496 Mag Dyno testing and myth busting!

[Petesflht]

Ftmbob-
Thanks for the great info...
I pretty much have the same set up. And it's always great to get some "straight" info...
Have you done the same with a whipple install?
Just curious on what the real numbers turn out to be...I went the whipple route and love it..
Thanks again
JF: You running the Whipple on a 496? Any problems, have been contemplating this route. Thanks

[brad22]

Results are in. IÂ’ve finally completed some comprehensive dyno testing of a 496HO and various exhaust systems. ItÂ’s rather lengthy so I published it on our web site. Please check it out. I spent all the time and effort for you guys. Go to www.fullthrottlemarine.com and click on high performance projects.
Bob
Hi Bob,
I looked at the dyno sheets and I have as many questions as I do answers. The information you provide looks very inaccurate or at least confusing. The prop Dyno from Land and Sea is not a bad unit. However can you explain what type of engine dyno and data acquisition hardware you are using as at first glance it seems some what of a lower end system. As it should be able to produce consistent results within 1 to 2% if the dyno room air is adequate, which it looks like it wasn't ?? :idea:
The Dyno sheets don't have enough information to prove much more than the engines were run ? Can you provide brake hp and explain why the fuel flow was so different from run to run ? Also when the exhaust was changed without returning for re-calibration of each combination, how could you expect the best from each part? It looks more like a novice operator other than deceit but with more than 3000 dyno hours under the belt I would love to see the non-corrected information in its complete form so the world could understand the "truth or Myth"
Looking forward to your response,
Brad

[Dave C]

thanks for that info.

[DMOORE]

Bob, thanks for the post. It's great to see what bolt on's really do for a motor.
Darrell.

[Just foreplay]

Petesflht
I'll send ya a pm, I don't want to jack the thread

[ULTRA26 # 1]

Thanks for taking the time to do this. Several of us are curious what this motor will and won't do. The data you have acquired thus far is a great help. I also like that you didn't correct the numbers at all. I, for one, don't care what the numbers are on a perfect day (29.92) at sea-level. I don't ever recall boating on a perfect day on the ocean. Therefore, real-time, real-world numbers are what we deal with day to day.
The video of the red Nordic engine that you guys did a Raylar package on is one of my favorite vids. I have posted the link several times here on the exhaust threads, since it shows Lightnings on a 496.
Thanks again.
I couldn't agree more. That motor sounds good. Mean ldle

[ftmbob]

Hi Bob,
I looked at the dyno sheets and I have as many questions as I do answers. The information you provide looks very inaccurate or at least confusing. The prop Dyno from Land and Sea is not a bad unit. However can you explain what type of engine dyno and data acquisition hardware you are using as at first glance it seems some what of a lower end system. As it should be able to produce consistent results within 1 to 2% if the dyno room air is adequate, which it looks like it wasn't ?? :idea:
The Dyno sheets don't have enough information to prove much more than the engines were run ? Can you provide brake hp and explain why the fuel flow was so different from run to run ? Also when the exhaust was changed without returning for re-calibration of each combination, how could you expect the best from each part? It looks more like a novice operator other than deceit but with more than 3000 dyno hours under the belt I would love to see the non-corrected information in its complete form so the world could understand the "truth or Myth"
Looking forward to your response,
Brad
Brad, I appreciate your thoughts. As I stated in the article I'm using a Land & Sea unit. No it's not a DTS but does a pretty good job. I use the same absorber on the engine stand. I'm using L&S data acqusition system(as stated in the article) and wide band 02 for A/F data. Not sure what you mean by repeatablility, I made several pulls in each configuration and they were all within 1-2 HP. The fuel flow variance is an issue with the transducer. The pulls were all data logged using Diacom software so I've got the actual fuel flow data from the computer. Additionally The BSFC on the prop shaft is skewed because of the loss through the drive. I can certainly give you the non corrected data. I can tell you that the correction factor varied from 4-5% on all the runs. As far as tuning with each combination there is no doubt that each could be optimize. I'm sure you are aware you don't have any tuning control with the PCM 555. The A/F ratios were within an acceptable range in the higher RPM ranges on all the tests(slightly lean on a couple in the lower rpm range). Weather data was collected using an automatic weather station directly connected to the dyno. The sensor was situated near the flame arrestor.
Bottom line is I have no interest in what the results are. I'm just trying to provide data that so far has not been available. I'm confident the readings are accurate, plus the in boat performance correlated exactly with the data.

[cfm]

Brad22 - I don't know you thus these questions.
Do you engine dyno with full wet exhausts ie: where water actually enters exhaust stream?
Do you have a propshaft dyno ?
Just asking since I'm always looking for more data and seeing 'who does what.'

[brad22]

Brad, I appreciate your thoughts.The fuel flow variance is an issue with the transducer. The pulls were all data logged using Diacom software so I've got the actual fuel flow data from the computer. I can certainly give you the non corrected data. As far as tuning with each combination there is no doubt that each could be optimize.
Bottom line is I have no interest in what the results are. I'm just trying to provide data that so far has not been available. I'm confident the readings are accurate, plus the in boat performance correlated exactly with the data.
First of all I do appreciate your attempts and efforts that you have put into this Bob there is no doubt about that.
Now that I got that out of the way
On any DAQ system we have used, the fuel flow transducer reports to the DAQ systems logger. How can you get good numbers from a transducer with an issue?
I understand that you need tuning control. You need to understand that you cannot test parts that require changes if you are unable to make them. The only acceptable AFR is the correct one. This needs to be done with air flow and fuel flow instrumentation.
Good data that is not available is far better than bad data that is available. This is especially important when results are being interpreted by layman who only know how to read a dyno sheet by looking at peak numbers of TQ and HP. Bottom line is you need to provide BHP, Fuel Flow Air numbers as well as tuning techniques so readers have a chance at making an educated decision on parts purchases.
If you say you have no interest in results, why care enough to provide information that is not 100% accurate??

[slovolvo]

We're running a 24P B1 prop at 5000 RPM on this boat, for 65 MPH, right on the rev limiter of 5050. You would need to be turning over 5300 RPM to get 69with the same setup. You are getting some incredibly good slip numbers to get that speed with a 24P prop or you've had the PCM reprogrammed to raise the rev limiter.
Must be excellent slip numbers, the boat is stock, I don't get it. I ran 70.1 and 70.4 on two separate passes 3/4 full of fuel with 4 people yesterday(same 24p B4). Maybe the handheld GPS lies?? The boat speedo was reading over 75, which seems to be consistant with its inaccuracy. 7% slip seems tough to believe though...