S480/3794 high EGT’s

[Creeker15]

I know these numbers are childsplay vs what some guys run.
so I’m around 750 horse and 50 ish psi and my EGT’s climb up to 1550 which I know people see higher but I want to get those down

I have a cast (billet wheel sitting in garage) s480 1.32 AR and a base 3794 in the valley. It’s not crazy responsive (I think it might need new bearings) anymore. But I don’t tow anymore and I’d like to get my EGT’s down and I’m considering a billet 465 in the valley.

Once I’m finished with the front end I’m going to be running the 1/4 a lot, but I still drive the truck quite a bit.
wanting enough air for 1000 wheel as the engine build is going back under the knife sometime after deployment.

after searching on here it seems the S4 is the best way to go for compounds or what a lot of people like. I just wanted to hear what you guys have to say.

thanks fellas!

edit: meant to mention I have profab headers and up pipes on order as well as a mishimoto IC and radiator (currently upgrading all the coolers)

 

[Chevy1925]

the mishimoto crap is junk, waste of money and will leak on you. bad choice.

what size injectors do you have, how big is the tune, any engine work, and has it been dyno'ed or to the track for those numbers you posted? you need to find teh problem before throwing parts at it and hoping it fixes it. that boost is on the low side for said HP numbers and egt's are high. yes it points to the turbo but what you described could be a boost or drive pressure leak or something else that is not letting boost build like it should.

 

[Creeker15]

the mishimoto crap is junk, waste of money and will leak on you. bad choice.

what size injectors do you have, how big is the tune, any engine work, and has it been dyno'ed or to the track for those numbers you posted? you need to find teh problem before throwing parts at it and hoping it fixes it. that boost is on the low side for said HP numbers and egt's are high. yes it points to the turbo but what you described could be a boost or drive pressure leak or something else that is not letting boost build like it should.

Well that was a long phone call to cancel but sure glad I know that now. I had always thought mishimoto stuff was good.
I didn’t want to make the OP too long and hard to read.

engine is S&S 60 overs,
S&S 10mm,
Mahle race cast pistons
Stock keyed crank/cam
Head studs
Billet main caps and girdle sitting in garage


and you know I’ve thought I’ve had some sort of boost leak but I just CANT find anything. It’s hard for me to tell at time because my job I leave a lot and whenever I come back the truck feels fast as hell.
drive boost is always 3-5 psi as it always has been and EGT’s are normal driving.
I could’ve SWORN the truck hit 60 psi turned up before and around 40with the DSP on 3 but now it’s mid low 30’s but maybe I’m inside my own head.

haven’t taken truck to the track, yet (seems like I’m always chasing a problem) and I asked Mark to tune it for about 750, it needs a dyno tune and I plan on taking it to Indiana when I get back stateside next year. Right now I’m just making money and figuring what parts I need.
I really appreciate you helping out, your posts particularly have taught me a lot.

edit:
I have an LML block I was planning on building but I just found out I’m having twins (kids not turbos) so I might be sitting at this power level for a while

 

[OleBlackyLBZ]

A buddie of mines lbz with 10mm cp3, 60% injectors and single 3794 made 725 at danville. And his egt's aren't much higher than yours. I'd bet money you have a boost leak.

 

[Chevy1925]

it wont hurt to verify your rail pressure on the big tune. with 60 overs and a 10mm, you gotta run a pretty high uS to get the power your after which will in turn increase EGT's. If it were me and looking at the direction you want to go, id look at doing some larger injectors before much else. something in the 150% range or more. Your Cp3 will be the limiter then (and is probably close to it now, if it aint already is). Then from there, look into more air. Going to the larger injector will drop EGT's and help those pistons live longer. Dont expect a huge amount but id say 100-200 degrees

 

[Creeker15]

it wont hurt to verify your rail pressure on the big tune. with 60 overs and a 10mm, you gotta run a pretty high uS to get the power your after which will in turn increase EGT's. If it were me and looking at the direction you want to go, id look at doing some larger injectors before much else. something in the 150% range or more. Your Cp3 will be the limiter then (and is probably close to it now, if it aint already is). Then from there, look into more air. Going to the larger injector will drop EGT's and help those pistons live longer. Dont expect a huge amount but id say 100-200 degrees

Rail pressures normal, gets around 32k turned up.

yeah it wouldn’t cost much to send my injectors back to S&S and add a second 10mm or stocker on the belt drive.

