2seater

Dumping or limiting boost isn't a bad idea. The GN type cars had programming to operate a wastegate solenoid to reduce boost in upper gears, but that is usually one of the first things to be deleted The centrifugal superchargers work exactly the same as a turbo supercharger (turbo for short), the drive system is simply different, except the belt drive does operate based on engine speed and not exhaust flow. The turbo wastegate operates just as you suggest, except, it cannot dump more boost than the boost pressure working against the spring in the wastegate. It would require some sort of other type of control to do it and the performance would likely be uninspiring. The car would launch well and fall on it's face, so to speak. If you watch the MAF air flow signal while driving, a normal maximum air flow reading will be in the 125-140 gm/sec range, depending on altitude and such, but it is using a fair part of it's range without boost. At full throttle, mine will go beyond the 170 gm/sec limit in only a few seconds from idle speed. In normal driving, and using part throttle, the car drives normally and air flows remain in the readable range. The response to the throttle is simply stronger, and most people don't drive at full throttle anyway, plus it isn't good for the engine or transmission. If you could figure out how to ramp up boost at first and then reduce it to a few psi to stay within limits of the ECM, performance would still be better than stock. The problem is, once the boost starts working, you won't want to reduce it

GM did make both rwd and fwd turbocharged experimental Reatta's. The rwd was a GN style engine (I have no idea how they modified the steering system) but strictly speaking, the GN motor isn't compatible with the fwd setup, at least for the hobbyist, and the engine parts do not interchange, for the most part, with a 3800. It really is a less evolved engine, not that it didn't perform, but the 3800 is superior in the oiling system, head flow and the control system. I probably lucked into the T25 trim compressor when I was fooling with assembling my parts, and works great for a low boost application. The other comments about fooling the ECM about air flow, should work, but it isn't easy. I have been trying to replicate the air flow through the MAF to see what could be done but generating a useful, and readable frequency have proven to be a problem on the flow bench. In the simplest terms, my logic indicates the stock MAF bypass passage needs to be opened up about 30% in area to slow the flow past the sensor to capture my calculated air flow requirement. Work continues.

The O2 sensor reading during the initial warmup may be erratic and the ECM is ignoring it during warmup anyway. It should probably become even more active when hot, it should not settle at a single number. It is designed to constantly cycle around the proper fuel air mixture of 14.7:1, and the more active, the better. It will indicate a fairly wide range of voltage as it continues to go from rich to lean and back again. It is possible for the sensor to cool below it's operating range of 600*F+ after a prolonged idle, and that is pretty much normal. Most manuals recommend the engine speed be increased to something like 1500 rpm or so for 30-60 seconds occasionally while testing to keep the sensor hot. If the O2 sensor is sluggish or reads a single voltage for extended periods it is likely in need of changing. Usually will help the mileage as a side benefit. The O2 should have no effect on starting. The most common cause of slow starting, if it runs normally otherwise, is the fuel pump relay is defective. If you cannot head the fuel pump run for a couple of seconds when you turn the key to "on", the relay is probably bad. Another telltale is if it is hard to start the first time, like overnite, and starts normally after it has been run for a while and then restarted after short time, before the fuel pressure can bleed off. There can be many other causes, but the relay failure is somewhat common.

The TPS is located on the lower front of the throttle body. It operates from the shaft that runs through the throttle body for the throttle blade. Throttle linkage on upper rear and TPS at the other end. It is fastened with two non-magnetic stainless steel screws, be careful you don't drop them.The holes in the TPS itself are actually slots so a small amount of movement is available to adjust the voltage.

It is a question that has been explored on some other sites also. The L27 intake "should" bolt up to the earlier engine (LN3), but there may be a difference in the coolant passage from the later model head to the manifold. There were evolutionary changes as time went on, and the mid '90's engines, the L36 I think, did have some changes to make them less compatible with earlier ones. I believe the basic block and rotating assembly of the LN3 is the same, although the cam is different on the L27. It will interchange with the LN3 cam but the cam chain assembly has a different fastening to the cam so the later model timing set would need to be installed if the cam is changed. The cam that is already in the '88 block should work okay as is. This area is a little murky, and it would be interesting if this works out. Keep us informed if possible.

