Dyno Results
07-03-2014, 11:29 AM
#21
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I'd probably be bumping that timing a bit. 9:1, aluminum heads, more agressive cam, short stroke, I'd prob be shooting for 34 at least, maybe 35-36. Did you guys play with the timing on the dyno?
Its common in the car world to pull timing back for a safety margin. In marine engines, doing so, can lead to high exhaust temps, tuliped valves, etc. I woulda been giving it some timing on the dyno to see what it likes after getting the AFR close to where I wanted it.
It almost kinda sounds like you didnt get your moneys worth on the dyno session. I think the whole reason to dyno, is to get a good tune, rather than power numbers. If he didnt give the engine the fuel it wanted, timing it wanted, etc, than its kinda a waste of time. Its not usual that you remove a properly tuned engine off the dyno, install it in a boat, and then have to ADD more fuel. Usually if anything, you'd need to remove a little fuel when in the boat. The BSFC numbers on your sheet look all over the place, I'd like to see what the 02's were reading.
Its common in the car world to pull timing back for a safety margin. In marine engines, doing so, can lead to high exhaust temps, tuliped valves, etc. I woulda been giving it some timing on the dyno to see what it likes after getting the AFR close to where I wanted it.
It almost kinda sounds like you didnt get your moneys worth on the dyno session. I think the whole reason to dyno, is to get a good tune, rather than power numbers. If he didnt give the engine the fuel it wanted, timing it wanted, etc, than its kinda a waste of time. Its not usual that you remove a properly tuned engine off the dyno, install it in a boat, and then have to ADD more fuel. Usually if anything, you'd need to remove a little fuel when in the boat. The BSFC numbers on your sheet look all over the place, I'd like to see what the 02's were reading.
07-03-2014, 12:14 PM
#22
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I couldn't be there for both dyno sessions. I know he told me he did try spacers but they made things worse and he checked the jets to know what was in there. They switched out carbs, fp, distr to try and identify the power difference between the two engines but all still the same. Also due to lack of communication, they had the timing locked at 32. They didn't have my TB IV ignition module so they used their dyno stuff. When i went to check the timing i noticed it way up and had to bring it down due to the 24degree advance in the module.
Should i set initial timing at 10 and let the module do the rest or set to total of 34 at a certain rpm and let the initial fall where it may?
While on the dyno we discussed trying to simulate cruising speed but the dyno just can't do it. it's WOT or nothing, he tried but it wasn't worth it. From reading on OSO I've always seen that they way the motor reacts on dyno is usually different than what you see in actual boat due to cruising loads and actual resistance due to weight of boat. This leads me to believe that even thoughit dynoed ok with 85 jets it's no wonder I need to step up the jets due to the extra load present in the boat. I'm still trying to learn all this stuff and apply it so I appreciate all of you guys taking the time to give your thoughts on this.
Should i set initial timing at 10 and let the module do the rest or set to total of 34 at a certain rpm and let the initial fall where it may?
While on the dyno we discussed trying to simulate cruising speed but the dyno just can't do it. it's WOT or nothing, he tried but it wasn't worth it. From reading on OSO I've always seen that they way the motor reacts on dyno is usually different than what you see in actual boat due to cruising loads and actual resistance due to weight of boat. This leads me to believe that even thoughit dynoed ok with 85 jets it's no wonder I need to step up the jets due to the extra load present in the boat. I'm still trying to learn all this stuff and apply it so I appreciate all of you guys taking the time to give your thoughts on this.
07-03-2014, 12:58 PM
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Joe,
I know this isn't the same but I wonder why merc pulls timing on NA 350 MPI Mags at 3800 rpm's from 32 to 29 and at WOT it's 27. Most guys I talk to with NA dyno experience say the HP / Torque gain is minimal with more timing. But these are street NOT marine guys. Hard for me to believe that though. I know Vortec heads burn pretty quickly but saving the exhaust valves from unnecessary abuse and gaining some HP makes sense to me.
