I'm planning on a basic mild boost (8 psi) non-intercooled turbo project for my 2.8 L.
92 octane pump gas.
In summer it doesn't get hotter than 32 Celsius or 90 Fahrenheit.

I'm not looking to produce maximum power, I would be happy with a somewhat safe and retarded tune.
Any sort of guidelines as to what kind of timing can I be running at WOT?

Start at 12 and go up from there. My guess is you won't get much over 15 without intercooling. I'd start at 12 and then go up from there. Do you have a knock sensor?

I could tell you to start at 15 and up but you need to be careful. If you see sparkles coming out of of the exhaust, you need to back off.

An exhaust temp gauge would be helpful too.

Boosted cars run lower compression. Theres no need to run 92 high octane gas. I ran 87 regular in my 3.1 turbo engine for 7 years. I even retarded the timing a degree or two. High octane gas is for high compression engines to stop spark knock.

I don't have a knock sensor - hence why the timing needs to be conservative enough such that a hot day will not spell the demise of my 2.8.

As much as it may be possible to run 87 octane on retarded timing, I'd prefer the extra safety margin that 92 octane provides, especially considering my lack of experience as a tuner.

When you suggest 12* - 15* advance, is that the total advance? I'm surprised, considering stock timing is 32* BTDC, that's 2.5 deg/psi of retard! (just seems like a lot)

quote Boosted cars run lower compression.

When you force air in you raise the compression in the cylinder. I think it would be crazy to run shitty gas in a non intercooled turbo setup. You will see nice gains being able to increase the timing with higher octane gas for only 20 cents more a gallon.

------------------
Turbo 3800 E85 5spd spec3
11.74@123@16:1afr :-o

Rogergarrisons information is blatently wrong, you will need the highest octane pump gas you can get ahold of as boost will raise the effective compression ratio generally much higher.

That said you will want to run it more or less as far advanced as you can without getting any knock, a knock sensor is a huge help as is quality tuning equipment. I dont generally go that far because I like to keep some safety room myself. I dont recommend any tuning by specific numbers or by ear when it comes to boost do it right the first time and enjoy the longevity of the entire system. Every system will be different and run different air intake temps then the next so no one can really give you a number to go by.

Most boosted engines Ive seen had about 8- 8.5 to 1 compression. Cars needing 92 octane are high compression.... as much as 13 to 1. Mine ran fine with over 275 hp and well over 150 mph and never had a problem. The guy who bought the engine when I sold the car still uses it in his race car. How many boosted cars do you have ? Most street cars run about 8-12* advance at idle and mid 30s at operating speeds. Maybe you might need 92 octane if you ran 20* advance at idle, but youd blow the engine up before you run out the first tank of gas. Octane rating has nothing at all to do with power...its just the higher ratings give it more resistance to knocking/pinging.....nothing else. Has nothing to do with the price or quality of the fuel. Higher pump price is just because of the additives to resist that knocking. Another words, if you car only NEEDS 87 octane your dumb to spend the extra on 92 octane thinking its making your car faster. Thats ricer thinking. ie/ " I just put a can of #104 Booster in my tank and my cars got 100 more hp.........."

[This message has been edited by rogergarrison (edited 02-14-2010).]

quote Originally posted by rogergarrison: Most boosted engines Ive seen had about 8- 8.5 to 1 compression. Cars needing 92 octane are high compression.... as much as 13 to 1. Mine ran fine with over 275 hp and well over 150 mph and never had a problem. The guy who bought the engine when I sold the car still uses it in his race car. How many boosted cars do you have ? Most street cars run about 8-12* advance at idle and mid 30s at operating speeds. Maybe you might need 92 octane if you ran 20* advance at idle, but youd blow the engine up before you run out the first tank of gas. Octane rating has nothing at all to do with power...its just the higher ratings give it more resistance to knocking/pinging.....nothing else. Has nothing to do with the price or quality of the fuel. Higher pump price is just because of the additives to resist that knocking. Another words, if you car only NEEDS 87 octane your dumb to spend the extra on 92 octane thinking its making your car faster. Thats ricer thinking. ie/ " I just put a can of #104 Booster in my tank and my cars got 100 more hp.........."

