Brad Zastrow

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.

ROB FREEMAN

iTrader: (2)

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

mrhorsepower1

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!

articfriends

iTrader: (1)

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

Brad Zastrow

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.

Smitty

iTrader: (1)

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.

mrhorsepower1

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!

RunninHotRacing163.1

.......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 good luck KIRK call me need some 8 mm # 48 pulleys

articfriends

iTrader: (1)

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

articfriends

iTrader: (1)

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