|The CONS of modifying a Series 1 for better performance
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|Author:||willwren [ Sat Mar 12, 2011 2:21 pm ]|
|Post subject:||The CONS of modifying a Series 1 for better performance|
From my several years of experience making power with the Series 1, I'd like to share some thoughts to carry us through the next couple years. Take my advice seriously if you have any thoughts about boosting the factory horsepower or torque, especially if you don't want to see your car rusting away at a salvage yard within a year or two.
These cars are aging, and it's age will be represented in more than just the drivetrain. Suspension, braking, and subframe components, as well as mounts are already beyond their lifetime on the car you are considering the power increase with. When a single component fails, it can transfer more load to another one, cascading the problem throughout the suspension and drivetrain. All of these components will rapidly fail when you add power, shortening whatever short life they have left. Unless your budget supports replacing all these components UP FRONT, you should scratch your plans now, and if you have the budget to consider them, you have the budget to buy a newer car.
The Series 1 motors (yes, this includes the L27 when compared to the newer L36) produce their torque peak at a lower RPM than the Series 2 engines, and put more load on the suspension, subframe bushings, and braking on hard acceleration and stopping, regardless of the Series 2 having higher peak numbers. The key is WHERE (at what RPM) in the power band those peak values are achieved. With the Series 1, it's at a low enough RPM to achieve those peak numbers very soon after launch, which is the most damaging time period for these components, including the transmission, differential, and axles, which I'll cover as a seperate subject in this article. In basic terms, the Series 1 motors apply more torque abuse at a more deadly lower rpm on the rest of the drivetrain on a heavy car (the weight of the car causes damaging resistance to that torque applied by the motor) than the Series 1 motor’s Series 2 counterparts do. For each ONE horsepower you add to the motor, it gains more than 1.5 ft/lbs of torque. Torque is the drivetrain killer, and this 1:1.5 ratio is due to the fact that the motor was designed specifically for torque, not horsepower.
Your fuel pump is very likely either very old, or is an aftermarket lower quality replacement, unless it was already replaced by a quality (OEM) replacement. If you run lean under boost on an L67, you can blow your motor. Replace it with a Walbro 255 before even starting any other go-fast modifications. Your fuel injectors should be pulled at the same time, cleaned and flowmatched, and any of them that fall more than 3-5% out of the range of the others should be replaced with a matching (flow) injector. If one single cylinder goes lean under boost, you could blow that piston. If your fuel pressure doesn’t meet factory specifications after replacing the fuel pump, replace the fuel pressure regulator with an OEM (AC Delco/Bosch) replacement. This should be 3.0bar for 91-93, or 2.7bar for 94/95. Your oxygen sensor should be replaced with an AC Delco replacement at the same time as the other fueling components if it’s any brand other than AC Delco or Denso, or if it’s over 50k miles old, or if you don’t know how old it is. NEVER use Platinum plugs in any boosted (supercharged or turbo) application, and never use Bosch plugs, wires, or O2 sensors at any time on a Buick 3800 motor.
GASKETS AND OTHER CONSUMABLES:
Lower intake manifold gaskets must be changed as a major preventive maintenance item before any modifications. This would include replacing the factory plastic coolant bypass fitting with an aftermarket steel replacement part. This is also a good time to carefully inspect any idler pulleys on the accessory side of the motor. If you lose a belt and the water pump stops spinning, you run a good chance of seizing a motor, particularly due to the short period of time it takes to pump heat into the motor under boost with an L67. Consider replacing your water pump early in the process as a preventive measure, and use ONLY an AC Delco replacement with a cast (not stamped) impeller. It goes without saying that a full cooling system flush should be done at this time. It also goes without saying that you should replace drive belts now, and use only Gates or Good Year Gatorback. The Series 1 L67 has a poor wrap circumference dictated by factory design, and needs one of these two belts in order to prevent belt slip on the supercharger pulley or excessive wear due to slip.
All Series 1 exhaust manifolds (especially the L67 Supercharged) crack with age. Find me an owner that says they’re not cracked, and I’ll show you an owner that either had them repaired already or didn’t look at them close enough with them removed from the car. The cracks are very small and hard to find. This topic is a good example of this problem: viewtopic.php?f=12&t=23880
And a related Techinfo article: http://www.pontiacbonnevilleclub.com/fo ... =44&t=1660
This article details all the ‘motor killers’ you need to address before even thinking about running a smaller pulley on the supercharger, not to mention any other go-fast mods, either bolt on or custom.