are you telling me you ran 30* of timing at wot with 87ocatane???????? that engine must be worth its weight in gold

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Turbo 3800 E85 5spd spec3
11.74@123@16:1afr :-o

As much as I would love to have an LS-series V8, and optimize the spark advance and mixture for each cell on a steady-state dyno, it's just not going to happen on my budget.

Realistically though, I can afford $10 to spend a day at the local dragstrip's test-and-tune.

Would it be a good idea to spend a day at the local dragstrip's "test-and-tune", and then finding the advance that gives me the best trap speed, and retarding a couple degrees for safety?

I'm also thinking that I don't have to roast my clutch for tuning purposes, and that street starts (as opposed to my typical 4000 RPM clutch drops) will suffice...

quote I just put a can of #104 Booster in my tank and my cars got 100 more hp...

I guess someone forgot to tell my turbo car that octane doesnt mean anything.... I only made an extra ~80HP or so after adding in NOS brand octane booster a few times over the last summer...

Oh, and someone forgot to tell my motor to blow up, because I run 45 degrees of timing at cruise, and 30 at idle... and about 20 at wot.

I agree that forced inducted engines run a lower compression ratio, BUT, I own two Grand Nationals and right on the dash inside the cluster under the fuel gauge, it has from the factory, high test fuel only. Run the good stuff, even in your regular cars. You will find that you actually do get a little better performance and better fuel economy with the higher grade fuel.

I'm going to be tuning for 92 octane, end of story.

I'm sure I could benefit from higher-octane fuel, but 92 is the highest octane fuel readily available in my area.

Back on topic, are there any other suggested timing guidelines for a 2.8 under boost, or tuning (is the dragstrip trap speed experimentation a good idea) suggestions?

For the safest and best tune you really need a knock sensor and a wideband o2 sensor.

------------------
Turbo 3800 E85 5spd spec3
11.74@123@16:1afr :-o

I have a wideband, so fuelling is completely not an issue... Just timing.

Although I may look into making "detonation cans", a glorified stethoscope that bolts onto the engine block to hear detonation better. The ECU I am using does not have knock sensing capability.

I also have the plugs to look at, and I have small arms, so I don't find removing the front bank a problem at all...

[This message has been edited by pmbrunelle (edited 02-15-2010).]

quote Originally posted by pmbrunelle: I'm going to be tuning for 92 octane, end of story. I'm sure I could benefit from higher-octane fuel, but 92 is the highest octane fuel readily available in my area. Back on topic, are there any other suggested timing guidelines for a 2.8 under boost, or tuning (is the dragstrip trap speed experimentation a good idea) suggestions?

IMO, the best way to set peak timing on a turbo car is to factor 2 things, compressor potential, and octane.

If you have a large turbo, more specifically a large compressor, then typically your air temps are going to be lower vs how much boost you run. You can also factor your intercooler in here, but typical intercoolers are making the same efficiency as most any other ones. Anyway, the fact that you have airflow available, your dynamic compression is able to go a bit higher at little cost for compressor efficiency, and in turn you can turn down your timing quite a bit, and still make more power on the higher boost setting.

If you have a fairly small compressor, then you would most likely benefit from running lower boost, with higher timing, as you can make up for the "parasitic trade off" of running more boost at lower efficiencies.

Now, the octane part is more of a "limiter" of max timing no matter what boost you run, and I look at it as more of a science than an the balancing act that is tuning timing vs boost pressure. After you tune a specific platform for awhile you begin to notice what the peak timing per type of gas is, and you sorta try to set it at that... Some guesses of WOT timing I would have would be like this (assuming stock 2.8 compression and a decent sized turbo)... The rest of your timing can be increased over stock without issue, as you can easily take advantage of the 92 octane at cruise for extra MPG's, by running up to 15 degrees extra timing across the cruise cells, and up to 4-5 degrees extra at idle.

