Renegade "downdate"
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Like they say " same sh*t ; different smell"
Racer
Joined: Jul 2010
Posts: 261
Likes: 0
From: Spokane WA
Exactly especially the last part. Good job on the research. Now all we need is a write up on the renegade
From Hib Halverson
Set the Wayback Machine for mid/late-70s.
"GM was busy deciding what the new Corvette (originally planned for 1982 then slipped to 1983 and finally going to production as an 84 model in the Winter of 82-84) was going to be. There was never any intention to drop the 350 as the Corvette base engine.
The rumor that: GM was going to kill the 350 and go to a 305 and that's why the 2xTBI intake manifold has such small parts is either just plain bull or it's rumor stemming from confusion about the origins of the design of Tuned Port Injection which appeared in MY85 on both F- and Y-car.
The TPI intake manifold was sized for a 305 because GM believed that Camaro and Firebird Tuned Port 305s would outsell the L98 Corvette engine by a significant margin and GM didn't want to spend the money to tool-up two intake manifolds. So the L98 and LB9 hardware was the same.
Another reason the "kill-the-350-for-the-305" thing might have gotten started was the rare, 1980 LG4 California 305. All MY80 Vettes sold in CA had a 180-hp five-liter engine which was one of the first production cars with electronic engine controls. The reason why the CA cars for MY80 had a 305 is not because the 350 was doomed, but because the LG4 was destined as the base engine for other GM vehicles.
Examples are the Monte Carlo, the Caprice, light trucks and other platforms. GM was already working on the LG4 prior to its decision to use it in Corvette as an answer to the last-minute, exhaust emissions regulations, more stringent than those in the other 49-states, which CA implemented for all MY80 cars sold in CA.
Confronted with either not selling Vettes in CA that year or trying out the already-under-development LG4, GM made the smart choice.
Now, the final issue...why are the L83's intake ports so darn small?
In the mid/late-70s, with the new Corvette's powertrain under development, the state-of-art at the time was throttle body injection, however, Delco-Rochester did not have a throttle body assembly which flowed enough air to use on a Corvette engine. So someone thought,
"Why not use two of them?"
Rather than use two on an in-line intake manifold and create a hood clearance problem, deep inside Chevrolet Engineering, some genius remembered that back in the late 1960s, the Camaro's '67-'69 302cuin had a factory dual-four-barrel, low cross-ram that Chevy homologated for the SCCA Trans-Am series. They took that idea and figured since it worked great on a race track, the same type of intake manifold would work great on a Corvette street use if fitted with two Rochester throttle body injectors.
Bad idea.
As the system proceeded from design to development, Chevrolet soon found that while the system made pretty good high rpm power, it had terrible throttle response and awful low-speed driveability...so bad that not only was the engine off-idle and low-speed response very poor but it's exhaust emissions were lousy too.
What these wizards had forgotten is that the long runners, the huge plenum volume and the throttle body injectors so far from the intake valves, had fuel condensing out of the air stream and puddling on the runner floors when the velocity of the charge air dropped as the throttles were opened quickly.
What GM should have done was either stick with the QuadraJet 4ME for another two years or use a time machine to bring TPI from the future. But, most likely, for political, marketing and perhaps cost reasons, Chevrolet continued to try and put lipstick on a pig.
The development of CFI was long and difficult. I interviewed a GM Engineer back in the late 80s who told me he knew personally two powertrain engineers who paid for new homes with the overtime it took to get the CrossFire Injection to run well in the 82 Vette with an automatic trans and tall gearing.
The biggest problem was low port velocity at tip in. The eventual solution was to drastically decrease the port volume so that, when the driver whacked the throttle open at low rpm, port velocities remained high enough such that the air/fuel mix remained a vapor and little or no fuel condensed out of the air flow onto the port floors.
Of course, the end result of the tiny, high-velocity ports was significant restriction and poor performance at high rpm."
Set the Wayback Machine for mid/late-70s.
"GM was busy deciding what the new Corvette (originally planned for 1982 then slipped to 1983 and finally going to production as an 84 model in the Winter of 82-84) was going to be. There was never any intention to drop the 350 as the Corvette base engine.
