Dyno BSFC question
 

Engine with quad rotor EFI that makes 1000 hp at 6000 rpm.
Brake specfic on the dyno was .603 at 4400 rpm and .650 at 5000 rpm and .701 at 6000 rpm at peak HP. Really fat engine. Question is can a very rich engine make power on the dyno yet be a real turd in a boat. The owner has been battling a boat that is slower than same hull setups. One engine builder told me horsepower is horsepower. I am wondering if the rich condition will not allow the engine get past the torque curve.

This is a more accurate picture

What did Bill think guys ? Isnt he a top notch builder you guys both know ? good luck , been reading the ongoing threads, good luck kirk

Running that rich is hurting you. I would run the BSFC at .50-.55. . .500 at the low end of the pull and .550 at the top end. Your giving up a ton of horsepower and yes it will run like a turd in the boat. Hope the rings are still in it! :eek:

Kirk this "motor" in question,it had high bsfc numbers before too but the afr's were correct?-was this the dyno sheet the owner got with it-
Smitty

Its not in question to me.

Yes its fat, but Gary Taylor has run this set up in his Howard Bullet for years with no issue. He builds the engine, rigs the boat and has done 130 MPH in a single. There is nobody on this board or industry that can claim that type of success in a single V. He built this engine and I trust him more than anyone. Is is the only engine he builds.

I might tune it in the boat, but it is not the reason why I am down 10 - 15 MPH. The torque and horsepower are there.

If I get ambitious and want to fine tune, its very easy and I have the program, laptop and cable. I have learned to modify the tables with a mutliper and have an O2 meter.
Piece of cake on an EFI.

I have bigger issues unfortunately. Drive? Hull??

I need Brads Skater with 6 drives. I can sell the 525's and buy another TPI engine! Problem solved. :evilb:

Bill (Ateco) and I are both wondering if the rich engine would hold it back in real world application versus a dyno pull where an engine brake matches the power. The obvious fix is to lean it down and install it back in the boat. But we are trying to figure out why Kirks boat would not run faster after such a great dyno pull. I can not help but think the fat engine won't run in a boat under a heavy load even though it makes 1000+ hp on a dyno.

I am also thinking a stepped hull like a Gary's Howard would allow the boat to get past the rich setup. I think I also heard Gary does not run his personal engine this rich.

IMO I have looked at the pictures Kirk has posted and I think the problem is with the hull/drive setup. I had a running rich problem when I put new motors in my boat and after it was dialed in running the boat, I saw no increase in top speed, just better running/idle and no more black transom.

I think that hull needs to go back to Florida and let the guys who built it take a look at it.

All my point is .......why leave power on the table. Yes, the power is very good , but can be better. And your EXTREMELY safe . It looks like a great combo!:cool-smiley-027:

.......why leave power on the table. ??? absolutely plus chance washin the cylinders down .....& losin the rings .... We were at .500 - .550 and made max hp and on the water plugs are coffee brown :cool-smiley-011: good luck KIRK call me need some 8 mm # 48 pulleys

I will verify the set up with an O2 in the boat under the real world load.. Its not a real bad suggestion Brad makes.

I've known him for a couple years and its actually the first time he made some sense to me. :)

Kirk, I spent some time comparing your dyno numbers to mine, although Crockett hasn't taken the time to get his fuel metering set-up working to get BSFC numbers,he does have wide band 02 sensors that read correctly. Your AFR'S are actually slightly leaner then mine,mine are closer to 11.5 under boost which makes my tune even richer then yours. I have no problem pulling past the tq peak,I highly doubt your AFR'S need to be leaner,your bsfc is a measure of how much fuel it takes to make 1 hp (overall effieciency),the numbers seem high BUT I wouldn't want to see you try to put your afr's into the 13's under high boost just to get lower bsfc's.
Dean Gellner-I have never heard of tuning a motor from the bsfc's,if a O2 sensor reads 12-1 at a given amount of boost,load and rpm and the bsfc ends up at .650 lbs per hr and you were to re-tune it to achieve let say .550 (a 18 % difference) wouldn't the afr theoretically change 18% also to 14.18-1? I agree the bsfc's seem high but they are what they are. Now maybe in your personal experience if you feel the afr's could be a little leaner,you would re-map the fuel injection map slightly until you achieved the afr reading you were looking for,lets say you went from 12-1 to 12.5-1 (4% leaner) the bsfc's would theoretically drop 4% also (.650 would now be .623),not a whole lot numerically. Just playing with the numbers.
I have been present when Crockett dynoed and tuned the last 3 motors I built and he swears a blower motor needs to be around 11.5 give or take a few tenths under hard,long sustained boost to stay together,whats your opinion on afr's under these conditions,Smitty

