what is an LT4?
06-17-2003, 05:53 PM
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what is an LT4? hi im new to the site, and my knowladge of LS1 and lt1's are limited to what makes them fast and their diffrences.
i always see stuff about LT4 in magazines, and have no idea
what it is about. what is an LT4? its not a zr1 motor is it? thats lt5 right?
thanks
wow this site has so many cool smileys!
i always see stuff about LT4 in magazines, and have no idea
what it is about. what is an LT4? its not a zr1 motor is it? thats lt5 right?
thanks
wow this site has so many cool smileys!
06-17-2003, 07:53 PM
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Re: what is an LT4? LT4 Story
By 1995, the industry was preparing for GM's launch of the next generation small block, which was to be all-aluminum and redesigned from the ground up – a real engineering marvel. That engine, now known as the LS1, was to be introduced in the 1997 Corvette, which was also to be completely redesigned stem to stern. Meanwhile, the last of the "King of the Hill" ZR-1 Corvettes, with the monster-horsepower LT5 dual overhead cam engines, rolled off the assembly line in 1995. Thus, 1996 presented somewhat of a performance "gap" for the General. GM was concerned that sales of the 1996 Vettes would slump because many customers might wait for the introduction of the totally redesigned (inside and out) 1997 Vette. What to do?
GM gave its engineers free reign to "hot rod" the LT1 for 1996. This high performance 350 would hopefully fill in the gap between the LT5 and the LS1. GM also created two special versions of the 1996 Vette, namely the Grand Sport (1,000 Admiral Blue/white stripe were built, all of which were LT4- equipped) and the Collector Edition (5,412 Sebring Silver were built, 2,009 of which were LT4-equipped). However, all 1996 Corvettes with manual transmissions were produced with the LT4, while the automatics were only produced with the LT1.
The LT4 was a huge success. Using traditional hot rodding techniques, horsepower jumped to 330 net (30 more than the LT1). Internal differences include better flowing heads, bigger valves, a lumpier cam, and a 10.8:1 compression ratio (rather than the LT1's 10.4:1). The complete list is a page long (see, e.g., Steve Herrick's LT1 v. LT4 comparison chart), but suffice it to say the modifications were rather extensive. The engine's redline was raised from 5,700 to 6,300 RPM, giving the engine better pull through the upper RPMs where the LT1 began to fall off.
Production of the fuel injected LT4 version was finished in 1996 (there is a carbureted, non-emissions crate LT4 available now through GM Performance Parts). A few hundred of those engines, however, remained unused after production had been completed.
By 1997, SLP's relationship with GM was well established, with the 1992-96 Firehawks, 1996-97 Camaro SSs, and the 1996-97 WS6 Firebirds. The success of the LT4 spurred SLP to propose a limited production run of LT4s in the 1997 SSs. Because the external dimensions of the LT1 and the LT4 are identical, the LT4 is an easy fit in an F-body. Plus, the stout Borg-Warner MN6 6-speed transmission was strong enough to handle the extra horsepower.
Chevy and SLP agreed to produce 100 1997 LT4 SSs, all white with hugger orange stripes, celebrating the Camaro's 30th birthday (the original white/hugger orange stripe Camaro was actually a 1969 model, but it looked cool, so who cares!). The LT4 SSs sold like hotcakes, with rumor that some dealers were selling them for upwards of $60k (the MSRP was right at $40k).
With the success of the LT4 SSs, and with some LT4s still in inventory, GM and SLP agreed to produce another 100 1997 LT4 Firehawks. Unfortunately, by the time word got out and orders began coming in, and with production deadlines at Pontiac, only 29 were ultimately built (with one prototype also in existence).
The actual swap of the engines was done by SLP. Essentially, an F-body was built with an LT1 at GM's Ste. Thérèse plant, and then shipped to SLP's nearby facility in LaSalle, near Montreal. There, the LT1 was swapped for a balanced and blueprinted LT4. The final LT4 F-bodies were shipped in covered transports directly from LaSalle to the various dealerships nationwide (as opposed to going back to Ste. Thérèse for final inspection and placement on regular transports, as LT1 SSs, Firehawks, and WS6s were).
