Marine 18:1 Pistons

[92 Diesel Dude]

I am currently in the middle of a overhaul and am considering using the low compression marine pistons because of their durability factor. I don't need anymore than 200 to 225 hp. My engine currently has a timing gear set, reconditioned updated cylinder heads, crank gridles, turbo master manual boost adjustment, 60 g glow plugs, Bosch marine injectors and DB2 manual injection pump calibrated to the upper level of factor metering tolerences to match the injectors.I also have a 3 inch mandrel bent downpipe, pro flow muffler, ISSPro pyro and boost gage set. My concerns regarding the marine pistons are:

Will this engine start without glow plug assitance when warm? Or cold with use of glow plugs?(Alberta temperatures range from -38 C to +38 C.)

Will this drop in compression burn the fuel properly at idle speeds and high idle? Currently, this engine burns extremely clean from 20 secs after start up to full load conditions pullling.

With my fuel pump and injector calibrations as of now, will I experience a loss of power/exceleration due to compression drop?
Currently, my boost is anywhere from 3 psi empty driving to 14psi to towing at 925 degrees in down pipe.
Can anyone comment on my questions or does anyone currently have these pistons? What are your feelings or experiences?
Thanks Diesel Dude :confused:

[More Power]

Extend your initial cold glow time an additional 4 seconds, and you'll not likely notice any difference in cold starts. There's another topic thread here that discusses how to do that.

We've gone through three cold Montana winters with an 18:1 engine.

MP

[richard7]

The late model year 6.5L engines like my 2001 are at 20.2 to 1 CR. I think it is a better compomise than a 18 to 1 piston for very low temperatures you will enconter, and for everyday start.

[Tough Guy]

My truck has and will start in below zero weather at 5000 feet in elevation without being plugged with the extended glow time.

Cheers

[92 Diesel Dude]

Thanks for the input guys. Still wondering about how efficent the fuel will burn with the compression drop???? Or will I notice a milege drop with the calibration settings I have now?
I'm not interested in metering more fuel.
I am currently getting 18 mpg empty and 13-14 mpg pulling with a 3:42 rear ratio. (auto trans)

[Kennedy]

Starts fine, smells different (especially when cold) and is a little "soft" on responsiveness with the drop in compression, but worth every penny, and when you run 25psi of boost, it isn't so nerve wracking... :D

[92 Diesel Dude]

Thank's for the input guys, but all of my questions still are not answered! I am worried about making a mistake with low compression pistons because milage and durability are more important to me than 250-300hp.
Will milage drop with original feul and boost setting's with low comp???????
maybe 21.5:1 is better for me.
please coment on this issue!
Thank you,
Diesel Dude

[DogDiesel]

18:1 pistons, marine pump and hi pop injectors. 4x4 /5 speed 1Tn SRW. Ceramic coated internal heat areas. Coated pistons. Hi O/P cooling system. I use the peninsular glow plug controller and 60G glow plugs. 40K so far on L-C engine.

Durability. My marine pump still has bench calibrated settings. My EGTs with intercooler never get over 750. Never. My temps never get over 200. Never. I tow with it most of the time. Pull the snot out of it, AC on, towing a CAT D4 sized crawler, etc up 7% long grades; I believe I am defining durability.

Starting. Oh yeah, it will start right up in most any temp. Smokes like a big diesel for the first few seconds, but clears up for the rest of the day. The glow cycle just needs lengthening.

Mileage. Mine has improved, even over the modified stock block. Especially towing mileage.

Noise. It is more noisy than stock. If noise offends you, stay stock. Its like comparing the 160 HP cummins to the 230+ engines. Noisy. When I let the clutch out, empty or not, the engine has a power-stroke sound on clutch let out.

Power. My stock engine, would not pull my RV below 65 up to 4%, it lacked torque to hold cruise. It would pull down. Had to pull 64+. This L-C engine will pull 50-62, and GRUNT on in 5th up 6% with the same RV.

Measured power. Just the other day, a late model PS pulled up beside me to pass up a hill, I was on cruise. It was a no brainer I was loaded more than his truck and resigned to the right lane where I should be. When the PS fizzled back and mine pulled a consistent 68 where I had cruise set, I smiled in my rear view as he distanted. ;) Now I am not saying I have more power than a PS or a cummins, but I have pulled with them and done well. I don't have dyno results or pull-off results to prove a measure result. But, I get to smile in the Rr-V-Mirrow. I have quite a few of these type comparisons. I've been asked "what the hell you got under the hood, over the radio..." smile.gif

For a boat motor, not bad.