Since they list the backspacing, (simpler to use than offset IMHO), you should be able to compare that fairly easily to what you have now. The outside diameter of the tire you choose should be as close to the original diameter as possible, so the offset of the wheel and width should be all you need to worry about. As long as the inside edge, with the tire mounted, clears the strut mount, probably the only clearance issue would be a full lock rub in the wheelwell.

The basic engine internals have been investigated before, and there does not appear to be any evidence the crank, rods and pistons are any different, except for some of the s/c engines having full floating piston pins. Differences may exist, but so far no definite evidence has surfaced that this is true, at least on the early 3800's. The transmission is certainly a concern for any amount of boost.

While not common, it is possible the intake manifold is eroded where coolant passage meets the head. Every manifold I have removed showed some signs of galvanic erosion around these passages. The modern silicone o-ring style gaskets do a pretty good sealing but the FSM recommends a sealer in the coolant every time it is changed. Coolant leaks can be a devil to find. Many times they are temperature sensitive and only leak in a narrow temperature range.

My personal experience has been it is better to leave it sit rather than start it once in a while. I do pull the battery, no harm to the electronics that I have found. The battery is washed with baking soda and trickle charged once a month. I have stored it for six months every year since 1993, with no ill effects I can detect. It does get a fresh oil change, tires pumped to their maximum rating, Stabil in fuel, wipers propped off the windshield, leather conditioner on the seats and such. Generally just a good wash and detail before going to sleep. Mine is stored in a storage facility, unheated, but the floor is insulated below the concrete so it doesn't sweat when the weather warms. The storage is fifteen miles away (less $$$) so it is put away with everything hot and dry and the Stabil is circulated. Just a cotton dust cover over the car. Never fails to start immediately in the spring, ready to drive.

The TCC gets it's 12 volt power through a switch on the brake pedal. There is more than one switch on the pedal. If tapping the brake helps engagement, the switch may be out of adjustment or the pedal isn't returning all the way.

Too much EGR flow can cause the BLM to go low also. I believe yours is vacuum operated. If the fuel pressure is slightly high, it will need to lean out a little to compensate. Maybe a slightly leaking injector? The number isn't really that low to start with, it has a much larger range of operation and you aren't close to the limits. If the integrator is bouncing around 128 everything should be fine. The BLM isn't a single value either, it is stored in different cells the ECM reads based on rpm and throttle position, so it will likely be different at different throttle positions and the load the engine is under. It is a constantly moving target, and conditions are rarely ideal. It is a good idea to take a look at the readings once in a while, just as you have, to see if there s a trend and possibly shortstop a problem. If it runs normally and mileage is what you expect, it sounds like normal operation.

There is a electric solenoid in the transaxle that engages the lockup. It is controlled by the ECM to engage and disengage the clutch. Several items need to be correct to allow lockup. It is powered through a switch on the brake pedal and the ECM switches the ground on and off. The engine must be up to a high enough temperature to go to closed loop operation, as correctly pointed out in the other post. That temperature does vary from car to car but is in the 130*-145* range for closed loop operation. The last item is the TPS must be at a high enough voltage to allow lockup. In other words, the throttle must be open a small percentage to allow it to engage. Below a certain percentage of opening, like close to idle posistion, it will disengage. A manual switch can be used to operate the lockup, but it would require a lot of manipulation in normal driving to turn it on and off without either lugging or killing the engine. It can be a useful testing tool, but isn't really practical for normal use. I do not know about the marble rolling sound might be, and the dealership could be correct. One other common cause for a noise at idle, that goes away at higher rpm is the damper on the front (belt end) of the engine. You can use a mirror to look at it or simply run your fingers over the outer face of the damper. The front face is large piece of rubber and it should be smooth. If you can feel cracks or pieces missing, it is likely the source of the noise.

I believe the '87 uses a vacuum operated EGR valve. The diaphragm is semi open on the lower side and it can be moved by hand. I suspect that is what was meant.

There was a guy on another forum that had a similar problem, primarily at low speed and idle, okay at higher rpm. He had recently done work on the car and discovered he had reversed two of the injector connectors, #3 and #5 I believe. His had numbers on them, although I have never checked mine to see if they are all like that? Long shot maybe.

I think the guys name was Slagg or something like that. Incredible that that stuff was about 40 miles away for all of these years and nothing circulated in the hot rod community? Yenko Camaro's @ $7k-$8k when new would be cheap by todays standards, but that was a fairly pricey car 35 years ago. Apparently the "found in a barn stories" can be true, and to an extreme level. The sheer volume of stuff is mind boggling.

I had a Taurus that had a heated windshield. My wife loved it. It did work incredibly well, but was a large current draw. The entire glass area had a metal film between the glass layers, no lines of wires. The alternator and some other wiring was special. It would only run for four minutes at a time, and the output to the windshield was something like 60 volts a/c. I believe cost was the big reason they stopped using them. My insurance guy mentioned something about it when we we talking. He said you had better take care of it as no replacements were available and that was over five years ago. That sorta gold/red color they had did tend to cut down on light transmission, particularly at night. If the other windows were tinted, like mine were, you couldn't see through the windshield from the outside, during the day. I think that intimidated some people. They would slow down for no apparent reason and make me pass them.

Both are rwd cars and I suspect it may be easier to do, but not impossible for fwd. I do agree it does work. I have imagined how it could be done on our cars more than once. A turbocharger is approximately twice as deep as either the cat. or the muffler. Finding a place to tuck it up out of harms way would be a challenge. Just ahead of the fuel tank where the natural 90* turn in the turbine housing would mimic the first 90* in the piping might work? I hope someone gives it a try.

While I don't like censorship per se, there are rules to be followed. Some other forums have a "rants and raves" section, maybe something like that would be appropriate? Feedback is used to good purpose on places like Ebay, and it would seem this is a rather strong example, but similar. The unfortunate problem with segregating feedback like this would be it would be less visible. Too bad there isn't an impartial arbitrator available to present an unbiased evaluation of the situation.

I have seen articles about this setup and apparently it does work. The turbo needs to have a lower A/R ratio (as compared to an engine mounted one)on the turbine side to get it to spin up with the lower heat of the exhaust. There is a small attraction in the greater room available, but there is no free lunch. It needs to have a long oil feed line and a scavenge pump to return it to the crankcase. That alone would make me a little concerned. It also has no good way to get cool clean air into the compressor. The long pipe back to the engine intake would probably have a slight cooling effect but on our car you would need to run another pipe of approximately the same size as the exhaust back into the engine compartment, essentially the same as running a true dual exhaust from the engine out the rear. It would be "fun" to try to get a second pipe around the rear suspension. The location of our fuel tank, while good for protection, weight distribution and such, is really in the way for routing piping. I don't think lag would be a huge problem, probably no worse than a conventional intercooler. According to my flowbench spreadsheet, 331 cfm, a reasonable figure for a boosted engine of our displacement, the air is moving at over 14,000 feet per minute through a 2" i.d. pipe. Of course that is when the turbo is wound up, so there would likely be some lag, but that isn't necessarily a bad thing. It would allow for a relatively slow buildup of boost which would be easier on other parts. Just my .02.

Thanks for the site. I read through a good bit of it but the point was made right up front. I would think the tuning of fuel and timing could be restructured to get the values where they belong for it to run correctly, but it would be a lot of work and is beyond my level of expertise. I understand the theory okay, but not how to correct it without a lot of dyno or scantool work, plus the programming itself. Padgett is probably right that starting with a system matched more closely to start with would do a lot of the initial work for you and make the process faster. Both would require custom programming, and therein lies the rub.

If you can find the website about the bigger MAF theory, I would appreciate it. In the past I did talk with Bob Bailey @ Bailey Engineering, the maker of the MAF Translator. His take on the situation was the limit in the ECM would make that product unusable for my purpose, but a larger MAF wasn't part of that conversation. My original thought was sorta the same, shrink the air flow range to fit within the table size in the ECM. As for a big MAF making idling and very low speed a problem, that is a question. The GN guys have been using the 3" MAF from the LT1, or something like that, to allow more air flow, and have been pretty successful with it. They have also been working on a 4" unit but unstable idle has been a problem, so it is possible to go too big, but this is way bigger than we need.

Regarding the system used for boost, it is really up to personal preference. All systems have pros and cons. In my case, I had some turbo parts already, and fabricating the hookup was a great winter project, actually a couple of winters. Total cost will depend on how much you can do yourself. The factory supercharger is pretty much already engineered, so less total fabrication is needed. The turbo installation requires more fabrication until a reasonable kit comes along, and an aftermarket supercharger will require some ingenuity to make a drive system. The two systems do act differently, as I mentioned previously, but both are going to give good performance. In a street driven application I do believe a turbocharger has more total power potential. The faster it goes, the faster it wants go. Boost makes more exhaust, which makes more boost (within limits). Some of the supercharged guys are gutting their s/c housing and using it as the manifold and plenum for a turbocharger application, (and going faster). The greater torque production, no matter the system, does make blipping through traffic quicker, passing power is greatly increased, and just the basic fun to drive is enhanced. I do avoid the urge to spank as much as possible, there are other weak links to be concerned with. I lean toward the turbo, because I have one, but I have driven a couple of s/c cars (older ones close to our vintage), and they have no real holes in their performance. They probably have a more seamless power delivery, it just acts like a bigger engine. I can't speak for Greg, or Don, but once boosted, I would find it hard to go back.

Greg sums this up very well. I too agree that the base engine is just fine for modification without complicating it by using additional mis-matched parts. Forced induction, whatever type is chosen, will overcome a less efficient system. It even extends the power band beyond where the stock cam goes dead. Yes, greater gains could likely be made with an engine that has more built in performance, but we can build more power with what we have now, probably more than other parts will live with. I use the GN's as an example of what can be done with an even less efficient design. They found the general rule is, you can make more power with less compression and more boost (or NO2). Greg has found the same thing I have: for everyday driving, even without a perfect solution, the car can be made to perform well beyond the original design, and reliably. Only when pushed beyond the programming limits, does the control issue show up, and most people do not constantly push the car to the maximum, no matter if normally aspirated or boosted. Yes, the problem exists, and hopefully together we can find a solution.

Forced induction is probably going to be easier to make emissions friendly than a radical high overlap cammed engine. Forced induction also adds even more torque than hp. Air flow measuring limits will be the same for the ECM, so once you pass a particular point, the issues will likely be the same, although probably more predictable with normal aspiration. It really depends on the ingenuity to get to the goal you are aiming for. Aluminum heads do offer better detonation resistance, so more compression would likely be possible, but aside from weight, they don't improve performance by themselves. Put another way, without other changes, they will likely decrease performance since they transfer heat from the combustion chamber more quickly. I suspect, the cost for a special crank and rods, plus non-existant heads would be more expensive than swapping in a stock s/c engine and work out the control bugs. Just my .02.

No, I don't think the Reatta is bad to start with. The original GM system works pretty well together, or I should say it is well matched. If the car weighed less, say 500# or so, it would be a completely different car. The other alternative is to increase the engine output. The car should really have about 200 hp. as a good base engine option, and maybe 250 hp as the upgrade. In N/A form, 200 hp or maybe a little more is certainly possible. They did it a few years later and the technology isn't much different. The Vin "L" pistons in the vin "C" block picks up a little more than .5 compression ratio, plus a little more cam should do the trick. While apart, a little cleaning up of the ports can be done, as well as standard hot rod stuff like port matching and helping the intake and exhaust. The stock ECM will read the air flows at that power level just fine, so chip tuning "should" be more straightforward. To get a lot more power will require forced induction, unless the engine is a lot more radical which probably wouldn't be emissions or ECM friendly. My original airflow calculations assumed 65% stock engine efficiency, and that should allow the MAF to read air flows equal to 220+ hp. That must be in error, or I wouldn't max the air flow within two seconds of launch.