pump gas 540...
11-23-2015, 12:35 PM
#1
pump gas 540...
I was going to post this in the 310 thread but it's gotten so far off track that I figured I'd run this up it's own flag pole and show the kind of power a pair of AFR 305's with a hyd. roller can make on pump gas. No need to make the argument that this is a "car" engine...an engine doesn't know what it's going in, it only knows to make a given amount of power in a given rpm range. Compression, cam and headers probably wouldn't make this too marine friendly but you have to love the power @ 6100-6400 and how it holds almost 670 tq for over 1400 rpm. Just showing the potential for the 305's on a very mild pump gas 540. I'll try to get more details on the build for comparison sake. It's a 4150 carb on a Vic Jr.
Here's the dyno sheet. This is one of our "car" customers, not even sure who's dyno but I think Owens.
Here's the dyno sheet. This is one of our "car" customers, not even sure who's dyno but I think Owens.
11-23-2015, 05:23 PM
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I would love to see the specs also.... seems my 325 CC heads are WAY too much for my application..... I hope I can get them on a Dyno soon, but the speed results of my boat this summer tell me I am not making near 700 hp, really looking to see where It went wrong...
11-23-2015, 10:07 PM
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tim,plenty of 540s out there with 320-325 heads making good power.i would love to see your engine on the dyno with your 325s,then install to a set of 305s.imo with the right cam&intake-carb the 325 will make good power.i had a set of 540s in my cat.dart 320s crane 139651 cam,8.71 blower,innercooled holley 850s,,8 lbs boost 950 hp at 6300.
11-23-2015, 11:29 PM
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You went with 25 cubic inches less than old engines. Might not seem like much, but an engine making around 1.2HP per ci, that alone could be 30hp .
Your compression ratio dropped going from a 565ci 4.560 bore engine with 115cc heads and a flat top, to a 4.500 bore setup, with 121 cc chambers and flat top. This could have been nearly a full point of compression, depending on deck height, gasket thickness, and what not. Again, maybe another 15-25hp.
You have longer duration camshafts in new combo. Probably making less power at 5500rpm, than the old engines, when all things factored in.
Your old heads had some work done to them to improve them by dean gellner. While the castings were known to be crap, those heads actually did pretty good at making power, and after a nice valve job, some throat/pocket work, they were probably pretty good, and the new AFR's, simply aren't enough to make up for all the other changes that were made. Had no changes been made, I'm sure the afr may have made a "little" more power by themselves, although probably not enough to notice speed differences in your heavy old cig.
If I was in your shoes, and I wanted to go faster, I would yank those heads off this winter, slap some thicker cometic gaskets in them, bolt on some blowers, and enjoy a BIG speed increase. This back and forth crap about 10-15cc of runner size, few degrees of cam duration, doesnt mean a fukin thing in a 12,000 lb old 35 Cig. Its great for arguing who can "design" the best engine, but if you want results, you need to make significant changes to the recipe. What you gonna do, install smaller heads, smaller cams, and then have a better "designed" engine, that might net you 1-2mph top speed, and get you from 50mph to 75mph, 2 seconds faster?
IMO, this is stuff that real marine engine builders should discuss with their customers. This persistant repetitive information, that defines a "marine" engine builder here, about "reversion", and clearances, while true, is only 1 part of the equation. True offshore builders, know what it takes to meet the customers goals, hull relative, and it isn't going to be found, in bickering over 10-15cc of runner volume.
Last edited by MILD THUNDER; 11-23-2015 at 11:55 PM.
11-24-2015, 05:18 AM
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I guess I am just blown away that my new engines were supposed to be so much more then what I had that's all, seems everyone is using 305/315's now that I built mine lol
M
M
tim,plenty of 540s out there with 320-325 heads making good power.i would love to see your engine on the dyno with your 325s,then install to a set of 305s.imo with the right cam&intake-carb the 325 will make good power.i had a set of 540s in my cat.dart 320s crane 139651 cam,8.71 blower,innercooled holley 850s,,8 lbs boost 950 hp at 6300.
