pkopalek

After digging in, looking at maps, and asking around, I still can't figure this quandry out.

Take a general 'safe' rule that Evans uses when he starts to tune (obviously, he doesn't want to blow up anyone's car on the first dyno pull). I've read that he retards 1 degree per pound of boost, then advances from there (to be safe). Many suggest .75 per pound, or .5 per pound, etc.

Obviously, these are incredible over-simplifications. Many will say that 1 degree per pound is not necessary at 3-5psi. Maybe a degree or two altogether. Then by the time 10-15psi rolls around, it better be 1 degree per pound retarded from 0psi...

But, I ask, and maybe I should start a new thread for this... to what end?

If I'm at 20psi, and retarding 20 degrees before advancing, then (using a GSR base map, as I am for my ls-vtec), I am literally running 8 degrees of advance at full boost in VTEC. Eight degrees.

It sure seems a lot like, no matter how much boost you run, if your IAT's stay cold, your A/F's stay in check, and your motor is handling things just fine, there's no way you'll see detonation at any (reasonable) boost level at 8 degrees advanced.

So, then I say, ignition retarding must go not linear (a certain degree per pound), but exponential (a little retard at lower boost, accelerating to 1 degree per psi at 1 bar, and decelerating back down to what will end up being .7 degree per total psi at 1.4 bar)...

I mean, if I project 1 degree per psi ahead, I will literally be about to TDC with ignition timing at 28psi... and that doesn't seem right at all. Now clearly, I could have chosen .7 degrees per psi of boost, and not be at 0 advance, but my point remains.

I made this awesome Microsoft Paint illustration to help show what I'm trying to say:

https://i.imgur.com/iY4MiJk.jpg

Now I've been tuning my own Hondas (and my friends') for years. But I've never tuned a turbo setup until managing to crack my block last year on .5 bar (very high IATs to be sure and almost NO retard at 7psi). Obviously, I needed to do some homework (which I have dozens of hours into at this point). Looked through a hundred tuned cars' BIN files in Crome, finally got datalogging going (to watch what the computer is ACTUALLY doing to advance, rather than just hoping that it's following my tables), and talking endlessly about it with tuners and car builders.

So, I ask, and as is the point of this thread: to what end do we retard ignition? Without keeping in mind that stock VTEC obd1 base maps have linear ignition advance (from 0 at 0rpm to 15 degrees at 9000) built into their maps anyway, let's just talk about the total timing here... how low can we go?

10 degrees BTDC on pump gas?

0 degrees advance?

is 14 degrees good for anything after 15psi?

Now, I realize there are many variables here. Higher compression? Probably more retard (I'm at 9.6). Ridiculous cams? Maybe a couple of degrees there. But I'm looking for a consensus. The average mild streetable build with forged internals, 9:1 compression, and ITR cams (for example) and good cool (<120F) IAT's. How low do we go?

Thank you for reading, and I hope everyone's summer is fantastic. I love this site.

boostedgeezer

Go to a dyno and you will see exactly where your timing needs to be. You are asking very general questions as far as how much to retard. We have no idea what kind of timing number are in your table, how do you know your not going to have to advance them?? Your not unless you go to a dyno.

bgdriver

With high enough octane you can get away with running very little retard.

turbodcxbro

iTrader: (1)

Its also going to differ on EVERY combo, even engines built the same. Its just the nature of the beast. Biggest factor here is fuel quality and type.

pkopalek

I'm not asking specific questions here, gentlemen (and gentleladies if it applies).

bgdriver gets at it a little here, pointing out that the fuel matters a lot. I'm giving a very basic hypothetical scenario here.

A stock-block GSR

A bolt-on turbo kit

A chipped ECU

93 Octane gas with 10% Ethanol (common around the country)

Big enough fuel system to stay at 11.5 in boost (hypothetically).

Is a linear ignition retard really the place to start?

I was getting at the philosophy of how low it can go. At 20psi, you're BARELY before TDC. It seems a little strange to me that anyone's total timing would be below 5 or 10 degrees advance, ever. I notice, looking at .bin files of tuned cars (from professional tuners AND amateurs alike) that total timing is typically still in the teens (12-16) at high RPM under 15-22psi of boost. Yet these motors eventually detonate, and you don't hear about them running for more than a few months (anecdotally).

