Re-turbo and two questions

[2seater]

Update on the turbo installation using only the front exhaust to power the turbocharger. The turbocharger is an essentially stock Garrett T3 from a 4-cyl. turbo Thunderbird. The only modification is a custom exhaust outlet to connect to the stock rear manifold. I am also using an external wastegate rather than the standard internal design, although tests indicate no wastegate is required. Installation shown in signature.

The cruise control servo was relocated to the strut brace to make room for the wastegate but would not be necessary without a wastegate or use the stock internal one. The vacuum reservoir was relocated many years ago for the previous installation. Air filter shown is too small and may contribute to the low boost. More tests will be needed to determine.

The short test run shows seamless power delivery, although boost is somewhat lower than targeted, hence the lack of need for the wastegate. Maximum observed boost was (4) psi just after the 2-3 shift. This was tested using the stock chip, injectors, 195* thermostat and 91 octane.

A screen shot is shown below from near the 2-3 shift point. The air temperature F. shown is from a modified stock sensor located inside the MAF housing. This is with ambiant air temperature of 37*F. and this installation is intercooled. It shows the injectors are nearly static and the exhaust is lean, which is to be expected using the stock injectors and programming. I really need a wideband O2 to tune properly but funds don't allow at this time.

The questions are these: The MAF reading equals approximate hp. of 220+, but that would only make sense if the normally aspirated level was closer to 180hp. or, the small 2.25" inlet pipe "fools" the MAF into thinking air flow is greater than it is. Perhaps it needs a short section of larger diameter to not bias the flow toward the center of the MAF? Note: the MAF/throttle body is from a TPI manifold and sensor reads in the same range as the stock LN3 MAF. The engine internals are bone stock with 93k miles. I do have a high flow cat. and 2.5" Dynomax ultraflo muffler.

The second question is more involved: I cannot get any readings from the knock sensor (very important in a turbo install). I have tried two knock sensors which both show resistance values near the middle of the FSM range. The connection from the ECM to the sensor shows 4.95 volts, again near the center of the expected range. One of the knock sensors is more sensitive when tested for voltage output when istalled in the engine using a VOM from sensor to ground and tapping the engine block. I tried two different ECM's but only the stock chip has not been changed. Is there anything that can go wrong that could "take out" the replacement chip I received from J. Finn.

[padgett]

Just be aware that wih the stock chip, the MAF reading maxes at 172 gm/sec. Real value could be higher.

Also the stock crossover has a heat shield under the throttle body.

[2seater]

I appreciate the encouragement. I do know of the MAF limitation but at this poiint, I don't believe the air flow is much, if any, above that level. I have recorded the entire run and have examined it closely. The indicator actually drops slightly just before the shift, assuming it is getting beyond the comfort zone of the mild cam. The piping is all ceramic coated and the pipe under the T/B is after the turbo so a fair amount of heat has been removed by the turbine. My biggest concern at this point is the lack of knock sensor response. I do not have any more stock chips but I do have a couple of turbo calibrated ones that fit the ZIF socket. It is the only variable that has not been changed.

[padgett]

I would not use a stock PROM (chip) with a boosted engine, the curves are wrong. Early on we tried a blend of the supercharged maps and stock maps and there was still a leanout/detonation problem. That will do Bad Things if continued though it will develop a lot of power while it lasts.

Type of thing where you could generate maximum power for 1/4 mile but should tear down afterwards.

[2seater]

I agree completely. The chip is wrong for the application. Probably stupid to test without changing the chip or injectors, but snow is coming on and I wanted to see if it worked at all before winter closes in. The lack of knock sensor is the show stopper now.

[2seater]

Uh, the knock sensor works fine. I must have taken my stupid pills by mistake. The FSM says to check for knock signal with the engine idling. Some of the other tests, with the sensor disconnected, can't be done safely with the engine running, so, I ass-umed it could be tested with the ignition on, engine off. Not so appaently.

[Guest marchi1]

Intersting installation, but it looks as if you need a bigger injector as at the pulse width you are currently running it loks like the injectors are basically static (anyhting over 80% duty cycle or 22 ms).

Also with the location why not feed it off of both the front and rear bank or cylinders?

[Guest Recian]

The rear bank runs directly into the tunnel. Not easy to feed off it without a purely custom manifold or downstream turbo. My question is this seems to be a low boost almost stock application so what gains have you experienced so far over n/a and supercharged?

[Guest marchi1]

actually there is a company that makes a pretty slick crossover, though you may need to tweak it a little to roll the turbo over a little more where the air box used to be...

[2seater]

I do have another complete setup that uses both banks of the exhaust that I did many years ago. It actually works too well. I had some tuning issues that were not completely resolved which has been covered in depth previously. This was an alternative to see if a simpler system could be made to work for a low boost application. More development needs to be done but winter weather took the car off the road. I do have several sets of injectors of various sizes and a few different chips from the previous turbo installation. For this limited installation I suspect a small increase in injector size to 22# or 24# will be enough. There is a smaller A/R turbine housing available for the T3 turbo which would likely spool better to get the boost closer to what I want, but I need to optimize what I have now first.

The crossover pipe shown doesn't look like it will work to me but perhaps I do not understand the application. One of the largest hurdles to overcome in the physical installation that uses both banks is space to get exhaust up from the rear and back down and out. My previous installation did use a completely new fabricated rear manifold that crossed to the front side on the passenger's side of the engine. Someday I may go back to that install now that I have an intercooler in place which was not part of the original install. Time will tell.

Performance hasn't really been evaluated to any real extent. It needs to be tuned to be safe before a lot of that can be done.There is no doubt it is faster, but it is so seamless there isn't anything dramatic, which is what I am really after. Eventually I'll try a G-Tech to see what it shows but my recordings so far are in the sub-seven second range for 0-60. No great shakes but we will see where it ends up.