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SVTPerformance's Chain of Restaurants
Road Kill Drive-Thru
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<blockquote data-quote="Blue03Cobra" data-source="post: 552886" data-attributes="member: 675"><p>From BuickGNX.com:</p><p></p><p><em>There is no difference internally between the 3.8 liter SFI Grand National engine and the GNX engine. Initially, there were plans to perform standard performance tricks like blueprint the motor assembly, but tests proved that wasn't necessary to achieve the goal.</em></p><p><em></em></p><p><em>For example, a port/polish job was considered. This would require a tear-down of a brand new engine, because Grand Nationals were delivered whole to ASC for the conversion. From start to finish, the process of removing the upper half of the engine and performing the machine work could easily be 50 hours of labor. Only to reassemble it and risk premature failure due to any error or defect in the process. Not to mention the cost.</em></p><p><em></em></p><p><em>It would be impractical to perform such precision modifications to 547 cars post-production in a short time frame. So, McLaren specified these external improvements:</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Turbo- a modified T-3 turbo was used with a ceramic impeller wheel, which provides a lighter rotating assembly for quick spool-up and more efficient operation at higher boost. This led to concerns that rough (factory) wire-feed header welds might dislodge under stress and shatter the ceramic turbine wheel. They addressed this fear with a contamination trap on the turbine wheel which is unique to the GNX turbo. It looks like a "bump" on the exhaust side. Replacement GNX turbos DO NOT have the ceramic wheel, so be careful with your original.</em></p><p><em></em></p><p><em>The compressor A/R remains .60 and the turbo is equipped with an adjustable wastegate. The stock turbo cover was swapped out for a more attractive unit. Prototypes said "Buick Turbo" while the production units simply said "GNX".</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Intercooler- the GNX intercooler has a slightly higher fin per area count, making it a little more efficient at removing heat from the air charge. Each intercooler contains a label from ASC/McLaren and an individual serial number.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>ECM calibration- the GNX PROM contains a slightly improved calibration, which capitalizes on the more efficient components above. The maximum boost is increased to 15psi. Rumor has it that the GNX doesn't idle as smoothly as the stock calibration.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>The oxygen sensor is upgraded to an AFS-22, which is able to tolerate more exhaust heat than a stock AFS-20. In development, McLaren had a stock O2 sensor break down and shatter a turbo (OUCH!). They attributed this to the higher exhaust gas temperature of the increased power, so they specified an Inconel oxygen sensor.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Intake pipe- the "up pipe" between the intercooler and throttle body is treated with a heat-resistant paint called "ceramatel" , which is supposed to protect the intake charge from engine compartment heat.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Louvers- the functional openings on each quarter panel (sometimes called Venti-Ports) were added to remove hot air from the engine compartment. The theory was to improve the efficiency of the intercooler. To accommodate these louvers, a set of relays on the driver's side needed to move off the side sheet metal to a custom bracket by the wiper motor. Rumor is that you can stick your hand out the window while driving and feel the heat coming out. Click here for a view through the louver into the engine compartment.</em></p><p><em></em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Exhaust- a custom 2-1/4" dual exhaust system was added to clear the new suspension cross member. Instead of the stock "crossflow" muffler, 2 separate small mufflers were used. This is also supposed to provide better performance, but based on the bends and peens they needed to clear the suspension, it may not be very significant. It does have a deeper tone. GNX owners have limited options finding a replacement because normal turbo regal exhausts will NOT clear the rear suspension.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Emissions certification- the emission control label, located on the air conditioner box, is applied over the factory Grand National label. The only difference is that the manufacturer is listed as "ASC" and not Buick. It's unclear whether this was a requirement or to circumvent some emission concern with the more powerful motor. The factory rating is 276hp@4400 and 360ft-lbs@2600 of torque, but in reality those figures are conservative. God bless America.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>Transmission- the transmission is basically the same Turbo Hydramatic 200-4R as the Grand National except for some recalibration of the hydraulics. The shifts are noticeably firmer. There is no difference in the torque converter, however you can expect a little more stall speed from the stock D5 due to the increased torque. ASC added an aluminum transmission oil cooler in front of the radiator.</em></p><p><em></em></p><p> <em></em></p><p><em></em></p><p><em>The differential gear remains stock at 8.5" 10-bolt with 3.42 gear ratio, but a new cover is put on to support the suspension improvements. This increases the gear lube capacity and makes it possbile to change the fluid without removing the torque arm.</em></p><p><em></em></p><p></p><p>The accepted times for production models were 0-60 in 5.3 seconds and quarter mile in 13.4 @ 104mph.</p></blockquote><p></p>