After getting some sleep and thinking about my conversation with kirk yesterday and after having a in-depth conversation with bob madera this morning I stand corrected on my last post. BSFC's are a measure of a engines effieciency at a certain rpm and load,PERIOD. In my last post I presented a scenario of "adjusting" the bsfc and having a resulting afr change reflected by the percentage of bsfc change,generally this can only be done on a 2 stroke engine. A 4 stroke engine has a bsfc or a certain amt of fuel its going to take to make each hp at a given load and rpm based on how effiecient the motor is. You CAN"T change the effiecieny without changing something mechanical (better scavening exhaust,less parasitic loss,better or more ideal camshaft events-ie lift/duration/timing of events,different or better flowing cyl heads). In kirks instance-you could change his air fuel ratio but why,its not pig rich by any means at 12-1 under boost. Something that isn't mentioned is his motor was dynoed with full accessorys and CMI elbow tops,they say you can't make 1000 hp with CMI elbow tops but he did. However it doesn't mean that they were ideal by any means,with his cubic inches and quad rotor whipple it is a fact that the exhaust will be backing up or be slightly in-effiecient which would give a higher bsfc number. Blower motors have inherently higher bsfc numbers due to the amt of power it takes to turn the blower (pumping losses,parasitic losses),there is also a certain amount of "blow-thru of fuel on a blower motor",fuel that does nothing other than simply pass thru the motor purging spent charge thru the combustion chamber un-swept area , kirks is no different especially at the power levels he is at,Smitty

I think you might be making a skewed comparison here without enough input calibration. BSFC's are very diificult to calculate on most dyno's , especially if the fuel flow rate sensors and such have not been exactly calibrated before the runs. When measuring fuel flow in Lbs. to calculate exact BSFC's the slight variations in fuel flow can skew the BSFC calculations quite a bit. That being said, I don't think if your wide band O2 sensors are calibrated and giving accurate readings that can be relied on that you would ever want to run a 1000Hp huffer at anything beyond 12.0 to 1 for sustained persiods in a boat. What were the EGT numbers at these readings and were they rising under a sustained pull with a slow rpm per second rate?, or did they level off at a sustainable number? Our dyno work tends to show that there obviously is a point where a fat motor will give up some power and rate of rise in power under loads, but its a pretty small percentage and the totally overfueling beyond whats needed for the blower life will definitly effect ring life and oil life.
I suspect the loss in boat performance here as it does in many boat powers is a hull, drive or prop issue.

Best Regards,
Ray @ Raylar

As I stated above I feel that the issue here is with the boat, not the motor. I looked in one of my books and here is what it says about BSFC.

"Fuel consumption over time can be used to measure efficiency as well. Fuel consumption is represented as a flow rate in pounds per hour, (i.e., mass flow per unit time). Brake Specific Fuel Consumption (BSFC)--fuel flow rate per unit power output--is the industry standard and measures how efficiently an engines uses the fuel to generate work. (HP) BSFC is another measure of how well an engine converts chemical energy into mechanical energy. It is computed as follows: BSFC=fuel flow in pounds per hour/ divided by/ brake horsepower. The BSFC will vary with rpm. A BSFC of
.50 or lower at peak torque is acceptable and considered normal. The lower the number, the more efficient the engine. A number of variables, such as frictional losses, parasitic drag, and pumping losses, will reduce overall efficiency."

