Since our cars run rich even after pulley swaps etc. has anyone tried leaning thier cars out? Has anyone installed an adjustable fuel pressure regulator and bumped it down a pound at a time then took readings with a wideband during normal driving and wot?

 

That sounds like a very dangerous and blunderbuss approach.

Get it wrong under boost and good night Irene.

I think they run them very rich too though.

Frankly, the mileage is embarrassing when compared with other cars that have even more HP. I don't know if it's as simple as that though. Jag didn't do so well with the supercharged engine in terms of fuel economy.

 

If someone would ever crack the ecu we could have some really good gains.

 

Crack the ECU? It's been done...

 

Who has a tune for it? (that can be dyno proven)

 

I think our systems are returnless and don't work quite that way,

Common misconception is that leaning out the tune at WOT/torque peak makes huge gains, it really doesn't. Depends how rich we are talking, but judging from the (very few) from the a/f traces I've seen of modded STR's on the dyno, they are hardly running 'pig-rich', high 10's afr, and the only one I can reference now with an a/f trace is showing a steady mid 11's AFR...
Sorry but you're not going to be able to lean it out much at all; a boosted setup on pump fuel shouldn't run leaner than 12:1 in my opinion, so leaning out an STR running a so called "rich" 10.9 a/f tune to 11.8 a/f won't gain much...

Although I've hardly done any significant logging or tuning on my STR, I would say the amount of safety buffer in the factory tune isn't excessive, there's not much to be gained by narrowing it. You want to make more power, flow more air. Too many STR owners are brushing around the edges looking for big gains where there simply aren't any to be made.

 

Is it possible that we think the af ratio number increments are so small that when they move a small amount that it means nothing. I don't think we look into areas on str that shouldn't be looked into for hp gains. Every little mod adds up we do mods that shoot at minimal hp like using a k&n. The gain isn't much but it collectivly works with other mods. The example from 10.9 to 11.8 is almost a whole point. I think were at the rich side of the spectre where we would experience a good gain. From 1 point. On the other side of the spectre I've seen someone make a pass at 12.5 on the edge and at 13.5 would burn a hole in the piston which is still only a point away. Can anyone else chime in? When we all speak that we want the twin screw how is the af managed? Or fuel managed, is there and adjustable fuel regulator set up at that point? It's just always in the back of my heads that our cars af deserve to be dead nuts to match our mods if there rich why not give it what it deserves. Has Anyone else played with this aspect please help.

 

From my own dyno tuning experience, that 'whole point' from 10.9 to 11.8 doesn't net significant power gains, but depends on what sort of power output we are talking and what sort of engine/setup of course too. Every engine responds differently really, and has its sweet spots. I've found there's times when I make really small a/f ranges from rich to less rich, and sure, nice gains are made, but from then on the power returns start diminishing really quickly.
Every engine is different, and power is made differently across the rpm band, and the liberties you take with a/f ratio will also vary across the band, so in the case of some engine 'tunes' , its easy to see superficial gains in peak horsepower for instance, but you have to take measured gains in context...

I used the leaning out 10.9:1 to 11.8:1 merely as an example; I'm not certain what AFR the STR targets at WOT/open loop, maybe richer, maybe leaner?

You keep saying that they're rich, but according to who? And whats your idea of 'rich' or 'too rich?'
The one dyno I found of an 05 STR with an a/f trace showed it running high 11's AFR... Not sure how much leaner any sensible tuner would take that... you would have to be very very certain of the quality and consistency of your fuel before trying to eek out possibly single digit gains going maybe half a point in AFR at that point...

No one has really played wih this aspect because there's no readily available tuning software or other form of adjustments that we've heard about or seen tested, so I doubt anyone can give you a conclusive answer that you're looking for. Maybe consider contacting the 'ecu tuning group' for their STR tune and be sure to do a before and after dyno, because you'll be the first to have done it.

I agree with you, every little mod 'adds up', but its not wise to compromise aspects of safety and drive-ability, chasing incredibly incremental gains that will never give your butt dyno the satisfaction of moving up a power class like a real 50, 100, or more gain does,

The avos twin screw kit seems to successfully produce an additional 100-200 horsepower on mostly factory electronics, tune and injectors (and probably thanks to some additional fuel flow through a meth injection kit to hit those really high numbers)
Avos does recommend a boost-a-pump, but that seems about it. The factory electronics are adaptable enough to cope and adjust for 20% or so additional airflow and fueling requirements, seems all the 4.2 cars running his kit are compensating well. Anything more, I would think you need to consider a fuel injector upgrade and a MAF interceptor like tuning box (such as MAP-ECU) to play with the MAF signal in order to compensate.
I'm also certain if you talk to avos directly and pull the trigger on his twin screw kit, he will give you the complete run down, including tell you to do your own datalogging in order to ensure safe operation and further fine tuning on your end.