Should guys with stock sleeves be running THAT LITTLE advance? (and by that I mean under 10 or under 5 total BTDC at high RPM and 20psi).

How low do you go? Every motor is different, and even the same stock motors can behave slightly differently. But they ALL have very similar characteristics in terms of when detonation and knock will happen due to the same rod ratios, piston speeds, and combustion chamber shapes, when they started with Honda OEM stuff. Therefore, ignition timing REALLY ISN'T that variable here with similar fuel, stock internals, and similar boost conditions. I'm getting at here -- how low does it go?

15 degrees retard at 15psi is reasonable. But most tuned cars, I find, are at 15-20 degrees at 20+psi. The path isn't linear. Less retard at <.5 bar, more leading up to 1 bar, and then less again at over 1 bar seems to be where tuned cars end up. But they also break. Advanced ignition timing creates higher cylinder pressure (even when premature detonation or serious knock isn't occurring), breaking stock cylinders like it's nobody's business.

Should tuners be going lower? Do they? How low?

This is the kind of conversation I'm looking to generate (though I don't like linking to other forums):

http://www.evans-tuning.com/forums/v...+retard#p13280

They're talking about when you stop retarding (do you not retard any further after 15psi?)

boostedgeezer

Notice how Jeff himself didnt comment at all in that post??? Because those are the same questions that a dyno will answer, all part of finding MBT. Every setup is different, so u really cant say when you will stop pulling timing out of it. If you were on a dyno u can pull timing until tq starts to drop off and increase until it stops making power and u will find where your timing wants to be. I might be misssing something here, but i believe your question cant be answered with a general timing value or load value as to where timing would remain the same....

pkopalek

Sure.

I'm not talking about all kinds of different setups.

I'm talking about a hypothetical stock VTEC motor with a turbo and upgraded fuel system. where do those motors tend to start knocking? it's certainly not linear. and many in this tuning section don't have access to a dyno ( including myself) and will be street tuning.

I shouldn't have mentioned Jeff, so forget that. he does an amazing job and i should have said " common forum wisdom" instead of that. My fault. the point was that it's never linear, so why even start linear?

I'm gong to be moving timing around at different boost levels and will be WAY off in some places and closer in others. but starting linear would be a waste of my time and an unrealistic way to set a base map retard.

I'm asking, based on the countless turbo vtec motors that have been tuned by amateurs and professionals, what does this curve look like, and how low does it go? if a stock block is running 20psi, it is surely with plenty of retard, but how much?

tuning to power is only a small part of the story. with better internals one can handle higher cylinder pressures. plenty of boost will create that. especially where " you' re making the best torque on the dyno". that point would be a great point to back WAY off of at high boost on a stock block. it needs to be reliable.

guys that run 400hp on stock blocks reliably have to have enough timing taken out that cylinder pressures are reduced enough to make the engine reliable. those motors are out there running. they're not tuned for best power. they'd last a week that way. how retarded does their total timing get?

VegasInvasion

First: you don't boost a stock GSR to 11psi unless the car belongs to someone you hate, or you live in the alps where 11psi is 1psi.

Second, nobody runs 400hp on a stock block "reliably" and if you retard the ignition enough to make it "reliable" you're not making 400hp.

More to the point: ignition is different for EVERY ENGINE. There is absolutely no guaranteed base values. I've fully tuned two identical turbo Z6 engines back to back and had timing variations up to 5*. Linear boost retard is not a waste of time, this conversation is taking more time than it would to tune the ignition.

The bottom line: you don't have a clear understanding of tuning or engine dynamics yet, and I suggest you do more reading AND practicing.

The helpful paragraph: read my manual COMPLETELY, and read through the street tuning section until your eyes bleed.
www.gravityimports.com/CROME_v1.6.x_Manual.pdf
.

pkopalek

I had no idea you had anything to do with the manual. Donation sent. Thank you for it, it's fantastic. It unturns a LOT of the stones that I'd been looking to unturn in other ways.

I've read the manual several times (that's not a joke) in the past month.

I've tuned plenty of N/A builds (of my own and of friends') and the boost dynamic adds a lot of different variables that I'd never had to deal with. Which makes perfect sense.

I'm going to see if I can dig up an old book I have (a la 2000-2001) that's titled something corny like "honda power secrets" where the writers do several builds, including a 81x95 n/a build, and go through what they did to make 250whp reliably, and their b16a build with a completely stock motor running a jackson racing supercharger at 24psi to reliably make 400whp -- [they disable VTEC and insist you don't need more than 7000rpm to spank mustangs, and that at that high RPM and high cam, you make it a lot more difficult to maintain reliability]. It's all about reducing cylinder pressure enough to allow the stock components to handle the load. A built motor (like mine, with CSS, forged everything, ARP everything, etc) can handle a little more cylinder pressure (clearly).

I hear what you're saying with "nobody". It surely is, practically "nobody". No shops will tune a stock VTEC motor on 20+psi. The margin for failure is huge. It's obviously difficult to tune to reliability when you're blind to precisely how much cylinder pressure is being created.

I'm planning on far less than 20psi with my built motor. But I'm sure as hell not going to tune for 'best power, then back off the timing'. I'm going to stay VERY far from knock and significantly far from peak power. There's no need to maximize cylinder pressure. 2 more psi of boost will produce the power I want, more safely than 2 psi less with almost-maximum-torque ignition timing. I want this car to last for several years (seasons, in the north east I should say). Rather than blow up after a few runs, or when I get one slightly worse tank of gas, or (insert random scenario here that can create detonation).

Detonation is the end of most of the motors on these forums. I'm not just looking to avoid detonation. I'm looking to be nowhere near it. Which is exactly what makes it technically possible to run high boost on a stock bottom end (although it is rarely done).

On a second note, does everyone leave that 'base ignition advance' set the way that Honda has it? (where it advances proportionally to 14.5 degrees at 9000, increasing total timing as RPM goes up, on top of the ignition maps) Or do tuners tend to set that at 0 (where it seems to be in the Gold ROM that I'm using) and modify the maps?

I can't find the Base Timing Advance in Gold ROM (unless it's underneath 'Tip-In' settings, and it's just mis-labeled... but those Base Timing Advance settings do appear to just affect Tip-In in practice, it seems).

VegasInvasion

Cylinder pressure is power; if you reduce one, you reduce the other. The only exception is detonation, but that's unrelated.

The stock b16a cam literally can't flow well enough below 7000 rpm to push 400hp, I'm willing to bet that article was made by someone who sells JSRC kits and isn't a very good liar. If it was reliable, it'd still be seen and talked about.
The highest pulley they have for it is 12psi which is out of its efficiency range and runs hot as hell. 24 psi would run at 400 degrees and probably melt the valves.

If you don't tune for peak power, then how do you know if you're backed off or not? A few knocks during tuning isn't going to melt your pistons, you need to know your limits in order to avoid them.

Again, you literally can't make any power unless you advance ignition. It's a paradox. If you retard ignition too far, you'll cause carbon buildups which will flake off and preignite your engine.
I don't like rules either and I have a habit of breaking them, but tuning rules are in place because the engine is a consistent science and unless you add a new variable, you can't change the science.

There is no base timing advance in gold, and you can't change it. But you should never have to change base timing anyway.

pkopalek

I'm picking up what you're putting down.

but if I'm not using Gold ROM, I'm inclined to remove that stock advance-by-rpm that's built into vtec stock roms so that it's factored out as a variable. I like to tune with the tables. no need to make a linear increase in advance just because Honda does it stock!

VegasInvasion

if you flatlined advance by RPM you'd have to make huge table changes, you'd waste more time that way. it's not a variable, it's a constant. inputs are variables; those are what need to be minimized.

2000CTRSi

Just use a dyno. Answer to all your questions.

all this talk about 5 degrees you guys are trying to melt some s***

pkopalek

Playing with a mostly-stock GSR, I'm running into this same situation.

