50% versus 70% over

[68skylark455]

Trying to find some input on the LB7 Injectors. I am pulling the heads off blackie so I thought I would remove the DDP tips and go with something bigger. Just looking for some people who actually have made the swap from stock or close to stock and gone with the 50% or 70% bigger.
Is it drivable and idle smooth, can you still tow heavy loads? We are thinking about the supercharger kit in the near future so now is the best time to upgrade. Just looking for some advice.

 

[bcjoe]

I run 40 overs in my dd and the only downside is a little extra noise when the truck is cold. I run nathans big kit with them and the truck is very driveable idles really smooth(socal injectors) and tows without issue. I am not sure how 70's would be but I love my 40's.

 

[SIKDMAX]

I forget, whats the turbo setup on there?

I have 60% overs from SoCal and havent run them yet, but with my twins some are saying 80% overs as a minimum. well see, I may change them in the summer.

 

[bcjoe]

80 over for a minimum seems a bit extreme but what do I know, the 40's with a s366 over an s480 are very happy together :hug:

 

[sweetdiesel]

Are you wanting more fuel? Or comfortable with the PW you have now?

 

[68skylark455]

This is the 7.1 stroker. If we go twins or procharger the 50hp DDP tips aren't enough. Since I have to pull the heads I figured it would be the right time to upgrade just not sure where to go. Trying to get a feel of what everyone else has tried and how they like it. I have 2 telling me 70% and one says 50 to 70% and 1 more saying just go 100% and be done with it. He needs to be able to tow 10,000 to 20,000lbs reliably across Texas. I think after talking with Pat that 100% is way to much for a DD and towing so I am debating between 50 to 70.

 

[sweetdiesel]

I have 40 overs and allready want bigger JMHO
But If I wanted a good towing beast casual racer i would stick with that as in 50%again JMO.

If you are going to need wads of fuel for the supercharger then you kinda defeating it as a tow rig , No?

If you want wads of fuel on command then dont waist your time on 60-70 and just go to 100+

 

[68skylark455]

he hates the lag and we were told the charger gets rid of it. What kind of lag is common with twins like the GT55 and our GT42 mag?

 

[turk walker]

I've been running Extrude Honed 60% overs for about 9 months now.
3 months with the twins, the other 6 with a big single.

good dd and with no problems towing.

 

[Builtlngbd]

i have 70's but am goin to go with 100's later on. They are so-cal. and i love them

 

[duramaximizer]

I know a guy that has injectors/tips that are a lot bigger than 100, the truck is NOT daily driven, but IT COULD BE! If you tune them right, there is only a very very light smoke at idle and these are rediculously big. They are fine though, very driveable even though the big single is so-so. My vote is go big. Yes they tick a little, but you can't hear it over the straight pipe.

 

[mytmousemalibu]

50% in mine, all stock long block and turbo for now, idle, dd and all are fantastic, no issues. Havent towed on them though. Only real weight challenge ive given it was pulling a dead, half submerged 50ft cottonwood out of a pond No issues doing that either!

I wouldnt hesitate to go bigger even on my stocker, needing them or not, as well as these run, i'd bet 70% would be fine too. 50% is approx 100hp worth.

 

[othrgrl]

I run 100% over injectors in my 6.6L LLY and see no reason why you couldn't run them in your stroker and be able to daily drive it. I'm not going to BS you, it will take some tuning to have it run clean under part throttle - but can be done. The thing I like about them is that you have plenty of room for tuning without running high PW and timing. On my 11.18 pass I was around 2000 max PW. I am actually getting another set of injectors done right now (I over-pressured mine and ruined the bodies) and am going with 100% over again. I still daily drive and tow with my truck, although it's heaviest load is typically another Duramax on a trailer. With your added displacement and plans for more air I would definately go with 100%.

I have seen you say in the past that a GT4202 is very streetable on the stroker and spools like stock, correct? If you want a very streetable set of compounds I would recommend you pick up Rob Hall's GT42/GT55 setup - it would give you back the streetability you had with the 42 and add a big brother to give you the top end you need.

 

[rcr1978]

How pressure did it take to hurt your injectors, did the bodies crack?

 

[ChevyDieselLLY]

i say 100% that is what i will be going with, figure if Dustin can use up the fuel with a 475 then i should be able to with MPI's big set of twins. plus i dont want to do it over again just once and be done.

 

[othrgrl]

How pressure did it take to hurt your injectors, did the bodies crack?

The LLY fuel pressure sensor can only read to 26,851 PSI - even if you scale out B0203 in the tuning to read higher. I have no way of knowing what my pressure got up to, but I know it was over 26,851 PSI - whether it was 30K or 40K I couldn't tell you. The return rates are now horrible and they seep fuel out of the check ball in the side of the body, so I assume the bodies are cracked.

 

[68skylark455]

I run 100% over injectors in my 6.6L LLY and see no reason why you couldn't run them in your stroker and be able to daily drive it. I'm not going to BS you, it will take some tuning to have it run clean under part throttle - but can be done. The thing I like about them is that you have plenty of room for tuning without running high PW and timing. On my 11.18 pass I was around 2000 max PW. I am actually getting another set of injectors done right now (I over-pressured mine and ruined the bodies) and am going with 100% over again. I still daily drive and tow with my truck, although it's heaviest load is typically another Duramax on a trailer. With your added displacement and plans for more air I would definately go with 100%.

I have seen you say in the past that a GT4202 is very streetable on the stroker and spools like stock, correct? If you want a very streetable set of compounds I would recommend you pick up Rob Hall's GT42/GT55 setup - it would give you back the streetability you had with the 42 and add a big brother to give you the top end you need.

PPE has the twin with the 55 so all I really need is the kit minus 1 turbo. I am nowhere near good enough to try and tune this thing. If we go that big I would need someone like Pat who has tuned 100 over and twins to help me. I just have to keep it towing reliable and still make it fast. Damn customers want everything! LOL. He is a great friend and would do anything for me. He even offered to loan me the Escalade I put the magncharger on to make my vacation trip to Cali. I just want to keep him happy as well as build a badass truck. I am still trying to figure out how we blew a headgasket?

 

[Mike]

PPE has the twin with the 55 so all I really need is the kit minus 1 turbo. I am nowhere near good enough to try and tune this thing. If we go that big I would need someone like Pat who has tuned 100 over and twins to help me. I just have to keep it towing reliable and still make it fast. Damn customers want everything! LOL. He is a great friend and would do anything for me. He even offered to loan me the Escalade I put the magncharger on to make my vacation trip to Cali. I just want to keep him happy as well as build a badass truck. I am still trying to figure out how we blew a headgasket?

I hate to hear of that blown head gasket. Have you sent it Guy or had someone look at it just to see if maybe they could pick up on the issue. I might have missed a post relating to this and if so, excuse please.

I can't wait for that truck to start ripping again. I just hope you can take it down our local track again. Keep us up to date Larry.:thumb:

 

[68skylark455]

I haven't even got the truck yet to take it apart to find the actual problem.
Yes I have talked with Guy and after our discussion we agreed it must be a leak on a headgasket. Black oily substance in coolant bottle and it takes a gallon every other day or so of coolant.

 

[Mike]

O I C Larry. I took it as you'd removed the heads. :baby: