TXZ28LS1

iTrader: (5)

Guys,

I was wondering what is the difference and performance difference between both of these tunes? I plan on adding heads and a fast intake and getting retuned.

One shop i called local from me said that they do a pretty conservative tune. Any idea what that actually means? When i think of conservative tune, im thinking of giving up a few hp?

thunderstruck507

iTrader: (18)

Probably less timing and more fuel (say 24-25* and 12.0-12.5 a/f ratio) versus a more aggressive 26-28* and 12.5-13.2 a/f ratio.

If they mean any less aggressive than the first I would discuss with them why. Either way it sounds like they might lean more towards a set method of tuning rather than trying to find out what the car really wants to make the best power.

That might not be the case but the way you worded it, that's the impression I get in my mind.

You should have asked this question to your tuner IMO. His answer is the one that matters.

Gabbiani

iTrader: (20)

Every car will be different. In most cases conservative should be a good word. Trying to get that last degree of timing with it knocking every other pull isn't worth a couple of hp.

Then again make sure conservative doesn't mean lazy.

matrixiskool

iTrader: (12)

Yeah make sure conservative doesn't mean just a generic tune.

TXZ28LS1

iTrader: (5)

Thanks alot guys. These guys are a small local shop, but actually have work featured on GMHTP.

I will give them a call to discuss more. But when i just first called to get pricing on a tune, they did say that they tend to do more of a conservative tune because they dont feel the need to put any wear and tear on the engine for a few more HP.

Frost

iTrader: (45)

For an N/A car, the difference in ragged edge vs. well safe could be as little as 4-6 rwhp.

Alvin

iTrader: (2)

I agree, or even say it might be a difference smaller than that. Of course every situation is different but typically the last 2 or 3 degrees of timing added even without knock makes absolutely no difference in power. Same goes with fueling. Every car is different but this is typically the case.

edcmat-l1

iTrader: (10)

Yep. It's that tuning "window" that all engines have, where a couple degrees of timing either way, or adjusting the A/F a little either way makes little difference. Every engine has their "happy spot".

Slowhawk

iTrader: (12)

Pretty much what they said.

jimmyblue

iTrader: (11)

One thing I've been searching for but have only found
one barely relevant reference (a Subaru motor if I recall)
is the relation between MBT and ping-onset timing. That
is something that would be deducible from a dyno pull
series if it was broad enough. It would be a nice useful
rule of thumb for the shade tree tuner; run it up to KR
and then pull out N degrees (probably varies by RPM
and build, but still).

The Subaru writeup I think was saying -2 - -3 degrees,
which is kind of edgy in my book.

Any thumbs?

ysb02

It's probably going to vary how much to back off after you get knock. I think Greg Banish was showing you want to set it right before peak power in the timing curve. After that will only get you less power + knock. Running it slightly before peak power will give you a safer margin.

jimmyblue

iTrader: (11)

Right. It's the offhand relation between peak power point
and ping point I'm interested in (the latter being easy to
determine, the former requiring you so sit on the rollers
at time=money.

Alvin

iTrader: (2)

Most NA LSx's are this way. Every case can be different but generally the last 2-3 degrees does nothing. When it continues picking up power with timing up till knock I either look back at what fueling I'm shooting for or call it "octane limited". For instance if the car is picking up 10 rwhp with every degree of timing but it also gets into knock I first try doing a sweep test with the fueling to see if there is something better, if that doesn't get it its time to go with a better fuel.

mike13

iTrader: (27)

I've only tuned my own car but it's interesting when you hear people talking about timing because they usually talk about the numbers at the top of the rpm limit. I've noticed for me it was the peak torque area that required the most concern for not getting into KR and allowing a safety margine.

Alvin

iTrader: (2)

Inductance period, swirl, cylinder filling all have an effect on timing. You might find you can run the same timing at 6000 RPM as 3000 RPM, or you might not. Without a dyno your just guessing.

Slowhawk

iTrader: (12)

Thats correct. Also tuning off the factory knock sensor's isn't the best thing. You can get real kr,false kr or no kr (with audable pinging). The dyno (load dyno) is probly the easiest to tune in WOT by seeing the results on each change.Then still, you do not have the airflow across the front of the car to mimic highways speeds which can certainly change A/F mixtures which affect timing.

mike13

iTrader: (27)

That's my point exactly, having a turbo'd stalled auto the midrange tune was the hardest, where the converter is hooking up and the boost is rising. I pulled timing and richened it up until the car was sluggish and slowly pulled fuel and added a little timing. in the 4-5k where the car is starting to pull hard I'm at 10.5afr and 15 degrees timing and as the rpm goes up I lean it out to 11.5 and 18 degrees timing, this is with pump gas and methanol.

I then go and test it on a steep 5 degree 2 mile uphill by my house, leaving the car in 3rd and doing some pulls from 40-80mph 3.73's making the motor work hard in the midrange.

I don't know if it's the right way but it's my conservative tune.

Gabbiani

iTrader: (20)

^^ Nothing wrong with that. I like to load the dyno a little more than the car will ever see in normal use to make sure it is still safe.