Using Crome Gold ROM, and tossing in the GSR fuel and ignition values (and as many settings as possible from a stock P72 .bin file), I need to add the appropriate ignition per-RPM to the entire table, since Gold ROM doesn't have it.

I may make a base P72 Gold ROM and upload it for people to use, such that it will run a GSR the same way a normal Crome P72 ROM will (for the most part).

Just tossing in the tables will run a stock GSR motor VERY retarded in the Gold ROM without that all-the-time-base-timing adjustment..

Having a dyno (and taking the car to a tuning shop) would, of course, be ideal.

I think that discussing how to set up base maps, how timing curves wind up going, and where to get an idea to safely set up timing until you properly dyno (and/or street) tune it in the right conditions is very appropriate in this forum. I think that this is what it's all about.

If everyone browsing these forums were using Full-Race or JSRC kits with motors built in race-shops, no one would be posting here, because they'd be paying someone $150/hour (or whatever) to dyno tune their car for their entire setup.

The point here is more the DIY-crowd discussing things, in my experience. Which, as far as I know, is what this is.

I can't find a single example of an uploaded Gold ROM or professionally tuned .bin on any .bin repository.

They're all kids who uploaded the .bin files they made themselves for their cars that 'sort of' run.

So there's no one who's dyno tuning, then showing the results of what the tune entails at high boost, high RPM, with big cams, under medium load, etc etc etc with regard to where ignition timing goes.

Does it wind up being non-beneficial to stop retarding after ignition advance is almost 0 BTDC? Do some high-boost cars wind up with negative advance? Those that do -- are they leaving the 'Base Ignition Timing' advance table in there (which would imply that 0 degrees on the table is, for example, 13 BTDC at 8000rpm, or thereabouts)?

That's what I'm trying to explore here. Of course every car is different, and you only find out 'what applies to your motor exactly' on a dyno. But that defeats the 'not everyone here is a professional with a dyno' point. Because, it seems to me, that is the case.

Black R

^

I always try to street tune before and after hitting the dyno anyway.
The dyno only seems to hit to wot tables at a certain load, and while that's nice, I also value the drivability and mileage I get from street tuning.
Timing is hard to get right if you don't have a reliable knock monitor.

VegasInvasion

solution: load bearing dyno.
if you're not using a knock monitor you shouldn't be tuning. at all. even a basic det can is mandatory for all of my tuning regardless of the application or tuning method.

Black R

^ what knock detection do you use?

VegasInvasion

I designed my own module, I tune a lot of cars and wanted full control over the range and threshold. Although if you're in the market for one, Haltech's knock ears are pretty solid. Otherwise if you're looking to build your own, there are tons of threads on it here or some information at the end of the manual in my sig.

pkopalek

Thank you for that information.

I just got a normal VTEC one from Advance, and have built all kinds of extra retard into my tune (for break in) before using the knock sensor. I will investigate further into your endeavors there.

2000CTRSi

Once you have tuned several of the same motors... you will be familiar with the volumetric effeciency and how certain variables can change what would at some point be around normal values to approach mbt. Fist cup of coffee this morn sry guys

motoxxxman

OP, you're forgetting about the base timing table, the one you don't see in the normal ignition map, the one that the ignition map gets added onto. if like you say you end up at about 8 degrees at 20psi, that 8 degrees gets added to the base table which is a linear advance based solely on rpm. and at 7k its about 12 degrees. so 8 + 12 = 20 degrees BTDC at 20psi.

and to answer your other question, yes, when ignition is set ideally for all manifold pressures it will have an exponential curve to it, which you can see when using software that allows three dimensional map viewing.

Black R

Vegas, where are you?

I want to come get a tune by you.

efinimazda

I like the title, "philosophy" haha

Muckman

iTrader: (2)

Thank you! Everyone forgets about RPM based ignition compensation that exists in every Honda EMS.

pkopalek

I specifically get frustrated when talking to people about ignition timing, and always have to ask if they're considering this when they tell me how much timing they're running at 8000@10psi!