2seater

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.

Well stated. While the GN community had (and still has) a large performance following, the Reatta was never intended as such, so never generated the hackers to decode the system. The late models cars, particularly the supercharged ones again have a reasonable following, and a fair sized aftermarket. We are pinned right in between the two, and the operating system is out of date. Even for the GN's, there were only a few people that did the majority of the decoding, so one person can make a difference. I would be happy to contribute to some of this work that is beyond my knowledge. Padgett can certainly speak for himself, but I imagine the reality of his real life leaves little time for this project.

I'm with you on that one. Now finding someone with the time and expertise will be the hard part

The BLM is reading pretty low for cruise mode. It looks like it is pulling fuel for some reason. Did you read the integrator at the same time to see if it is bouncing around 128? If the system is somewhat out of balance, it may make it more knock sensitive. The knock retard seems a little high, but it isn't terribly unusual to see a little when the throttle is changed rapidly. It is possible to catch the ECM at a high timing number like used for cruising and then load the engine to where timing should be lower and it may knock momentarily before it can adjust. This will be especially true if the octane isn't what it should be. I know I had a fair amount of knock retard when I took the car to Kansas this past summer and the best gas I could find was 91 octane with ethanol in it as well. The car would hardly tolerate even moderate throttle input witout showing some retard. Of course mine is boosted, but the result is the same on any engine that wants more octane.

An expanded table would be a help, but I do not know enough about the programming to say if it would be a cure. Padgett's point is exactly right, it isn't as simple as it first appears. There are a lot of interelated tables, one modifies another when a lookup point is reached. For example, there is a table for timing modification based on air temperature vs engine load (LV8) When inlet air temperature is high it will roll back timing and actually add timing when cold. The table can be tweaked, and the GN guys used the IAT sensor input with a modified MAP sensor to tell the ECM a substitute for true boost sensing. Sort of a work around to get variable timing based on boost. This sounds sort of encouraging and given the time and expertise, maybe something could be worked out, BUT, if the engine load is maxed out at even a little boost, the table becomes almost irrelevant, since there is only a small portion that can be of use. Essentially, there are a bunch of tables to modify things, but they were designed to work in the expected range. When boost is added, it goes to the top of the table, so there is only one cell that is active. Engine load or LV8 is a key element in the programming, it determines a lot of what portion of a table to read, and in my case, the LV8 goes to maximum, a reading of 255, within a second or two of heavy throttle input. It isn't hopeless, but some bandaids will probably be needed, rather than pure programming, but that is a weak area for me

The GN's did not have boost sensing per se, but, they did have programming designed for boost from the start. Their MAF range went to 255 gm/sec, which by my calculation can measure air flow for over 300 hp. The programming can be used to modify fuel and timing over that entire range, which would be all of what a stock GN could produce. The programming also would start to pull boost at some programmed point, partially based on what gear they were in, of particular interest in a turbo application, where greater engine load actually produces more boost. When the GN pilots modified their engines for more boost, they too would push beyond the limits of the programming and they had to resort to the same sort of dead reckoning we are forced to do, ours will just occur sooner. Initially they used things like a seventh injector to add fuel at some point, alcohol injection systems, bigger injectors, MAF translators, or pushing the fuel pressure higher and of course reprogrammed chips. In this respect the supercharger offers some advantage in that the s/c is coupled directly to the engine where it will be more linear in the air flow capability relative to engine speed. If you load an engine hard at low rpm with a turbocharger, like against the brakes, the turbo will spool up independant of the engine speed. Essentially a turbo is sorta load based and a supercharger is rpm based. Internally, the GN's were somewhat different and similar at the same time. They used rolled fillet crank, similar to ours, but the rods are shorter and the pistons were a cast design with a steel insert. Very heavy by comparison to ours, which look like race pistons in comparison. The oiling system wasn't as good, and the heads are less efficient than ours too. The placement of the intake valves was also different, making the intake manifold have two side by side ports on each side, sorta like a Chebbie small block. If you look at our firing order, this isn't terrible since the two close together ports are not in sequence on each side, but I believe ours is somewhat better with even spacing. I know I digressed but the problems are the same, we just don't have the same broad ECM hacking and experimenting that has been done for the GN's. Even though our ECM has a bigger chip and more capacity, it wasn't designed from the start with boost in mind, so we need to take a best guess and modify from there. The whole system is probably more fragile, but can produce very noticeable gains, and should be used with discretion to make it live. A steady diet of drag racing and high boost would not be a good idea. Even if the engine behavior can be brought under control, the next weak link will be the transaxle. High speeds are not a problem and power for passing and such is relatively safe, where the trans can handle it better. It doesn't take much space for passing slower traffic, and I am sure Greg can attest to that. Oop's, almost forgot Don B.

The supercharger has a captive oil system, no external lube required. It is also a separate part that sits on top of a lower intake manifold, in other words, it is two pieces to get it to fit the engine. The first s/c engines were rated @ 205 hp, then 225 and 240 when Series II came along, as well as a larger s/c which required the injectors to be moved to the heads. The Series II engine is also slightly smaller externally. It has a lower deck height for the block which moves the heads somewhat closer together, so it is probable the upper parts of a Series II won't fit a Series I. I believe there are other differences as well. The Series I stuff "should" fit our engines. I know there has been much discussion of the engine internals and as far as I can find from other sites, the internals are the exact same, the only possible difference being some did use full floating piston pins. The materials are the same, but the part number on the rod and possibly the piston may be different due to the floating pins. The crank is definitely the same. No exotic parts were used, at least none that I can find. When I rebuit mine, I did use hypereutectic pistons, an upgrade over stock cast, but not as strong as forged. Many years ago a guy tested an LN3 engine to destruction to see what sort of power it could hold. He was looking for viable replacement blocks for the older GN style. According to his dyno data it blew the crank out the bottom @ 500 hp. It would seem some headroom is available for moderate upgrades and using the power with discretion. An oil cooler for the engine is a good idea in any case, I run a B&M stacked plate type as welll as one for the trans.

It may be fun to watch, or even do, but not a good idea.

Maybe? Old, rock hard tires would be easy on the transaxle, they will simply go up in smoke No offense meant on the original thread.

Is $500 for the whole package or just the injectors? New injectors in a decent upgrade size will cost about half of that. The whole project will take a while, swapping injectors should take less than an hour.

Good idea to keep them for judging purposes if that is your goal. If not, the stock tires are way behind the newer technology available. Even carefully stored tires gradually deteriorate just from atmospheric effects. The good thing is most of us don't stress them close to their design limits so they last longer in careful use than they should. Tire manufacturers are of course trying to sell tires, and minimize their liability, but 15 year old tires are well beyond their recommended lifespan.

The stock transaxle will last for a while if you do little drag racing. So far I have 25k miles on mine turbiocharged, 121k total, and still works well. The stock injectors can take you to maybe 200 hp or so, no matter what you do with the programming. For anything more, you will need more fuel through larger injectors, although they should come with the top end of the donor engine. GMTuners can help with getting the larger injectors to run well using the stock ECM.

I've done it two ways. One is with a die grinder and a long carbide burr. The other is with a good hole saw that just fits inside the opening (and lots of coolant). It doesn't hurt to take out the part of the O2 bung that hangs inside the hole as long as a couple of threads are left for the sensor to screw into. In both cases the manifold was off of the car.

RPM stay around 1500 in neutral coasting at 50 mph or so. Read the counts for the IAC and it will be elevated. I am not certain why it does this, possibly to keep the engine close to the rpm it would be in for the speed and gear for smooth transition when shifted back into gear? I don't believe it turns the injectors on an off like it does coasting down in gear.