Anyone Know Torque Limit of #6 Drives For Twin Turbo Diesels
08-14-2017 | 12:43 PM
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Anyone Know Torque Limit of #6 Drives For Twin Turbo Diesels
I am interested in repowering my CAT with some built and balanced 6.7 cummins Twin - Compound turbo motors.I am looking for 1000 to 1200 hp.Now I have twin gas supercharged and run at 112 mph and want to do it to not loose top speed so to make up for the exta diesel weight I want to have 1000hp and maybe gain speed. The only problem seems is that motors of this power will make about 1500 pounds of torque and I have Mer #6 drives. I found that the #6 drives can handle 1200 lbs torque the most, if that is correct not much information on the internet about that.Some ideas are to
1= change the gear ratio in the merc #6
2= only make engines to 800 hp
3= get everythign setup and baby it, no pounding the acelerator...not exciting though
4= try to build engines lower in torque if possible
Ideas anyone, diesel pros
1= change the gear ratio in the merc #6
2= only make engines to 800 hp
3= get everythign setup and baby it, no pounding the acelerator...not exciting though
4= try to build engines lower in torque if possible
Ideas anyone, diesel pros
08-14-2017 | 12:50 PM
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08-15-2017 | 01:35 PM
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Been there done that and learned a lot, if you use a gearbox with an overdrive as apposed to reduction your #6 input shaft speed will be higher and the torque from the diesel reduced.
Much better to do the overdrive in the gearbox than in the drive, the drive will then see less torque and hold up better.
A 1350 has a max rpm of around 6600 rpm and most run a 1.3-1 ratio giving a maximum prop speed of 5076rpm and 1456 lbs torque at the prop.
I guess your safe maximum engine speed for the cummins is around 3800rpm and an OD ratio of 0.91 giving you a prop speed of around 4200rpm and 1250 lbs torque at the prop.
I have been through all of this with my diesel Nortech it makes 1000hp at 3300 rpm with a ratio of 0.881 that gives me a prop speed of 3750rpm and 1400lbs I opted for the Arneson route better to be safe than sorry.
Much better to do the overdrive in the gearbox than in the drive, the drive will then see less torque and hold up better.
A 1350 has a max rpm of around 6600 rpm and most run a 1.3-1 ratio giving a maximum prop speed of 5076rpm and 1456 lbs torque at the prop.
I guess your safe maximum engine speed for the cummins is around 3800rpm and an OD ratio of 0.91 giving you a prop speed of around 4200rpm and 1250 lbs torque at the prop.
I have been through all of this with my diesel Nortech it makes 1000hp at 3300 rpm with a ratio of 0.881 that gives me a prop speed of 3750rpm and 1400lbs I opted for the Arneson route better to be safe than sorry.
08-16-2017 | 05:21 PM
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From: Miami Beach
I am interested in repowering my CAT with some built and balanced 6.7 cummins Twin - Compound turbo motors.I am looking for 1000 to 1200 hp.Now I have twin gas supercharged and run at 112 mph and want to do it to not loose top speed so to make up for the exta diesel weight I want to have 1000hp and maybe gain speed. The only problem seems is that motors of this power will make about 1500 pounds of torque and I have Mer #6 drives. I found that the #6 drives can handle 1200 lbs torque the most, if that is correct not much information on the internet about that.Some ideas are to
1= change the gear ratio in the merc #6
2= only make engines to 800 hp
3= get everythign setup and baby it, no pounding the acelerator...not exciting though
4= try to build engines lower in torque if possible
Ideas anyone, diesel pros
1= change the gear ratio in the merc #6
2= only make engines to 800 hp
3= get everythign setup and baby it, no pounding the acelerator...not exciting though
4= try to build engines lower in torque if possible
Ideas anyone, diesel pros
I would very surprised if diesel engines making 1000-1200 hp only make 1500 ft lbs of torque. Typically the torque is close to double the HP figure.
08-16-2017 | 10:53 PM
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I am talking with some people on the cummins forum where these people race and build these engines.One person posted this message to my topic:
"You're not going to get as low a torque number as you want with compounds. Only time I've seen a 6.7 run that little torque with that much horsepower was running a 102mm single, and spinning 5500rpm (it made peak power at 5200rpm), so realistically if you want to max out at 1200lb-ft while making 1000-1200hp running 94-102mm singles are going to be your best bets. Odds are they'll be lighting at 26-3000rpm, so you'll want to be able to spin them over 5 grand to get a decent rev range."
So now it looks like
1) Use the drive guard
2) build engine with 1 turbo but a big 102 mm turbo
3) Use gear box with overdrive
So now it looks like
1) Use the drive guard
2) build engine with 1 turbo but a big 102 mm turbo
3) Use gear box with overdrive
