Dyno proven 675-700 HP 540CI recipes?
08-05-2015, 06:49 AM
#261
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I find that very hard to believe, especially with gil manifolds at that power level. Ive seen many marine exhaust comparisons over the years. Blown engines, not as sensitive to exhaust tuning. Bigger ci na stuff, prinary diameter, length, collector length, collector size, all can have a major effect . One in particular 2 weeks ago was a NA 572 build with cmi tractor pipe headers. They had short 6 inch tails with a small silencer type of baffle to keep the noise down. Not really a restrictive looking piece, but , i suggested to remove them and do another pull. 41hp gain, and 38ft lbs if i recall.
Also, a well known oso marine engine builder recently ran a mild 509 build on the dyno with the stock 4780 holley 800. He borrowed a 1050 quick fuel 4150 blower carb from us. After fine tuning it, as it was pretty rich, the engine picked up 50-60hp over the stock 800 holley.
Of course, this is where the dyno comes to play. I try to keep my advice on oso based on what ive done, seen, etc.
Also, a well known oso marine engine builder recently ran a mild 509 build on the dyno with the stock 4780 holley 800. He borrowed a 1050 quick fuel 4150 blower carb from us. After fine tuning it, as it was pretty rich, the engine picked up 50-60hp over the stock 800 holley.
Of course, this is where the dyno comes to play. I try to keep my advice on oso based on what ive done, seen, etc.
08-05-2015, 06:51 AM
#262
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Not that this has anything to do with Tim's motor but I thought it was very interesting. Talking to guy at the Marina last weekend (builds a lot of nice motors) years ago he built an 850 for a Pantera. Had the dyno setup to run Marine Headers. Dyno'd with CMI's made 850 put on dry dyno headers (car) made 850 and some change. Thought for the heck of it throw on some Gil's went over 900. Hmmm put dyno headers back on 850 and change.
08-05-2015, 07:06 AM
#264
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I find that very hard to believe, especially with gil manifolds at that power level. Ive seen many marine exhaust comparisons over the years. Blown engines, not as sensitive to exhaust tuning. Bigger ci na stuff, prinary diameter, length, collector length, collector size, all can have a major effect . One in particular 2 weeks ago was a NA 572 build with cmi tractor pipe headers. They had short 6 inch tails with a small silencer type of baffle to keep the noise down. Not really a restrictive looking piece, but , i suggested to remove them and do another pull. 41hp gain, and 38ft lbs if i recall.
Also, a well known oso marine engine builder recently ran a mild 509 build on the dyno with the stock 4780 holley 800. He borrowed a 1050 quick fuel 4150 blower carb from us. After fine tuning it, as it was pretty rich, the engine picked up 50-60hp over the stock 800 holley.
Of course, this is where the dyno comes to play. I try to keep my advice on oso based on what ive done, seen, etc.
Also, a well known oso marine engine builder recently ran a mild 509 build on the dyno with the stock 4780 holley 800. He borrowed a 1050 quick fuel 4150 blower carb from us. After fine tuning it, as it was pretty rich, the engine picked up 50-60hp over the stock 800 holley.
Of course, this is where the dyno comes to play. I try to keep my advice on oso based on what ive done, seen, etc.
08-05-2015, 07:14 AM
#265
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When you have guys like david vizard, whos spent a lifetime on a dyno, porting heads, chasing and testing theories, companies who build and manufacture carburetors for a living, and many others whove proven a dominator carb is worth power on a big block chevy making in excess of 650hp or so, its kinda hard to argue unless you are willing to dyno yourself and make the changes. Slapping on a 1993 dominator to replace a well tuned 4150, and doing 1 pull,, doesnt tell the story.
In each of my above examples both carb and exhaust, the engine needed retuning for the changes. Ive seen guys bolt on a different exhaust, watch the engine get substantially leaner, and power go down. And vice versa. This goes for all mods. You dont slap on a new set of heads, or new intake, and not bother retuning to get the engine back to a proper state of tune.
