3208T Turbo Conversion from 375 HP Marine

Topic: 3208T Turbo Conversion from 375 HP Marine (Read 836 times) previous topic - next topic

3208T Turbo Conversion from 375 HP Marine

September 11, 2020, 02:14:42 am

I read an older posting about possibly changing out my single turbo on my 250 HP for twin turbos off a marine 3208 375 hp unit. Can anyone help on that? I can't seem to locate the posting.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #1 – September 11, 2020, 05:58:40 am

WoW... I had a 88 GV with a 300 CAT, I found this out after giving CAT MY SN.

Had no issues with a Z71 Avalanche towing until 6% grade, that 4 speed is great.

The issue you will have is cooling that rocket your building... and perhaps over torquing the allison.
Good Luck

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #2 – September 11, 2020, 08:40:58 am

Quote from: warbirdlvr – September 11, 2020, 02:14:42 am

I can't seem to locate the posting.

Probably this one? A familiar "campfire story" around here. Pursue this upgrade at your own risk.

Has anyone driven a 1986 ORED GV 40 ft with NA Cat 3208?

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #3 – September 11, 2020, 09:05:43 am

Quote from: warbirdlvr – September 11, 2020, 02:14:42 am

I read an older posting about possibly changing out my single turbo on my 250 HP for twin turbos off a marine 3208 375 hp unit. Can anyone help on that? I can't seem to locate the posting.

The coach I'm buying is also a 250hp 3208T, I also plan to do some performance work to it, but, I wouldn't consider the marine twin turbo mod viable. The marine engine has access to unlimited cooling. Increasing/improving the single turbo is probably what I'll work on; installing a Charge Air Cooler/dedicated electric fan would be the first step. The other mods to increasing fuel would compliment that. I'll probably install a larger more aggressive 9 blade composite cooling fan as well to stay ahead of the curve on keeping it cool...while the MT643 is only rated for 250hp, it is rated for that at over 70000lbs GCWR, so, there is some considerable margin to work with, my set up will likely never see north of 30000lbs GCWR.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #4 – September 11, 2020, 09:52:36 am

Quote from: len.barron – September 11, 2020, 09:05:43 am

The coach I'm buying is also a 250hp 3208T, installing a Charge Air Cooler/dedicated electric fan would be the first step.

It sounds so easy to just put a electric fan on too cool it. Once you start looking at fans large enough to actually do what you need they are very large power consumers. Alternator will need to also be adjusted to handle continuous duty requirements. My current project uses 36 amps dedicated for cooling power requirements at idle rpm. Just a different angle to the problem.
Scott

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #5 – September 11, 2020, 09:56:11 am

I've got a lot of experience repowering older rigs, I just sold my duramax converted FMC, dual 3700cfm Taurus fans pulled 70amps on high to cool a large 30" x 24" CAC and aux trans coolers. I ran a dual alternator set up both were 270amp units.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #6 – September 11, 2020, 11:12:58 am

There is not enough radiator to cool this upgrade. On top of that, the 3208 is physically a very small engine for 10 liters and the TBO at that power rating is short. The engine is so small and light that it can be installed (and is) in a pickup truck.

Consider plumbing your coach for a couple of front radiators like it should have been originally. No room for large tubing but even using the existing heater hoses will give better cooling. A couple of members have done this with success in a GV.

Pierce

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #7 – September 11, 2020, 11:14:17 am

I guess if it's a hobby or fun seems like a lot of work and $$$ for little gain. Those old 3208s had plenty of power and good reliability in stock configuration. If I where going to do something to one of them a serpentine belt system would in top of the list. Did belts on a bunch of then in old crane carrier chassis, no fun, rear radiator even less fun.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #8 – September 11, 2020, 11:16:21 am

I am the one who posted about the marine conversion.

Customer had 95k miles on it after the twin turbos. Rear radiator. He stated he never got into it hard unless in high gear, no issues.

I think he had a pyrometer on it,

Watch your temps and enjoy, would do it in a heartbeat after I drove it,

643 Allison.

Like cheating. He had a boat place in Galveston install it.

280's should have more than enough radiator as far as I know

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #9 – September 11, 2020, 03:01:28 pm

Question, the heads were not part of the conversion, were they? I would certainly want a pyrometer, and not push it until in high gear. How did things work in the mountains? Any over heats then? I really don't have power issues now, but haven't been in the Rockies yet either. Don't want to do something that will jeopardize the engine and cut the TBO in half. She has approx. 70K on the clock now.....

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #10 – September 11, 2020, 03:57:38 pm

I think the heads are the same. I do think all of the 375/435hp marine versions were roller cam , 3 piston ring engines; I haven't been able to get clear research/info on what year the rest of the 3208s went to roller cam or if any of the non-ATAAC engines ever had 3 rings...but again...hard to get definitive info on that..