92 octane = 6-8 to degrees less than a N/A tune.

104 unleaded = 2-5 degrees less than n/a.

110+ = slightly leaner AFR and stock timing.

I dont claim to be an engine expert, thats why I do body and paint work and generally farm out the engine stuff. So your telling me your running 35* timing initial advance....I didnt even know an engine would start or run with that. I know our 400 hp Nascar stock car I drove didnt use half that, or the supermodified I started with. The fact is my specific car, was that the race shop that built my engine for me told me to run regular gas, that there was no benefit to using premium. It ran like that perfectly fine for 100,000 miles and I ran the pizz out of it. Ill guess I didnt put premium gas in it 10 times I owned it. Your surprised my engine lasted the same as Im amazed that 45* advance didnt turn your pistons to molten steel. I know enough to take apart and put together carbed old school engines so Im not totally in the dark. If I remember, I think my 3.1 ran at about 7* advance and 32* fully advanced. I used DS1s turbo system and with it being a daily driver for years, normally ran it around 5 pnds boost with a 160* thermostat. Like I said it ran perfectly for 7 years like that and a lot of road trips where I ran 100+mph for hours. I dont think I even put in more than 2 or 3 sets of plugs in it the whole time.

Im not saying any of you are 'blatently' wrong, just combiniation of what I was always told, what I know and my own experience with my car. Im building a 413 for my Mopar now and its being built to run regular gas too with a single 4 bbl.

[This message has been edited by rogergarrison (edited 02-15-2010).]

quote Originally posted by pmbrunelle: I'm planning on a basic mild boost (8 psi) non-intercooled turbo project for my 2.8 L. 92 octane pump gas. In summer it doesn't get hotter than 32 Celsius or 90 Fahrenheit. I'm not looking to produce maximum power, I would be happy with a somewhat safe and retarded tune. Any sort of guidelines as to what kind of timing can I be running at WOT?

I didn't see where you indicated what type of code you are planning to use, modified stock naturally aspirated programming, or boosted code from another production vehicle. The latter is better as it allows a progressive timing retard as boost increases.

Running premium fuel adds a good bit of safety but with a cost not just at the pump. Advancing timing is not exactly the same as having a higher static compression ratio. As a result, running premium will likely hurt off boost performance due to its slower burn rate and you may not be able to recover it just by advancing the timing in those areas. My experience with a tank full of premium in a non boosted nearly new MPFI 2.8L was an immediate noticeable reduction in performance and much higher than normal engine temperatures plus the smell increased emissions. I was warned in advance by my Uncle that premium was too rich for the car. I didn't understand what he was talking about which meant to me he didn't know what he was talking about. I still remember the I told you so. It also went through the engine as if there was a hole in the tank. Amoco was sited by the government years ago for running adds stating premium fuel would provide better performance when if you didn't have sufficient compression to take advantage of it, it would do just the opposite.

You can cheat yourself out of performance by jumping to premium fuel before finding out what the standard fuel boost threshold is, if the engine is safe on 3-4 psi on 87 octane then midgrade with a small timing adjustment maybe all you need. I ran all of my turbo engines on 87 octane and reduced wideopen throttle timing.

Your choice of turbo as dark suggested will have an effect on this also, whenever you bring up the subject of boost, the lower compression rule always follows and that's a remnant of the early years of production turbocharging, to my knowledge all boosted domestic production cars have at least a 9:1 compression ratio if not slightly higher. Your engine specs and goals alone should determine the compression ratio and fuel that you use. If you're really serious about being safe, add a knock sensor and airfuel ratio meter. Premium fuel alone is not going to protect you from destroying a motor if you don't know what you're doing or what's going on inside it.

