xxxhp

If the cylinder heads in the LSA engine shares its valvetrain components with the vette LS3 cylinder heads, why did GM limit its rev to 6200rpm vs the vette's 6600 rpm rev limiter?

The LSA specs shown in GMPP catalog shows a 6600 as max recommended rpm




Besides, New Era Performance took a stock LSA to 6600 rpm and the power continues to go up




Does anyone know any info why the LSA engine rev limiter is set at 6200 rpm? Is GM too conservative here?

Old SStroker

GM certified the LSA @ 556 fwhp @6100 per the SAE tests they are required to do. They achieved their 550 fwhp goal. Sure there is more in the engine, but it should live longer with a 6200 rpm redline than a 6600 as the loads are considerably less @ 6200. I suspect that the engine, valvetrain, etc. is stable to 6600.

The marine version of the LSA-SC is rated at 530 fwhp (or 540 depending on when the numbers were published) at 5400 with a fuel cutoff @5600. Marine engines are normally tested with fewer accessories than cars and with freer exhausts. As you can see in the link, power certainly hadn't peaked @ 5400. I make it ~550 at 5600. Boats are much harder on engines than cars. The run at high load, high rpm for long periods of time. It's hard to run uphill at 150 in a CTS-V for an hour or more at a time.

http://www.gm.com/experience/technol...LSA_Marine.pdf

DVS99TRANS

iTrader: (7)

I think the LSA doesn't have the same blower as the LS9 as I read somewhere. That may have a possibility but am doubting that. That is the only thing that I can come up with unless GM wants to keep everythings power levels as far way from the ZR1 as possible.

Transgression

LSA's blower is a TVS 1900 and the LS9 is TVS 2300 and the 1900 has a single row intercooler while the 2300 has a 2 row intercooler

DVS99TRANS

iTrader: (7)

The TVS 1900 is a 3 screw and the 2300 is a 4 screw i think too. I could be way wrong and going on something I read quite a bit ago

Old SStroker

Google is your friend. Use your friend.

http://reviews.carreview.com/blog/ch...orvette-zr1/2/

http://www.media.gm.com/us/cadillac/...CTSVindex.html


LSA has 1.9L blower and a single brick IC, LS9 has a 2.3L blower and a dual brick IC as noted above.

Design goals were 620 hp for the '9 and 550 for the 'A. Generally the "platform people" (those responsible for the overall car) decide how much power/torque they need and Powertrain people deliver that.

If the Camaro ever gets the SC engine, my bet is the LSA, not the LS9.

dlove

iTrader: (23)

your screen shot of the specs says 6600....

got-a-ls1

iTrader: (12)

the lsa isnt a forged motor?? really?

xxxhp

Yeah, Iam wondering why the LSA engine in the CTS-V has a 6200 rpm rev limiter instead of 6600 rpm. That itself is worth additional 10-15 hp

Old SStroker

You didn't like my previous explanation of that, I guess.

I'll make it more explicit: The Old Farts (OF) that buy CST-Vs have slow reaction times, so when they try to shift at 5600, they finally get the shift done about 6100. Hence the 6200 fuel cutoff. If GM let us old guys have 6600 we'd probably be in the warranty shop all the time.

Now, what did they do to prevent us OFs from downshifting from 5th to 2nd when we were trying for a 5>4 shift and overreving the urine out of the LSA? They use a Dealer-Only (DO) hidden function in the PCM called RSSPA (Reverse Skip-Shift Prevention Algorithm). It is pronounced "riss=pah", the sound remarkedly similar to an OFs sound when he breathes, and is activated by the dealer before delivery of a CTS-V to anyone over the age of 60. LSAEdit can bypass it however.

Does that clear things up?

Jon

xxxhp

LOL thanks for the info. Iam just trying to gather more info about the 09 CTS-V powertrain. Iam seriously considering getting one as a daily driver

Robin L

DrkPhx

iTrader: (15)

Those are outstanding numbers, but the 6600 rpm run is not stock. According to the dyno chart the 6600rpm run was with a CAI and tune. The bottom run is stock. It would be interesting to see a stock LSA with the rev limiter raised to see how well it carries power past 6200.

I think OldSStroker answered it perfectly. GM purposely set it low based on the platform application and for warranty concerns. It will be interesting to see how GM rates the same motor if they release the new Camaro Z28.

Bink

Thanks, man.

Nothing better than specific info and excellent humor!!!

Blackdevil77

Same rev limiter in the upcoming ZL1. Would you say it's "safe" to increase the rev limiter of this engine to 6600 rpms or so? Just as safe as say, the ls3 or ls9? Or is there something about the LSA that makes it a bit more risky to rev as high as its 6.2liter siblings?

IDRIVEAG8GT

HP Tuners. Quick fix.

good2go

In the wait4me canned tune on a SCT handheld he raised the shift points to 6,400. Because of the heavier valves in the LSA (compared to the LS9), he doesn't recommend going higher without stronger valve springs and pushrods.

Blackdevil77

Is that all that's holding it back? I thought it had something to do with the cast pistons. The LS9 has forged pistons. I thought the valve train was the same on the LSA and LS9?

good2go

Different valves, titanium Vs steel intake, steel Vs hollow stem steel. LS9 valves much lighter. Cams are different, don't know if the springs are the same.

Bo185

Also the max shift speed of the 6l90 used in the CTSV is 6200RPM's I would suspect thats the real reason as the 6l80/90 doesn't like RPM's higher than that.

That would explain the the auto units as for the manual cars are the limited the same?