What's in a safe tune?

[spederman]

My car has been in the shop for 5 weeks getting all the mods in my sig installed. The V2 S trim will be running a 3.33 pulley. Stopped in yesterday and the shop just warned me that i am pushing my limits and if something blows its not there fault and they will give it as safe as a dyno tune they can.

When i get it back, what am i looking for to determine if the tune is good/safe or not? I didnt think that i would be that far over 400rwhp that i would really have to worry about it, but i guess it might be.

 

[the98stang]

My car has been in the shop for 5 weeks getting all the mods in my sig installed. The V2 S trim will be running a 3.33 pulley. Stopped in yesterday and the shop just warned me that i am pushing my limits and if something blows its not there fault and they will give it as safe as a dyno tune they can.

When i get it back, what am i looking for to determine if the tune is good/safe or not? I didnt think that i would be that far over 400rwhp that i would really have to worry about it, but i guess it might be.

Sounds like that shop is trying to make excuses . I would have them stop what they are doing and get your car OUT of there. Take it to a reputable shop. You shouldn't be hitting more than 400WHP with the s-trim. Not with that pulley anyway.

 

[sgarlic]

What makes a safe tune is a slightly rich A/F ratio at WOT, and not being too agressive with the timing.

You can make more power by advancing the timing, but you risk having problems with detonation. The power gained on a boosted but stock engine, IMHO, isn't worth the risk.

I believe 11.4 is the ratio at WOT you want to be at. Anything higher is leaner, anything lower is richer. Too rich = lose power, waste gas. Too lean = gain a bit of power, higher temps, more chance for pinging.

The best thing in my opinion that YOU can do, is to invest in a quality wide-band oxygen sensor and gauge or display. Then, before you go stomping your local Z06 community members, make a few passes up the on-ramp at WOT, and have a buddy watch that A/F gauge. If it gets too lean, you're going to have issues.

The other problem is, a dyno tune doesn't necessarily simulate "real world" driving conditions. In other words, just because on the dyno you have a stoich cruising A/F ratio, and at WOT you're at 11.4, doesn't mean that driving around town you're going to be perfect every time. There are thousands of debates as to whether or not dyno tuning has any applicability to actual driving conditions or not, but I'd rather not bring that up.

You really just need to run quality high octane gasoline (91+ .. possibly 93 if your tune requires it, and if you can get it in your area,) and have a wideband gauge.

My only other advice would be to have a fuel pressure gauge, and watch for dropping pressure at WOT.. although it's difficult to keep your eyes on much else besides the road and the tach while accelerating that quickly.

Also, I wanted to add, that using the word "safe" when using any sort of forced induction on the stock engine is a stretch. There isn't a magical point where our engine internals fail. You may blow it up at 350, or 400, or 500. There are guys I read about every so often who work at MM&FF that are PAST 500 on the stock block. Conversely, there are guys I've read about here who've broken a rod with under 400.

 

[the98stang]

Also, I wanted to add, that using the word "safe" when using any sort of forced induction on the stock engine is a stretch. There isn't a magical point where our engine internals fail. You may blow it up at 350, or 400, or 500. There are guys I read about every so often who work at MM&FF that are PAST 500 on the stock block. Conversely, there are guys I've read about here who've broken a rod with under 400.

VERY true. An engine running lean with 300WHP is bound to fail before an engine with perfect AFR and 500WHP, assuming both are on the stock block/internals

 

[Don 95Vert]

You can have as 'safe' a tune as a shop can do and the motor can still go. It's all about cylinder pressure. On a stock 2v the design limits of the motor as far as cylinder pressure is concerned is probably in the neighborhood of 350 RWHP as far as Ford is concerned. Not meaning they fail there. meaning they are mostly OK there - and this is just an estimate on my part. I say that because stock internals start failing at around 400 RWHP - some more, some less. Not all will fail though because of manufacturing defects or the lack of them.

A SAFE tune is one that sets the spark curve so it is a long way from detonating under most circumstances and where the AFR is richer than it needs to be, but not too rich - because that's bad too.

I do not blame the shop for saying that. They have no idea how the car will be treated or what gas anyone will run in it - I've heard of people taking a blower motor, running 87 octane in it, beating the crap out of the car, blowing the motor, then blaming the shop. The shop has to warn you of the possibilities - we do, because it IS a real possibility. If you slap a blower or turbo or nitrous on any stock internal vehicle, you are rolling the dice. Chances are it'll be just fine, but there is a chance it won't be. And it isn't the shops fault if something breaks.

 

[spederman]

Yeah, i guess the shop needs to warn about the chances of blowing the stock engine. So i guess if you i get a good tune, its all luck if the engine stays strong or dies. And with my luck, looks like i'll be needing a new engine soon, LOL. I might invest in a wideband A/F gauge, that would be nice, ive already spent a ton of cash, whats another $350 or whatever they run. I do have a fuel pressure gauge and a boost gauge on it now.

BTW, anybody have a similar setup to what i'll be running with the intercooler also? Just curious what kind of HP numbers everybody with a similar setup is making.

 

[rconaway]

I've been running that set up for 65K miles. Blew an engine around 45K but not due to the blower. Seems you can't run the car at 5500+rpms for 30 minutes without upgrading the oil system with a bigger pan at least. That being said, the car has made about 370 rwhp with an 8lb pulley (not sure of the diameter) and after the rebuild and the addition of new cats, about the same with a 10lb pulley with no intercooler. The car has had numberous dyno pulls and even after that, when driving on the highway for long distances, the car started pinging again, meaning that my tune was good for most apps, just a little too much when the car got hot. Back to the dyno to take it down another notch. After the tune, start running it in various conditions. If you ever hear a knock, back off immediately, note the conditions and go back and have them make additional adjustments for that. The best bet is to get an SCT tuner with multiple programs, one for really crappy gas (like the kind you get in noplace, Arizona while traveling), one for decent 91-93 octane or whatever you get in your area, and one for 100 octane if you race. I have one that is for 90 octane, long highway drive, one for 93 octane, street/race conditions, and one for 100 octane Silver State Classice runs.

 

[blacksheep-1]

I would agree with Donvert. I'm running a KB @ 6psi, no intercooler. Vehicle rwhp is 342 (I forget the torque but it's pretty even from 1500rpm to about 5800 where is drops off. the rev limiter is at 6500. I requested a conservative tune from these guys: www.racerelated.com
The car gets 22-23mpg on the highway and 19-20 around town. It is a stock 99Gt /5spd with a BBK offroad x-pipe and a KN intake tube. When you step up to 8 psi KB highly recomends the intercooler,(they won't sell you a kit without one). Saleens which are basically 4.6 GTs, and most closely resemble our cars,run 8psi with an IC. and that car gets a warranty, so I'm thinking 10psi is max with a cooler and brand name pump gas. That being said, there was a magazine article in recent years that got over 400rwhp out of a 2 valve 4.6, but they stated that you had to be pretty much nuts to do that all the time. If you figure 15% in the drive train for a stick car that's 460 at the flywheel.
I'm thinking about 3 bags of oil dry should cover it.

 

[DBMSTNG]

Sounds like that shop is trying to make excuses . I would have them stop what they are doing and get your car OUT of there. Take it to a reputable shop. You shouldn't be hitting more than 400WHP with the s-trim. Not with that pulley anyway.

wanna bet?

 

[blacksheep-1]

Did I tell you that I just did a 1400 mile round trip through the Smokey mountains and back to Tampa, Fl?
Low altitude, high altitude, the car never missed a beat, it's been dependable as an anvil with 65,000 miles.