11-24-2015, 05:20 AM
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True and we have had this discussion, in the end I am probably better off I think I just expected too much, on a good note I beat the engines all summer with no issues!!
My overall guess on your build is this.
You went with 25 cubic inches less than old engines. Might not seem like much, but an engine making around 1.2HP per ci, that alone could be 30hp .
Your compression ratio dropped going from a 565ci 4.560 bore engine with 115cc heads and a flat top, to a 4.500 bore setup, with 121 cc chambers and flat top. This could have been nearly a full point of compression, depending on deck height, gasket thickness, and what not. Again, maybe another 15-25hp.
You have longer duration camshafts in new combo. Probably making less power at 5500rpm, than the old engines, when all things factored in.
Your old heads had some work done to them to improve them by dean gellner. While the castings were known to be crap, those heads actually did pretty good at making power, and after a nice valve job, some throat/pocket work, they were probably pretty good, and the new AFR's, simply aren't enough to make up for all the other changes that were made. Had no changes been made, I'm sure the afr may have made a "little" more power by themselves, although probably not enough to notice speed differences in your heavy old cig.
If I was in your shoes, and I wanted to go faster, I would yank those heads off this winter, slap some thicker cometic gaskets in them, bolt on some blowers, and enjoy a BIG speed increase. This back and forth crap about 10-15cc of runner size, few degrees of cam duration, doesnt mean a fukin thing in a 12,000 lb old 35 Cig. Its great for arguing who can "design" the best engine, but if you want results, you need to make significant changes to the recipe. What you gonna do, install smaller heads, smaller cams, and then have a better "designed" engine, that might net you 1-2mph top speed, and get you from 50mph to 75mph, 2 seconds faster?
IMO, this is stuff that real marine engine builders should discuss with their customers. This persistant repetitive information, that defines a "marine" engine builder here, about "reversion", and clearances, while true, is only 1 part of the equation. True offshore builders, know what it takes to meet the customers goals, hull relative, and it isn't going to be found, in bickering over 10-15cc of runner volume.
You went with 25 cubic inches less than old engines. Might not seem like much, but an engine making around 1.2HP per ci, that alone could be 30hp .
Your compression ratio dropped going from a 565ci 4.560 bore engine with 115cc heads and a flat top, to a 4.500 bore setup, with 121 cc chambers and flat top. This could have been nearly a full point of compression, depending on deck height, gasket thickness, and what not. Again, maybe another 15-25hp.
You have longer duration camshafts in new combo. Probably making less power at 5500rpm, than the old engines, when all things factored in.
Your old heads had some work done to them to improve them by dean gellner. While the castings were known to be crap, those heads actually did pretty good at making power, and after a nice valve job, some throat/pocket work, they were probably pretty good, and the new AFR's, simply aren't enough to make up for all the other changes that were made. Had no changes been made, I'm sure the afr may have made a "little" more power by themselves, although probably not enough to notice speed differences in your heavy old cig.
If I was in your shoes, and I wanted to go faster, I would yank those heads off this winter, slap some thicker cometic gaskets in them, bolt on some blowers, and enjoy a BIG speed increase. This back and forth crap about 10-15cc of runner size, few degrees of cam duration, doesnt mean a fukin thing in a 12,000 lb old 35 Cig. Its great for arguing who can "design" the best engine, but if you want results, you need to make significant changes to the recipe. What you gonna do, install smaller heads, smaller cams, and then have a better "designed" engine, that might net you 1-2mph top speed, and get you from 50mph to 75mph, 2 seconds faster?
IMO, this is stuff that real marine engine builders should discuss with their customers. This persistant repetitive information, that defines a "marine" engine builder here, about "reversion", and clearances, while true, is only 1 part of the equation. True offshore builders, know what it takes to meet the customers goals, hull relative, and it isn't going to be found, in bickering over 10-15cc of runner volume.
