what's the secret
05-30-2017, 09:51 PM
#61
TECH Enthusiast
Cold plugs gapped to .020
moderate compression....9.5:1
Cams timed to reduce dynamic compression.
10:1- 11.3:1 air fuel ratio...slows flame travel speed
itgntion timing set by a loaded dyno.
If you go with a higher compression ratio, you will get big power with racing gas.
The fatter the AFR gets from 11.5:1 the safer it is, but the more power you lose.
moderate compression....9.5:1
Cams timed to reduce dynamic compression.
10:1- 11.3:1 air fuel ratio...slows flame travel speed
itgntion timing set by a loaded dyno.
If you go with a higher compression ratio, you will get big power with racing gas.
The fatter the AFR gets from 11.5:1 the safer it is, but the more power you lose.
05-31-2017, 06:44 AM
#62
Cold plugs gapped to .020
moderate compression....9.5:1
Cams timed to reduce dynamic compression.
10:1- 11.3:1 air fuel ratio...slows flame travel speed
itgntion timing set by a loaded dyno.
If you go with a higher compression ratio, you will get big power with racing gas.
The fatter the AFR gets from 11.5:1 the safer it is, but the more power you lose.
moderate compression....9.5:1
Cams timed to reduce dynamic compression.
10:1- 11.3:1 air fuel ratio...slows flame travel speed
itgntion timing set by a loaded dyno.
If you go with a higher compression ratio, you will get big power with racing gas.
The fatter the AFR gets from 11.5:1 the safer it is, but the more power you lose.
05-31-2017, 07:35 AM
#63
The 9/10ths solution is plenty for anyone not seeking to be an internet hero. Everyone likes to feel validated for their achievements, sure - sometimes the greatest validation is always being out in your car, not in the garage fixing it.
To OP's question: Manage your IATs, AFR, and timing wisely - especially at MBT. You must creep up on the number that works best for your combo, not just assume that pulling a tune from the internetz and letting it eat is going to be enough out of the gate. There is no one size fits all solution. DA also has an impact that is a variable that you cannot plan for (hence 9/10ths leave some room for error).
I would also add that reducing the load on the engine (weight of the car, reciprocating mass, etc) is going to ease the strain when pushing the limits of pump gas.
05-31-2017, 09:57 AM
#64
Funny how many top "tooners" only write FI tunes in SD - I believe that just goes to prove just how incapable they are. I am running the same LS7 MAF/4" tube/Saxon PC screen in a blow-through configuration in our Procharged stock long block LS2 TBSS. I am pretty certain most everyone has an opinion on how "wrong" that was. Oh well, it went 11s at 5200+lbs....
05-31-2017, 10:49 AM
#65
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Speaking from only my limited experience, the reason I choose to run everything SD is that when I started on DSM's the MAF was a serious problem and we went SD just as soon as we could with software. Got used to doing it then and have continued that way without issues.
One thing I noticed the other day is that my 2016 VW GTI that I drive daily has no MAF from the factory. Is this a trend for the OEM's or just more VW strangeness?
One thing I noticed the other day is that my 2016 VW GTI that I drive daily has no MAF from the factory. Is this a trend for the OEM's or just more VW strangeness?
05-31-2017, 11:08 AM
#66
There is nothing wrong with SD only tunes - I am running CLSD on our wagon; the only reason being I cannot "afford" the restriction of a MAF in NA application. Also, the SD conversion was a by-product of an unknown cracked/crumbled PCV line behind the intake when the donor engine was still in the Camaro which caused a nasty lean condition when it went into CL on the blended side (MAF/VE). The more you know...
So yes, a good state of tune with a leak-free engine is also paramount to getting the most out of it.
So yes, a good state of tune with a leak-free engine is also paramount to getting the most out of it.
05-31-2017, 11:20 AM
#67
I don't typically post my stuff cause you get idiots like Hio and Rotary who just bash what I consider true street cars.....i.e. full weight, AC, stock like daily driver manners, and require no maintenance except spark plugs and oil changes. But because they don't run 8's they're garbage. My current toy in sig, 2000 SS has a D1SC, 230 cam, 3600 stall, 295/50/16 drag radials, and my wife goes shopping in it with AC, but will tear your face off when you put your foot down.