The rumor that: GM was going to kill the 350 and go to a 305 and that's why the 2xTBI intake manifold has such small parts is either just plain bull or it's rumor stemming from confusion about the origins of the design of Tuned Port Injection which appeared in MY85 on both F- and Y-car.
The TPI intake manifold was sized for a 305 because GM believed that Camaro and Firebird Tuned Port 305s would outsell the L98 Corvette engine by a significant margin and GM didn't want to spend the money to tool-up two intake manifolds. So the L98 and LB9 hardware was the same.
Another reason the "kill-the-350-for-the-305" thing might have gotten started was the rare, 1980 LG4 California 305. All MY80 Vettes sold in CA had a 180-hp five-liter engine which was one of the first production cars with electronic engine controls. The reason why the CA cars for MY80 had a 305 is not because the 350 was doomed, but because the LG4 was destined as the base engine for other GM vehicles.
Examples are the Monte Carlo, the Caprice, light trucks and other platforms. GM was already working on the LG4 prior to its decision to use it in Corvette as an answer to the last-minute, exhaust emissions regulations, more stringent than those in the other 49-states, which CA implemented for all MY80 cars sold in CA.
Confronted with either not selling Vettes in CA that year or trying out the already-under-development LG4, GM made the smart choice.
Now, the final issue...why are the L83's intake ports so darn small?
In the mid/late-70s, with the new Corvette's powertrain under development, the state-of-art at the time was throttle body injection, however, Delco-Rochester did not have a throttle body assembly which flowed enough air to use on a Corvette engine. So someone thought,
"Why not use two of them?"
Rather than use two on an in-line intake manifold and create a hood clearance problem, deep inside Chevrolet Engineering, some genius remembered that back in the late 1960s, the Camaro's '67-'69 302cuin had a factory dual-four-barrel, low cross-ram that Chevy homologated for the SCCA Trans-Am series. They took that idea and figured since it worked great on a race track, the same type of intake manifold would work great on a Corvette street use if fitted with two Rochester throttle body injectors.
Bad idea.
As the system proceeded from design to development, Chevrolet soon found that while the system made pretty good high rpm power, it had terrible throttle response and awful low-speed driveability...so bad that not only was the engine off-idle and low-speed response very poor but it's exhaust emissions were lousy too.
What these wizards had forgotten is that the long runners, the huge plenum volume and the throttle body injectors so far from the intake valves, had fuel condensing out of the air stream and puddling on the runner floors when the velocity of the charge air dropped as the throttles were opened quickly.
What GM should have done was either stick with the QuadraJet 4ME for another two years or use a time machine to bring TPI from the future. But, most likely, for political, marketing and perhaps cost reasons, Chevrolet continued to try and put lipstick on a pig.
The development of CFI was long and difficult. I interviewed a GM Engineer back in the late 80s who told me he knew personally two powertrain engineers who paid for new homes with the overtime it took to get the CrossFire Injection to run well in the 82 Vette with an automatic trans and tall gearing.
The biggest problem was low port velocity at tip in. The eventual solution was to drastically decrease the port volume so that, when the driver whacked the throttle open at low rpm, port velocities remained high enough such that the air/fuel mix remained a vapor and little or no fuel condensed out of the air flow onto the port floors.
Of course, the end result of the tiny, high-velocity ports was significant restriction and poor performance at high rpm."
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Racer
Joined: Jul 2010
Posts: 261
Likes: 0
From: Spokane WA
Last I heard they are going to use another foundry. If it were me I would make 2000 at a time to get the orders filled. They can quit making them if they want. The could sell the casts and let someone else do it, I bet tom400cfi could take it over he seems to think he has a handle on crossfires.
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
You MAY have a Renegade. But you sure as chit don't know WTF you're talking about. To wit; I DO have a Corvette; which you can see HERE. OOPS! It looks like you've seen it already; evidenced by your retarded posts on that thread too! I'm "good" on the Corvette ownership, I'd say.
As I've said already, same dumbass poster...new name.
As I've said already, same dumbass poster...new name.
They arrived safe & in very N.O.S nice condition.
I see many are stressed out all over.
Not just me.
