108.5 mph in the 1/4

[camcojb]

although this involves drag racing I think it's more of a parts question. As some of you know I lost a piston(s) in my LMM recently. I found another low mile LBZ and had ordered an MPI twin kit which will be here next week. My question regards the water injection on the truck.

My truck is a 4wd CCSB, full weight with spare, tailgate, etc. I only took it to the track one time, made two passes. I did not lower the t-bars or tire pressure, so it wheel hopped badly but ran two identical 12.75's at 108.5. The mph seems really good for stock turbo with exhaust, tuning, and water/alky. I haven't seen any other stock turbo full weight trucks running that much on #2. I run about a 40/60 water/meth ratio.

Since I broke the piston I'm now wondering if the water injection contributed to the mph and to the engine failure. Some feel it adds pressure on the piston. I know that stock LBZ's and LMM's are losing pistons, so it may have just been one of those deals. Trying to prevent breaking the new engine, so at this point I don't think I will be putting the water injection back on. Don't really need it with the twins anyway.

Any thoughts?

Jody

 

[calabria69]

I really watch the oil temps and oil psi....hot thin oil could be the reasoning for piston failures...twins will help keep temps and drive pressure down...thats all i can think of that could be the problem...

 

[McRat]

There is always a risk to the diesel engine when you introduce fuel into the incoming air, be it propane, CNG, ether, or Methanol. You can't always control whether it ignites prematurely. For cooling, ethanol would be safer than methanol, and it's what the Germans used to cool the V2 rocket engines to keep them from melting.

Methanol is a great fuel, but it is a fuel.

 

[dmax687]

if you have twins I would ditch the water inj. Your egt's should be lower with the twins and i don't think you'll really need the water. Good luck on the new motor!!!

 

[McRat]

I'm trying to remember who blew their engine up on the dyno by injecting large amounts of methanol in an LB7, it was ~4 years ago.

 

[gmduramax]

Jody I really dont think the water methenol did much to make your truck faster. Mine runs at 106mph

 

[TIM Z]

Wow Jody, sorry you lost a piston, you really had your truck haulin in a short time!

 

[camcojb]

I really watch the oil temps and oil psi....hot thin oil could be the reasoning for piston failures...twins will help keep temps and drive pressure down...thats all i can think of that could be the problem...

There is always a risk to the diesel engine when you introduce fuel into the incoming air, be it propane, CNG, ether, or Methanol. You can't always control whether it ignites prematurely. For cooling, ethanol would be safer than methanol, and it's what the Germans used to cool the V2 rocket engines to keep them from melting.

Methanol is a great fuel, but it is a fuel.

if you have twins I would ditch the water inj. Your egt's should be lower with the twins and i don't think you'll really need the water. Good luck on the new motor!!!

Jody I really dont think the water methenol did much to make your truck faster. Mine runs at 106mph

Wow Jody, sorry you lost a piston, you really had your truck haulin in a short time!

all good thoughts, thanks guys. I guess I'm trying to figure out why it broke after 15K miles on that tune, but I'll probably never know. Just trying to prevent another breakage, yet I still want a fast truck.

Hopefully the original engine can be built with rods and pistons so I can swap it later and lean on it a bit. Ideally I'd love an 11 second daily driver out of it.

Jody

 

[Noreaster]

I'm trying to remember who blew their engine up on the dyno by injecting large amounts of methanol in an LB7, it was ~4 years ago.

I think I remember the guy(forget his name) lived in Oregon or Washington?

 

[RPM Motorsports]

The water/meth might have added to your MPH. I was running 12.71 @ 105.5mph 1.71 60' on the stocker (LBZ) FWIW.

 

[IdahoRob]

I think I remember the guy(forget his name) lived in Oregon or Washington?

Karl

 

[slowlmm]

all good thoughts, thanks guys. I guess I'm trying to figure out why it broke after 15K miles on that tune, but I'll probably never know. Just trying to prevent another breakage, yet I still want a fast truck.

Hopefully the original engine can be built with rods and pistons so I can swap it later and lean on it a bit. Ideally I'd love an 11 second daily driver out of it.