Many have already made general statements about timing, which is very important. But I am also a strong believer in having a MAF on the car. When I turned my Turbo TA up to 900hp that was 93 octane, 15 psi, 12 degrees of timing, and I was using an ls7 cartridge maf in a 4 inch tube with a Saxon airscreen. The entire tune was scaled 50% so as not to max the airflow hard coded limit in the stock 98 computer....or any stock computer for that matter.
Something else I do is look at others Dyno graphs based on the cam they have so you can see where peak torque occurs and make sure to drop timing in those areas. The majority of my timing tables never exceed 14 degrees total, even at high rpm. Am I sacrificing some power, yep; but since straight 93 octane can vary and so can weather conditions, I err on the side of caution and haven't blown a motor yet. I also am a big fan of pulling IAT based timing. I start pulling at 113*. Any power lost from a few degrees of timing can be made up with more boost if you really want.
Frcefed has some good info on plug reading which is another biggie for me. I ALWAYS use BR7EF on anything boosted. Running 1 step colder of a plug can be huge when keeping detonation away and sacrifices very little if any over the standard TR6 everyone throws in their cars. Keeping the spark plug from being a glow plug is important Also while I agree that you really need to read clean plugs at the end of a pass with no idle the on them, checking your plugs regularly tells you in general if your spark is too much, since it burns off the outer layer on the ground strap. If you have too much timing you'll see that even after 1000 miles of daily driving with short pulls. It's also a good indication of any specs on the porcelain which is a bad sign.
In general I'm more methodical and conservative than most. Someone may make another 50-75hp over me, but my stuff runs in FL Summers and doesn't blow up.
Many have already made general statements about timing, which is very important. But I am also a strong believer in having a MAF on the car. When I turned my Turbo TA up to 900hp that was 93 octane, 15 psi, 12 degrees of timing, and I was using an ls7 cartridge maf in a 4 inch tube with a Saxon airscreen. The entire tune was scaled 50% so as not to max the airflow hard coded limit in the stock 98 computer....or any stock computer for that matter.
Something else I do is look at others Dyno graphs based on the cam they have so you can see where peak torque occurs and make sure to drop timing in those areas. The majority of my timing tables never exceed 14 degrees total, even at high rpm. Am I sacrificing some power, yep; but since straight 93 octane can vary and so can weather conditions, I err on the side of caution and haven't blown a motor yet. I also am a big fan of pulling IAT based timing. I start pulling at 113*. Any power lost from a few degrees of timing can be made up with more boost if you really want.
Frcefed has some good info on plug reading which is another biggie for me. I ALWAYS use BR7EF on anything boosted. Running 1 step colder of a plug can be huge when keeping detonation away and sacrifices very little if any over the standard TR6 everyone throws in their cars. Keeping the spark plug from being a glow plug is important
Also while I agree that you really need to read clean plugs at the end of a pass with no idle the on them, checking your plugs regularly tells you in general if your spark is too much, since it burns off the outer layer on the ground strap. If you have too much timing you'll see that even after 1000 miles of daily driving with short pulls. It's also a good indication of any specs on the porcelain which is a bad sign. In general I'm more methodical and conservative than most. Someone may make another 50-75hp over me, but my stuff runs in FL Summers and doesn't blow up.
BTW - I want my car to rip my face off one day, LOL.
05-31-2017, 12:13 PM
#69
TECH Addict
That's awesome. I rarely see/hear people running MAF's, and NEVER hear about anyone scaling their tune like I did. Lot's of hate on Greg Banish for whatever reason, but his injector data and his video's haven't led me astray yet. Not to mention I can dial in a MAF curve a hell of a lot quicker than a VE table
05-31-2017, 12:21 PM
#70
so your validation is calling everyone that uses SD stupid?
its all about what you are comfortable with. i had a olsd tune on my 4.8 that i didnt even need to change when i moved it from a single s10 to tt silverado, and drove it daily for over a year with no adjustments and it was always dead on. when i went to a 5.3 it took about 4 driving logs and its right where i want it again. Im sure you could do the same with a maf, but it would take me forever to figure that stuff out.
its all about what you are comfortable with. i had a olsd tune on my 4.8 that i didnt even need to change when i moved it from a single s10 to tt silverado, and drove it daily for over a year with no adjustments and it was always dead on. when i went to a 5.3 it took about 4 driving logs and its right where i want it again. Im sure you could do the same with a maf, but it would take me forever to figure that stuff out.