After reading this article, my take is that his motor is just not that efficient, as we all know boat motors are not. He has verified that it is making the correct amount of horsepower that he paid for. I agree with Ray, the problem is probably not with the motor, but with the set-up on the boat.

Smitty

So Smitty and Ray are fixing my boat for me? Thanks guys!! When do we start?

Kirk

If I knew how to fix a hull problem I would gladly lend a hand. I am somewhat in the same position as you are. I have a ton of power but I am not as fast as I should be, and I know that someone out there is knowledgeable about setups on baja's. I just don't have the cash or time right now to dig into it.

I am sorry you are having so much of an issue. Don't for one second think that I am gloating about your issue. I would be just as frustrated as you are. I am just offering up my knowledge and think the hull is the issue here. Why don't you take it to Pantera and find out ???

Smitty

I'll stick to fix'in motors. I know just enough about hulls and drives to be dangerous!! I'll leave this type of fix'in to the real experts!

Best Regards,
Ray @ Raylar

I was just kidding Smitty!! :D

Kirk,
I know you were kidding. I just hate it when we work so hard and sometimes the $hit still doesn't work as planned !!

Kirk,

Seeing some of the other problems you have posted (boat listing to one side etc) I think your problem is in the setup and not necessarily the engine even though it is rich.

To me is sounds like you need to re-tune the engine, optomize drive height and reverse the rotation of your prop (new drive).

Just an educated guess based on what you've posted in the past.

PS, I have the same speed issue with my boat but I don't have the time or feel like spending the money to get the optimum setup...but I know what can be improved upon. Little here, little there....ya know.. ;)

I don't know if this is relevant, but if I run an outboard on a dyno (stuska), and then try and run the same fuel map on the lake, I have a pig fat motor. At least in my case, I can never get the motor to load like the water brake.... not even close. I have to takeout 5%ish.

Depending on the exhaust used on the dyno the engine is ususally a little fatter in the boat, at least from what I've seen...

in our case, we run it on a midsection so it is like it is on the boat.

My plan this summer. Pull the extension box off, remove one water pick ups and longer tabs.

I will set the X dimension where it was before with the bravo drive. Removing the intercooler pick up will help with wate flow to the prop and the longer tabs will stop the port tab from sticking into the water like a spike. I HOPE!!

At least these are inexpensive ways to change the set up for the better. I'll then run an O2 meter and fine tune the engine.

Then it will be new hull time.

I appreciate the input guys.

Hi Kirk,

As requested, I posted my emals to you on the forum.. (I added some more stuff, hope it helps)

Are you using an intercooler for that Quad Rotor, or are you using fuel to cool the charge instead? Was the VE indicated for the motor in the dyno run? Was the AFR on the very rich side? Was the reading on the dyno taken with 1 wideband, or 2 widebands? (Hopefully NOT a narrow band, as it will not give a correct reading at WOT. You must use a wideband, and better yet, 2 widebands, one in each header collector) Were EGT’s used on the dyno? (This would be the best, as you could correlate directly to cylinder to cylinder)

Reason I ask, is that I think the motor is not as efficient as it can be. However, it also depends on the design of the engine. If you are not using a big cooler, and run a bunch of heat through the motor, some people use the fuel to help cool the charge, which will affect the BSFC, the AFR, and the fuel comsumption.

If you are running a big cooler that is awic, then you also have to consider the size of the tank and the amount of flow of the pump, and the ability of the heat exchanger for the after cooler to reject heat into the raw water stream. Water has a speific thermal capacity, and can only take so much heat. The abiltiy of the second heat exchanger will play a part in the efficiency of the specific system based on coolant storage volume, heat input, coolant flow, intercooler efficiency, and secondary heat exchanger efficiency.

I have done extensive research on the intercoolers and efficiency, and the best I can find to date for AWIC is Laminova... (www.laminova.com)
Do you know the rated heat exchanger's efficiency that you are using? If so, at what airflow rate, and at what coolant flow rate is this efficiency level? Are you exceeding that level?

On another note, how fast are you spinning the compressors? (Are they Whipples? DO you have a compressor map that tells you the heat gain, pressure ratio, and airflow rate? ) What is the pressure drop across the core of the IC?

