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Old 07-26-2016, 10:39 PM
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Sweep 6 , is using 75lbs more fuel per hour, yet with a leaner air fuel ratio according to those sheets?
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Old 07-26-2016, 11:06 PM
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Sweep 6 was with 86/90 jets. I don't have the notes with me for jetting on sweep 11. It looks to me like 6 is using more fuel when you look at bsfc and lbs but like you mentioned sometimes leaner or very little change in O2. And get this, even though he told me he was fattening it up to get egt down the cooler egt is with the leaner bsfc/lbs. Sweep 6 had some egts close to 1500, sweep 11 was cooler. I just started looking at the sheets today. He says it must be burning more efficiently even though we are putting more fuel in. Keep in mind we also saw a power loss from sweep 6 to 11. I'm at a loss.
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Old 07-27-2016, 04:20 AM
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Lol, so mis informed, as usual... don't forget, YOU bashed ME.... good luck carry on..

Originally Posted by bck
full force, i figured with no interaction with you for several months i'd check and see if you grew up a bit. Guess not, so i'll take the low road with you for a post. The engines made over 700hp back in feb and made over 700 again this week.they made more torque than yours made horsepower even with your blog cabin build threads and two failures due to your incompetence before they ran. What will mine make with accessories? Whatever they make, i don't care. If you actually read the many dyno sheets i took the trouble to post instead of just rambling on like a child you'd see where some of your missing hp is. I'm happy with the parts that i approved of and purchased like an adult and the power results i'm seeing. I don't need to have a boat as an extension to look down and see my p*nis so i'm not losing sleep over when or if i get the engines in. I also don't need you to tell me if i'm happy with my engines or the people that helped build them. I'm going to sum up every post you make very nicely " i don't like bob or phil, i really can build an engine, it's someone else's fault, my cigarette is better than whatever you have and i run my boat harder than everyone else". Now you can go back to being blocked and maybe i'll see if you have anything intelligent to say in another 6 mos or so. My apologies to everyone else for derailing my own thread, but i have dealt with so many disappointing people in the marine industry that my tolerance level for any form of bs is nil even on a forum.

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Old 07-27-2016, 06:09 AM
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Originally Posted by MILD THUNDER
Sweep 6 , is using 75lbs more fuel per hour, yet with a leaner air fuel ratio according to those sheets?
This is very odd. But is it ?

Below are my experiences and thinking, which is not anywhere near as some people, but more than some others. So, always take what I say with some grain of salt, but atleast think about it. LOL.

I have a semi theory - semi meaning I have seen this a few times and usually on a faster sweep rate like the OP's dyno has been using. 600rpm/sec.

What causes less fuel flow but richer fuel A/F's other than equipment not reading correctly ?

Fuel bowls !

If the needle and seats are closed (bowl is full) what happens ? Less or no fuel flow into them. Yup ! But there is still fuel coming thru boosters and into engine right ? Yes. So, of course fuel is still flowing into engine , but the fuel flow meters are measuring fuel flow into the bowls.

Furthermore, having much larger Needle and seats than what is needed causes longer time periods between 'on/off' of fuel flow into the bowls. Why ? They fill the fuel bowls faster. Note: this is effecting dyno sensor readings, not actual engine performance.

So....just something else that throws some curve balls into things, especially when total faith get's put into data without knowing everything that effects it.

Thios is yet another reason I'm a bigger advocate of slower sweep rates.

Why are their many different choices of sweep rates on dyno's ?

To better mimic the actual acceleration rate of the engine in the vehicle it's going in.

Boats obviously have a very slow acceleration rate because of 1 speed 'transmission', weight, and load.

How fast does the typical performance boat accelerate from say 3000-5500 ? A while. Definitely not 600rpm/sec, nor even close too that. 300rpm/sec (lower setting for most dynos) - nope ! But atleast this is twice as slow as 600rpm/sec. Which is twice as long for things to 'stabilize' if that's even possible at 300rpm/sec.
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Old 07-27-2016, 06:25 AM
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I discussed sweet rates with him and attempted to get him to slow the sweep rate to 200- 300. He tried to do it, I saw him turn the sweep rate control down. The sweep rate did slow down from the previous 800 but did not come down to 300. He has no idea why. He continues to challenge my faith in his abilities at every turn. When we discussed the fuel issues last night he said he places little faith in any data and based most of his tuning off plug readings.
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Old 07-27-2016, 06:32 AM
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Heres a question I have, regarding plug readings.

Lets say, you have a -6 NGK plug in the engine, and you are looking for timing . You are on the dyno doing pulls. You adjust the timing to where the heat line looks "good" to you. What happens when you stick a -8 NGK plug in it? Theoretically, you would be able to put more timing in it, to get the heat line where you want it. But does that mean the engine likes or doesnt like it? Who says what plug is correct heat range?

My thought process would be, give the engine the timing it likes, and check the plugs. Then , adjust your heat range from there.
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Old 07-27-2016, 06:45 AM
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All the fuel data I have is in the attachment on my other post. The engine made 5- 10 hp and ft lbs less on sweep 11. The egts were also cooler on sweep 11. The other engine is going on tomorrow I believe. I'll get print outs of every jet change, not just first and last. All the runs from this last engine might still be in the computer so I'll see if I can grab them. Anyone plan on being in Bflo tomorrow and want ro attend? No charge.
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Old 07-27-2016, 06:54 AM
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Sb, you mean something slower sweep rate like this? https://youtu.be/OeJ_7-hpzq0

Last edited by MILD THUNDER; 07-27-2016 at 06:58 AM.
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Old 07-27-2016, 07:32 AM
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Yup. Was that 200rpm/sec ? Appears pretty slow.

Just so people know, 600rpm/sec seems to be the standard rate as 95+% of sheets you see show 600rpm/sec. I'm just proposing here, and others agree, closer to actual engine accelration rates will of course be better. That's why OEM's and big $$$$ race outfits will dyno (huge $$$ dyno) for actual conditions. Example: road race engines will be dyno'd as it's at a certain track. Acceleration, deceleration, shifts, and etc will be done as close to exact on dyno as it's 'being driven' . Obviously not just for power/hp, but for tuning and alos component durability, and etc.

https://www.youtube.com/watch?v=J-62SiWKJzM
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Old 07-27-2016, 07:36 AM
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One last distraction , just cause I love this stuff.

Most extreme I have seen is Porsche's oil sump dyno testing. It simulates running the Nurburgring (sp?) track Yikes !

https://www.youtube.com/watch?v=fv53RbvgfGc

Last edited by SB; 07-27-2016 at 07:38 AM.
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