I’d like to get around 1000 wheel eventually.

this being my first diesel I’m not sure about VGT’s but if it’s a bearing issue but my s480 like all turbos I’ve had spins for a long time after killing the truck but the 3794 stops faster then I can walk over to it. No shaft play, maybe bearings?

what intercooler would you pick up?My fabricator is willing to put on v bands on everything and I already have solid mount everything, just wondering if it’d hurt the turbos having no flexibility in the piping

 

[Chevy1925]

whats the model of your truck? is the truck an LML? for some reason i was under the assumption you had a LBZ based on the avatar pic

 

[Creeker15]

whats the model of your truck? is the truck an LML? for some reason i was under the assumption you had a LBZ based on the avatar pic

I really didn’t put LBZ, it should be in my signature maybe I messed that up.
Yes she’s and 07 LBZ. I Just have a new LML block sitting in the garage that needs building.

 

[OleBlackyLBZ]

As James has already said though, I wouldn't start throwing parts at it until you figure out what's going on. If your going to 1,000 later you will need more injector but 60's isn't a terrible match for that 10mm and 750hp and won't be your high egt issue.

 

[Creeker15]

As James has already said though, I wouldn't start throwing parts at it until you figure out what's going on. If your going to 1,000 later you will need more injector but 60's isn't a terrible match for that 10mm and 750hp and won't be your high egt issue.

You guys are right. I didn’t even think of it as a problem I thought that the turbo just ran hotter and wanted to change em out but I just found a video on my phone. More boost. Lit up crazy fast.
Right now I’m getting parts for the front end getting her ready for 4x4 launches figured I’d update the cooling stack while there.

my current thoughts are getting the headers and up pipes on and then getting a new IC and v banding it should really secure whole loop I’d think.

I really appreciate everyone’s input I still have lots to learn with the dmax world. Being an LBZ I’ll probably never sell this one like I do most projects. I love this thing a little too much. I just want to restore her, make her show truck pretty and be a pretty nasty street truck. 100% pavement princess now.

 

[Chevy1925]

I really didn’t put LBZ, it should be in my signature maybe I messed that up.
Yes she’s and 07 LBZ. I Just have a new LML block sitting in the garage that needs building.

ok, then are you really pushing 32k rail pressure to the injectors or was that a typo and its 22k? you would have to have a different rail pressure sensor to go that high and iirc injectors get real finiky on opening and working well at that pressure.

 

[Creeker15]

ok, then are you really pushing 32k rail pressure to the injectors or was that a typo and its 22k? you would have to have a different rail pressure sensor to go that high and iirc injectors get real finiky on opening and working well at that pressure.

My gauge only goes to 30k so 32 is a guess because it goes a bit past it. It’s just an autometer rail gauge. Maybe my sending unit is bad or the gauge is off.
on 2/3/4 on DSP I typically see 25-27k psi
Maybe I need to log and have mark revise the tune.

im starting to think my stock IC is having a leak somewhere, either way I planned on upgrading the IC anyway and get rid of that plastic boot on the passenger side.

edit: gauge is tapped into sensor on the neck of the passenger rail

 

[Chevy1925]

My gauge only goes to 30k so 32 is a guess because it goes a bit past it. It’s just an autometer rail gauge. Maybe my sending unit is bad or the gauge is off.
on 2/3/4 on DSP I typically see 25-27k psi
Maybe I need to log and have mark revise the tune.

im starting to think my stock IC is having a leak somewhere, either way I planned on upgrading the IC anyway and get rid of that plastic boot on the passenger side.

