Alfa Romeo Forums banner

21 - 40 of 69 Posts

·
Registered
Joined
·
717 Posts
AR4me said:
... My general feeling was that many recorded less than expected...
I thought the same that the numbers seemed on the low side. However, what is the typical loss of hp and torque from the engine to the rear wheels? As an example, if your engine puts out (or you think it puts out) 140hp but at the rear wheels it comes up with 97hp, would that be a typical loss?
 

·
Registered
Joined
·
333 Posts
My 65 Spider Veloce curve was almost identical to the 1965 issue of Road & Track - actually a little higher. :cool: 94+ horses at the wheels is approx. (+/-)130 at the flywheel. Max torque just under 90 was around 4500 rpm. MPH in 4th at dyno red line was 104. Sound was smoooooth awesome. :D
 

·
Registered
Joined
·
913 Posts
MagnaFlow Dyno Accuracy

I suspect the dyno was fairly close to right. The relative humidity was a bit high (this reduces air density) but air temp and atmospheric pressure were reasonable. My stock twinspark engine in a rear drive car hit 112 bhp @ 5600 rpm. My guess is that the rear drive nets a loss of 30 to 35 bhp. So, let's say it was a loss of 35 bhp; that, plus the 112 measured would be 147 bhp at the flywheel. That's darn close to the "advertised" 148 bhp @ 5800 rpm.

I think what we are seeing here is a just an example of how small seat-of-the-pants (SOP) horsepower are compared when with dyno (SAE) horsepower. It looks like it takes about 1.3 SOP horses to equal 1 SAE horse.

Now I must admit, I'm not immune to the SOP hp problem. I had expected my twinspark race engine to be showing something like 140 to 145 bhp. It didn't even get close. However, it was spitting some good sized bits of muffler baffle out the tail pipe which I'm guessing became partially blocked. Guess I should get a MagnaFlow installed!
 

·
Registered
Joined
·
913 Posts
75evo said:
Did you all get the corresponding A/F values graphed against bhp & rpm? That would be extremely useful.
Can't get A/F on the Motronic twinspark because there's no O2 Sensor. It seems there wasn't much unleaded fuel in Europe in the mid to late 80's when the 75 TS was in production. Hence, Motronic wo/O2 sensor feedback to control A/F. I assume it's a nonaddaptive 4.x Motronic system. Interesting isn't it? I wonder if the ECU is coded to take O2 sensor input but that it's just not used on the European engines of that time frame. Any thoughts?
 

·
Registered
Joined
·
2,602 Posts
At WOT, the Motronic will ignore the O2 sensor and will run on a given map in the ECU. But what's important is the A/F given by the wideband O2 sensor.

Did they use a wideband O2 sensor during dyno?

Its useful because then you can figure out where your car is running lean and where it is running rich. Then you can start tweaking the ECU a little.

For max power, I was told, 12.7:1 A/F is good. Actually using a Lambda value is better.
 

·
Registered
Joined
·
1,898 Posts
Bruce Colby said:
Can't get A/F on the Motronic twinspark because there's no O2 Sensor. It seems there wasn't much unleaded fuel in Europe in the mid to late 80's when the 75 TS was in production. Hence, Motronic wo/O2 sensor feedback to control A/F. I assume it's a nonaddaptive 4.x Motronic system. Interesting isn't it? I wonder if the ECU is coded to take O2 sensor input but that it's just not used on the European engines of that time frame. Any thoughts?
I Have never even heard about a 75 TS without a O2 sensor. And I've seen quite a few... ;)
There is a jumper (looks like a relay socket) in the harness near the ECU where you can set the engine up for different octane ratings and the legend goes that if you remove this jumper the engine disregards the O2 sensor and runs the engine as if it was without a cat.
 

·
Registered
Joined
·
913 Posts
75evo said:
At WOT, the Motronic will ignore the O2 sensor and will run on a given map in the ECU. But what's important is the A/F given by the wideband O2 sensor.

Did they use a wideband O2 sensor during dyno?

Its useful because then you can figure out where your car is running lean and where it is running rich. Then you can start tweaking the ECU a little.

For max power, I was told, 12.7:1 A/F is good. Actually using a Lambda value is better.
If you mean "Did the dyno have a wideband O2 sensor?", I don't really know. But if it had one, they didn't use it. This wasn't a serious tuning session, it was just a "put your car on the rollers and see what it'll do" type thing. There were about 14 cars processed in 3.5 hrs (about 15 min/car) so it had to be pretty straight forward. I think the Motronic TS results were fairly consistent with the original factory specs so I believe it's running the way they intended. That makes me happy.

My interest in the possibility of hooking up an O2 sensor is primarily academic. If the facility exists to run the engine with adaptive feedback, that would be interesting to try. The 75 shop manual (TS engine supplement, in English), shows both a knock sensor and O2 sensor on the wiring diagram page. The problem is, they are only listed in the key at the bottom of the page; they are not shown in the diagram itself. All of the ECU pin-outs for AFM, TPS, rpm, relays, power, ground, etc., are the same as say a 1990 US spec, Motronic spider. Even one side of the dual ign shares pin-outs with the '90. It's just tempting to extrapolate.
 

·
Registered
Joined
·
2,602 Posts
Mats,

Early cars had no lambda. My uncle's TS was an '87 (old style grille, yellow corner lights) and it had no lambda.
 

·
Registered
Joined
·
2,602 Posts
Let me correct that, his was an '89. You could be correct that the first production 75 TS rolled out in '88. Still, his had no close loop control. Actually my dad's '93 164 V6 has no closed loop control either.
 

·
Registered
Joined
·
913 Posts
BigSwede said:
Different markets... Thats why they have that jumper. ;)
Mats,

You make it sound as if I could at least get closed loop control if I install an O2 sensor and eliminate/add the "jumper". Care to comment?

Then there is the knock sensor. Did the closed loop TS's of this vintage have one to help control timing?
 
21 - 40 of 69 Posts
Top