502 Mag MPI Throttle body question?
01-16-2012, 04:07 PM
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502 Mag MPI Throttle body question?
would there be any benifit in adding a high flow bored out throttle body to a mostly stock 502 Mag MPI? The engine curretnyl has Gill wet exhasut and a K&N flame arrestor and an adjustable fuel pressure regulator. Any advice would be much appreciated.
01-17-2012, 04:08 PM
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well... you are going to see a huge difference because that 540 is a world different from the 454 so that is about as far from an apples to apples comparison as there is. my guess would be that on like type 502, a fractionally larger throttle body might buy you a small amount but there is only so much the programming can adjust for before it simply doesn't know what to do. again, im guessing here but i would think that , assuming the intake or heads wern't the limiting factor, that a meaningfully larger TB would require a dyno session and remapping the fuel and ignition curves to get the benefit you want. having said that, the stock 502 stuff is a bit rich already so you might get a pleasent surprise...
01-18-2012, 01:45 PM
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Sounds like you are doing the same thing as I did. I have a heavily worked intake and TPiS has my throttle body right now. I had a '97 502 MAG originally, built it to a 540......blew that up, now it will be a 572 so I think I can benefit from the throttle body...hehe. I am still doing some additional work on my intake maifold because I sent mine out to AS&M to be extrude honed.....got a total basket case in return for my money....after all of the problems that they caused me, I wish I would have just spent the extra money originally to go with a whole new intake and EFI. But I have too much into this thing now to scrap it.
01-19-2012, 03:40 AM
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i found that intake manifolds were pretty " magic" to work with and often what you thought would work because it was so obvious just wasn't correct at all. we worked with one small, heavilly rules restricted motor where one of the areas that could be modified was the intake. i gave everybody i knew in the business 3 each to do the best they could do with and then when they were done, ran them all on the dyno. these were some pretty sharp guys with flow benches and lots of experience. on the dyno, most of them were , essentially no better than stock...statistically identical. a few were marginally better .. 2 or 3 hp on a 150 hp application. a couple and in fact the ones with the most internal work, were much worse... the volumes had gotten big and the velocity had gone away... and one... and ONLY one was very very good. and it was 5 hp better and gave up nothing across the range. and it had what appeared to be the least work of all of them.
what that guy had done was look at the manifold with an eye to what was " wrong " with it... and simply attempted to " fix those " issues" .... a short turn radius here, a difference in CA there, a blended turn here... and it clearly worked.
my point is that by just modifying " everything " you might actually be changing some area that is pretty good and making it worse.
a case in point is the notion of " polishing" ... on a carb motor the intake port with a slightly rough finish will often make better power than a highly polished one. the polished one tends to cause the fuel to seperate while the slightly rough surface tends to keep the fuel /air charge well " mixed" for better combustion. not an issue on an injected motor where the fuel is introduced downstream but on a carb motor was often a meaningful thing and not at ALL what you would intuitively think could be correct.
Last edited by stevesxm; 01-19-2012 at 03:43 AM.
01-19-2012, 12:27 PM
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I agree with Raylar.......might actually loose bottom end with no gains on top if you add that to a stock engine.
01-19-2012, 06:55 PM
#9
it looks like you are working quite hard on this intake. i'm curious... do you have some plan or some real data based insight into what you are doing or are you just intuitively doing the work figuring "smoother is better" or " bigger radii are better than tighter" etc ?
i found that intake manifolds were pretty " magic" to work with and often what you thought would work because it was so obvious just wasn't correct at all. we worked with one small, heavilly rules restricted motor where one of the areas that could be modified was the intake. i gave everybody i knew in the business 3 each to do the best they could do with and then when they were done, ran them all on the dyno. these were some pretty sharp guys with flow benches and lots of experience. on the dyno, most of them were , essentially no better than stock...statistically identical. a few were marginally better .. 2 or 3 hp on a 150 hp application. a couple and in fact the ones with the most internal work, were much worse... the volumes had gotten big and the velocity had gone away... and one... and ONLY one was very very good. and it was 5 hp better and gave up nothing across the range. and it had what appeared to be the least work of all of them.
what that guy had done was look at the manifold with an eye to what was " wrong " with it... and simply attempted to " fix those " issues" .... a short turn radius here, a difference in CA there, a blended turn here... and it clearly worked.
my point is that by just modifying " everything " you might actually be changing some area that is pretty good and making it worse.
a case in point is the notion of " polishing" ... on a carb motor the intake port with a slightly rough finish will often make better power than a highly polished one. the polished one tends to cause the fuel to seperate while the slightly rough surface tends to keep the fuel /air charge well " mixed" for better combustion. not an issue on an injected motor where the fuel is introduced downstream but on a carb motor was often a meaningful thing and not at ALL what you would intuitively think could be correct.
i found that intake manifolds were pretty " magic" to work with and often what you thought would work because it was so obvious just wasn't correct at all. we worked with one small, heavilly rules restricted motor where one of the areas that could be modified was the intake. i gave everybody i knew in the business 3 each to do the best they could do with and then when they were done, ran them all on the dyno. these were some pretty sharp guys with flow benches and lots of experience. on the dyno, most of them were , essentially no better than stock...statistically identical. a few were marginally better .. 2 or 3 hp on a 150 hp application. a couple and in fact the ones with the most internal work, were much worse... the volumes had gotten big and the velocity had gone away... and one... and ONLY one was very very good. and it was 5 hp better and gave up nothing across the range. and it had what appeared to be the least work of all of them.
what that guy had done was look at the manifold with an eye to what was " wrong " with it... and simply attempted to " fix those " issues" .... a short turn radius here, a difference in CA there, a blended turn here... and it clearly worked.
my point is that by just modifying " everything " you might actually be changing some area that is pretty good and making it worse.
a case in point is the notion of " polishing" ... on a carb motor the intake port with a slightly rough finish will often make better power than a highly polished one. the polished one tends to cause the fuel to seperate while the slightly rough surface tends to keep the fuel /air charge well " mixed" for better combustion. not an issue on an injected motor where the fuel is introduced downstream but on a carb motor was often a meaningful thing and not at ALL what you would intuitively think could be correct.
Wilson Manifolds actually did the work ....and if you notice most mods include lowering the divider between the runners and Wilson said it wasnt necessary ... Keith Wilson himself checked off the design ...we did raise the lip of the uppers to match the lowers .....yes there is some monkey see monkey do going on but I have tried to get as much input as I could ....but after a while you have to take a direction ....not sure if I have mentioned but these are ProCharger motors ....Bob Madara did the design on all the top end ...He's an unlimited resource of information ......m
01-20-2012, 04:33 AM
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Alot of research ..talking to others that have done the mods ...Articfriends ....ASM ... Eddie Young...
Wilson Manifolds actually did the work ....and if you notice most mods include lowering the divider between the runners and Wilson said it wasnt necessary ... Keith Wilson himself checked off the design ...we did raise the lip of the uppers to match the lowers .....yes there is some monkey see monkey do going on but I have tried to get as much input as I could ....but after a while you have to take a direction ....not sure if I have mentioned but these are ProCharger motors ....Bob Madara did the design on all the top end ...He's an unlimited resource of information ......m
Wilson Manifolds actually did the work ....and if you notice most mods include lowering the divider between the runners and Wilson said it wasnt necessary ... Keith Wilson himself checked off the design ...we did raise the lip of the uppers to match the lowers .....yes there is some monkey see monkey do going on but I have tried to get as much input as I could ....but after a while you have to take a direction ....not sure if I have mentioned but these are ProCharger motors ....Bob Madara did the design on all the top end ...He's an unlimited resource of information ......m
