My Dyno results

Stevehose

Stevehose

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Brought my car in to have dyno'd this weekend, the goal was to set the timing for max performance, and to fool with jetting if needed. The first pic is the baseline. Pulls were done in 4th gear so the horsepower may not be accurate because they wanted to use a 1:1 gear ratio in order to gauge rpm (is this correct?) but consistently showed the results of tweaking. The first thing we did was add bigger main jets because I was leaning out at higher rpm and bingo - 15 hp.

Next we fiddled with timing and settled on 30 degrees all in (I had it at 32), it flattened out the torque curve at the expense of some gained hp (second pic and 4th pull) but it drives much better now.

Are these results ok for a stock engine 40 years old (with triple Webers)?

I think the Webers help produce the nice torque curve. The mechanic seems to think my plug gap could be enlarged to correct the hiccups at high rpm so I opened them to .030 later. What else could cause the spikes?

Please chime in with comments/suggestions, I am a noob at this dyno stuff, but it was pretty cool to do.
 

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I wouldn't count the spikes in gauging your horsepower. Your peak power for the first chart looks to be around 132hp, and for the second chart it is around 134hp. The gain is about 2, not 15. That said, the curve is a lot smoother, and your torque (which matters more), especially at high rpm, improved quite a bit.
 
I gave some horsepower gains back when the torque improved with the timing adjustments.


sreams said:
I wouldn't count the spikes in gauging your horsepower. Your peak power for the first chart looks to be around 132hp, and for the second chart it is around 134hp. The gain is about 2, not 15. That said, the curve is a lot smoother, and your torque (which matters more), especially at high rpm, improved quite a bit.
Click to expand...
 
Do you have the dyno results from the run before you dialed back the timing? It would be interesting to see that as well.
 
DO you guys save the image and then look at it off the forum? I can't see any detail in the pictures
 
Click on the thumbnail, click it again, then another to zoom it.

I don't have the other printouts, just the first and the last.


Bwana said:
DO you guys save the image and then look at it off the forum? I can't see any detail in the pictures
Click to expand...
 
You need to run in 1:1 ratio on the dyno to get peak horsepower, any other gear would give you less due to transmission gear losses. Your 4th gear is best case.

I am supprised that your rear wheel horse power is only 135ish, and at sea level.
It looks as if the torque curve peaks very low.

What size chokes are you running on your webers?
 
32mm chokes which I read for better torque vs 34?

waynesie said:
You need to run in 1:1 ratio on the dyno to get peak horsepower, any other gear would give you less due to transmission gear losses. Your 4th gear is best case.

I am supprised that your rear wheel horse power is only 135ish, and at sea level.
It looks as if the torque curve peaks very low.

What size chokes are you running on your webers?
Click to expand...
 
Just wondering if you could go bigger on the chokes with the longer GS manifolds.

Not sure how much more length they give you over the Cannon (straigth) manifold, but a longer intake runner will move the torque curve down. Looks like you have plenty of low end torque with it peaked and flat from 3000-3700 and might be able to go a little bigger choke without affecting the torque curve too much.

I have spent lots of hours over the last months investigating acoustic supercharging / ram theory as it relates to intake runner length for use on my race car.
http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm
There are many other equations, calculators, and papers I dug up, but this is the good for explaining the reason for longer intake manifolds = more low end torque.

I think this is also why most tuners choke down side drafts, the runner length with the stand manifolds is far too short for good low end torque.

Anyways, great to hear you are making good progress with your webers.
 
I ran a Dynojet 248 for a few years, and your results look fairly typical for an engine factory rated in the 180-200 brake hp range. Most guys are fairly optimistic about what their engines will produce at the rear wheels. We had more than a few guys come in with new "450hp" crate motors that only put 275-300 to the rear wheels.
 
I also read that ram tube length affects torque, longer providing more. I have 70mm ram tubes under the filters. These would presumably provide more torque than the usual set up of filters bolted to the carbs. Am happy with the results, maybe someday will fiddle with 34mm chokes because I have a set in my impulse-purchased Weber spare parts bin. I don't have the budget to chase more horsepower, I have plenty to get to Starbucks and back :-)

We were standing next to the intake side of the carbs when doing the tests, after the adjustments the noticeable increased howl from the ram tubes told us we were on to something!

IMG-20130330-00336.jpg


3%2520Webers.jpg



waynesie said:
Just wondering if you could go bigger on the chokes with the longer GS manifolds.

Not sure how much more length they give you over the Cannon (straigth) manifold, but a longer intake runner will move the torque curve down. Looks like you have plenty of low end torque with it peaked and flat from 3000-3700 and might be able to go a little bigger choke without affecting the torque curve too much.

I have spent lots of hours over the last months investigating acoustic supercharging / ram theory as it relates to intake runner length for use on my race car.
http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm
There are many other equations, calculators, and papers I dug up, but this is the good for explaining the reason for longer intake manifolds = more low end torque.

I think this is also why most tuners choke down side drafts, the runner length with the stand manifolds is far too short for good low end torque.

Anyways, great to hear you are making good progress with your webers.
Click to expand...
 
135 rw bhp is the figure from BMW for a new and healthy euro 2.8 The 3.0 should give at least that figure with stock euro spec, up to 145 for a top factory engine. What cr and cam do you have?
 
I had more hp but gave some back for the flat torque curve. I am all stock except 3 Webers. So I guess not too bad for the old girl.

DerSchwede said:
135 rw bhp is the figure from BMW for a new and healthy euro 2.8 The 3.0 should give at least that figure with stock euro spec, up to 145 for a top factory engine. What cr and cam do you have?
Click to expand...
 
I know its an old thread but have just had a ignition 123 system fitted and mine has just dynoed 147bhp at the wheels.

My standard zenith carbs flutter a bit around idle then the fueling settles down as the rpm raises.

3 speed auto must sap the power.
 
I've also installed the 123 since this was done, one of these days I will do final tuning with that on the dyno and plot a perfect advance curve.

Mattiee7 said:
I know its an old thread but have just had a ignition 123 system fitted and mine has just dynoed 147bhp at the wheels.

My standard zenith carbs flutter a bit around idle then the fueling settles down as the rpm raises.

3 speed auto must sap the power.
Click to expand...
 
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