I'm confident you will get better results with water meth injection and low grade fuel than just switching to premium fuel. You should also research for recent info on the subject for better planning in addition to what you get here as you see most of us have different views and experiences with the subject. Start with low boost and work your way up making the necessary changes along the way. Good luck.

Thank you....................

I get better mileage with more timing and higher octane, with 8.5:1 compression... Highway mileage after you tune for the high octane is just as good as a high compression car.

quote Originally posted by darkhorizon: I get better mileage with more timing and higher octane, with 8.5:1 compression... Highway mileage after you tune for the high octane is just as good as a high compression car.

Yes up to a point. If you don't have sufficiently high enough compression to burn premium fuel properly the most you can advance timing to compensate before it is ineffective is upto where combustion occurs at TDC, any more and you will periodically be attempting to push the piston down before it reaches the top of the compression stroke. If that degree of advance is still not sufficient to make the best use of the premium grade fuel in your engine the only thing left to do is increase compression or go to a lower grade fuel. On the high compression engine the limit is the fuels ability to prevent detonation, or running out of combustion space to increase compression any further.

Performance tuning has proven on many occasions that some stock cars come from the factory with more potential than what was programmed into them on the fuel that they were rated for.

I would expect more people to be running premium fuel with timing advance if it were that simple or productive, particularly the manufacturer on a car rated for low grade fuel, if it were that simple it would prove too much of an efficiency and fuel economy potential to ignore. If the engine is already at its limit for maximum timing advance or close to it, switching to premium fuel is not going to improve on that situation much and perhaps that's why few are putting forth the effort to do it. I have about 100 chevy HP mags and I just don't recall any articles promoting much benefit upgrading to premium fuel and advancing timing on a low compression engine. I'd be willing to try it though.

[This message has been edited by Joseph Upson (edited 02-15-2010).]

While I can't tell you what exact timing to use I'll try to give you some quidance.
1) Before you get your turbo installed, think about a fuel enrichment strategy FIRST. Turbo horsepower usually uses a little more (sometimes a lot more)fuel than N/A horsepower. How about a rising rate fuel regulator, supplemental injectors, etc?
You CAN'T cover for a ping caused by a lean mixture with spark timing. At least not for long............ Say bye bye headgasket and turbine section of turbo!
2)Think about retarding the spark timing 1/2 to 1 degree from stock for every pound of boost. Consider an MSD boostmaster module with your new MSD ignition that you will now buy.
3) See if Design 1 (if they're still around) , will sell you the chip for the computer so you can worry less about points 1) and 2). A neater, more integrated solution.
4) Read the book "MAXIMUM BOOST" by Corky Bell.
5) Always use the highest octane gas you that's available in your area. So you can run the most spark advance and the best mileage. Don't count on octane boosters.
6) See point 4!
------
This is from my amateur experience with a 1966 Corvair with a big Rajay turbo, a 1988 Fiero2.8 with a Design 1 kit, a modded 1989 Lotus 4 pot with a 18 pound boost hybrid T4 turbo and a 2003 Lotus V8 TT (almost stock-- phew!).

quote Originally posted by Black Lotus: 4) Read the book "MAXIMUM BOOST" by Corky Bell.

This book is must for anyone intrested in forced induction. Especially if you wanna build your own system.

