Some video info on the LT5...

[Roadster]

Passing time and searching the net for some ZR-1 related items and came across this video that was part of the 93 Corvette Owners Manual pack. Scrolling through the video there is just about 3 minutes dedicated to the technical advancements from the 92 LT5 to the 93 LT5, which of course also effected the 94 & 95 LT5's.
It starts at 46:42 and ends around 49:22
Thought it may be of interest to those who haven't seen this video.


https://www.youtube.com/watch?v=XerFBc0Qmrg

[Dynomite]

Thank You.....

That is some interesting Technical Information for sure and I am assuming here that starting in 93' those changes were not altered through 95'

[Hog]

Originally Posted by Dynomite

Thank You.....

That is some interesting Technical Information for sure and I am assuming here that starting in 93' those changes were not altered through 95'

Thanks for the vid Roadster!
Considering that all those engines were manufactured by the end of 1993 I bet your correct. Some LT5's waited around at Bowling Green for a couple years until they bodies that would house them were created. Some service engines are still waiting. It would be sickening to see exactly what GM paid for these units.

There are some inaccuracies in the specs shown at 4:09.
GEN 1 LT5 90-92
375hp@6000rpm/370lb/ft torque@4800

GEN II LT5 93-95
405HP@5800rpm/385lb/ft torque@4800rpm.

GEN III LT5 96+
475+hp
http://www.enginelabs.com/engine-tec...s-alive-again/
475+hp It woulda been great! This is where GM customers would see the affects of earler decisions to drop DOHC and go with the 3ed iteration of the SBC in the 1997 Y-body(Corvette), 1998 F-body(Camaro/Firebird) and GMT-800 trucks replacing the GMT-400 trucks in 1999. The only DOHC V8 engine was the Northstar (Aurora) which came 4.0/4.6 naturally aspirated sizes from 250-330hp and 4.4 liter supercharged sizes with 443/469 hp available in the Vette'like XLR-V both the 04-09 Cadillac XLR/06-09 XLR-V and the 04-09 Corvettes were BOTH GM Y-bodies and travelled down the same assembly line.
IIRC the 1st and only time the Corvette has shared the assembly line with another vehicle.
06-09 STS-V had the higher rating with 469hp @ 6400rpm/439lb/ft torque @ 3900rpm. Both the XLR-v and STS-V share the same 4.4L s/c Northstar rpo-LC3, but both applications were tested using the new SAE "Certified Power" standard, of which the 7.0/427 GEN VI SBC was the 1st engine to use the new power rating spec. Packaging which changes air intake and exhaust designs accounts for the 443hp in the XLR-V LC3 and the 469hp rating in the STS-V's LC3.

Since both the Corvette and Cadillac XLR and XLR-V both shared Bowling Greens assembly infrastructure, the XLR guys have events which they call "Rendezvous". Total XLR sales were 15,360 over 7 production years or 9 sales years as in 2010 188 were sold as 2009 leftovers and
in 2011 just 12 were sold as 2009 leftovers.
The naturally aspirated Northstar in the XLR (non-V) was rated at 320hp@6400rpm/310hp @ 3900rpm an did the 0-60mph in 5.8 seconds with 0.90 g's of cornering..
The XLR-V runs 0-60mph in 4.8 seconds that extra 123hp/104 lb/ft sure helped move those V-spec XLR's with it's portly()for a Y-body) 3840 curb weight.
The last Northstar engine was produced for MY2011 after being introduced mid year for the 1993 Cadillac Allante at 295hp@5600rpm/290lb/.ft torque @ 4400rpm and went out with a rating of 292hp@ 6300rpm/288lb/ft torque@ 4500rpm in the 2011 Buick Lucerne and Cadillac DTS-the last DTS rolled off the assembly line at 11:51 a.m. on May 27, 2011.

Sorry for the novel but its good to cover the GM DOHC engine story with all its intertwined aspects, used in FWD/AWD/RWD the Northstar series did its job, if only the GEN III LT5 was allowed to road in 1996 or in 1997 with the new C5 Corvette line along with the Lotus designed "power bulged" C5 hood which allowed the GEN-III LT5 to fit in the C5 Vette package.

It'll be interesting to see exactly GM will be releasing so far as a DOHC nengine. We know that Cadillac is going back to DOHC V8 with turbocharging. In what form will it take in the Vette??

[Roadster]

Originally Posted by Dynomite

Thank You.....

That is some interesting Technical Information for sure and I am assuming here that starting in 93' those changes were not altered through 95'

Glad you enjoyed the video info.... to my knowledge no other changes were made from the 93 to 95 LT5's. When I spoke to Tim Holland a few years back, he was really surprised that his "chip" was still in my 94. He indicated that there wasn't any problem with that still in the ECM, as the actual production chip was exactly the same as his (as he was in charge of the engine calibration & parameters for the LT5), and no changes were made for the rest of the production going into and through the 95 MY. My 94 ran great with that chip, but I did add Marc's chip to pick up the additional 10HP and to get the fan control.

Originally Posted by Hog

Thanks for the vid Roadster!
Considering that all those engines were manufactured by the end of 1993 I bet your correct. Some LT5's waited around at Bowling Green for a couple years until they bodies that would house them were created. Some service engines are still waiting. It would be sickening to see exactly what GM paid for these units.

There are some inaccuracies in the specs shown at 4:09.
GEN 1 LT5 90-92
375hp@6000rpm/370lb/ft torque@4800

GEN II LT5 93-95
405HP@5800rpm/385lb/ft torque@4800rpm.

