Stupid question

[Bell Curve]

If p&p of the IH, plenum, TB gives more hp, why didnt they do it at the factory for even more gains for the king?

[ZRWON]

If p&p of the IH, plenum, TB gives more hp, why didnt they do it at the factory for even more gains for the king?
The most probable answer to your question is buried in the following quotes from a Corvette Action Center's story about the attirude of GM towards the ZR-1 at that time
( http://www.corvetteactioncenter.com/specs/c4/zr1/blackwidow.html

"In 1992, the LT5 Gang at MerCruiser offered to paint the engines in all 40 th Anniversary ZR-1s black as part of the 40 th [Anniversary] package. Although this was offered at no additional charge, to GM, the folks at GM, already knowing the inevitable, decided against bringing more attention to the ZR-1. The program was denied...

...came up with the idea to offer the black engines as a factory option, similar to the [RPO B2K] Callaway option of the '80s. ...soon found that Lotus had begun to develop their own 475 hp version of the LT5 which they offered GM for production in all 1995 models which were to be the last produced. One of the thoughts behind this special high horsepower engine was the Viper was coming in '95-'96 at 450 hp many wanted the King to stand on its own for years to come....
Again, due to the fact that the ZR-1 needed to be gone by the time the C5 got here, the program was squashed by GM"

Heart of the Beast and most other documents available to ZR-1 lovers show that GM got everything they ever wanted from the ZR-1 when it captured all those world records for quality, speed and endurance. GM and the rep of most all US automakers in the eighties was that quality and endurance sucked. Honda, Toyota and Datsun were cleaning their clock! The marketing people milked the KOTH's accomplishments dry in '90 and '91 and from '92 on the ZR-1 was no longer "needed"...production was decreased to a few hundred cars per year for the remaining 4 years of build out life. :blahblah:

[tccrab]

There's lots of room for improvement in the LT5, i.e., porting, stoking, turboing, variable valve timing, cams, etc.
600hp+ easily possible in a normally aspirated engine, sky's the limit for a forced indction version.
GM just didn't do it.
Money, corporate power struggle, low production numbers all contributed to the demise of LT5.
Sad but true.

[GOLDCYLON]

There's lots of room for improvement in the LT5, i.e., porting, stoking, turboing, variable valve timing, cams, etc.
600hp+ easily possible in a normally aspirated engine, sky's the limit for a forced indction version.
GM just didn't do it.
Money, corporate power struggle, low production numbers all contributed to the demise of LT5.
Sad but true.

I agree plus the time to perform the porting operations. Hell Locobob puts over 100 hours in his busy like a beaver operation alone.

[DaveK]

The simple answer is probably just cost. At some point everything is a trade off between perfection and how much it takes to get there. The aftermarket guys and tuners simply shift the balance towards a higher price trade off.

[Jeffvette]

The simple answer is probably just cost. At some point everything is a trade off between perfection and how much it takes to get there. The aftermarket guys and tuners simply shift the balance towards a higher price trade off.

The time and the cost that would have been associated in doing something like that would have killed GM. The LT5 program itself was a major money juggler in the first place. To added an additional 20 hours per motor for just light work would not have made good financial sense.

[DaveK]

The time and the cost that would have been associated in doing something like that would have killed GM. The LT5 program itself was a major money juggler in the first place. To added an additional 20 hours per motor for just light work would not have made good financial sense.

Thank goodness we still have people like you and all the other's who make up for all the bean counters! :thumbsup:

[XfireZ51]

... Hell Locobob puts over 100 hours in his busy like a beaver operation alone.

Having started my "winter project" I am gaining an appreciation for Bob's etc work. :worship:

[Paul Workman]

Thank goodness we still have people like you and all the other's who make up for all the bean counters! :thumbsup:

It's because Jeffvette needed something to do to pay for those excellent "Vette Babe" avatars and convinced GM to let him handle the finishing touches!:mrgreen:.

(Jess pullin yer chain, Mr Jeff!:wink:)

P.

[Locobob]

Several things come into play here.

First: the 90-92 motors have a very large primary injector boss which was intended for an air injection system of sorts which would have piped air behind the injector. This did not make production but apparently it was too late to change the casting. The casting did eventually get revamped for the 93-95 cars, the large boss was removed resulting in part of the 30hp improvement seen in the 405hp cars. More detail on the experimental air system can be found in the HOTB book.

Second: the LT-5 is a Chevrolet production motor - albeit a rather exclusive one. Production motors are built to be within certain tolerances - not perfect. The type of hand craftmanship involved with intake porting simply does not fit in with the big auto maker mentality. Only exotic, high dollar autos have this kind of hand crafted work done by the builder.

Third: see above posts, Chevrolet was pretty well done with the program by the time the engineering team started bringing up improvement ideas.