The BallSS

iTrader: (9)

Hello gents,
I'm looking for a little guidance regarding a build I'm looking at under taking very soon.
Currently running an SBE LS1 w/ CNC Ported 317's and specific turbo cam with a T56 manual trans at around 690rwhp, I've had a few people tell me I'm on borrowed time with that much power through a SBE LS1 so before I scatter that engine I'm going to start putting together a plan to replace it.
Uses for this car is street bruiser with mostly roll racing, won't see an digs or drags but maybe once or twice a year for fun, car is setup for handling so digs suck no matter what lol.
Here's what I had in mind and would appreciate any constructive feedback you gents can spare:
The Build-
LM7 Gen IV 5.3 w/ flat top 4.8 pistons assembled for boost (w/ 317's should net me 9.5:1 static comp. ratio)
CNC Ported 317's (because I already have them)
LJMS Stage 2 Turbo Cam or some variant
Current V1 Huron Speed Hotside
Turbonetics T7875 turbo (because I have it)
T56 Transmission (already built)
Three boost settings with different fuels: Pump @ 10lbs. for street / Trick 100 @ 14 lbs. / C16 at 18-20lbs. for hero numbers
Currently using 80lb. Siemens injectors w/ twin 255's (may replace the auxiliary 255 with a 340 or 450)

Goals-
7,500 rpm shift capabilities
800rwhp on hero setting
Top ramen budget

Will the T7875 and LJMS cam support a 7,500 rpm shift point and 800rwhp?
Thanks!

Game ova

IMO, that turbo will not support shifting at 7500. May make 800 on kill, but it won't be up that high. I've never ran a 5.3, but I know on a 6.0 it ain't happening.

The BallSS

iTrader: (9)

Yeah on my 5.7 I get about 6,500 out of it but that's also because I don't feel comfortable going any higher given the wimpy rods and current horsepower level.
I'm hoping that with the slightly smaller displacement of the 5.3 I may be able to squeeze a few more rpm out of it. and was hoping maybe someone else had done it and could recommend a cam too.

The BallSS

iTrader: (9)

Nothing else?
Nobody is running a 7875 on a 5.3 that can chime in on rpm capabilities?

ddnspider

iTrader: (26)

Is there a reason you want to shift at 7500? There are serveral on here revving the 4.8 to 7500+, not sure about 5.3's. A 7k is reasonable. I'm not sure I've seen a 7875 make 800w on a 5.3 either.

The BallSS

iTrader: (9)

Not particularly other than I'm currently running a 3.73 gear in my 12 bolt and don't want to have to change the carrier to run a 3.40 or higher ratio, I like the drivability of the 3.73 gears around town.
If I could squeeze a few more revs out of it like say a 7K shift point I'd be happy.
Again if I fall short of 800 whp I wouldn't be heartbroken, I'd like to take this cast Turbonetics T7875 as far as it can go before changing to another turbo/setup.
To change to a different turbo with a larger turbine would require completely changing my setup and I'm pretty happy with it as a whole so I figured let's take it as far as it'll go and see where I end up.

ddnspider

iTrader: (26)

I only bring up RPM's because shifting a 5.3 @ 7k and it should last a long time and is done regularly....the higher you rev the harder it is on the engine. Stock LS6's are my frame of reference and they're stock redline was 6800 so shifting a 5.3 at 7k should be fine. Do a trunion upgrade if you haven't already. I agree with trying out the turbo and see where it maxs out. If you're running good fuel anyways you should be ok. Once you stop seeing good hp gains/psi increase you know you found its sweet spot.

The BallSS

iTrader: (9)

I'm curious, Comp Turbo has a unit with an 80mm turbine utilizing a T4 flange w/ 3" v-band outlet that would bolt right into my setup.
Would this be worth looking into for the additional 5mm of turbine and the 5.3?

The BallSS

iTrader: (9)

See that's what I'm looking for, decent longevity coupled with performance.
That's what I'll do then, keep the rpms at 7K ish and use good fuel and see where it tops out.
I just didn't want to waste time going down this road if you guys came back and said the 5.3 would choke out at 6,700 when I'm shifting at 6,500 right now lol.

ddnspider

iTrader: (26)

The 80mm would certainly raise the ceiling on the RPM range, but I'd stick with the plan of 7k shifts and maxing out the 7875 and see where that gets you. It literally costs you nothing above and beyond your current plan of swapping in the 5.3.

The BallSS

iTrader: (9)

Sound advice DDNSpider, thank you for your input.
You mentioned a trunion upgrade, I was looking at the CME kit based on reviews of people who have used them, any recommendations?

ddnspider

iTrader: (26)

I went with the Straub kit. Others like the CHE kit. No issues so far on my ls6 shifting at 7k.

Photochop

iTrader: (74)

I wouldnt be too overly concerned about how tight you twist the motor. The decision to go with a 5.3 and the 7875 is a good one. The 5.3 has thicker cylinder walls, and the gen 4 rods will be a def improvement. The 7875 is better matched size speaking with a 323 cubic inches than 346. Stock48 on here advised me before that the turbo will dicate RPM. While it may peak at 6600, it may go flat but not fall off til 7200+, which would be good with a stick since you lose more RPM between shifts than an appropriately stalled auto. You should be able to hit 800 tire with the good gas and the right boost number. Just keep turning up the boost til you hit the mark and be careful of how much timing is in it with more boost, it may take 22-23psi to hit that. Theres tons of variables.

The BallSS

iTrader: (9)

Excellent, that's what I'm hoping for.
Currently my combo goes flat around 6K so I shift just over that using the stock tachometer.
Currently looking at an LJMS Stage 2 Turbo cam but am open to recommendations as well. (LJMS recommended the cam btw)
With the 3.73 gears I don't need and or want a lot of low end so I'm kinda considering the Stage 3 but at the same don't want it to be a pig.

Game ova

That's a lot of gear IMO^^^

Photochop

iTrader: (74)

A local buddy with a gen4 5.3, the same cam you're talking about with a s476r t6 turbo with 1.10 a/r and 87 exh wheel made 850 tire on 22psi thru a 6 speed with a monster 3 clutch with a 3.73 geared 9" with 29" tires. He always said it was too much gear and was going to change to a 3.25 or 3.50 gear, but ended up selling the car.

The BallSS

iTrader: (9)

I would agree that the 3.73 is a bit much but unfortunately to change to a higher ratio I'd have to buy a new carrier.
Currently running a Truetrac which I love so I just can't weigh the benefit over cost to make the change right now.
I'm sure at some point it will change but for now the 3.73's will stay until a 3 Series Truetrac carrier falls into my lap lol.

The BallSS

iTrader: (9)

Just a quick update, I'll be picking up my 5.3 short block here next month!
Unfortunately it got a little rusty sitting in my garage so I had to move on it, already cost me a crank. >=(
Its getting a light hone and new rings, reusing the main/rod bearings since they were perfect, new cam bearings and a hot tank.
Gonna add a HP/HV oil pump since I'm using an oil cooler and my builder said it can't hurt since he has a lightly used one sitting on the shelf for cheap.
Currently looking for a used BTR/LJMS Stage 2 Turbo cam and boost controller of some type, perhaps an eBoost or some variant.
Hopefully I'll have some dyno numbers come spring and we'll see how far this little 7875 will go!