionable realm of cam/injector stress, some change the injectors in the heads with ones that have a higher flow rate and modify the injection pump to match. This mod makes it UN-necessary to increase the stress on the cam since more fuel can be delivered with the larger orifice on the injectors and the matched flow from the modified PT pump. The wide accepted opinion is these mods are best done by a shop like Pimco. You send them your pump and injectors and they send you a worked over set to the specifications they help you figure out. Those who go this route seem very happy with the mod and it's cost to get it.
6. Depending on the MV 809 or 923 series, You will need:
6a. to modify the exhaust, possibly loosing a muffler all together,
6b. the intake tubing/housing etc... to make it connect to the opposite side of the engine,
6c. turbo oilier to cool the bearing of the turbo,
6d, Plugging the ports in the head
I already spent over an hour searching the forum. Scrolling through 15 page threads etc., so I tried. I found mention of them, but that's it. I paid my dues! Where are they!
6E. adding a Pyro mentioned above has a preferred by most mounting position to be pre turbo, in the rear exhaust manifold port that is fed by the three rear pistons.
6F. Possible hood modification or bumping up the cab to clear if you have an 809 series.
6G,H,I,J,K LOL I am sure I am leaving something out like moving the overflow for the cooling system etc... Make a list it is long.
That is my take. If I was done with the other mods I am looking at, I would go this route as obviously I am interested. Let us know how it works out for you if you take the "spin". Would love to read about it.