Jody

I think its truly just our crappy crappy crappy dimsum yung pistons. I would bet if we had mahle pistons in there still. we would be good to go for alot longer. if you look at the lb7/lly pistons failures in stock motors they are way less then lbz/lmm lb7/lly failures seems to be from weak rods. I bet the lbz or lmm by far would of taken the most hp in stock fourm if we got those pistons along with our better rods JMO

 

[SteveFord]

I think its truly just our crappy crappy crappy dimsum yung pistons. I would bet if we had mahle pistons in there still. we would be good to go for alot longer. if you look at the lb7/lly pistons failures in stock motors they are way less then lbz/lmm lb7/lly failures seems to be from weak rods. I bet the lbz or lmm by far would of taken the most hp in stock fourm if we got those pistons along with our better rods JMO

True statement. What sucks is you don't know if you got good ones or bad as some live in high hp applications and some don't. Tunning I'm sure has influence as well. Maybe it's their way of getting back at us for banning other asian products like toys with high lead.

 

[NemesisDP]

I think its truly just our crappy crappy crappy dimsum yung pistons. I would bet if we had mahle pistons in there still. we would be good to go for alot longer. if you look at the lb7/lly pistons failures in stock motors they are way less then lbz/lmm lb7/lly failures seems to be from weak rods. I bet the lbz or lmm by far would of taken the most hp in stock fourm if we got those pistons along with our better rods JMO

LB7's and lly's don't make enough power to break things:hehe:

 

[TrentNell]

True statement. What sucks is you don't know if you got good ones or bad as some live in high hp applications and some don't. Tunning I'm sure has influence as well. Maybe it's their way of getting back at us for banning other asian products like toys with high lead.

i still thing the lbz/lmm pistons failures are increased by egt's i dont think anyone running twins has lost a piston have they , i could be wrong but it could be the weak casting dont tolerate the extreme heat and cooldown that has been seen with the single turbo trucks were as the twin trucks dont ever go above 1350 or so wich is within what the motor was engineered to run stock . dont know if there are enough twin trucks to give good examples because they might have just got good castings by luck of the draw .

 

[gmduramax]

i still thing the lbz/lmm pistons failures are increased by egt's i dont think anyone running twins has lost a piston have they , i could be wrong but it could be the weak casting dont tolerate the extreme heat and cooldown that has been seen with the single turbo trucks were as the twin trucks dont ever go above 1350 or so wich is within what the motor was engineered to run stock . dont know if there are enough twin trucks to give good examples because they might have just got good castings by luck of the draw .

I have around 15000 miles and I'm running nitrous, I haven't had any problems yet. I think keeping the pistons cool will help them live
I also don't hot lap my truck, I let it idle to cool down.

 

[TheBac]

Your MPH should have been a ~12.40 run. You did not state if you boosted up at launch. That would make a big difference in ET.

IMO, the meth did what Pat said...it burned hotter, so you lost the piston. In the meantime, you were making a lot more power than you thought. Curious if you ever dyno'd that tune while using your meth setup.

 

[camcojb]

Your MPH should have been a ~12.40 run. You did not state if you boosted up at launch. That would make a big difference in ET.

IMO, the meth did what Pat said...it burned hotter, so you lost the piston. In the meantime, you were making a lot more power than you thought. Curious if you ever dyno'd that tune while using your meth setup.

did a boosted 4X launch, but wheel-hopped badly. Full 70 psi in the tires and no lowered t-bars plus a stickier surface than where I datalog......... it's never hopped on the street with the same launch.

There was a lot more in it I'm sure, but I never made it back to the track before it broke. I actively looked for someone to dyno the truck, but gave up, none of my usual dyno spots could do a diesel, and the one who could had a broken dyno, still broken as far as I know.

Jody

 

[camcojb]

I have around 15000 miles and I'm running nitrous, I haven't had any problems yet. I think keeping the pistons cool will help them live
I also don't hot lap my truck, I let it idle to cool down.

that's what makes me feel much better with this MPI twin kit I'm putting on the new motor; egt's are real low from what I've heard.

Jody

 

[slowlmm]

the other problem i see is the bowl design. and the need to open them up like guy does. I didnt crack a piston ether i put a hole in one within direct corolation with a injector hole. I def agree cooler egts will help but not the answer. I want to see wht the out come of mats motor is if its a hole or a crack or somehing else