In my several year search for parts for my restoration I've seen a number of cars that were "rednecked" out for street racing and a few that looked like they were seriously worked on for the track. I've looked around on the web but can't really find any information of LT-1's in racing history. When I was younger I remember seeing Corvettes out at Road Atlanta for SCCA races but wasn't really looking close to see whether they were big blocks or LT-1's (though an LT-1 would seem the obvious choice on a track with curves) So, does anyone have any info or rememberances of LT-1's and SCCA racing? or any racing?
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Re: LT-1 racing history?
By the time the LT-1 was introduced, SCCA rules were pretty liberal. C2 and C3 small blocks ran in BP, had big flares, lots of head work, almost any flat tappet cam, FI or a single 4bbl., and I think some aftermarket manifolds were legal. As time went on the rules got more liberal until they finally allowed tube frame silouette cars sometime in the eighties and A, B, and C-production got lumping into a single "GT-1" class.
It was not like a decade earlier when production rules called for an essentially "stock" car with removal of bumpers, trim items, and open exhaust. That was closer to Showroom Stock racing of the seventies than "production class" racing of the seventies.
So there was really no such thing as a BP "LT-1" comparable to the Z-06 nearly a decade earlier.
Beginning in the mid-sixties, Chevrolet's product performance priorities were the big block for Corvette and Can-Am racing, so if you had the means to build a new Shark into a race car, the obvious choice would be a big block to run AP or FIA GT. The highest displacement GT class had no displacement limit, so use of the big block was axiomatic.
Some of the key parts than went into the LT-1, like the manifold and carburetor fell out the the Trans-Am program, since early Trans-Am cars had to run essentially "stock" engines of no more than 5L displacement.
The LT-1 was a last gasp to give retail customers a high performance, road-worthy, solid lifter small block of yore, but Chevrolet had no racing ambitions for it. All of the parts were off-the-shelf - a four bolt 4" bore block, basic production heads machined for the big valve set, and the afore mentioned induction components. The LT-1 was basically a '69 L-46 with a mechanical lifter cam and the Z-28 induction system.
Even the camshaft was a retread. The inlet lobe is identical to the L-72 lobe with a slightly smaller base circle and the exhaust lobe is from the 30-30 cam. They just took these two off-the-shelf lobes and diddled with the indexing to achieve a very good and broad torque bandwidth.
It's a great high performance road engine because it was configured with proven, off-the-shelf performance parts (which meant the development cost was low), and the engineers knew how to set it up to yield a very broad and useable, road-friendly torque bandwidth.
As the seventies moved on, high fuel prices and tightening emissions regulations refocused Chevrolet's engineering resources on these issues. The old Can-Am died, and a lot of production racers converted AP Corvettes to BP. It was the cost of fuel and maintenance. A competitive BP car was a lot cheaper to race and maintain, and on a one-and-a-half minute course like Riverside and Willow springs a small block BP Corvette was only a couple of seconds slower than a big block AP Corvette. AP basically died!
By the mid-seventies when I was racing a TR-3 in EP, the basic BP Corvette engine was pretty generic. You could run virtually any production block and heads with a 3.48" stroke, unlimited compression and any flat tappet cam, any 180 deg. manifold with a Holley 800 CFM four-barrel, and none of these items trace back to anything that originated with the LT-1 engine option.
A lot of guys with Rochester FI removed it in favor of the above mentioned induction system. I don't think that was a good idea because the 360 degree manifold architecture of the big plenun FI system has greater top end power potential, even with the air meter flowing less than the Holley, but the air meter can be modified to flow nearly as much. Then the FI manifold architecture rules at the top end for sure.
A lot of CP guys running 283 C1s stayed with FI, but it essentially disappeared in BP.
DukeLast edited by Duke W.; February 12, 2010, 10:16 PM. -
Re: LT-1 racing history?
Thanks for an informative post on the evolution of SCCA racing vis a' vis the Corvettes. I'm not an SCCA racer and have often wondered what happened to the A & B Production classes that back in the day were the domain of the Corvette.
Best regards,Comment
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Re: LT-1 racing history?
Duke,
Thanks for the info. I obviously researched the early 60's A and
B production because my 62 Gulf car ran AP in 62, but my late 60's-early 70's frame of reference was very limited. Thanks again!Comment
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Re: LT-1 racing history?
Another part of the reason for the LT-1's existance was that Duntov did not want American Motors to dominate B production in SCCA with the '69 AMX. I believe this is mentioned in either Burton's book on Zora or McClellan's book on Corvette.Comment
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Re: LT-1 racing history?
Thanks for the info, very detailed. After reading old Motor Trend (and other mags) comparison of the LT-1 to the Porshe 911 and the better weight balance in the LT-1 compared to the Big Blocks i thought it would have had a more prominent role on the road race circuit given it's handling advantage but then again I never raced so I guess the driver skill makes up for it and cubes, cubes, cubes rule the day.Comment
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Re: LT-1 racing history?