The 6.5TD is indirect ignition. Doubtless, direct is better for pulling and cold starting. The 6.5 is a legacy engine. But, it is cheap to maintain, provides in L-C mod, equal or better power and economy to similar sized engines.

How long it takes to recoup your investment into L-C 6.5???? I will--I don't know about others.
Wayne

[gmctd]

GM went with the higher 21.5 cr because of low temperature cold starting issues with indirect injection. Low compression would have required intake air heating system to satisfy most consumers for starting and warmup driveability.

The 18:1 setup should not degrade fuel mileage, exception being - more power = more fun = heavier right foot.

The Diesel Page Project Truck, 2500 4wd long bed extra cab with 18:1, marine injection system, intercooled, regularly returns 18 - 22 mpg, has been in constant service for 3 years, over a hundred k miles.

Try it, you'll like it.

jd

[Mark Bajus]

my setup is almost exactly what you have, other than I have the 18:1. My pump is turned up obviously more than yours- towing I can get to 1000+ in downpipe, plus heavy black smoke at 15 lbs (I need new turbo and/or intercooler!)

Start when hot: instant.
Start when cold: slower than with 21:1, you will need longer glow cycle, Penninsular programmable works well.

Longevity: I would say longer: lower stress on the bottom end I would think.

Enjoy!

[92 Diesel Dude]

Thanks for the reply guys, now that's what I wanted to hear! It is obvious what direction I am heading for now! Those last replies have even convinced my wife! I can't wait to order my "MODIFIED" engine kit tomorrow!
Thanks'from your fellow Dieselmaniac:
92 Diesel Dude :D

[Jim P]

My truck is a 95 2500hd with 4:10 gears and a manual trans. I just rebuilt my engine this summer so I haven't been through a winter yet. I dropped my compression to somewhere around 18:1 by making the rods shorter and by doing some trick machining on the heads but I just used the pistons that are .010 shorter. It will start without the glow plugs when hot but cold definitely needs longer glow time. Here, the temp. in the morning has been around 40 F and I wait for the glow plug light to go out and then glow manually another 5 sec. By doing this it starts instantly but still makes some bluish smoke for a few seconds and it smells like a torpedo heater that is running out of fuel. I have found if I after glow manually on and off for about 10 seconds that it makes no smoke whatsoever. I do notice that it does miss slighlty when you rev it up until the boost starts coming up. I only notice this if I rev it while in neutral or with my foot on the clutch. The boost is running around 15 psi but the fuel is stock. Just driving to work which is only 8 miles, I am getting 18 mpg. It seems to have good power. If I take off hard in second gear it will just white smoke the back tires.

The other day I was sitting at a traffic light waiting to turn left and there was a power stroke across the intersection that was turning right. I heard him really get on it so I decided to see if I could keep up but after we both went through a couple of gears I had to let off so I wouldn't run into him. I could've easily passed him but I didn't want to get a ticket.

[david]

Don't for get to balance the engine !!!!!!!!

[david]

More Power or anyone that might know,
What brand pistons are used??for 18to 1
I was thinking Mahel(sp) ,i need part numbers.
David :confused:

[More Power]

I think Mahl pistons are being used by Peninsular - and now The Diesel Depot.

For a good number of years, Peninsular had exclusive rights to these pistons, due to a contractual arrangement with the piston manufacturer, and because Peninsular apparently had a hand in the piston design. Rumors have indicated that the contract expired a year or two ago.

Peninsular's pistons have anodized crowns while The Diesel Depot adds a ceramic coating to theirs. I can't speak to the advantage of ceramic coating, except to say that the Project 6.5 has had no piston problems (Peninsular's), and have seen short term EGT's of up to 1400 (Pull-Off & dyno). Longterm EGT's (>10 seconds) are limited to 1250, like when pulling grades.

MP

[tom.mcinerney]

92 D-Dude: Before the forum erasure Dr Lee{aka 'Clevite Kid', a consulting engineer on large diesels, and mettalurgist} addressed the issues you mention. He clearly stated that compression above 18:1 {my memory says 13:1 will work on diesel, but that's just memory!}was ONLY used to improve cold starting characteristics. If frigid weather starts are important, the charge air heaters [like a 'heat gun' in intake air flow, used by Cummins, lots others] are a very effective solution....

[david]

Thanks for the reply all,but i need the part numbers so i can find the best deal on them!!!!
Thanks :eek:

[Kennedy]

Why not just build your own? :rolleyes:

[david]

kennedy
I have set for about 5 min. thinking How should i take this statement.
I was in the auto industry years before you and i still know a thing or two.
If you want to help please do so!!!!!!!!!
David tongue.gif tongue.gif