The transmission is the most important, most vulnerable, and most expensive part of adding power to the Series 1. It’s also the component that will quickly end your car’s useful life when it fails, unless you like pouring money into a pit. Because of the torque and torque peak rpm issues detailed in the SPECIFICS section in this article, a full performance rebuild will require all hardened internal parts available to your shop, all Sonnax update components, and a full install of a Transgo 4T60E Jr. shift kit, which requires machining of the valve body in the transmission. This process must also include carefully inspecting the differential for wear (they are prone to shearing the pinion shaft lock pin and blowing up, one of my cars has blown 2 already, and is currently trying to blow a custom limited-slip unit), as well as replacing the torque converter with a QUALITY name-brand proven replacement. A cheap or poor quality (or old) torque converter can take out the entire transmission when it pukes it's guts into the fluid.
It sucks to start spending money on intakes, exhaust, and a smaller pulley, then get hit by a $2500 transmission bill. That’s what sends these cars to the wrecker. How do I know? I’ve had to do this on two Series 1 L67’s already. I have now begun the de-modding process on one of them in order to extend its useful life due to its age and further protect the investment I have in both transmissions, which cost me over $2k each.
In basic terms, modding a Series 1 requires a $2500 transmission rebuild (not street rebuild, but performance rebuild including all Sonnax updates, Transgo shift kit, and hardened internal part replacement), typically a new fuel pump, and possibly an FPR, Exhaust manifold crack repair that will cost you a couple hundred bucks unless you own a TIG welder (and ceramic coating to prevent further cracking, plus exhaust manifold gaskets that were not originally factory installed), replacement of all of the motor and transmission mounts simply due to age, and possibly having to replace the subframe bushings as well. This could also go as far (and likely will) as a full brake upgrade (disk, drum, pad, shoe, flex lines, and full flush, possibly calipers and rear brake cylinders, and a master cylinder rebuild or replacement) as well as swaybar bushings. As the car gets quicker, more stress is applied to all of these parts. Struts would also fall under this category. Many of the suspension components are CRITICAL for proper safety and handling, and the quicker the car gets, the more important these components become, and may also include all 4 coil springs, as they sag with age. Another up-front requirement will be a scantool capable of reading KR and other live data, and a Factory Service Manual. You will absolutely need both of these tools as a MUST very early in the process of modding. Supercharger pulleys cannot be swapped until you have a proper scantool. This is taking for granted that you are already running the required octane of fuel (91 minimum) and are prepared to go higher as you decrease pulley size. If your car has run regular (87) octane fuel during its life, you very likely have already suffered long-term engine damage. This starts to become apparent in erosion of the piston ring grooves, and quickly weakens the top groove (even though it’s lower down on the piston to prevent this) and can chip (taking out a valve and spark plug) or simply blow as the damage continues over time. This can be accelerated by too low of an octane or by running lean. It’s a sad fact, but most L67’s out there of this vintage have already suffered the early damage due to the wrong fuel being used.
If you don’t do everything detailed here before modding, the modding process will nickel and dime you to death in a very short period of time. Does all this sound daunting or over-kill? Keep in mind these cars are OLD. It’s years of wear and tear and normal aging of parts (even if the car was stored and not driven) that you have to overcome first or pay for it later. Pumping money and performance into a car nearly 20 years old just isn’t a practical thing any more, especially when that car is a big, heavy, 4-door front wheel drive V6. You can still get plenty of enjoyment by repairing the car and updating preventive items without abusing it, so I suggest you seriously consider going that route rather than speeding up the death of your car by throwing money into performance that will only cascade into more and more of an expense over a very short period of time.
Simply put, modifying a 20-year old car like this is a big old hairy pain in the ass, and you won’t enjoy it nearly as much as if you’d started 5 or 10 years ago on that car. I know this, because I started in 2002 when my car was only 10 years old, then 2 years later on a 2-year newer model. Maintaining the car to hold that power today is a very expensive proposition I deal with on a daily basis. If you have the budget to support everything in this article, you should be selling the older car and buying one newer before you start. In my opinion, you’re modifying the right car at the wrong time. Its useful life may still exist, but its modified potential faded at least 5 years ago.
Without spending the money detailed here before you begin, you will lose your initial purchase price of the car and the cost of any modifications you made to it by the time the transmission or other components fail and the car goes to salvage, because you realized you were at a point when the cost of repairs were greater than the value of the car.
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