[QUOTE="Blue03Cobra, post: 552886, member: 675"] From BuickGNX.com: [I]There is no difference internally between the 3.8 liter SFI Grand National engine and the GNX engine. Initially, there were plans to perform standard performance tricks like blueprint the motor assembly, but tests proved that wasn't necessary to achieve the goal. For example, a port/polish job was considered. This would require a tear-down of a brand new engine, because Grand Nationals were delivered whole to ASC for the conversion. From start to finish, the process of removing the upper half of the engine and performing the machine work could easily be 50 hours of labor. Only to reassemble it and risk premature failure due to any error or defect in the process. Not to mention the cost. It would be impractical to perform such precision modifications to 547 cars post-production in a short time frame. So, McLaren specified these external improvements: Turbo- a modified T-3 turbo was used with a ceramic impeller wheel, which provides a lighter rotating assembly for quick spool-up and more efficient operation at higher boost. This led to concerns that rough (factory) wire-feed header welds might dislodge under stress and shatter the ceramic turbine wheel. They addressed this fear with a contamination trap on the turbine wheel which is unique to the GNX turbo. It looks like a "bump" on the exhaust side. Replacement GNX turbos DO NOT have the ceramic wheel, so be careful with your original. The compressor A/R remains .60 and the turbo is equipped with an adjustable wastegate. The stock turbo cover was swapped out for a more attractive unit. Prototypes said "Buick Turbo" while the production units simply said "GNX". Intercooler- the GNX intercooler has a slightly higher fin per area count, making it a little more efficient at removing heat from the air charge. Each intercooler contains a label from ASC/McLaren and an individual serial number. ECM calibration- the GNX PROM contains a slightly improved calibration, which capitalizes on the more efficient components above. The maximum boost is increased to 15psi. Rumor has it that the GNX doesn't idle as smoothly as the stock calibration. The oxygen sensor is upgraded to an AFS-22, which is able to tolerate more exhaust heat than a stock AFS-20. In development, McLaren had a stock O2 sensor break down and shatter a turbo (OUCH!). They attributed this to the higher exhaust gas temperature of the increased power, so they specified an Inconel oxygen sensor. Intake pipe- the "up pipe" between the intercooler and throttle body is treated with a heat-resistant paint called "ceramatel" , which is supposed to protect the intake charge from engine compartment heat. Louvers- the functional openings on each quarter panel (sometimes called Venti-Ports) were added to remove hot air from the engine compartment. The theory was to improve the efficiency of the intercooler. To accommodate these louvers, a set of relays on the driver's side needed to move off the side sheet metal to a custom bracket by the wiper motor. Rumor is that you can stick your hand out the window while driving and feel the heat coming out. Click here for a view through the louver into the engine compartment. Exhaust- a custom 2-1/4" dual exhaust system was added to clear the new suspension cross member. Instead of the stock "crossflow" muffler, 2 separate small mufflers were used. This is also supposed to provide better performance, but based on the bends and peens they needed to clear the suspension, it may not be very significant. It does have a deeper tone. GNX owners have limited options finding a replacement because normal turbo regal exhausts will NOT clear the rear suspension. Emissions certification- the emission control label, located on the air conditioner box, is applied over the factory Grand National label. The only difference is that the manufacturer is listed as "ASC" and not Buick. It's unclear whether this was a requirement or to circumvent some emission concern with the more powerful motor. The factory rating is 276hp@4400 and 360ft-lbs@2600 of torque, but in reality those figures are conservative. God bless America. Transmission- the transmission is basically the same Turbo Hydramatic 200-4R as the Grand National except for some recalibration of the hydraulics. The shifts are noticeably firmer. There is no difference in the torque converter, however you can expect a little more stall speed from the stock D5 due to the increased torque. ASC added an aluminum transmission oil cooler in front of the radiator. The differential gear remains stock at 8.5" 10-bolt with 3.42 gear ratio, but a new cover is put on to support the suspension improvements. This increases the gear lube capacity and makes it possbile to change the fluid without removing the torque arm. [/I] The accepted times for production models were 0-60 in 5.3 seconds and quarter mile in 13.4 @ 104mph. [/QUOTE]
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