All these things add up to inefficiencies in the system...

If you are running efi, the computer could be trying to compensate for detonation by richening the mixture. If carb, then it may be jetted rich etc. The thermal capacity of the water in the tank could be exceeded if the tank is too small, and the cooler will not be as efficient. You can calculate all this out if you have the info.

In general, though, I believe your engine is using more fuel than it should to produce the stated power. Question is, why? I would examine sensors, and design of the motor for the given power output. There is something in the calculation that will not jive when compared to the Dyno readings.

Hope that helps with your diagnosis..

Richard

Quad Rotor Whipples, large intercooler.

Kirk,
Meet you at oshkosh poker run. We had a 27 daytona with a Pfaff 1000 in it. Let me say one thing tuning is not easy in a boat with EFI. We have had every expert brought in. I believe we can all say Pfaff is a recognized engine builder. You can ask any good marine builder after tuning on a dyno for a base line you must retune in a boat. They all build cookie cutter motors but every hull,gear ratio, prop size and every altitude puts different loads on motors. Put it this way G.M. puts 10,000 hrs of tuning to try all posibilities in each of there motors so they can recognize the changes needed. I believe you are on the right track by running the boat with an o2 sensor and see where you are. We gained an honest 12mph by tuning in the boat. Bottom was very lean and top was so fat it was washing the cylinders. Also remember every prop change or gear ratio effect the load times the computer reads. Just curious what system your using.

Hi Kirk,

Just browsed some of the posts again, and as you have EFI, I agree with BBoater. You must tune the EFI in the boat. The lake/river/sea is a perfect dyno, the prop functions as a water brake. You will need a good baseline, and then can play with the fuel and ignition maps as a function of load at various rpm points. Not sure which EFI you are running, but ideally, you would want to do some datalogging, and then evaluate on the laptop in the boat, then retune for optimum, then make some more passes, and tune some more until you have comfort that the system is operating as desired.

The land calibration dyno tune will need to be readjusted for your application, hull, prop, driving habits etc..

Hope that helps,

Richard

Its an Autronic and it appears much simpler than the Merc MEFI software I learned on. We actually have an Autronic tuner/distirbutor abut 4 miles from my boat and he said he would assist.

Maybe all of this together will help my cause.

Bboater - It was great meeting you, werent you guys talking about drive issues? How did you work that out? I cant believe you picked up 12 MPH with the tuning!! Honestly?

Get a hold of Enzo... JCPERF and Richie Zul's EFI wizard....

He recently tuned Byrdmans 1700+ engines "in the boat" and also assisted Gatorone in tuning his new rig....

Enzo tunes realtime while you're driving the boat, he's excellent from what I've been told!

Tyler Crockett did mine while on the fly. My buddy held his laptop while we were moving and he made his adjustments.

3000 rpm to 5400 rpm in 200 rpm increments.

The Autronic is a piece of cake. I need to get the boat back together first.

Ordered longer tabs today and will order a two staged water pump tomorrow. Will pull one pick up off the transom.

Waiting on info on the plate to pull of the extension box and bolt the transom assembly on the transom direct.

Autronic is what we ran on the 27. I will tell you that depending on which Autronic program you have its a great program but one of the hardest. Seems easy but there is a massive amount of small tunes that are preprogramed. Carl Summers is the god of EFI he has tuned on all programs. He was our third tuner we had come out. Worked wonders.

As far a the 27 goes shes gone! It ended up running 126mph better than its 114 we started with. Drive issues played a massive role in our tuning problems. We went through 5 drives last year. Finaly got to the point that we tell B-max either give us our money back or we were going to have to sue. So they finaly after the entire season sent us an actual new drive. Never drove it after that.
We just brought back the new boat after Desert storm poker run. 33 daytona with 700mercs Nxts couldnt be happier an HONEST 137 on the limiter. No issues at all! Ran 126 with 6 200 lbs+ guys, two coolers,100 degress and full of fuel.

You dont talk up a boat like that without pictures!!!!!

Lets see them!!!

I will learn some more before tinkering with the program. There is a very well known Autronic guy near me that will help if needed.