Ratical

iTrader: (82)

It sounds like a silly question, but I wasn't sure how else to word it. My car is a stock stroke forged 6.0.

I have seen threads with people shifting at 8000+ rpm on stock internal 5.3's and have seen bone stock LS1's with a cam and spring change shift at 7K. I picked up 3 mph going from 6K to 7K shift point and currently shift mine at 7K, but my power had not peaked yet with the turbos. I am used to N/A combos that are more sensitive to cam timing and head flow to determine shift points. I don't want to blow my shyt up, but just wanted to get a rough idea how these engines are holding up to rpm.

gnx7

iTrader: (28)

All depends on cam, intake, head flow, turbo/Turbine choice. You have the bottom end potential to spin it some RPMs Higher RPMs with heavy valves (7500+) will wear out the valve job quicker... ask me how I know forged LS9 block, 88mm precision turbo, Mast LS3 heads with heavy 2.16" intake valve after about 2-3k miles of street and hard racing (1/2 mile) needed a valve job. Machinist said 7800rpm shifts are a no no! Ran stock LS7 lifters and hydraulic cam which also wasn't best combo! Johnson link bars going in next and 7500 max RPM.

Game ova

6300 here. No need to buzz it.

sweet99ss

iTrader: (41)

I agree I shift mine at 6200rpm.. Personally I would rather let the boost do the work and not be hard on the valve train...

JoeNova

I shift into 2nd and 3rd at 6200/6400.

gtistile

Shifting mine at 7400 now and it feels like it wants to go higher... Haven't dyno'd so no idea what the power curve is like, just going off butt dyno.

simple

iTrader: (8)

That an SBE?

Forcefed86

iTrader: (4)

Bigger/heavier the rotating assy, the greater the stress at RPM. (Same with valve train as mentioned. ) Smaller/lighter pistons (and many times valves) allow the small bore engines to be more rev happy out of the box. I think that’s why we don’t see any SBE 6.0’s revving to 8k+.

The more power you average over peak torque, the easier it is on the rotating assy. I’d say if it’s a “race car” and you feel it’s still pulling… Try bumping it 200rpm at a time until it stops picking up. If you want reliability leave it at 6800-7k. If you want more MPH out of the combo at less RPM, bump the boost a few lbs after peak torque.

hellbents10

iTrader: (10)

Most customers are around 6000-6500 on plastic intakes and mild cams. This is just to keep them 100% maintenance free. Jon shifts his at 8100 with the BEI Big Mac cam.

tblentrprz

Care to share a little on the rotating assembly and valve train?

General thinking - cubes make horses and increased rpm simulates cubes. Why not design motor to run 8K reliably (if not crazy expensive) and spec cam to shift at 7500?

rworcester

SBE 6.0, gen 4 rods/pistons, BTR turbo cam here. I shift 1-2 at 6450 or 6500. Feels to be pulling very strong still, only on 12 lbs so far

06murder

yea I shift my turbo setup around 6400 as well. Figured rpm would kill it early and it doesn't need the rpm with the turbo. NA nitrous setups ive built shift at 7k.

scottywheels

8000 with my set up...

67Firebird455

iTrader: (27)

I shift my 4.8 at 7,000. Have shifted at 7,200 and like others have said, it feels like it wants to keep pulling, but since it's a Gen III, i'll stop at 7k.

Game ova

The beauty of a decent sized v8 is short shifting it, and letting the turbo and abundance of torque do the work, exception being high strung race cars that are rebuilt every year. All that high rpm buzzing does is wear out valvesprings, make you more susceptible to dropping valves...kills valve seats....and stresses the rod bolts needlessly. Talking about the average turbo street car here.

gsteele

Have you ever run it on a dyno to verify that 8000 is the correct shift point or do you do it for another reason? Such as running out of gear etc.

Ratical

iTrader: (82)

I had only planned on shifting this combo around 6500 but was just shocked to see my horsepower still climbing when I let off at 7K on the dyno with such a small cam. (LJMS stage II). I assume it is the turbos making that power curve as I would think the engine itself would be peaked around 6200 or so with my head/cam combo N/A. I will get another dyno day this year now that I have some baseline numbers and this time have the shop email me some actual dyno graphs so I can save them for reference when I get home.

I have cathedral small valve heads so I don't think valve weight will be as much of an issue as LS3/LS7 square port heads but I guess to keep it on the safe side I will play around with shift points under 7K and boost levels this year. I only have 3 full passes on the combo at the track since I got it done so late last year so there is still a lot of fine tuning to do.

Thank you for the replies everyone.

Ratical

iTrader: (82)

Your thread is one of the ones I was talking about shifting at 8100 rpm.

3pedals

iTrader: (3)

I run my sbe junk to 7800 every shift

3 window

iTrader: (1)

Every "one" shift?! Lol. Just kiddin', I know you use to row a stick in that car!