05-31-2017, 01:06 PM
#72
The other limit is the maximum airflow which is something like 68lb/min of airflow. This is when scaling the tune comes in. You take some factor, like 50% or 70%, and anything in the tune that is in terms of g/cyl, you multiply it by this factor. EG, your 60lb injectors scaled 50% become 30lb injectors. Basically the PCM thinks the motor, air, and fuel is all smaller than it really is. This allows your 1000hp motor to look like 500hp to the computer but all parameters in the logging tool like injector pulsewidths are still to scale.
05-31-2017, 01:46 PM
#73
Assuming your hard parts can handle the power, there is no practical limit to the power you can make with 93 octane. Just drop the compression to accommodate for the fuels knock threshold. Each hit you take on compression will allow you to run more boost without detonation. Unfortunately you trade response time and engine efficiency for each hit you take on compression.. So no reason to run a super lazy low compression engine if it’s not needed.
IMO 1000HP could easily be made with 93 octane, even on small bore motors. Drop some gen4 short rods on a 4.8 crank with some small chamber heads and you’ll have a very boost friendly (and lazy) engine. Run a large turbo capable of 30-40lbs of boost and a loose enough stall (or nitrous) to get into boost on the line.
I built a mild 7.8:1 383 a few years back with a pro charger. Ran 8lbs on 87 octane, no intercooler, no water meth. Worked great used it as my daily for 5 years without hurting the motor. (Gas mileage was horrible) Easily made over 600 whp going by trap and weight.
With an intercooled turbo setup and 93… sky’s the limit at low compression ratios. You’ll break the crank/block before you detonate if you tune it right. I think it’s weird we don’t’ see any low compression LS stuff. The tuning window opens up a ton and likelihood of hurting parts without a perfect tune also goes way down.
IMO 1000HP could easily be made with 93 octane, even on small bore motors. Drop some gen4 short rods on a 4.8 crank with some small chamber heads and you’ll have a very boost friendly (and lazy) engine. Run a large turbo capable of 30-40lbs of boost and a loose enough stall (or nitrous) to get into boost on the line.
I built a mild 7.8:1 383 a few years back with a pro charger. Ran 8lbs on 87 octane, no intercooler, no water meth. Worked great used it as my daily for 5 years without hurting the motor. (Gas mileage was horrible) Easily made over 600 whp going by trap and weight.
With an intercooled turbo setup and 93… sky’s the limit at low compression ratios. You’ll break the crank/block before you detonate if you tune it right. I think it’s weird we don’t’ see any low compression LS stuff. The tuning window opens up a ton and likelihood of hurting parts without a perfect tune also goes way down.
05-31-2017, 04:17 PM
#74
IMO 1000HP could easily be made with 93 octane, even on small bore motors. Drop some gen4 short rods on a 4.8 crank with some small chamber heads and you’ll have a very boost friendly (and lazy) engine. Run a large turbo capable of 30-40lbs of boost and a loose enough stall (or
With an intercooled turbo setup and 93… sky’s the limit at low compression ratios. You’ll break the crank/block before you detonate if you tune it right. I think it’s weird we don’t’ see any low compression LS stuff. The tuning window opens up a ton and likelihood of hurting parts without a perfect tune also goes way down.
05-31-2017, 06:57 PM
#77
i doubt anyone has specific quantitative data. But perhaps an apples to apples, i.e. same cubes, same turbo/blower, same or close to same cam. Then we can look at the shape of the Dyno graph or log and see if you actually have a faster boost threshold or hit max boost faster. Surely someone has stock cube low compression turbo and someone has high compression stock cube setup with the same turbo. Would just require some digging and I'm too lazy lol.
05-31-2017, 07:50 PM
#80
So it is a 8.3 to 11.8 test. That gain at boost though.
http://www.mustangandfords.com/how-t...ression-ratio/
http://www.mustangandfords.com/how-t...ression-ratio/