W2 408 Dyno results today !

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Hysteric said:
... It took 3 trips to the parts store to get 8 good spark plugs that all tested correctly...
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20 years ago when I worked in parts stores, I would never have believed that statement. With my experience buying over-the-counter autoparts the past 10 years, I'm more surprised it didn't take 5 trips!
It's almost as if the OEMs for the mfgs no longer make the parts for 'everything else' these days, and it shows.

Hysteric said:
You cant beat a gas bench for understanding what is really going on but an ignition scope will tell you plenty also.
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I bought another hotrod recently. It ran great (I thought), but was nearly impossible to start. It would only fire quickly with the battery freshly topped up, or with a jump from a running vehicle. Chased down voltage drops (meter on dash showed under 10 during crank, even with a brand new optima), wiring junctions, even tightened the gap at the reluctor which seemed to help. Finally decided to swap the distributor since the one that came on the engine is no longer supported (thanks Holley). When I went to swap it, I found the distributor ground was on a loose bolt, not even clamping the wire in-place. I felt stupid.. With the bolt tight, it fires right off. Then the coil died during my test-drive. Turns out it was not rated properly for the ignition module.

Long way of saying: the right testing tools absolutely help! Had I simply hooked up my timing light and cranked it, I would have found the no-spark issue. It's no scope, but it's a tool I have which can help figure out wth is going on. With it all fixed, car runs amazing and I've not flattened the battery again since then. Turns out the voltage drop during cranking is only in the dash wiring up to the meter - real battery volts are fine.

Now that makes me think maybe @mbaird might clamp a timing light to #7 and see if he gets regular pulsing or if it drops out at some point. Easy enough to duct tape it to the hood during a test drive to see what happens under load ;) (only half-kidding). If not, it may just be 'how it is' with that particular motor.
 
Phreakish said:
Now that makes me think maybe @mbaird might clamp a timing light to #7 and see if he gets regular pulsing or if it drops out at some point. Easy enough to duct tape it to the hood during a test drive to see what happens under load ;) (only half-kidding). If not, it may just be 'how it is' with that particular motor.
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That's actually a very good idea and I've done that on occasion. You would be surprised what you actually find when you bother to test. If you're really serious buy a data logger for your car and then you'll know what is really happening and where.
 
Frank called and said the engine is ready to be picked up. So I now have all the dyno sheets .
I was confused about which pull we installed the Super Sucker . It was before pull seven not six . It corrected the fuel distribution issue . Pretty good testimonial actually ! At least in this case...

Here are the pulls and corresponding AFR charts for pulls 4-7.

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Wow, the BSFC's are VERY high. Did he go over the results with you? Did he have any input to the low power output and High BSFC's?
 
ou812 said:
Wow, the BSFC's are VERY high. Did he go over the results with you? Did he have any input to the low power output and High BSFC's?
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He did say that the engine seems to want fuel.
What is your opinion on this ?
 
Something is just not right...I'm not sure what it is, sorry I don't have any real ideas but I normally see .400-.430 for BSFC's on similar builds. If his meters are reading correctly, something is not happy. I hate naming things, because until you actually "see" the parts, like ported heads, and look at the machine work with the proper gauges and tools, it's just a guess. I figured if he dyno tests quite a few engines, he might have some insight for you. Get a pic of some of the plugs, and ex. ports if you can....
 
ou812 said:
Something is just not right...I'm not sure what it is, sorry I don't have any real ideas but I normally see .400-.430 for BSFC's on similar builds. If his meters are reading correctly, something is not happy. I hate naming things, because until you actually "see" the parts, like ported heads, and look at the machine work with the proper gauges and tools, it's just a guess. I figured if he dyno tests quite a few engines, he might have some insight for you. Get a pic of some of the plugs, and ex. ports if you can....
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Whatever was done for this pull seems to have cured the #7 flatlining down at 10:1 or below.

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Are there other pages for each run with fuel flow data on them?

In case there are some reading along and not comprehending the significance of the high bsfc....... what it’s saying is that you’re using a lot of fuel....... but not getting any power out of it.
The bsfc numbers are derived from fuel flow and uncorrected HP.
 
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Looking at these two shots of run #4......
Just picking a line...... peak hp @6000......
Fuel flow is 233.3lbs/hr, bsfc for that line is .540.
233.3/.540= 432.0hp, uncorrected.