Nick

quote Originally posted by darkhorizon: IMO, the best way to set peak timing on a turbo car is to factor 2 things, compressor potential, and octane. If you have a large turbo, more specifically a large compressor, then typically your air temps are going to be lower vs how much boost you run. You can also factor your intercooler in here, but typical intercoolers are making the same efficiency as most any other ones. Anyway, the fact that you have airflow available, your dynamic compression is able to go a bit higher at little cost for compressor efficiency, and in turn you can turn down your timing quite a bit, and still make more power on the higher boost setting. If you have a fairly small compressor, then you would most likely benefit from running lower boost, with higher timing, as you can make up for the "parasitic trade off" of running more boost at lower efficiencies. Now, the octane part is more of a "limiter" of max timing no matter what boost you run, and I look at it as more of a science than an the balancing act that is tuning timing vs boost pressure. After you tune a specific platform for awhile you begin to notice what the peak timing per type of gas is, and you sorta try to set it at that... Some guesses of WOT timing I would have would be like this (assuming stock 2.8 compression and a decent sized turbo)... The rest of your timing can be increased over stock without issue, as you can easily take advantage of the 92 octane at cruise for extra MPG's, by running up to 15 degrees extra timing across the cruise cells, and up to 4-5 degrees extra at idle. 92 octane = 6-8 to degrees less than a N/A tune. 104 unleaded = 2-5 degrees less than n/a. 110+ = slightly leaner AFR and stock timing.

I actually have a rather large compressor. To be honest, I'm crossing my fingers hoping that it won't cross the surge line, although this turbo will give me room to grow when I want to increase the displacement to 3.4 L, and port the heads (or possibly aluminum heads) and otherwise increase airflow.

But anyway, thanks for the guidelines; I guess I'll just have to see through experimentation! I have no other experience with iron head 60*V6s, so I don't have a baseline to compare this engine with.

quote Originally posted by Joseph Upson: I didn't see where you indicated what type of code you are planning to use, modified stock naturally aspirated programming, or boosted code from another production vehicle. The latter is better as it allows a progressive timing retard as boost increases. Running premium fuel adds a good bit of safety but with a cost not just at the pump. Advancing timing is not exactly the same as having a higher static compression ratio. As a result, running premium will likely hurt off boost performance due to its slower burn rate and you may not be able to recover it just by advancing the timing in those areas. My experience with a tank full of premium in a non boosted nearly new MPFI 2.8L was an immediate noticeable reduction in performance and much higher than normal engine temperatures plus the smell increased emissions. I was warned in advance by my Uncle that premium was too rich for the car. I didn't understand what he was talking about which meant to me he didn't know what he was talking about. I still remember the I told you so. It also went through the engine as if there was a hole in the tank. Amoco was sited by the government years ago for running adds stating premium fuel would provide better performance when if you didn't have sufficient compression to take advantage of it, it would do just the opposite. You can cheat yourself out of performance by jumping to premium fuel before finding out what the standard fuel boost threshold is, if the engine is safe on 3-4 psi on 87 octane then midgrade with a small timing adjustment maybe all you need. I ran all of my turbo engines on 87 octane and reduced wideopen throttle timing. Your choice of turbo as dark suggested will have an effect on this also, whenever you bring up the subject of boost, the lower compression rule always follows and that's a remnant of the early years of production turbocharging, to my knowledge all boosted domestic production cars have at least a 9:1 compression ratio if not slightly higher. Your engine specs and goals alone should determine the compression ratio and fuel that you use. If you're really serious about being safe, add a knock sensor and airfuel ratio meter. Premium fuel alone is not going to protect you from destroying a motor if you don't know what you're doing or what's going on inside it. I'm confident you will get better results with water meth injection and low grade fuel than just switching to premium fuel. You should also research for recent info on the subject for better planning in addition to what you get here as you see most of us have different views and experiences with the subject. Start with low boost and work your way up making the necessary changes along the way. Good luck.

I am running a MegaSquirt 2, an aftermarket standalone ECU. Its maps (ignition and fuel) are completely user-adjustable. I am planning on keeping stock-style timing maps (possibly advanced for 92 octane) in the 0-1 bar region, and then above 1 bar, progressively retarding timing until full retard at full boost.

I have read that some blends of premium have less energy density than regular fuel. That said, I would prefer lousy off-boost performance than burning a hole in a piston. This will be the first time I ever tune a boosted engine. I'm not taking a chance.

I'm planning on water/alcohol injection eventually (to permit more boost/timing), in addition to the 92 octane. Now I just want to get the car running without it.

