LS7 reliability

[stigmundfreud]

I heard there were problems with the LS7 valve train but all google searches pull up threads that descend into how an engine should only last 500 miles with a strip down if its used heavily, anything more is a bonus. Anyway I remember ringram blew his ls7 but how reliable are they really and what preventative medicine can be taken?

[S800VXR]

Stock LS7 should be bullet proof from what I've read...... Why!?

[stigmundfreud]

Just curious, you hear a horror story of exhaust valves dropping and costing the block and was sure I heard Richard had similar problems

[S800VXR]

Rich had a cam in his which caused the issue I beleive. Mine has the sodium valves too I beleive but with sensible double springs there should not be an issue really. Go OTT on spring closing pressure and yes the tips can break.

[ringram]

Some report dropped valves and bust rocker bearing chases.

Mine was due to lack of control over US engine builder. He chucked in solid 2.2" steel valves instead of OEM Ti in the OEM Heads.
Been running for 60,000+ on Ti valves this time around..

Nothing blew, valvetrain just got hammered till a lifter failed.

Stock they should be pretty good if maintained. I suspect abuse is the culprit most of the time.

Bores are wide and thinly sleeved so really no good for anything other than NA.

Later ones had enhancements etc (If you are looking at Z06's, 08+ MY is good due to trans changes)

[ARAF]

I think the LS3 also has sodium filled valves. You don't hear of many failures of them here, so I guess they will be fine, if not over-rev'd or have too wild a cam closing profile.

[stevieturbo]

S800VXR said:

Stock LS7 should be bullet proof from what I've read...... Why!?

You'd like to think so.

GM sell the LS7 Vette's etc with a warranty dont they ?

OEM engine should have OEM reliability.

I'm sure there are some that will have problems, same with any car, especially if seriously abused. But I'd hope they would be few and far between.

Obviously if you retro fit the engine, and someone else tunes it there is more potential for problems as you're introducing variables.
If an unopened factory engine should be very very reliable even when driven hard all the time

[ringram]

ARAF said:

I think the LS3 also has sodium filled valves. You don't hear of many failures of them here, so I guess they will be fine, if not over-rev'd or have too wild a cam closing profile.

Intakes are hollow in the LS3. So they are good. LS7 OEM are all good too.

Valve control is more to do with the weight of the components, cam profile and suitable springs. Aggressive lobes are ok as long as all the rest of the list is in place.. hence why solid steel valves weighting 1Kg each cause damage

[gsd2000]

Stig are you buying a Z06 vette?

[Black VXR]

I guess you can break anything if you try hard enough?

[bimbleuk]

Funny thing is that the LS engines are becoming a popular choice in autograss cars and I've had it mentioned to me by a garage owner that preps a few cars that he'd been told of some valvetrain issues and specifically mentioned the LS7 engines. I couldn't substantiate it as it was second hand info but he mentioned it because he helped me convert a car with my LS1 engine.

[MyM8V8]

ringram said:

Some report dropped valves and bust rocker bearing chases.

Mine was due to lack of control over US engine builder. He chucked in solid 2.2" steel valves instead of OEM Ti in the OEM Heads.

Probably due to the Ti items being 10 times the cost of heavy steel valves?

[ringram]

Indeed. Someone did state they wanted OEM LS7 heads.. but clearly not being specific enough on every detail allowed some questionable practice to occur.

[stigmundfreud]

interesting you mention the SS ones caused the problem Richard as it appears all the builders replace the sodium ones with SS

So if one has an LS7 would it be relatively "cheap" to fit some new rockers and double springs just to be safe? if the valve drops I presume its engine over?

GSD I cannot confirm either way but decided on a new toy and theres a few vettes I am looking at. I love the older C5 z06 which are cheaper but I can afford the C6 Z06, however to throw things into the mix there is a lovely LS3 C6 auto for sale too which comes with targa top but that lure of Z06 is strong

[ringram]

stigmundfreud said:

interesting you mention the SS ones caused the problem Richard as it appears all the builders replace the sodium ones with SS

The devil is in the detail. Sodium are usually on exhaust for heat management. These are the ones usually swapped for solid stainless.
GM OEM Intakes never have sodium in them AFAIK. They are either hollow or Ti for weight management.