If the efficiency of the motor was producing bsfc numbers in the .470 range, the uncorrected HP would be more like 496hp, with that same 233.3lbs/hr(or it would be using way less fuel to produce the 432hp).

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The thing I don’t think anyone mentioned yet is....... anything that causes the motor to make less power, makes the bsfc numbers look bad.
Even things that have nothing to do with the motor....... like poor air flow through the dyno cell.
 
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PRH said:
Looking at these two shots of run #4......
Just picking a line...... peak hp @6000......
Fuel flow is 233.3lbs/hr, bsfc for that line is .540.
233.3/.540= 432.0hp, uncorrected.

If the efficiency of the motor was producing bsfc numbers in the .470 range, the uncorrected HP would be more like 496hp, with that same 233.3lbs/hr(or it would be using way less fuel to produce the 432hp).

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The thing I don’t think anyone mentioned yet is....... anything that causes the motor to make less power, makes the bsfc numbers look bad.
Even things that have nothing to do with the motor....... like poor air flow through the dyno cell.
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We installed a 1" tapered spacer before pull #7 and that fixed the flatline. We tried 4 different spacers and even stacked 2 .
It was getting late and we never tried changing the jetting after pull 7. Maybe dropping 2 all around might help the afr and BSFC ?

I checked the rotational torque of the shortblock and it was 25 ft-lbs or less. Lowest my wrench will go... so I dont think friction is the issue. Could be the intake creating massive turbulance ?
The engine liked about 32* of timing so that should mean the chambers are efficient.
 
I alao meant to check the oil level by removing the overflow plug on the pan but forgot to do it . I am pretty sure I had too much oil in it . I had about 7 qts in the Kevco pan and the dipstick showed full but later I recalled that the dipstick was off a bit. I need to ad 6 qts and drill a small hole in the stick at that point .
 
mbaird said:
We installed a 1" tapered spacer before pull #7 and that fixed the flatline. We tried 4 different spacers and even stacked 2 .
It was getting late and we never tried changing the jetting after pull 7. Maybe dropping 2 all around might help the afr and BSFC ?

I checked the rotational torque of the shortblock and it was 25 ft-lbs or less. Lowest my wrench will go... so I dont think friction is the issue. Could be the intake creating massive turbulance ?
The engine liked about 32* of timing so that should mean the chambers are efficient.
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32 degrees of timing doesn’t always indicate combustion chamber efficiency. Too hot a spark plug will require less timing and usually a drop in power with it.
 
Unfortunately, there are often many unanswered questions when you go to the dyno, the numbers come in below expectations, and you don’t have numbers from similar combos to compare to....... that have come off the same dyno.

There’s a thread in the BB section where a 505 TF head combo was tested and the numbers seem low.
Don’t have numbers from that dyno for similar combos...... so there’s a little bit of the “who knows” going on with that one too.
The big difference between that one and yours is, his bsfc numbers aren’t bad.
The power seems kinda low, but it’s not using tons of fuel either.

I’ve seen too much oil cause some pretty significant power losses on the dyno in the past.
 
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Trying to read the plugs, if the same plugs were used for the whole dyno session, is really a mute point. That plug does show rich in the low and mid throttle but who cares. It’s an unclear photo so it’s hard to get a good look at the porcelain or the ground strap. And cutting the shell would be nice but won’t tell you anything if the same plugs were used for all 7 pulls and too many changes were made.
 
I do agree with @Rat Bastid though, that plug is likely a little too hot even for a low ish compression engine.
 
Test, test, test. I will not make a recommendation. But instead of typing it all out I’ll paste this from Mike Canter on dragstuff.com

Spark Plug Heat Range
If you keep on adding timing until your finish MPH falls off but you still have no color on the plug’s ground strap but the porcelain has good color then your plug is too cold.

If you have lots of color on the ground strap but the porcelain is clean and white then the plug heat range is too hot. The heat from the plug is cleaning of the fuel ring from the porcelain.
 
And I’ve posted this before elsewhere but I’ll share it here as well. Great explanation of how to read a plug, although I wish he would delve further in to heat range.
 
I was just curious why you came to that conclusion .... I have read up on plug reading but it is not as absolute today with ethanol etc.. I have had plugs that were bright white but the AFR was rich and I could smell the raw fuel. It makes a Dark Art even darker...lol
 
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