370 Marine Pistons [Archive] - TheDieselGarage.com

: 370 Marine Pistons

11-07-2005, 12:32 AM
I was wondering if anyone knows a good place to find 370 Marine Pistons? I'm looking for just a plain set, no fly cuts or coatings. There may a possible 1st Gen build-up in the future, Thanks. :smoke: :smoke:

11-07-2005, 02:03 AM
if you want marine pistons, check out Cummins...lol. go to a cummins repair, or parts dealer and request 5.9 liter marine pistons, no cuts.

if you want fly cuts go to Piers.

11-07-2005, 03:57 PM
What's the dif in the marine pistons vs our stockers?

11-07-2005, 11:15 PM
the marine pistons have a better design, making it more efficient, making more power. Over all they are very tough.


11-07-2005, 11:30 PM
Cummins South in Atlanta

Don't be surprised if they tell you, "If you're building one of those motors like Jeff Garmon builds we DON'T recommend it."

I'm not kidding either.

11-08-2005, 12:18 AM
Thanks for the replies, I wasn't sure who might have the best price Piers-Haisley-Cummins. Does anybody know what they go for, roughly? I've been to Jeff's shop a couple of times and I understand why Cummins South doesn't want to recommend anything he does. He is straightforward in telling you what you do and don't need. Plus he makes more power in these little engines than most people that work at Cummins would believe with many of the stock internals, and that's bad for the parts business. I met many nice people while I was there, and had a great time at his shop and the track. :smoke: :smoke:

11-08-2005, 01:29 AM

Try and find me a CPL number and I will call Cummins tommorow and see what I can get for a price.

Did you find a truck?

11-09-2005, 09:12 PM
marine 370 cpl # is 2208, ser#45432843 try these and see what gives.

11-09-2005, 11:43 PM
dumb question here but whats the difference between the regular pistons and the marine ones

turbo thom
11-10-2005, 07:24 AM
One, is the piston has a hole in it so the wrist pin to can get oil.

The bowl in the top of the piston is larger and a little more offset.

They are heavier and have a steel insert where the rings fit. Plus they cost more. Like $1000 per set of 6.

Remember, these are made for the 370 injectors and the spray pattern is nowhere like our land trucks. LOL


12-19-2005, 10:11 PM
hasiley quoted me $170 a piece. $150 a piece for aftermarket. try them.

12-21-2005, 02:51 AM
Cummins South in Atlanta

Don't be surprised if they tell you, "If you're building one of those motors like Jeff Garmon builds we DON'T recommend it."

I'm not kidding either.
Butt.... they want to go for a ride in it.

03-04-2006, 01:38 PM
Here is picure of 370 Hp Marine pistons .

Someone can send pictures of Dodge (automotive) pistons to see the difference.

03-04-2006, 09:55 PM
Stock Cummins 5.9 piston http://www.turbodieselregister.com/user_gallery/sizeimage.php?&photoid=17187&width=2

Machined Cummins 5.9 piston with 155 bowl http://www.turbodieselregister.com/user_gallery/sizeimage.php?&photoid=17188&width=2

Coated and flycut Marine piston with 155 bowl http://www.bigbaddodge.com/Motor.html

The reason some people machine the factory piston is to retain some of the stock compression but still have the larger piston bowl. The marine pistons that Van Haisley machines the dome out of will yeild a compression of around 13:1 I believe.

03-04-2006, 10:11 PM

This is why I'm not a fan of 370 injectors in a land motor, not how the spray pattern is outside of the piston bowl, and also how different the spray pattern looks from one nozzle imprint to the other. The spray pattern of a 370 injector is 155 degrees, the piston bowl on the land motor is 145 degrees, this poor atomization and delivery of fuel outside the piston bowl leads to excess smoke and heat. The 370's are a good injector for the money, but I believe that they are not a great injector without being honed and matched to a specific piston bowl. At the time this motor was runnig 370 injectors with 18* of timing, with more advanced timing the spray pattern would be wider.

Forrest Nearing
03-14-2006, 07:34 PM
not optimal by any means, but they still work great! :Thumbup:

03-15-2006, 01:01 AM
most shops will tell you to have your stock tips burned out to .12 ( = to a 370) that way it stays in the bowl. I was told a staock piston is good to
23.5* of timming befor you get outside the bowl, where a marine piston is good to 40* with staock spray angle before it gets outside the bowl.

03-15-2006, 05:16 AM
I thought I should add a little info to this list, I forgt to mention the 3rd Gen injectors. Also if you hear injector flow measred in microns, 1 thousandths~39 microns.

12v 5 hole
24v 7 hole
12v 300 marine 4 hole
12v 370 marine 5 hole
24v EDM 8 hole
HPCR '03-'04 8 hole
HPCR '04.5+ 5 hole

Marine 370's are actually 0.012's of an inch. But that is a very good and very true statement. This is also why I wouldn't recommend running over 24* of timing on a truck that is daily driven.

03-15-2006, 05:42 AM

Add third Gen, Pleazzzzeeee. :thanks:

03-15-2006, 05:59 AM
HPCR '03-'04 8 hole~0.005"~200 microns
HPCR '04.5+ 5 hole~0.008"~300 microns

Rough factory nozzle size.

04-04-2006, 01:40 PM
Have you seen the new Ross piston line for the Cummins yet? They look SSSSWEET. :popcorn: :sly: :evil:

04-07-2006, 04:16 AM
Yep, SWEET. Got any pics you can post?

04-07-2006, 03:05 PM
And don't forget the reason most people run Marine pistons,is to drop the compression from 17.5 to 1 to the Marine's 15 to 1!!!!!

Forrest Nearing
04-08-2006, 12:13 AM
12v's are 16:1 I believe... 24v HO's were 16.5, SO's were 16:1

04-08-2006, 12:50 AM
Heads make that much difference......