3timeracin

iTrader: (15)

I have just finished a 440ci lsx build 12.0 compression and has a set of TSP LS7 big cnc'd heads 400cfm. The motor is currently on the dyno have made several passes to 7,000rpm and the power curve is still climbing very hard at 7k. It has LS7 lifters, titanium intake valves ferrea spring 175seat and 475 open and lightweight valve train does anyone have a similar setup and how high do you turn yours ? I would like to spin it 7500-7600 to see where it falls off ? really dont want to have valve float on a new engine. Any help will be appreciated.

Grimes

iTrader: (3)

I would probably upgrade to morel lifters if you are spinning the engine that high.

3timeracin

iTrader: (15)

I did some thinking and the stock ls7 valvetrain is heavier over the valve than what I am running and they run 7000rpm with a 36,000 warranty so Im sure GM did some research on the safety and longevity factors. I have looked at Morel's and mechanically did not see much difference other than a nicer shiny finish ? actually the Ls7 plunger height was higher so I went with them I felt that would make it harder for the lifter to pump up ?

JPH

iTrader: (2)

I would have used an AFTERMARKET lifter from like Crane, Crower, Isky or Morels for the ultimate in valvetrain control/stability and HI-rpm capibility. Hope your valvetrain is "light" and your pushrods and springs are stout.

3timeracin

iTrader: (15)

Spring pressure is listed at the top 175 seat 475 open ferrea's duals, Crower .110" wall double tappered pushrods 3/8". Valves are the exceledyne titanium 5/16 stem swaps. Like I was thinking before, chevy spins the LS7 7000rpm in stock form I just need another 500 rpm that i understand is alot at 7000 already.

HTMtrSprt

Once again..... we turn NHRA stock eliminator engines over 8200 RPM w/ stock replacement lifters. The limit is not in the lifter, but in the rest of valvetrain..... light valves, retainers and springs..... rigid rockers and pushrods.

Greg Fell

iTrader: (9)

thats a pretty good piston speed running on what i assume is a 4.1" stroke. that being said, lots of turned big stroke motors hard and have great luck, just not sure about longevity.

also, what manifold will you be using? not sure that the ls7 manifold wouldn't slow you down at those rpms vs its bread/butter area, it has its limit. usually that high of rpms means a sheet metal or victor jr (and solid roller)

LLC

Shimmed?

HTMtrSprt

No...... stock.

3timeracin

iTrader: (15)

No actually I thought of the piston speed before hand its actually a 4.2" bore with a 4" stroke. I thought it was more important and more to gain by unshrouding the 2.20" intake valve than have more stroke. Also I was considering longevity of rings.

3timeracin

iTrader: (15)

Greg, I have the GMPP carb intake and QFT pro series 950 carb the motor is making power and climbing good right till we stop at 7000 I just made 1 pass to 7300 and seemed fine still climbing so we took it to 7600 and it dropped off just after 7500 with 768hp

3timeracin

iTrader: (15)

Hitech, I know exactly what you are saying about the setup for high rpm I have found the valvetrain weight before the rocker to be less critical but anything over the valve is very crucial to a high rpm engine. Rocker tip weight , valve and spring /retainer. Thats why gm narrowed the rocker nose to almost a point ?

HTMtrSprt

I would say you are going to need more than 175 lbs seat pressure to safely go beyond 7300. 200-220 lbs seat is a little more like it...

3timeracin

iTrader: (15)

I was thinking that but its hydraulic roller I was afraid of damaging the lifter ? have you ever ran that much seat on a hydraulic ?

3timeracin

iTrader: (15)

I was also thinking my solid roller setup on my other car has twice the valve train weight and a conventional core cam not a 55mm like the ls1. That small core/base circle makes the ramp speed alot higher on the solid roller, not to mention the difference in lobe intensity alone ? that engine normally sees 8000 for over 2 years now no problems. I was wondering how nascar teams do it ? I know they run a larger 50 -60mm cam core to keep the lobe intensity down alot like the LS1 and they are solid but they do not run crazy spring pressures. They run titanium valves as I do, but there valves are longer alot longer so thats more weight ?. They also use conventional dual springs alot of the time no weight savings on the retainers. They run 9000rpm all day ? amazing

HTMtrSprt

Yes, I have run that much on a hyd. roller lifter before without any problems.

NASCAR Sprint Cup engines have flat tappet cams but they do use large bearing diameters to stabilize the valvetrain. The spring pressures they use are lower than you might think since they run the springs submerged in engine oil to act as a damper which prevents coil surge.

ONEBADWS6

iTrader: (22)

I run a spring pressure of 180/400 with a comp R lifter and a steel valve to 8k rpm.

JPH

iTrader: (2)

Testing, testing, testing all day, everyday. Learn ALOT by doing it do much.

tektrans

iTrader: (23)

That carb intake is a high rpm intake from what I understand which is probably the reason she's pulling past the 7k mark so well. Nice #'s.
Is she suffering down low at all with that intake?

3timeracin

iTrader: (15)

Not really I compared the curves from this engine to my pump gas 408 injected engine from last year and this makes about 20-30 lbft torque more everywhere and that engine would run 1.40 60's of the footbrake. I was that concerned done low I run a 4.22 gear and 4500 converter.