The LT4 F-bodies are exceedingly rare (110 SSs and 30 Firehawks). Most importantly, these are the only factory 4th Gen F-bodies to date with significant powertrain enhancements (I think Lingenfelter's 383 Hurst/Firebird and Meecham's T/A's are not factory cars, but some may disagree). The most collectible first era muscle cars (1965 - 1973 or so) are those with the ultimate factory engines (the 427s, including the extremely rare ZL1s, 454s, Boss 429s, Hemis, 440 six-packs, 454 SDs, etc.). While the models as a whole may be collectible (Camaro, Chevelle, GTO, Cuda, Mustang, etc.), those with the highest performance engine are by far the most sought after. It is not the stripes, sound systems, colors, wheels, cup holders, etc. that make these cars desirable, but rather the top-of-the-line, racing heritage powertrains. The LT4 F-Bodies are thus in a league of their own when it comes to long-term potential
By 1995, the industry was preparing for GM's launch of the next generation small block, which was to be all-aluminum and redesigned from the ground up – a real engineering marvel. That engine, now known as the LS1, was to be introduced in the 1997 Corvette, which was also to be completely redesigned stem to stern. Meanwhile, the last of the "King of the Hill" ZR-1 Corvettes, with the monster-horsepower LT5 dual overhead cam engines, rolled off the assembly line in 1995. Thus, 1996 presented somewhat of a performance "gap" for the General. GM was concerned that sales of the 1996 Vettes would slump because many customers might wait for the introduction of the totally redesigned (inside and out) 1997 Vette. What to do?
GM gave its engineers free reign to "hot rod" the LT1 for 1996. This high performance 350 would hopefully fill in the gap between the LT5 and the LS1. GM also created two special versions of the 1996 Vette, namely the Grand Sport (1,000 Admiral Blue/white stripe were built, all of which were LT4- equipped) and the Collector Edition (5,412 Sebring Silver were built, 2,009 of which were LT4-equipped). However, all 1996 Corvettes with manual transmissions were produced with the LT4, while the automatics were only produced with the LT1.
The LT4 was a huge success. Using traditional hot rodding techniques, horsepower jumped to 330 net (30 more than the LT1). Internal differences include better flowing heads, bigger valves, a lumpier cam, and a 10.8:1 compression ratio (rather than the LT1's 10.4:1). The complete list is a page long (see, e.g., Steve Herrick's LT1 v. LT4 comparison chart), but suffice it to say the modifications were rather extensive. The engine's redline was raised from 5,700 to 6,300 RPM, giving the engine better pull through the upper RPMs where the LT1 began to fall off.
Production of the fuel injected LT4 version was finished in 1996 (there is a carbureted, non-emissions crate LT4 available now through GM Performance Parts). A few hundred of those engines, however, remained unused after production had been completed.
By 1997, SLP's relationship with GM was well established, with the 1992-96 Firehawks, 1996-97 Camaro SSs, and the 1996-97 WS6 Firebirds. The success of the LT4 spurred SLP to propose a limited production run of LT4s in the 1997 SSs. Because the external dimensions of the LT1 and the LT4 are identical, the LT4 is an easy fit in an F-body. Plus, the stout Borg-Warner MN6 6-speed transmission was strong enough to handle the extra horsepower.
Chevy and SLP agreed to produce 100 1997 LT4 SSs, all white with hugger orange stripes, celebrating the Camaro's 30th birthday (the original white/hugger orange stripe Camaro was actually a 1969 model, but it looked cool, so who cares!). The LT4 SSs sold like hotcakes, with rumor that some dealers were selling them for upwards of $60k (the MSRP was right at $40k).
With the success of the LT4 SSs, and with some LT4s still in inventory, GM and SLP agreed to produce another 100 1997 LT4 Firehawks. Unfortunately, by the time word got out and orders began coming in, and with production deadlines at Pontiac, only 29 were ultimately built (with one prototype also in existence).
The actual swap of the engines was done by SLP. Essentially, an F-body was built with an LT1 at GM's Ste. Thérèse plant, and then shipped to SLP's nearby facility in LaSalle, near Montreal. There, the LT1 was swapped for a balanced and blueprinted LT4. The final LT4 F-bodies were shipped in covered transports directly from LaSalle to the various dealerships nationwide (as opposed to going back to Ste. Thérèse for final inspection and placement on regular transports, as LT1 SSs, Firehawks, and WS6s were).
The LT4 F-bodies are exceedingly rare (110 SSs and 30 Firehawks). Most importantly, these are the only factory 4th Gen F-bodies to date with significant powertrain enhancements (I think Lingenfelter's 383 Hurst/Firebird and Meecham's T/A's are not factory cars, but some may disagree). The most collectible first era muscle cars (1965 - 1973 or so) are those with the ultimate factory engines (the 427s, including the extremely rare ZL1s, 454s, Boss 429s, Hemis, 440 six-packs, 454 SDs, etc.). While the models as a whole may be collectible (Camaro, Chevelle, GTO, Cuda, Mustang, etc.), those with the highest performance engine are by far the most sought after. It is not the stripes, sound systems, colors, wheels, cup holders, etc. that make these cars desirable, but rather the top-of-the-line, racing heritage powertrains. The LT4 F-Bodies are thus in a league of their own when it comes to long-term potential
06-18-2003, 10:14 PM
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Re: what is an LT4? I didnt know the WS6 was made by SLP???Or was that just the LT1s LT4s.Or is it the same with LS1s.I was told they had nothing to do with the WS6 and that they just made the firehawk. 
06-18-2003, 10:16 PM
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