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #11 – September 11, 2020, 04:31:43 pm

Stock engine. Bolted on the turbo's. He had a marine shop do it. He had no other info. Got 10mpg.

What hills. I assume the shop might have changed things in the motor to increase the fuel but maybe not.

I noticed the radar detector in his coach that's why I asked why?

Lifting the bed was impressive, 85 ORED 250 Cat nominally.

Texas customer. Maybe James T. had seen this coach way back when?

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #12 – September 11, 2020, 06:05:13 pm

Quote from: warbirdlvr – September 11, 2020, 03:01:28 pm

Don't want to do something that will jeopardize the engine and cut the TBO in half. She has approx. 70K on the clock now.....

It's not that I'm superstitious or anything but I treat old engines the same way I treat old houses: If it ain't broke, don't fix it.

Honestly, anything you do to increase the power output is going to have a negative effect on the lifespan of your engine.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #13 – September 11, 2020, 06:13:11 pm

Most all of our coaches will get 10 mpg at 55-60 mph w/o toad and on flat ground. Adding a turbo or twin turbos won't give much extra HP unless you have an injection shop add fuel. We cast up intake and exhaust manifolds for diesel Mercedes in the 1970's and 1980's and ran quarter mile times stock, with turbo (did drop EGTs a lot) and with turbo plus added fuel. Just the turbo took a couple seconds off the time but the big difference was when we added fuel.

The factory 300SD engine used a KKK turbo at about 14 psi boost. Our Rajay (later Roto-Master) turbo was only mapped to give 7 psi but with added fuel, it really made them fly. To make the factory engine live at 14 psi (no intercooler), Mercedes used oil sprayers, different rods, pistons, valves. The 6V-92TA Detroit Diesel installed in our Foretravels has a two point lower compression ratio than non-turbo 6V-92s. The point is that you can't just throw on a turbo(s) and expect the engine to be more powerful, more reliable, etc without a lot of homework. Homework best done by the factory or others with dynos, injection pump racks, etc unless you have lots of money for mistakes in your wallet.

With the inception of the HT746 Allison and it's increased torque capacity, Foretravel had Detroit do an update to the 6V-92TA's computer addling a little fuel to increase the HP to 350 from 300. Increasing the power adds heat so they went from the rear radiator to the side radiator in the 1992 model, the first year at 350 hp. The cooling was still marginal so they went from the upright side radiator with one fan to a larger horizontal radiator with two fans for the 1993 model. Our cooling is still marginal in summer on long grades. Last week, returning from a trip to June Lake, I had to drop to 2nd gear toward the top to keep the temp from exceeding 210 degrees on westbound Donner Grade on I-80. This is normally 3rd and 4th in cooler weather and 55-60 over the top.

So, blindly adding power to a medium duty 3208 CAT and hoping for both better performance as well as good reliability is asking for problems unless a lot of research is done. For years, there were lots of blown up 3208s sitting in boat yards and on wharfs from owner's who turned up the wick too far. Again, this a a small block, medium duty engine so get your ducks in a row before you cost yourself some $$.

Pierce

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #14 – September 11, 2020, 09:08:50 pm

JMHO, hotroding old 20+ year old anything usually doesn't end well. Back in the early 70s the guy I hauled produce for had some bad old V12s, 335s turned to 380 horse, and we ran em. Usually about 125k something would break. Went to 1693TA rattle Cat 475hp, left them alone I drove one 500K never a wrench on it, it got an inframe at 900K.
A 10 liter 3208 not exactly a small motor between 8.3 and an M11.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #15 – September 11, 2020, 09:33:43 pm

Quote from: bbeane – September 11, 2020, 09:08:50 pm

JMHO, hotroding old 20+ year old anything usually doesn't end well. Back in the early 70s the guy I hauled produce for had some bad old V12s, 335s turned to 380 horse, and we ran em. Usually about 125k something would break. Went to 1693TA rattle Cat 475hp, left them alone I drove one 500K never a wrench on it, it got an inframe at 900K.
A 10 liter 3208 not exactly a small motor between 8.3 and an M11.

The liter size is not what I'm talking about. The size of the 3208 block is very small, a fraction of the size of our 9 liter Detroit or Cummins M11. It's so small that it can fit in a PU. Small blocks with large displacement don't have much rigidity to withstand high diesel hp output for any length of time. The heavier the block, the more hp it can contain without blowing up. CAT already has to spin it fast to get the hp out of it.

