SCVCOA dyno run for baseline on my '91 745Ti, factory M46, 210+k miles and counting:

• Original Garrett T25, never been modified/tweeked/boosted/etc.
  
• Original engine/tranny, down to the original clutch, even.
  
• Original T-cam, which I doubt has even been reshimmed.
  
• Original cat, and despite being a 49-state car, it's way more than clean enough to pass CA emissions.
  
• OEM Volvo plugs, approx. 47k miles ago. Spark plugs wires definitely original ... which is making me wonder whether the cap/rotor has actually been replaced that same 47k miles ago in which the PO said he had a full tune up done. Whatever, though.
  
• No resonator or muffler. PO had a shop do it, and they didn't do too good of a job. That's gone, and in place from the cat-back, $4 Autozone straight pipe to a $4 elbow to a $12 new stock over-axle pipe to another $4 straight pipe and a $5 chrome tip.
  
• Synthetic Mobil 1 10w30, last changed at 206k.
  
• Regular Mann paper air filter, changed at 180k miles.
  
• Regular ATF type F in the tranny, Regular 80w-90 in the rear.
  
• Running on Unocal 91 octane, last filled up 2 weeks ago in Buttonwillow, CA.
  
• Tires are Kumho HP4 716 in 215/60/16, mounted on Ronal R25 16" x 7.5", for a combination weighing about 42lbs./each. This oversized tire corrects the speedometer, which is otherwise off on stock sized tires.
  

• 142.2hp ... factor in a typical (theoretical) 15% drivetrain loss on a manual, and I'm getting 167.3 hp @ 4800 rpm. The Volvo manual puts the turbo at 162hp @ 4800 rpm.
  
• 177.9 ft.lbs ... factored, 209.3 ft.lbs. @ 3700 rpm. Manual has it at 195 ft.lbs @ 3450 rpm.
  

How did you ever get the oringinal clutch to go that long?? I am on my third and have driven it lightly. You must spend all the time on the highway! db 745 tic w/208k

Yeah, it's my long distance weekend cruiser, but it has had its share of stop-and-go too. Worse one was 180 miles between Las Vegas and SoCal. :) That's what I get for doing a one-day turnaround on a Sunday.

Matching revs when shifting is a big key to longevity, or so I've been taught. I've never had to drive a car with a non-synchro gearbox, but I try to drive like it.

-- Kane
--

While I would never deliberately mislead anyone, take into consideration that any information and advice provided was at no cost to you.

After 210K miles, I think this is great.

I was looking at this page to see some different HP/Torque curves: RTEC/ Dyno Session Feb 1999

It's interesting why you are getting this high A/F mixture. Both HP/Torque curves have a slight blip at the same time the stoich zooms up to 18:1. Regardless of this lean condition, you are getting a steady incline in both curves.

I wish I had wisdom here but it's out of my league.
--
Norm Cook Vancouver BC; 1989 745T 204,000KM

How was the A/F ratio measured?

They have their own sniffers inserted in the tailpipe, which essentially works out as a wideband O2 sensor.

-- Kane
--

While I would never deliberately mislead anyone, take into consideration that any information and advice provided was at no cost to you.

I'm curious, 'cause as Norm says, if it were really that lean, you'd expect the power to fall off badly, and it only shows a small glitch.

Momentum in the powertrain will prevent major dips and peaks in the power output. Still, it's clear that there was some effect, as can be seen on the torque curve. If the A/F was going in the arc it should, the torque should end up as a typical arc curve too.

-- Kane
--

While I would never deliberately mislead anyone, take into consideration that any information and advice provided was at no cost to you.

im no expert (so my advice is agrueably not worth the screen space its written on...) but im guessing thats as the boost starts really pilling in...therfore indicating that the fuel supply cant keep up...

I would suspect (and replace) i nthe following order (based on cost/liekleyhood)

1. fuel filter
2. air filter (unliekly i know but its cheap and basic!)
3. FUel cleaner to clean the injectors
4. clean/deelectric the injector wirring connections.
5. FPR
6. o2 sensor
7. wires (well they are due anyway!)


the good news is lean means you probably dont have any turbo pipe leaks!

I would have *thought* wit that exhaust setup you should be looking at 15/20 hp over stock...but that a seat of the pants calculation...maybe turbobricks might be a better place to post - ?

Yeah, I'd be doing the zero-mile thing, but still, the dip is strange enough. Except for the O2 sensor, the other maintenance items would not explain why all is well at the other rpms. One t-bricker is mentioned it's possible that the MAF is being a bit screwy, which could make sense. I am looking for other suggestions, though.

-- Kane
--

While I would never deliberately mislead anyone, take into consideration that any information and advice provided was at no cost to you.