For entertainment purposes I've attached a tune screen shot video that is currently being edited by youtube. Info starts at 4:20 mark if the edit hasn't completed. Headed to the Lake to pull idle fuel and add top end fuel now. Cam change...
https://www.youtube.com/watch?v=8dPHaOpAFLI Andy
I know this isn't the same but I wonder why merc pulls timing on NA 350 MPI Mags at 3800 rpm's from 32 to 29 and at WOT it's 27. Most guys I talk to with NA dyno experience say the HP / Torque gain is minimal with more timing. But these are street NOT marine guys. Hard for me to believe that though. I know Vortec heads burn pretty quickly but saving the exhaust valves from unnecessary abuse and gaining some HP makes sense to me.
For entertainment purposes I've attached a tune screen shot video that is currently being edited by youtube. Info starts at 4:20 mark if the edit hasn't completed. Headed to the Lake to pull idle fuel and add top end fuel now. Cam change...
https://www.youtube.com/watch?v=8dPHaOpAFLI Andy
07-03-2014, 03:08 PM
#24
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Im not too familiar with the SBC stuff andy, but its all relative in a way. The fast burn chambers simply dont require nor allow, as much timing as your typical open chamber head. When you get into reshaping the chamber and the way the whole burn process goes down, it alters the entire combustion process.
Sort of similar when you get into different piston shapes and dome sizes and what not. I wouldnt recommend 36* of lead with a fast burn chamber marine deal. It all pretty much boils down to having the most efficient combustion process inside the cylinder. Generally speaking, if you light the combustion off too early (more timing), you can see an increase in power from a higher cylinder pressure, but also, too early and you could get preignition, or detonation if the cylinder pressures exceed the octane level fuel being used, which we all know is not good. Light the combustion off too late, and you can get away with a little more, but the power will be reduced, and the exhaust temps can get hotter. Finding that happy median is the goal.
I see lots of guys on the street stuff, pulling a bunch of timing, so they can run more boost say on pump gas. Which works in their application. But, they arent holding the throttles down for 15 minutes either, let alone even 15 seconds. I'd like as much timing as my combo will allow (octane, boost, cam, compression, etc) , without getting into preignition.
There is an area of the RPM band, that timing can usually be pulled from, or should be pulled from. And that is at Peak Torque. For example. A BBC marine build, might like 35* at 6000RPM. But, around peak torque, 35* might get into trouble. So for years, before we had any fancy ignitions, guys simply lowered the timing all together. Now they have stuff out, even for carb'ed engines, that you can map the curve, so that maybe you'll have 36* at 3500, 30* at 5000, and back up to 36* at 6000. Generally speaking, i think of ignition lead, as more of a tuning episode for a healthy engine, more so than a power adder. Giving the engine more timing in a quest for power returns, usually results in meltdowns. Retarding it in a quest for "safety margins" can also result in tuliped exhaust valves, etc. Also why inconel, or ferrea super alloy exhaust valves are so popular in marine, even N/A marine stuff. Simply put, the exhaust valves get fukin hot.
Most of this stuff is better answered by guys like Eddie Young, Alex Haxby, Bob Madera, and other guys much more knowledgeable than me. Im just a truck driver!
Sort of similar when you get into different piston shapes and dome sizes and what not. I wouldnt recommend 36* of lead with a fast burn chamber marine deal. It all pretty much boils down to having the most efficient combustion process inside the cylinder. Generally speaking, if you light the combustion off too early (more timing), you can see an increase in power from a higher cylinder pressure, but also, too early and you could get preignition, or detonation if the cylinder pressures exceed the octane level fuel being used, which we all know is not good. Light the combustion off too late, and you can get away with a little more, but the power will be reduced, and the exhaust temps can get hotter. Finding that happy median is the goal.
I see lots of guys on the street stuff, pulling a bunch of timing, so they can run more boost say on pump gas. Which works in their application. But, they arent holding the throttles down for 15 minutes either, let alone even 15 seconds. I'd like as much timing as my combo will allow (octane, boost, cam, compression, etc) , without getting into preignition.
