454 rebuild with blower... Pistons and clearances.
01-22-2015, 09:42 PM
#61
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I dont think anyone is challenging Bob. I've known Bob's capabilites, and seen him work his magic, for the past 11 years I have been here. I've had many conversations with Bob, and also have learned quite a bit from him. I also helped put Mike Tkach in touch with Bob in the last year. Mike has been building engines since the 80's with no help from anyone, including some big blown akly drag boat engines making gobs of power. Mike has the upmost respect for bob's knowledge, and has now used his camshaft's on the last few builds, as well as purchased heads from him. I think Mike Tkach can attest to my opinion of Bob, both as an engine guru, and as a person, and we both think highly of him.
So again, I dont think anyone here is challenging anyone. But, if we are going to criticize, or make suggestions on what works better, please, lets provide some data on HOW it did work better, not why is SHOULD work better. There are some guys here, that read this stuff, and invest money based on what they read here.
You contacted me for some thoughts on hopping up your engine. Which I tried to share some of my experiances with you. You have a 454 based engine, I have a 454 based engine. You have a 177 blower, I had a 177 blower, I have ran these engines for 7 years, with various combinations of blowers, tune's, etc, with a dyno sheet as well. These engines have never holed a piston, tuliped a valve, spun a bearing, or anything like that. I can only offer the advice based on what I learned, or experianced, when changing from this to that.
I was being honestly curious, if anyone has done a comparable build with the smaller oval ports in a forced induction application. Not because I am trying to prove they are not, but prove that maybe they are. I know what the rectangles can do, it be nice to see what the ovals can do as well.
So again, I dont think anyone here is challenging anyone. But, if we are going to criticize, or make suggestions on what works better, please, lets provide some data on HOW it did work better, not why is SHOULD work better. There are some guys here, that read this stuff, and invest money based on what they read here.
You contacted me for some thoughts on hopping up your engine. Which I tried to share some of my experiances with you. You have a 454 based engine, I have a 454 based engine. You have a 177 blower, I had a 177 blower, I have ran these engines for 7 years, with various combinations of blowers, tune's, etc, with a dyno sheet as well. These engines have never holed a piston, tuliped a valve, spun a bearing, or anything like that. I can only offer the advice based on what I learned, or experianced, when changing from this to that.
I was being honestly curious, if anyone has done a comparable build with the smaller oval ports in a forced induction application. Not because I am trying to prove they are not, but prove that maybe they are. I know what the rectangles can do, it be nice to see what the ovals can do as well.
Last edited by ealesh33; 01-22-2015 at 09:51 PM.
01-22-2015, 09:50 PM
#62
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Mine isn't assembled yet, actually the heads will be here tomorrow, and it probably won't go on the dyno till around early to mid March. I don't care as much of what the number is, i care more about where it makes whatever the number is, and dialing it in. I do have a number in mind, and that is 650hp. Although the builds are similar there are way to many variables that are different to compare a single component plain and simple.
Last edited by ealesh33; 01-22-2015 at 10:05 PM.
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01-22-2015, 10:11 PM
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I have noticed in other threads that the mention of the little 265's gets some people as irritated as mentioning how much better EFI is... 
Seriously though, here is what I can add to this specific topic after literally hundreds of dyno pulls, and in boat performance comparisons to similar sized builds using both heads. On a marine type BBC under 509"s spinning less then 6500rpm, the 265 will make a bit more power then the 305's every time, more peak torque, and more average power, and they're cheaper. I have done direct A to B testing on the same engine without removing it from the dyno too. Unfortunately the 265's give it a compression bump so there is that to consider as well. I built two identical 557's, one with 265's the other with 305's, same cam, same compression, both efi, same everything. The 265's outperformed the 305's up to 5200rpm. I have also switched from the 265's to 305's on a procharged 489 because I wanted to lower the compression to run more boost, and put in a bigger cam to turn some more rpm. So they're not perfect for every application. The 265's have a very fast port, and out of the box have a couple of localized areas that are too fast for bigger cubes, or a lot of rpm. With just a bit of work they'll support 700hp NA though. I haven't used any for a while because I've mostly been building bigger stuff, or LS's, but I wouldn't hesitate to use them any time, and think they're an incredible value.
For a build like Mike T's the performance would be so comparable that it wouldn't be worth changing the intake for though, in my opinion. I'll try and dig up some dyno sheets, but if I post them before I get Bob the ones from the testing I did for Johnson lifters, he'll kill me. So it'll have to wait til I get a bit of free time.
Seriously though, here is what I can add to this specific topic after literally hundreds of dyno pulls, and in boat performance comparisons to similar sized builds using both heads. On a marine type BBC under 509"s spinning less then 6500rpm, the 265 will make a bit more power then the 305's every time, more peak torque, and more average power, and they're cheaper. I have done direct A to B testing on the same engine without removing it from the dyno too. Unfortunately the 265's give it a compression bump so there is that to consider as well. I built two identical 557's, one with 265's the other with 305's, same cam, same compression, both efi, same everything. The 265's outperformed the 305's up to 5200rpm. I have also switched from the 265's to 305's on a procharged 489 because I wanted to lower the compression to run more boost, and put in a bigger cam to turn some more rpm. So they're not perfect for every application. The 265's have a very fast port, and out of the box have a couple of localized areas that are too fast for bigger cubes, or a lot of rpm. With just a bit of work they'll support 700hp NA though. I haven't used any for a while because I've mostly been building bigger stuff, or LS's, but I wouldn't hesitate to use them any time, and think they're an incredible value.
For a build like Mike T's the performance would be so comparable that it wouldn't be worth changing the intake for though, in my opinion. I'll try and dig up some dyno sheets, but if I post them before I get Bob the ones from the testing I did for Johnson lifters, he'll kill me. So it'll have to wait til I get a bit of free time.
01-22-2015, 11:07 PM
#67
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I chose the 305 for 2 reasons.first the existing manifold was rect port,second,if the engines owner decides at a later date to go bigger he won,t need to buy new heads.i will also add ,imo the oval port with a matching intake might have made a little more lower rpm torque but i am pleased with the end results of this build.
Last edited by mike tkach; 01-22-2015 at 11:14 PM.
01-22-2015, 11:19 PM
#69
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You asked if anyone has done a build with 265's on a similar set up, and he answered yes. He knows what works, as he has done the set up many times. His data isn't a dyno sheet, he knows what the heads flow, and he knows technical data based on head, chamber, runner design, bore size, etc... There are different approaches to a build on this specific motor, we all agree that the 177 is honestly too small, and you can't really build this like a blower motor per say, as it will not perform well blower dependent as we know. Your 420 with 308 heads is just a completely different ball game, and would have zero indication how a 305 would perform with a 177. You add alot of value to this site, and I know none of this information is of any kind of news to you. By big I mean that a 305 AFR based on what they flow and what bore size they accommodate they would be on the upper end size wise for a 4,250 bore, never meant for it to come across as them being too big and a bad choice, cause In reality neither build is a slouch by any means, and there really shouldn't be that much difference in measurable power between the head choices. Basically boils down to there is many ways to skin a cat, and none of them may be bad, but they all have there advantages for whatever the goals may be for the end user.
01-22-2015, 11:23 PM
#70
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Mine isn't assembled yet, actually the heads will be here tomorrow, and it probably won't go on the dyno till around early to mid March. I don't care as much of what the number is, i care more about where it makes whatever the number is, and dialing it in. I do have a number in mind, and that is 650hp. Although the builds are similar there are way to many variables that are different to compare a single component plain and simple.