I have a wideband oxygen sensor, and I'm comfortable with tuning the fuel map to maintain safe mixtures. I started from a table full of zeroes, and ended up with a decent fueling table, so I'm fine for that.

Timing on the other hand, and detecting knock early is more of a mystery to me... I want to keep a conservative timing table, so that I won't have to worry about detonation on a hot day for example.

I'll most likely use a stethoscope (aka detonation cans) as my knock detection method. The human ear is good at distinguishing detonation from other sounds, while a knock sensor module, not so much from what I have read, especially as RPM, and thus noise, increases. http://www.youtube.com/watch?v=GGJZ6kKzLus&NR=1

I was wrong, the later versions of MS (MS progresses quickly!) do feature timing retard based on feedback from GM knock sensor modules (my version included). I assume that a knock sensor + module combo from a 3.4 Camaro would work if this is the case? Do you know if the Fiero 2.8 L block has a mounting provision for a knock sensor? This is something I may consider at a later date, as a safety net for extreme circumstances.

quote Originally posted by Black Lotus: While I can't tell you what exact timing to use I'll try to give you some quidance. 1) Before you get your turbo installed, think about a fuel enrichment strategy FIRST. Turbo horsepower usually uses a little more (sometimes a lot more)fuel than N/A horsepower. How about a rising rate fuel regulator, supplemental injectors, etc? You CAN'T cover for a ping caused by a lean mixture with spark timing. At least not for long............ Say bye bye headgasket and turbine section of turbo! 2)Think about retarding the spark timing 1/2 to 1 degree from stock for every pound of boost. Consider an MSD boostmaster module with your new MSD ignition that you will now buy. 3) See if Design 1 (if they're still around) , will sell you the chip for the computer so you can worry less about points 1) and 2). A neater, more integrated solution. 4) Read the book "MAXIMUM BOOST" by Corky Bell. 5) Always use the highest octane gas you that's available in your area. So you can run the most spark advance and the best mileage. Don't count on octane boosters. 6) See point 4! ------ This is from my amateur experience with a 1966 Corvair with a big Rajay turbo, a 1988 Fiero2.8 with a Design 1 kit, a modded 1989 Lotus 4 pot with a 18 pound boost hybrid T4 turbo and a 2003 Lotus V8 TT (almost stock-- phew!).

I am running a MegaSquirt 2, with a 2.5 bar MAP sensor. I have 30 lb/hr injectors running at stock fuel pressure, so I should have easily ~240 hp ?? worth of fuel depending on my mixture and safe duty cycles...

I have the MS and 30 lb/hr injectors running on my stock N/A 2.8 L now, so I'm familiar with programming MS, so that when I tune it with the turbo, I'm less likely to make mistakes.

I was just planning on running colder plugs, gapped smaller, with an otherwise stock HEI ignition.

Does the MSD ignition offer any benefits that are non-timing related (I have timing control covered with the ECU), such as a stronger spark?

If the stock system is adequate though, I'd like to keep it that way. This is a budget build, and I like to keep the stock look, to an extent.

I still haven't read the proverbial "Maximum Boost" book. I think I'll enjoy it if/when I get around to going to a bookstore.

I accidently ran 87 on my boosted 2.8 and it detontated like crazy eventually leading to a rebuild because of a cracked piston. You absolutely can not run low octance, 87, on a boosted 2.8.

I can even see running 12psi of boost on 87, and I believe anything above 10psi needs to be intercooled unless you are monitoring that engine very closely.

Just my two cents.