Check this video of a Toyota Land Cruiser with the 3208 installed. Try that with a M11 or 6V-92TA. Put either one of those engines in the Land Cruiser's bed and they would break the springs.
https://www.youtube.com/watch?v=t1wRK4TEmQE

Pierce

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #16 – September 11, 2020, 09:53:22 pm

My '81 has the Cummins 555 or triple nickel as they call it. It is Cummins version of the 3208 I have it turned up as all you do to this engine is change the orifice in the return line to boost power. I have to use the pyrometer to keep from melting the pistons when climbing grades. If it is your own vehicle you will try to not blow it up.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #17 – September 11, 2020, 10:15:29 pm

Craneman, my Cummins guy says retarding the timing and turning up the pump gets the best results.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #18 – September 11, 2020, 10:27:43 pm

Quote from: Olde English – September 11, 2020, 10:15:29 pm

Craneman, my Cummins guy says retarding the timing and turning up the pump gets the best results.

A boat racing shop turned up the pump then handed me smaller and larger return orifices or buttons as he called them for me to choose what worked after driving the coach. He only had a machine tester for the pump no dyno. I went down one size for a little more hp but use the pyrometer. I will have to turn it back down if I ever decide to sell it.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #19 – September 11, 2020, 11:33:31 pm

I have driven quite a few 555 Cummins. Only diesel that had a top rpm power hit.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #20 – September 12, 2020, 09:51:55 am

I dump my air every time I store the coach. This keeps the system from continually trying to keep the coach level. What happened in the past, is the coach will settle over time and continually release air until it is all the way down. Dumping the air in the beginning prevents the coach from twisting while on its inevitable downward path.

It also makes it easier to get in and out of the coach.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #21 – September 12, 2020, 10:24:38 am

Quote from: craneman – September 11, 2020, 09:53:22 pm

If it is your own vehicle you will try to not blow it up.

The boss man rode with me now and then he liked to see his trucks strollin. We loaded em heavy and ran em fast, got to haul them groceries. Don't make money hauling produce blocking up the left lane. Back in 73 Belle Glade FL to Niagara Falls CN 30 hours 73,280 lbs. not a whole bunch of interstate back then.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #22 – September 12, 2020, 10:33:16 am

Quote from: craneman – September 11, 2020, 09:53:22 pm

I have to use the pyrometer to keep from melting the pistons when climbing grades. If it is your own vehicle you will try to not blow it up.

Sadly that's not true for many people who won't respect the hard limits of engineering and allow a desire to be somewhere at a certain time to govern their right foot.

In 1993 I rented a Penske International-Navistar box truck to drive to West Virginia and bring a complete Linotype shop to Manchester NH for my personal use. When I hit the hills I left the cruise control set at 62 MPH, flipped on the 4-way flashers as we passed 45 MPH and did my best to stay between the lines. Coloring inside the lines is not my strong suit, reading between the lines however is.
Anyway, once we arrived upon level ground I expected the computer to resume 62 MPH, instead, with the engine fan roaring its mighty roar we continued along at 45 MPH as the needles on the dashboard returned to safer zones before the computer decided that it was time to upshift the transmission and resume our pre-set speed. I was impressed.

Not that I would have abused a rented truck. No. Never. Not that far from home.

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #23 – September 12, 2020, 10:58:28 am

Quote from: Eric & Alena + 3 – September 12, 2020, 09:51:55 am

I dump my air every time I store the coach. This keeps the system from continually trying to keep the coach level. What happened in the past, is the coach will settle over time and continually release air until it is all the way down. Dumping the air in the beginning prevents the coach from twisting while on its inevitable downward path.

It also makes it easier to get in and out of the coach.

It also flattens the air bags so they have a tight fold where the rubber then comes off first, exposing the cord. That's where a couple of ours started to leak.

Pierce

Re: 3208T Turbo Conversion from 375 HP Marine

Reply #24 – September 12, 2020, 11:59:27 am

Thank everyone for their input. I asked and I received several opinions that I am thankful for. Now, I need to kind of sort thru the info and make my decision. I spent all my working life in auto dealerships as a tech, and then in management. I also used to hold the National record in the drag racing circuit campaigning a 66 Chevelle with a stock block 396 with all kinds of upper end mods. The big answer to it all is care and careful driving habits. I'm an old poor boy from the country who really thinks things thru before I twist off and do something disastrous. As I said, I asked and I got a lot of really GOOD info, and thats why I asked.
I also have driven diesels since the 70s when GM came out with their 5.7. That motor will live forever as long as its limits are respected and maintenance is done. I put almost 500,000 on a 79 Eldorado that was still tying bundles when I sold it, and no oil consumption between changes, and hiway speeds of 75 to 85 regularly. I improved performance on it by turning up the pump timing a smidge and knocking the restrictor out of the return orifice. Thanks again, folks. Lots of fat to chew!!!!

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