Interesting read on the DOHC, and the GEN III LT5. Also the Northstar and the XLR's. I always did like those vehicles (XLR's).
There may be two different video's out there for the 93 Owners Manual Pack, one for the LT1 and one for the LT5.
As in the very beginning of the one I have posted, it does say
"1993 ZR-1 OWNER'S VIDEO, with the 40th symbol above that text. I am assuming that the LT1 owners received a slight variation of that video. I am only assuming....
At time 4:09, I did not see anything that you mentioned.
On the video posted after you go past the 46:42 mark, is this the screen shot you are referring too?
As posted at that screen shot.....

.....................................LT5 Performance....................................... .........
..............................................1993 .................................................. .....
.......................................405 HP at 5,800 RPM........................................
...............................385 Lbs.-Ft.Torque at 5,200 RPM............should be 385 Lbs.-Ft.Torque at 4,800 RPM

..............................................1992 .................................................. .....
......................................375 HP at 5,800 RPM......................should be 375 HP at 6,000 RPM
...............................375 Lbs.-Ft.-Torque at 4,800 RPM...........should be 370 Lbs.-Ft.Torque at 4,800 RPM

Yes, it is the wrong info posted in that screen shot. Maybe they didn't review the final info before releasing the video. Who know's????



I also enjoyed the Yellow ZR-1 shown in the video along with JH and RM doing the driving. The 1992 video had some of the same clips as they were also used here in the 93 version.

[Roadster]

Going through that part of the video with the LT5 specs, the announcer mentioned the increase of Torque to 385 Ft.Lbs in 93 from 375 Ft.Lbs in 92.
Could it be possible that there was a slight increase of TQ in 92 of 5 Ft.Lbs. over previous years that GM didn't mention, only to be mentioned in this video? Or could it be the announcer made a mistake, and it was too costly to do a voice over correction on the stated TQ increase from 92 to 93???
Interesting........

[Hog]

Roadster, my apologies, it was a typo, my 4:07 was meant to be 47:09, which is indeed the same graphic in the video that we are both referring to.

The stated torque increase of only 10 lb/ft and the stated power peak of 5800 for the 1992 LT5 when the 90-92 LT5 had its rated power peak at 6000rpm are probably just simple mistakes by someone in the chain. These were the days when GM was rating their powerplants to the nearest multiple of 5 SAE horsepower and 5 lb/ft of torque.

This all changed in 2005 for MY2006 when the new SAE J1349 and SAE J1995 "Certified Power" standards came along.
The GEN IV 7.0 liter LS7 was the 1st engine to be voluntarily rated using the new SAE Certified Power testing procedures. Originally it was to be rated at 500hp@6200rpm rpm/475lb/ft torque@ 4700rpm (or something very close to this) but after the testing followed the new SAE power testing procedures, it final Certified numbers were 505hp@6300rpm/470 lb/ft torque @ 4800rpm.
This also accounted for the large difference in the ratings of the STS-V and XLR-V ratings of 469/443 hp and 439/414 lb/ft torque differences. 26hp/24lb/ft from air intake/exhaust packaging differences between the 2 cars. There was a time when GM would have simply dyno tested one configuration and use that same number for both vehicles. It was practices such as this that created the huge Ford Mustang Cobra power debacle. For MY 1999 the Ford Modular 4.6 DOHC engine was to have been rated at 320hp @ 6000rpm/317 lb/ft torque @ 4750rpm, up from the 1998 305hp/300lb/ft torque. Since 1996 all of the 4 valve 4.6 SVT Cobra engines were hand built by technicians at the Ford Plant in Romeo, Michigan.

People started running their new 1999 SVT Cobras at the dragstrip and performing chassis dyno tests and were not getting the numbers that they should have. It was determined that these engines instead of making 320hp that they were making about 285hp, not good.

Ford halted the sales of all unsold 1999 Cobras on dealership lots and recalled all 1999 Cobras that had been sold. Ford replaced the intake manifold, certain computer components, and the exhaust system from the catalytic converters to the tailpipes in order to achieve a "true" 320 hp at the crankshaft

For MY 2000 the only Cobra sold was the limited run of 300 SVT Cobra "R" the regular Cobras were held for 2000 because of the issues with the 1999 SVT Cobra.

Since the SAE Certified Power specifications is a 3rd party testing affair this would have been caught. In fact many Asian car makers suffered power hits sometimes losing up to 30hp from their ratings. There were some North American models that gained a few ponies. Testing the engines low on oil, or stone cold, without air filters, or with cold dyno cell temperatures are not allowed under the newer SAE specs. It levels the playing field so that we as consumers have a better idea of exactly what we are buying. You'll also notice that instead of the nearest 10hp or 5 hp, new engine power ratings go right down to the single horsepower. Like with the 403hp L92, the 638hp LS9 and 556hp Cadillac CTS-V version and the 580hp Camaro ZL1 version of the 6.2 liter s/c LSA GEN IV SBC.

The differences with the peak power rpm of the GEN 1 LT5 and GEN 2 LT5 along with the errant torque figure could come down to a simple "failure to communicate".

Thanks again for posting the video.

[Roadster]

Thanks for the reply Hog, I enjoyed reading your response and learned from what you posted. Makes perfect sense with your thought of "failure to communicate". An interesting procedure on the way the newer HP numbers were and are calculated. And also interesting info on the Ford Cobras. Learn something new everyday....

You welcome on the video.....always looking for some little tidbit of info on the LT5.....have to start reading more all of the ZR-1 material I now have, especially since I'm retired.....