fivelitrecobra

The C5Z and C6(LS2) engines are roughly about the same horsepower. If the same bolt-on's
......longtubes, exhaust, intake manifold, CAI, etc......were done to both, which would produce better numbers? What numbers would one expect to see out of each with the full list of bolt-on's?

zeevette

We're all C5Z owners, but obviously, given the similar modifications, the one with more cubic inches wins.

grantv

I'm almost thinking (100% guess) that the older motor might respond better. A common upgrade instead of headers are C6 exhaust manifolds, yes? As time goes on manufacturers squeeze every last drop out. Just a view...

Spaceme1117

This. I would guess the difference would be maybe 20 hp/tq between the two.

But the C5Z is about 250 lbs lighter than the C6 so I would think they would still be about equal in performance.

C5Dobie

LS3>LS6>LS2

LS2 = the truck motor, the oil burner, the rear main seal leaker, the motor that GM tossed after a handful of years....wonder why?

The LS6, IMO, feels snappier, faster to rev, comes stock w/ a "hot cam", does not suffer from oil starvation @ high G's, is just all around a more thought out/perfected engine vs. the LS2 which is an LS6.5 like a 1/2 *** approach.

While you don't see many people buying "LS6 crate motors" - how many LS2's do you hear about?

The LS3 is what they should have had in the C6 from day 1.....but its kinda par for the course as the whole C5 to C6 leap in vette history is more like a 1/2 step - the cars aren't much different vs. C3 to C4 to C5 - now, the C7 was a redesign & that LT motor entirely different beast w/ DI etc.

dbgoodwin

Well, on the same day my 01 (385 horsepower from the factory) made 376 rwhp with headers and catback with the stock intake. A friend's ls2 C6 made 365 with cai, headers, and exhaust, although that was through an auto.

They're gonna be fairly similar honestly, both use 243 casting heads (although I think some LS2's used 799's)

Once you start modding, it all goes out the window. Plenty of guys here use ls2 based builds, its not a bad motor at all.

C5Dobie

C6 w/ an A4 or A6? Either way you're looking @ 10-13% parasitic loss while an A4/A6 is like 15-18% - so conservatively your 376 = 430ish fwhp while his 365 = 445..........& not to pat myself on the back, but it essentially equates to the exact difference SAE the 2 had to start w/ lol

Doesn't change my opinion though in that the LS2 is just not as great a performer all around - & the oil consumption/rear main leak is well known

dbgoodwin

your math is a bit off there, I don't know how 365x1.15 or 365x1.18 either equal 445, but it's irrelevant.

His was an a6. We made virtually the same amount of power at the crank, though he had a better intake and I had a stock restrictive 01 intake.

I now now have a vararam and make a little more power.

Andrew

I think he took 376*1.18 to get ~445 and took 365*1.18 to get the ~430 number, then switched the values between the two. Some of that "new math" I guess. . Sorry C5dobie, could not resist.

Either way, don't sell the LS2 short. My 402 LS2 rear main does not leak, it is not an oil burner and makes over 500 hp without even breaking the 6k rpm barrier, so, yes, they respond really well to mods, just depends on the build. No disrespect to the LS6 either, both great platforms, but as mentioned, cubes make a big difference. There is a reason pro teams place the most ci's under the hood that is allowable.

dbgoodwin

ahh that makes sense. But yeah I was unaware that the Ls2 was a bastard child of the modern corvette.

C5Dobie

365/.82 = 445
376/.87 = 430

That's how I've always calculated parasitic loss - so take the avg. stock C5Z dyno # of 350-355 (we'll call it 352.5 ;-) / by .87 (13% loss) = 405 voila!!

You're welcome for the math class.

Back to topic - I still maintain LS6 > LS2

Andrew

Yep, got it. I have always increased the rwhp by the percent of loss, which results in a lower - more conservative number. But I am known as a sandbagger around here.

Agree with you in stock trim, but with equal platforms (i.e. LS to LS) and equal mods, cubes will always win. How those cubes are obtained is a whole other can of worms.

cv67

Spaceme1117

But again remember that a C5Z is about 250 lbs lighter than a C6.

killian96ss

250 lbs makes a big difference. Has anyone let one of their "big" friends ride along and notice the difference in performance? I have a few friends like this and when they're in my Z it feels like I lost at least 30 hp, lol.

Steve

radar502

I'm glad other people are finely saying the same on weight as I have been for years .. I have a good friend with a 2013 Z stock and I have a 04 Z-16 100 more Hp or about the same as the 13 Z . The 250 - + LBs makes a big difference in in getting it going ,my 04 comes unglued from dead start the 13 takes a wile to get moving .. We went to the track a few times the 04 smoked him .. Just saying..

C5Dobie

FWIW I work in a business that requires certified truck scales as everything is bought & sold via truck scale - my '03 Z w/ trunk tray/partition, nothing else but 1/4-1/3 tank of gas weighs 3080 lbs (without me in it)

That is LIGHT. It is difficult to tell b/c there are so many variations of the C6 but I would say it is safe to assume on average they're all @ least 200 lbs heavier. The C6Z is only about 100 lbs heavier

But the C5Z already feels like its factory modded while an LS2 C6 feels pretty soft in stock trim (you NEED to go to a used vette type place where you can drive back to back it tells the whole story) - the question is which car responds better to mods - ultimately do we mean which car will perform better @ the strip or @ the track or which one will show a higher dyno # @ a certain RPM for a split second @ a speed shop w/ a big fan blowing in its face? That's 2 different things. The answer to the first question is the C5Z as a CAR will improve more than a base C6 LS2 will in terms of total performance. The LS2 may or may not put up bigger #'s w/ similar mods, more often than not should dyno a little higher w/ bigger cubes, but you never know.

Also keep in mind 2 things when talking about dyno #'s & performance on the track between the C5 & C6 vettes - cooling is an issue w/ all vettes, but C5's in particular suffer from it - on a dyno its usually tough to get the ram air effect going that you experience @ speed on a track/road & that undercut the HP made on a dyno. The other thing to know is that the C5Z doesn't suffer from oil starvation @ high G's/cornering while LS2 equipped C6's DO - again, PERFORMANCE vs. dyno #?

Which are we talking?

Sic Liter

LS2 is a damn good engine. It is underrated and is actually closer to 410 to 415 hp at the flywheel in stock form. GM underrated it to not decrease sales on the C5 Z06 and they did not use the same SAE rating as the LS3. There is only a 2 mph trap speed difference between the LS2 and LS3. The LS3 weighs 38 more pounds than the LS2. The LS2 also has a higher compression ratio than the LS3 and it has higher rpm and a broader torque curve making it more fun as a daily. The LS2 was the last LS engine to have cathedral port heads and they are the best for building a modded engine.

dbgoodwin

Sounds like someone just bought an Ls2 car and is trying to justify his purchase.

Sic Liter

Saved me 5k getting a LS2 over a LS3. The difference between the two cars is only a car length. To each his own but the LS3 boys need to stop bashing the LS2s. The LS2s need more respect.