Would tims engines benefit from cleaning the procomp intake up or replacing it with a different intake, would changing the exhaust help, would changing the cam, advancing or retarding help, would losing the locked timing and doing a custom curve help, would a carb spacer help, would going to a smaller carb help, would going to a smaller runner head help, etc etc.
Its really just speculation on our part . I know i used to see haxby, and a couple others , put up some impressive numbers on 540s, using smaller heads than the 325s. Some pretty torquey setups using the 305s, 290s, etc that still pulled to 6000. Would that have been the way to go on this build?
I think at the end of the day, it is what it is. I think he may have been happpier with his old 420 mercs and a blower . He would have saved probably 50k dollars, and been going faster than he is now
In each of my above examples both carb and exhaust, the engine needed retuning for the changes. Ive seen guys bolt on a different exhaust, watch the engine get substantially leaner, and power go down. And vice versa. This goes for all mods. You dont slap on a new set of heads, or new intake, and not bother retuning to get the engine back to a proper state of tune.
Would tims engines benefit from cleaning the procomp intake up or replacing it with a different intake, would changing the exhaust help, would changing the cam, advancing or retarding help, would losing the locked timing and doing a custom curve help, would a carb spacer help, would going to a smaller carb help, would going to a smaller runner head help, etc etc.
Its really just speculation on our part . I know i used to see haxby, and a couple others , put up some impressive numbers on 540s, using smaller heads than the 325s. Some pretty torquey setups using the 305s, 290s, etc that still pulled to 6000. Would that have been the way to go on this build?
I think at the end of the day, it is what it is. I think he may have been happpier with his old 420 mercs and a blower . He would have saved probably 50k dollars, and been going faster than he is now
08-05-2015, 07:22 AM
#267
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Yes I do wish I kept the warmed up 420's and put pro chargers on them, that thoughts gone now lol
I have to work with what I got I think the combo just is too big for my heavy low rpm hull talked to Cigrocket got his combo, 315 heads and 741 cam pushed him 74-75 so again I guess I'm close just gotta tune it best I can and leave it alone, there is something to be said if it runs every weekend also....
I have to work with what I got I think the combo just is too big for my heavy low rpm hull talked to Cigrocket got his combo, 315 heads and 741 cam pushed him 74-75 so again I guess I'm close just gotta tune it best I can and leave it alone, there is something to be said if it runs every weekend also....
08-05-2015, 07:46 AM
#268
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I won't believe it NA, because I won't believe it. LOL.
Unless......the 'collector' lengths and ID where at 'worst' lengths with the headers. Be careful on this, even the dyno ! I had a 600hp 454 that gained almost 80hp (proven at track too) that by mistake found out it had 'worst' length and design collectors. More exactly, it was a 525hp motor that became a 600hp motor. Yup. Carburetor ended up 'taking' almost 10 more jet sizes. Best tune vs best tune.
Once figured out, even ran into mild 300hp level motors that where shot in the azz to the tune of 30 or so hp.
08-05-2015, 08:02 AM
#269
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Be thankful your boating FF, Im not
08-05-2015, 08:03 AM
#270
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Supercharged ?
I won't believe it NA, because I won't believe it. LOL.
Unless......the 'collector' lengths and ID where at 'worst' lengths with the headers. Be careful on this, even the dyno ! I had a 600hp 454 that gained almost 80hp (proven at track too) that by mistake found out it had 'worst' length and design collectors. More exactly, it was a 525hp motor that became a 600hp motor. Yup. Carburetor ended up 'taking' almost 10 more jet sizes. Best tune vs best tune.
Once figured out, even ran into mild 300hp level motors that where shot in the azz to the tune of 30 or so hp.
I won't believe it NA, because I won't believe it. LOL.
Unless......the 'collector' lengths and ID where at 'worst' lengths with the headers. Be careful on this, even the dyno ! I had a 600hp 454 that gained almost 80hp (proven at track too) that by mistake found out it had 'worst' length and design collectors. More exactly, it was a 525hp motor that became a 600hp motor. Yup. Carburetor ended up 'taking' almost 10 more jet sizes. Best tune vs best tune.
Once figured out, even ran into mild 300hp level motors that where shot in the azz to the tune of 30 or so hp.
