LB7: Rod limits

SickLL7Crenshaw

Billy The Kid
Mar 10, 2013
1,088
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Mexico
I'm at 600+ on stock rods. Running s475/stock setup and 40 overs. I have it detorqued. Been like that for 3 years and still on stock head bolts. 125k on her.
 

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
I've been over 600 for a year at least. I bought James' 80mm wheel and cover and will be making my 72 into an 80 next week. Doubt I will see any gains from it but still.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,610
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Last week I saw a topic on the limits of stock rods. Anyone have the link to it? I can't find it now.

Someone suggested I run a s475, and was wondering if anyone had any feedback on these turbos. The plans for my truck are 800hp street truck but I want to break 600 this year. Is the 475 too much for stock rods. I also still want to be able to pull my boat. Been thinking about the 366 because of all the good things I have been hearing about them. Is the 366 capable of 800hp? Any input would be nice.

An engine build in the next couple years is in the works. I just don't want to throw a rod in the meantime.


Just don't until you have the funds to deal with it properly. No amount of "detorquing" or "magic dust" will keep those rods from bending.

The two guys posting above this may think they're ok, but I'll betcha both those engines are a bit low on compression. ;)
 

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
Just don't until you have the funds to deal with it properly. No amount of "detorquing" or "magic dust" will keep those rods from bending.

The two guys posting above this may think they're ok, but I'll betcha both those engines are a bit low on compression. ;)

And I'll bet your wrong ;)
 

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
7,535
1
38
34
Lexington, Ky
Ill ask something, been wondering for awhile.... Has there actually been any factual strength testing on the difference in lb7 to lbz rods? If so, where's the test results?
 

PACougar

Active member
Jun 27, 2012
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El Dorado Hills, Ca
Regardless running a 475 as a single on a stock bottom end makes very little sense. There are much better choices especially if you're going to be towing. So a few people have had good luck, that doesn't make it a good idea. The reality is when you build your motor then you should start looking at what will work best and not try to run a one size fits all turbo to save a little money.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Did you compression test my engine while I wasn't looking Tom?

Naw, Utah is a bit of a drive. :rofl: I do notice you guys never say what these compression test numbers were. Hell, you may be seeing 250lbs/cyl and are calling it good.

Frankly, even IF your and Crenshaw's stock motors are somehow surviving 600+ hp, NEITHER one of you should ever post in one of these "What can a stock engine take?" threads b/c you are both uber-rare exceptions. Its even more irresponsible of anyone here to suggest its possible to someone who clearly doesnt have the $$ to rebuild their motor.
You both should just sit back and count all your blessings, keep praying to whatever Dmax god you pray to daily, and keep all your digits crossed.

Even when I was pushing it, I always made sure to tell questioners that it was an exception, not the rule.
 

Bustedknuckles

Honey Badger
Sep 25, 2010
1,308
2
38
33
Hagerstown MD
So what's safe one a stock bottom end? I dynoed 519 hp and just under 1000 ft lbs. Do I call it good and run it as its been running strong for 2 yrs or do I go to 30% overs for lower pulse width?
 

CaptPhil

Active member
Sep 10, 2011
1,012
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Delaware
Keeping a single stock cp3 will help keep the temptation down. Mine is still alive at who knows what hp, but pretty sure over 600. Have at least 50 passes at this power. It does Haze a little when it is cold at idle, hahaha maybe I should check my compression.
 

jacobdewey

This won't last long...
Jan 14, 2011
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Subscribing. I have a S366 and need injectors soon, trying to.... decide between 30% over or stock, I really don't want to bend a rod.....

I say at least 30 overs, if not 60's. You can tune them a little differently than stockers and be "as safe" as you are now. Your duration would be shorter with bigger nozzles.
 

DIESELMAFIAPER.LB7

<----new hotness
Jan 17, 2010
5,163
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idaho
shop.dieselmafiaperformance.com
I only bent one rod the rest of my compression issues were in the heads imo and I was at 680-700 about a year and over 600 for 2 years.

long story short 600 can be done but there is 0 and I mean 0 guarantee it will be ok for a day or years

for a turbo a billet 66 and 45 over nozzles for injectors and don't cry when it blows:thumb:
 

motoking_1990

Active member
May 9, 2011
1,957
5
38
Terre Haute, IN
Naw, Utah is a bit of a drive. :rofl: I do notice you guys never say what these compression test numbers were. Hell, you may be seeing 250lbs/cyl and are calling it good.

Frankly, even IF your and Crenshaw's stock motors are somehow surviving 600+ hp, NEITHER one of you should ever post in one of these "What can a stock engine take?" threads b/c you are both uber-rare exceptions. Its even more irresponsible of anyone here to suggest its possible to someone who clearly doesnt have the $$ to rebuild their motor.
You both should just sit back and count all your blessings, keep praying to whatever Dmax god you pray to daily, and keep all your digits crossed.

Even when I was pushing it, I always made sure to tell questioners that it was an exception, not the rule.

People like you are the reason I come to this forum. You don't just tell everyone to throw whatever on and go. If my truck were to go down I wouldn't have a weekend ride. So I am going to take your advice and just wait til I have enough saved to do it all.

What besides rods, main studs and head studs would I need to get to 800 HP? Cam? Heads? Pistons? I'm not to sure what all I would need to get there. I'm trying to get a grasp on how much I need saved. I have built many gas engines in my time but when it comes to diesel I don't know what needs to be done/changed and not.

Sent from my C811 4G using Tapatalk
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,610
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113
Mid Michigan
I've been over 600 for a year at least. I bought James' 80mm wheel and cover and will be making my 72 into an 80 next week. Doubt I will see any gains from it but still.

Hmm i don't remember suggesting it was ok and/or safe to crank out 600+ horse on a stock motor.

You freely, proudly state what you've done but nowhere do you say "this isnt normal". Same with Crenshaw. Thats the same as saying its ok. Many newer members would take your statements as "hey, this guy did it, so can I".

Yeah, tuning has come a long way, and our knowledge has furthered what we can/can't do, which is great and seems to help a stock engine last longer at higher power levels....but physics is physics. Stock rods were all made out of the same metal. You can't unbend that fact.
 

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
I've been over 600 for a year at least. I bought James' 80mm wheel and cover and will be making my 72 into an 80 next week. Doubt I will see any gains from it but still.

You freely, proudly state what you've done but nowhere do you say "this isnt normal". Same with Crenshaw. Thats the same as saying its ok. Many newer members would take your statements as "hey, this guy did it, so can I".

Yeah, tuning has come a long way, and our knowledge has furthered what we can/can't do, which is great and seems to help a stock engine last longer at higher power levels....but physics is physics. Stock rods were all made out of the same metal. You can't unbend that fact.

Well there ya go.
 
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