edit: gauge is tapped into sensor on the neck of the passenger rail

i will believe a log over the gauge any day. start looking into the rail pressure and seeing exactly where you are on the big tune via a data log from the computer, not using the gauge. 2k rail drop from commanded is a 50-60hp drop in the upper rpm's. you want that number following desired/commanded as best as possible. basically, this is a great place to start with "missing power" and can feel lazier than it did before. it also has a slight affect on egt's.

id also make sure how ever you tapped into the rail sensor is not affecting teh actual sensor readings to the computer. you DONT want that messing with that at all as it can create pressure spikes that will hurt the injectors or cp3 over time.

 

[Creeker15]

i will believe a log over the gauge any day. start looking into the rail pressure and seeing exactly where you are on the big tune via a data log from the computer, not using the gauge. 2k rail drop from commanded is a 50-60hp drop in the upper rpm's. you want that number following desired/commanded as best as possible. basically, this is a great place to start with "missing power" and can feel lazier than it did before. it also has a slight affect on egt's.

id also make sure how ever you tapped into the rail sensor is not affecting teh actual sensor readings to the computer. you DONT want that messing with that at all as it can create pressure spikes that will hurt the injectors or cp3 over time.

I’m seeing an average of 27000 on the logs with about that being commanded (very small marginal differences) with it increasing with boost.
rail seems to be responding boost Normally from what I can tell. It’s rained all day so it’s hard to get a good log and I can’t spin it (G80 ate its slip gear)

Had wife push throttle and I think I MIGHT be hearing something near the bottom passenger side but it’s hard to tell with the engine noise and only 1-2psi being made.

I think I’ll try to get a smoke test done, other question is. What’s the best bet for the diff? G80 rebuild? Dodge axle? Tremec hardware etc.
and what IC would you get?
not throwing a IC at it for the potential boost leak, just doing the rad and piping and figure I’ll do the IC while I’m in the stack

edit: I’m deploying in about two weeks so even if I don’t get her fixed finding the issue will be nice. That deployment moneys pretty good for the truck

 

[PureHybrid]

Like James suggested, sometimes the jumper for the rail pressure gauges can mess with things. Unhook that and then datalog. If you don't have a way to pressurize the intake system and check for leaks, try idling the engine and spray all the joints with brake cleaner.

As far as the differential, any aftermarket locker will be stronger (Grizzly or Detroit) but noisy. The silent but reliable option is a True Trac, the cheap side of that is the AAM tracrite (aka "dodge posi"). This is the route I went because you can find one used for a few Franklin's. Sounds like you aren't afraid to throw $ at it so might as well do 34 spline axles too

 

[Creeker15]

Like James suggested, sometimes the jumper for the rail pressure gauges can mess with things. Unhook that and then datalog. If you don't have a way to pressurize the intake system and check for leaks, try idling the engine and spray all the joints with brake cleaner.

As far as the differential, any aftermarket locker will be stronger (Grizzly or Detroit) but noisy. The silent but reliable option is a True Trac, the cheap side of that is the AAM tracrite (aka "dodge posi"). This is the route I went because you can find one used for a few Franklin's. Sounds like you aren't afraid to throw $ at it so might as well do 34 spline axles too

Man this forum is awesome everyone is so helpful. When you say noisy do you mean whining like a trans or it banging when it locks? I don’t mind whining, and I might get a dodge rear end if I find one, but I might get the true trac since she’s gonna be getting launched a hood bit and some burnouts done (I broke my G80 at my friends funeral, but I told him before they buried him that day I’d send it til I broke something)
As far as the diff goes, I’ll spend around a grand on it so long as she drives not too horribly when I’m trying to turn
And what’s the benefit of 34 spline vs 38?
I know engines pretty well (clearly not enough to fix it all on my own though) but gearboxes are new to me. Seems the cars I’ve owned just didn’t break em like the duramax likes to.

