Bottom End Power Xr6t

[Ninka]

Hear, hear

[Guest GIANT]

OK

A couple of you guys need to understand these mods may have adverse effects, get the latest zoom magazine to understand just how far they are going to stop simple mods.

there is an article in their about the LS1 engine computers on the holdens, and a new program they have developed(it took three years!). if you read it you will notice that there are all sorts of torque and power limiting devices built into the engine mapping(especially on auto's, as they control shift speed, shift harshness and the timing and fuel given at those shift points). also they have caculation tables on the engines volumetric effiency when these parameters are overstepped then cuts fuel and timing, and apparently it can cut back up to 90 percent!! when they started putting different cams in the engines they started to have cylinder cut probelms, some exhaust where causing drops in power due to being cut back when the torque figure was overstepped.

it also has abuse modes when the ecu sees throttle position without roadspeed or fuel mixture variantions it cuts back also.

you can put a tee piece on a rex , no problems(they dont have those kind of safeties). put one on a ford without testing anbd you may strike trouble.

its definately an interesting read!!

[bcl]

Sure, currently all responses are qualified with the word “may”, and it’s not currently suggested that anyone goes out right now and starts making changes without more information.

We know what works with other cars, but not with the Ford, especially because we don’t know what features are incorporated into the ecu. The best and most successful aftermarket mods incorporate ecu adjustments, as it’s the only way to tune the car.

Just because an LS1 has some ecu features, it does not mean that it’s in the Ford program.

Brian

[F6 RAPID]

I do!

I believe in safety in modifications. If you are stupid enough to do what I have suggested MAY help the bottom end by dialing in 12psi of boost straight up, you have issues - and I don't think anyone here would do that. What I did say was be conservative 2-3psi max and DO listen for pinging if you are going down this road. Be careful!

One thing to understand about ECU programming, they can change fuel/ignition maps and max boost pressure, but they can not alleviate wastegate creep because the wastegate is still controlled mechanically by a pre-set diaphragm which will bleed off boost gradually under max boost is reached. The only way to stop this bleed until max boost pressure is by a valve (either electronically or mechanically) intercepting the pressure.

[scott52]

Apologies to turbo6man for getting him mixed up with turbo6.

Restricting the wastegate hose with the $4.00 valve caused the boost to build very quickly. It felt as though it was at a greater pressure at < 2000 rpm for example than without the valve, however it is very difficult to tell because things happen quickly. when I first took off out of the driveway with about 30% throttle it just bolted and the gauge went over 12 psi. it was making strange popping noises which I think was the blow off valve and it just felt like it wasn't doing a new engine much good. I only travelled about 50m and stopped and cracked the valve open more. after a few adjustments it would not overboost under normal driving but it certainly was more responsive at light throttle openings. however when you gave it full throttle (or close to it), the boost gauge would climb up to 10 or more psi very quickly and the popping noise would start. I deduced that a proper boost control valve is the way to go.

[Mals BA XR6T]

That almost sounds like the rev limiter coming in... did the power drop when it was popping?

[Guest esky]

Call me a cynic, but I find it hard to believe some peoples technical vagaries about boosting up their XR6T. A simple dyno graph would expound all inconsistencies.

There are people on here who have never owned a turbo car and have never had the need to investigate turbo techniques and pitfalls until now.

So being a person who has written/writes for two particular magazines mentioned in this thread, I would suggest you weigh up what you read.

Someone pass me the salt please.

:banghead:

[F6 RAPID]

Which technical vagaries are you most concerned about?

And you are correct - a simple dyno graph with the mods I have mentioned would expound all inconsistencies.

I must get my dictionary out ....................

oh, as a matter of interest to all here, what were the articles? Were they technical in nature? More interesting, were they of turbos?

[Guest esky]

If you keep the increase to 2-3psi, you really shouldn't have a problem with reliability - of the engine anyway. I wouldn't go any higher without a chip for the timing (retard)

Hmm 2-3psi. Just wondering at what boost level do the injectors’ duty cycle reach saturation? What will the ECU do if you increase the boost? I’ve seen this on the dyno.

Why do you need to retard the timing? That would be a difficult algorithm to crack when dealing with dual variable cam timing, knock sensors and differing fuel types.

It’s been mentioned that 6psi is the boost level. I guess that figure has been taken from motor mag or something. I have seen three XR6T on the dyno and all have peaked at 6psi for a split second, dropped to 4psi and level out to 5psi. All running optimax on the same day.

I would wait for the people who know what they are doing to crack it, before hacking your way around a $50k car and kissing your warranty goodbye..

[F6 RAPID]

If I ever receive my car, I will wait until it is run in and then I will let you all know how I go.