Duke; Thank you very much for the history lesson.Bill Lacy
1967 427/435 National Top Flight Bloomington Gold
1998 Indy PacecarComment
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Re: LT-1 racing history?
In 1970, Chevy introduced the ZR-1 package for B Production racing. LT-1, cold air hood, HD brakes and suspension, no radio or heater.
ZR-2 was LS7 (stillborn) for AP.
Source: Ludvigsen, Star Spangled Sports Car.Comment
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Re: LT-1 racing history?
I've researched - to the best of my ability - the C3 ZR1's competition history. It's sparse. From what I can tell, most ZR1's were used for Autocross events sponsored by the National Corvette Council (NCCC) or were purchased by those who wanted to check-off all the trick stuff on the order form so they could brag about it in the DQ parking lot.
Since the ZR1 option was really never publicized and came with the warning "not intended for norman driving situations" some say people who were informed enough to know about the ZR1 package and/or allowed to order these cars were racers, or had to have some other "in" with GM. It stands to reason that GM wouldn't want to sell many since they had to be warrantied just like Mom's Kingswood Estate wagon. On the other hand, I would think that any salesman would salivate at the chance to tack-on a $1k option to a $5k car.
Burton does mention that Zora developed the ZR1 as an answer to the AMX, although the factory track wars were done by the time the LT1 Corvette came into being. If the LT1 option would have debuted on schedule in '69, we might have seen some track time in competition.
As Duke mentions, the loosening of rules by the SCCA allowed more modifications over stock spec. Once GM's participation in TA wained in 1970 (the first year for LT1 availability), the "win on Sunday, sell on Monday" mantra no longer directly applied.Last edited by Dan P.; February 14, 2010, 01:45 PM.Comment
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Re: LT-1 racing history?
I think the ZR-packages were aimed at stock class autocrossers where stock really means stock with virtually no modifications.
If someone wanted to build a SCCA production class car from a new 1970 model, it probably would have been cheaper to start with a no-option base model.
DukeComment
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Re: LT-1 racing history?
Agreed! I never saw a ZR run in SCCA road racing and I was at Elkhart Lake, Mid Ohio, Nelson Ledges, Road Atlanta, IRP, etc. but I knew two who autocrossed them regularly in NCCC and SCCA.
I miss the "real production" days. I have some pics of BP in the mid 60's with radios and license plates in the paddock at M.O.
Thanks for the info. Duke!
SteveComment
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Re: LT-1 racing history?
Steve-
I'd be interested to know more about those two ZR's that were autocrossed. I've been searching for the original owner of my '70 ZR1 with no luck yet. The car was most likely sold new in California (NA9 equipped), but ended up in Indiana sometime before 1977. Any info regarding ZR1's in competition would be greatly appreciated - as there were only 25 ZR1's produced in '70, and about 14 have been accounted for. This particular car is one of 5 equipped with 4.56 posi. - figure it'd be optimum gearing for autocrossing when mated with an LT-1:
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Re: LT-1 racing history?
Steve-
I'd be interested to know more about those two ZR's that were autocrossed. I've been searching for the original owner of my '70 ZR1 with no luck yet. The car was most likely sold new in California (NA9 equipped), but ended up in Indiana sometime before 1977. Any info regarding ZR1's in competition would be greatly appreciated - as there were only 25 ZR1's produced in '70, and about 14 have been accounted for. This particular car is one of 5 equipped with 4.56 posi. - figure it'd be optimum gearing for autocrossing when mated with an LT-1:
I shoulda' read it all! I sawyour article a few months ago. Nice car! Congratulations! Steve
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Dan, one of the cars was a '71 from Michigan IIRC and ran at an NCCC weekend at Mid Ohio in the very late 70's or early 80's. I think it was a red car, it was a coupe. I was paddocked near it and checked it out and commented to the owner about his ZR-1. Another guy standing nearby asked "a what"? The owner said it was just a 330 HP LT-1. After the onlooker left the owner said to me something to the effect "so you know about a ZR-1"? After we talked about the specs. of the car, it had a 3.70, he told me I was the only one who had said anything about it being a ZR-1 and most just commented about it having no radio. It was also autocrossed per the owner. Sorry I can't give you more info on that car. I will look to see if I still have pictures from the event and if so I will post.
The second car was owned by the fellow I bought my '57 from in Northern Indiana. He owned it in the late 70's - early 80's. It was a dark gray 1972, black interior, coupe, also with a 3.70 and a luggage rack. The car as he bought it had been autocrossed with an RV cam for torque and a different carb. He changed it back to stock after he stopped autocrossing it in SCCA and Fort Wayne Corvette Club events. It was mint when he sold it to a guy in the Fort Wayne, IN area and then to someone on the East Coast IIRC and restored with only something like 30,000miles.
Where in IN was your car? Colors and coupe or conv? The 70's are great!
SteveLast edited by Steven B.; February 14, 2010, 10:29 PM.Comment
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Re: LT-1 racing history?
Great ZR1 story Dan, I enjoyed reading it.
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