 

[PureHybrid]

I may have mis spoke on the 34 spline, I think you're correct on the bigger shafts being 38 spline. Not really needed at this power level, lots of truck pulling guys upgrade to the 38 spline when trying to get everything they can out of the stock housing.

As far as noise, a mechanical locker like a Detroit or the Grizzly will just make some clicking or ratcheting around corners. Not a big deal but some people are sensitive to certain sounds...

 

[OleBlackyLBZ]

A Detroit or Grizzly will stay locked until you put it in a bind such as turning then it will unlock with a clicking sound that you can feel. The Tru-Trac is just a limited slip, it's smooth and will act much like the G80 only it's gear driven instead of having a clutch, so it's much much stronger. I am running the Tru-Trac and absolutely love it!

 

[Bdsankey]

As stated by a few others, I'd start with a good data log (without the gauge jumper installed) as well as checking for boost leaks. You can get a PVC cap and a bulkhead fitting or metal pipe etc to fit into the inlet boot on the S480 to pressure test to ~40-50psi. Pressure testing the system is the easiest and best way to find a boost leak. You will always hear air moving as there will always be some valves partially open but what you need to listen/feel for is air coming out of any connections. I think your boost should be somewhere around the 60-70psi range on a bigger file with that fueling BUT I do think you will be better suited by a 150-200% injector if your goals are over 1k. You also can run a larger VGT (something like a big turbine 68mm vgt) and say a 484/485 (or larger) as an atmospheric in your current piping to not render the piping as scrap while still meeting your HP goals and still being fun to drive.


For an intercooler, I personally would get a Northern Radiator/BD or Banks. The Northern Radiator/BD (they're the same) and Banks are all extruded microfin which is the same type of construction as the OEM cooler but beefier. Bar and plate (Mishimoto, XDP, couple others) are good a pulling temperature out of the system but are typically more restrictive than extruded microfin cores.


Also, as for your differential, I personally am a huge fan of the Eaton TrueTrac/Torsen style limited slips. My competition truck is still 30 spline with an Eaton TrueTrac and Yukon 4340 cut to length axle shafts. While my splines have slightly twisted and "set", they haven't failed or moved enough to be a problem in 70+ sled pulls and 4 years of beating on em. I personally wouldn't go to a drive flange style axle on a 30 spline setup as I can't justify the

 

[Creeker15]

As stated by a few others, I'd start with a good data log (without the gauge jumper installed) as well as checking for boost leaks. You can get a PVC cap and a bulkhead fitting or metal pipe etc to fit into the inlet boot on the S480 to pressure test to ~40-50psi. Pressure testing the system is the easiest and best way to find a boost leak. You will always hear air moving as there will always be some valves partially open but what you need to listen/feel for is air coming out of any connections. I think your boost should be somewhere around the 60-70psi range on a bigger file with that fueling BUT I do think you will be better suited by a 150-200% injector if your goals are over 1k. You also can run a larger VGT (something like a big turbine 68mm vgt) and say a 484/485 (or larger) as an atmospheric in your current piping to not render the piping as scrap while still meeting your HP goals and still being fun to drive.

Man I can’t believe I haven’t been on this forum sooner, the help and advice is fantastic. I spend hours a day sifting forums and learning and see so much hate for people posting but you guys knock it out of the water. Getting to talk to people who actually have fast trucks and know how to wrench on them is a huge help.

I read somewhere people advise to pony up the banks over the BD couldn’t figure out why.

yeah I was hesitant on doing a full locker and 38 spline, lot of coin that I could put into a crank or rods as my motor is pretty stock other than fuel, studs, pistons and keying.

My trans was built from the previous owner and has an xcalibur build and goerend. From the paperwork I have it seems like a full build and pretty beefy but I haven’t seen anyone else run them, and while she’s held up to my abuse just fine, I was thinking about asking Dmitri to go through the trans.

last question, how about the front diff and axle shafts? Is she going to hold boosted launches over 700?

I’ll try to get some good logs today, it’s raining nonstop so far this week.