You want to make more power with the STR? Flow more air, the gains will come. Note, this may require a supercharger or other power adder upgrades to reach your goals.

 

It just believe the 4.2 are capable of so much it's ridiculous. In my head I keep thinking of we in the 3.8 turbo v6 Buick world are able to do. This little 4.2 heads flow so much better and being such a small bore v8 is perfect for something crazy. But it's the computers that are limiting. Oneday just oneday pro efi and a 76mm turbo!

 

Some time soon (within a month or two) I'm pulling the trigger on an ETG ecu tune. Hedging that it'll pull the mods together for a solid 475 chp (405 rwhp). This is possible due to it being a reality for European STR's with pulleys, intakes, and tunes.

 

Has ETG Tuning used a moded STR as a mule yet with supporting data, i know sometime a while back they were saying they only tune STR s with the 1.5 pulley and if it had other mods such as intake porting or head porting etc. that they choose not to tune them for safety or whatever reasons that they did not list. Maybe im behind on the latest and greatest with them plse enlighten...Do anyone know if can they correct where our cars short shift from 1st to 2nd gear at WOT?

 

Read posts by avos about the TS. He's added it and done lots of testing and says the PCM adjusts fuel fine even for the TS. You're guessing but he has done this with measurements. He says there's no need for a tune but I reckon others would love to see you post dynos before & after a tune. The ETG tune doesn't sound to be what I think of as a real tune, but see what you think.

 

Where's the tuning software and the person qualified to operate it?

Until then this all just speculation.

I suspect that the market place is just too small. It gets smaller every day too.

The prospects are probably much better with the newer models.

 

I don't know how many times I've mentioned this on the forum.

Our cars use a Denso MB079700 ECU...



...which can be reprogrammed using the J-Tag / K-Tag devices.

Alientech - K-TAG Protocols

The Slave version can only load an existing map. The Master versions can completely edit the maps in the ECU.

There are other devices that can do this as well, but the Alientech is the most "affordable" that i've found.

Apart from the costs (a slave K-Tag goes for around €1000, and you can't write your own maps!) the other issue is that a custom tune on the car will only suit that engine, in it's current state. If you start making mechanical changes the tune doesn't really suit it anymore.

This is the reason why the likes of ETG back off when a car is running meth, different pulley, snakebite gearing, custom exhaust, intake, etc. because thier off-the-shelf tune isn't going to work as well with a heavily modded engine.

Now....

The Denso ECU is used in a lot of Japanese cars; Subarus, Nissans, Mitsubishis, etc...

If you could find a workshop, with a dyno, who can tune those Jap cars, they might be able to do something with the Jag because of the Denso connection.

There are several tuners in the UK, who have dynos, and have done custom tunes on our cars. The harder part is finding an example of before & after runs on the same dyno...

But it can be done.

 

As you rightly point out all of those modifications are reason for a new map created by someone who knows what they're doing and these engines.

And yet there's no one in the US who does this for our cars.

When we find someone I'm sure many here will let us know.

I know I wouldn't want to get involved with a "tuner" who's never worked on these cars. Paying someone to learn is expensive and risky stuff.

 

From Search, you previously mentioned it once, very briefly. Looks like most people missed that.

 

The newer models with the 5.0SC setup are simply monsters in comparison to an STR, although the price spread is severe between the two, man, what a difference. Would need a twin screw kit with all the fixings to keep up with an XFR with basic bolt ons...

 

Yes the 5.0 sc engines are monsters and when the funds are right will def be my next purchase. One simple way to lean the car out would be to add a few gallons of e85 to a full tank of gas. It would also boost up the octane a few points. But in my case ill be going with a small shot of nitrous (50shot) with tps window switch just incase the traction control comes on in anyway.

 

Video of the kind of thing needed with K-Tag

 

Way to complicated, much easier to change the map file, and upload it with the jaguar dealer tool (which containes all the maps).