There is an area of the RPM band, that timing can usually be pulled from, or should be pulled from. And that is at Peak Torque. For example. A BBC marine build, might like 35* at 6000RPM. But, around peak torque, 35* might get into trouble. So for years, before we had any fancy ignitions, guys simply lowered the timing all together. Now they have stuff out, even for carb'ed engines, that you can map the curve, so that maybe you'll have 36* at 3500, 30* at 5000, and back up to 36* at 6000. Generally speaking, i think of ignition lead, as more of a tuning episode for a healthy engine, more so than a power adder. Giving the engine more timing in a quest for power returns, usually results in meltdowns. Retarding it in a quest for "safety margins" can also result in tuliped exhaust valves, etc. Also why inconel, or ferrea super alloy exhaust valves are so popular in marine, even N/A marine stuff. Simply put, the exhaust valves get fukin hot.
Most of this stuff is better answered by guys like Eddie Young, Alex Haxby, Bob Madera, and other guys much more knowledgeable than me. Im just a truck driver!
07-03-2014, 05:58 PM
#25
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I know I have been called out on this before by someone saying that BSFC doesn't matter, but everything I read is from 0.48-0.55 on a NA engine. (mine are 0.52) his look extremely high. What are the AFR #'s?
My 454's are 76 primaries and 82 secondaries with 6.5PV's at a 12.6-12.8 AFR's for reference.
My 454's are 76 primaries and 82 secondaries with 6.5PV's at a 12.6-12.8 AFR's for reference.
07-03-2014, 08:53 PM
#26
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Well with all this good advice, not to jack his thread but, I have a question myself! I just had a new motor built and don't want to see any problems down the road! My machine shop mainly does race car motors, and has done quite a few boat motors but does not special in boat motors! How ever we dyno'd it at a mild pull at 36* timing, 579 ft tq @4200 and 530 hp @5500 finial pull ended at 38* timing, 582 ft tq 550hp, @5500! All with a 800 cfm hp500 Holley 82 front 92 rear 6.5pv! Msd programmable box and msd dizzy! I've ran the boat twice but y'all kinda worrying me with all this timing stuff! So my Q? Is? I'm only running it at 36* right now and not sure I should put it where we dyno'd it at peak, bump it up or down are just leave it alone! Or pull a little out around the highest tq numbers and bring it back in after it starts to fall off! What do you guys think? It runs good just want it safe also!
07-03-2014, 09:16 PM
#27
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Carb should have a provision for a PV. Check both just to see if other carb has two.
The possible ding dong who owned them before could have put two primary metering plates on one carb and two secondary plates on the other.
I have never seen a 4150/4160 carb without atleast one metering block with a PV provision. With one provision, it will be in the primary metering block.
The possible ding dong who owned them before could have put two primary metering plates on one carb and two secondary plates on the other.
I have never seen a 4150/4160 carb without atleast one metering block with a PV provision. With one provision, it will be in the primary metering block.
07-04-2014, 08:32 AM
#28
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Those Brake Specifics (BSFC) are horrible !!! Both sheets, #2 sheet being the worse.At some points your #2 sheet is looking like a 2 stroke is being dyno'd. IE: in the 9's.
Rookie is correct in where most BSFC's fall.
Remember, BSFC show's how much fuel is being used for each horsepower.
Sorry, but your's are junk. No effort was made to tune these engine(s).
Was tuning part of the agreement for the dybo test - some places don't get involved and some do. Some do for extra $$$ and some don't. This always needs to be discussed when setting up a dyno session.
Rookie is correct in where most BSFC's fall.
Remember, BSFC show's how much fuel is being used for each horsepower.
Sorry, but your's are junk. No effort was made to tune these engine(s).
Was tuning part of the agreement for the dybo test - some places don't get involved and some do. Some do for extra $$$ and some don't. This always needs to be discussed when setting up a dyno session.
07-05-2014, 03:47 PM
#30
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I agree the bsfc numbers are awful. My assumption was that they were not true bsfc readings.
When you run a boat and go to shut it off and it "runs on " or "diesels" it's way hot in the chambers. If the fuel was that rich as the bsfc numbers show, I can't see that happening. It's all guessing without afr numbers or even plug readings at this point.
Rookie what size are your carbs ?
When you run a boat and go to shut it off and it "runs on " or "diesels" it's way hot in the chambers. If the fuel was that rich as the bsfc numbers show, I can't see that happening. It's all guessing without afr numbers or even plug readings at this point.
Rookie what size are your carbs ?