I guess thats why my 3.1 (same as a 2.8) ran great for 7 years, 100K and has put in about 8 more years running SCCA races without a rebuild. Like I said, mine rarely got better than 87-89 octane. I did usually run a tank of premium just for the hell of it every spring before cruising season started....mostly because it has better cleaning agents in it to keep the fuel system cleaned out.

quote Originally posted by RotrexFiero: I accidently ran 87 on my boosted 2.8 and it detontated like crazy eventually leading to a rebuild because of a cracked piston. You absolutely can not run low octance, 87, on a boosted 2.8. I can even see running 12psi of boost on 87, and I believe anything above 10psi needs to be intercooled unless you are monitoring that engine very closely. Just my two cents.

Change your "you" to "I". You couldn't do it, but all of my boosted Fieros ran well on 87 octane (7-8 psi) and modified 1 Bar MAP Fiero code. The exception is the 3900 and it has 9.8:1 compression and 7-8psi on mid grade fuel as a precaution with Turbo Grand Prix code and produced no detonation before the intercooler was installed running 212 degree inlet temps which means I can run 87 with the intercooler installed. The heads make a big difference in this case but the scenario is still similar in that many would have said "you can't do that" if I had proposed the idea in advance. It still has more room for boost without the intercooler as evidenced by lean spots that did not cause detonation under boost.

The tune has a lot to do with it and your engine is unique to everyone elses. 87 octane plus boost has been done successfully repeatedly, just not on your engine. Again I don't recommend it, just saying it has been done and that you should tune for octane in addition to erroring on the safe side. If I don't need it I'm not going to run it. It's perfectly okay if others do and not necessarily a bad thing depending on the circumstance is all I'm trying to point out.

quote Originally posted by pmbrunelle: I don't have a knock sensor - hence why the timing needs to be conservative enough such that a hot day will not spell the demise of my 2.8. As much as it may be possible to run 87 octane on retarded timing, I'd prefer the extra safety margin that 92 octane provides, especially considering my lack of experience as a tuner. When you suggest 12* - 15* advance, is that the total advance? I'm surprised, considering stock timing is 32* BTDC, that's 2.5 deg/psi of retard! (just seems like a lot)

Well, feel free to start really high and go down if you want, but personally I would start with at least 91 octane gas and 12 degrees in the spark tables under boost conditions. I also wouldn't do this without ESC (knock management) but that's just me (sarcasm intended). If I wasn't getting any knock then I would increase it in two degree steps until the knock comes up. Then you can decide if you want to go up or down on the boost or timing or add intercooling, water/meth injection/mortgage the house, etc.

I prefer to not wipe out a piston, exhaust valve or head gasket to find out I had too much timing for the given boost and IAT. Given your information, I would start VERY conservative and work your way up. The more you can measure the better you can tune. Exhaust temps are worth measuring too but it is an additional cost and you have to install the probe.

But please, don't toss in some huge numbers and then see what happens. Under boost, knock does damage far faster than you can let off the pedal. If you don't have ESC, you have to sneek up on it and just listening is for it isn't reliable. At least get a scanner to watch the O2 although the stock Fiero data rate is so slow the damage could be long done before the scanner showed that you bottomed out the O2. If in doubt, keep it rich (over .9V).

My recommendations are from tuning my 86 TR and 87 GN and some of the SC engines (mostly S1). It's not wise to guess and then see what happens.

There is tons of great information in this thread but if you want NUMBERS to start with, start at 12 and see if you get knock (I doubt you will). 1-2 degrees is about all I will tolerate but you are suggesting boost levels far lower than we used on the 3.8L turbo engines so you have "some" room. It was always a effort to balance boost vs advance given a specific intake air temp. Why start at 12? So you can't blame me for the damage.

I have never tuned a stock Fiero engine with boost using it's 8.9:1 pistons - that's not that high but high enough I would pay attention. TR/GNs were at 8.0:1 but they are all iron head engines. You can get away with more on aluminum head engines.

I can send you the turbo 2.8L binaries I have (as can several people on this thread) so you can compare but I don't know the source of all of them. I believe the 85 bin is from the Miller-Woods system that had the ESC enabled and was in control of the boost control solenoid.

[This message has been edited by TK (edited 02-16-2010).]