If people are swapping hollow intakes for solid (which does happen, but not normally on the larger valved LS7 stuff) then thats bad unless you have a horrible crap cam.. see above for combo comments.

Of course the L92/L76 heads which are mostly the same as the LS3 are solid, but designed for lower RPM, truck, heavy sedan action. (With horrible crap cams)

LS3 is higher performance/rpm use.

As usual it comes back to application and intended use..

[stigmundfreud]

I guess the question is do I go z06 for power I never would use or ls3 auto easier to drive but only 2k cheaper but with warranty etc then there's the c5 z06 a lot cheaper and best looking

[ringram]

C6 Z06 mate, look at the specs, weight reviews etc.

It will be a collectors one day, there is a nice 2008 blue one on PH that depending on when it was actually made would be the best buy as it will have the nicer TR6060 in it.

Thats what Id do for sure. The C6 Z06 is just an LS1 with heads. Though of course the body is uprated too.
The LS7 is one of a kind.

Failing that Id go for a cheapo 99+ C5 and throw a few mods at it. Use the balance to pay down the mortgage

[Harryoz]

What's the scoop on how far to take an N/A LS7? From what I read, 600 seems a no brainer, with 650 about the limit. 600 very street able, but 650 much less so.

It's in a 2014 Camaro Z28, for circuit and road use. Thoughts from the NA collective?

[ringram]

Oooh, nice car mate..!

Cam only, something sensible should add 100bhp to the 505fwhp factory setting, especially if intake and exhaust are good.
That should get you 480rwhp. Calling it a day at that point is probably "sensible".

Disregarding sense after that its a heads and perhaps intake job depending on where you like the power. Fast102 will add power over 5000rpm, but lose it under that.

Heads may gain you 30-40rwhp, look at the new RHS high port LS7 heads for example.
Add Meziere water pump for another 10rwhp and an underdrive pulley for maybe 5rwhp or so.

At that point adding a cam wont really extend your top end but will lose you bottom end. You may gain midrange, but the fast and Oem intakes wont carry RPM past around 6800 before falling off. This is due to intake runner size and length more than anything.

You then have to go after market intakes, the latest and greatest seem to be like this..



To do interesting things like this https://www.youtube.com/watch?v=R-TlIvXqcRQ
If you want 690rwhp! (Less 10% to convert to SRR numbers)

High BHP needs high rpm and therefore high CFM. This also means high ££ for the right valvetrain parts, shaft rockers, t-bar lifters, mega heads etc.
Air velocity will be slow and bad at low rpm leading to soggy bottom syndrome.

Everything should be in balance for best results. Mine I believe is under cammed
All the rest of my setup is sized for another 100bhp hence this..
Though even thats a bit girly. (Probably near ideal as a cam only in the Z28 LS7 IMO)

[SturdyHSV]

ringram said:

Add Meziere water pump for another 10rwhp and an underdrive pulley for maybe 5rwhp or so.

Got some evidence for those numbers mate?

Also, if he's thinking circuit use, I'd assume prolonged time over 3,500rpm, at which point the stock pump outflows the Meziere (in their own words, as seen here http://www.superchevy.com/how-to/vemp-0808-corvett... ) so worth considering.

They say they find 10lb ft gain, but they do that with a 160* thermostat compared to stock one, so not a good comparison...

This guy also finds zero gain back to back:

http://www.ls2.com/forums/showthread.php?887-Mezie...

There's also the question of whether an underdrive pulley and EWP together means you'll see less benefit from the EWP/pulley? As in, they probably won't see a gain that's the sum of their individual gains...

I'd be surprised if there's no gain at all though, as it certainly seems logical that you're simply taking less energy from the engine by not turning a mechanical pump, I presume the alternator provides sufficient excess power that the extra electric drain doesn't impact the engine's performance.

Will somebody make a clutched alternator like the E92 M3 has I wonder? Guess you need those tricks to make power when you've only got 4 litres...