BBC output overview.

General engine tech -- Drag Racing to Circle Track

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David Vizard
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Re: BBC output overview.

Post by David Vizard »

Frankshaft wrote: Wed Oct 17, 2018 10:21 am
Warp Speed wrote: Wed Oct 17, 2018 10:08 am
Frankshaft wrote: Wed Oct 17, 2018 10:01 am

But it flows better on the flow bench.
Of course it does, every time. Dynamically, it never shows a positive power gain.
If you haven't gathered, I am not a radius intake seat guy. I have tested it numerous times back to back, and I have concluded the same thing. BSFC's go up, fuel flow goes up, and power goes down. They are all tied together. My testing has shown ME, that the engine wants to be richer, and it wants more total timing. To make less power. That's why the bsfc's go up, along with fuel flow. This is a good discussion subject, but not really about bbc's in general.
Sounds like you did a true A-B test!
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Re: BBC output overview.

Post by RevTheory »

That is why I try to be patient and give a guy a chance to elaborate.
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Re: BBC output overview.

Post by CGT »

David Vizard wrote: Wed Oct 17, 2018 12:10 pm MT do the following figures look about inline with any A-B-A tests you might have done? :- Test engine – one of my 87 octane street build 383’s. Stock Dart seats – 536 lbs-ft and 592 hp. Cam power timed in with Jesel setup – optimal at (as it happens) 4 advance. Same Dart heads with my seats on and nothing else changed:- 525 lbs-ft 586 hp. Idle vacuum was less and the motor responded at low speed as if it had a bigger cam in it. These are the kind of results that I suspect end up condemning my seats. It is also proof that A-B-A tests fall far short of what professional grade engine builders should be doing to advance their technology.
• Next test – engine same as above but the cam advance/retard power timed. Original best timing with regular seats was +4 degrees. Best with radius seat -1. Output 542 lbs-ft and 611 hp. Just for the record can any of my regular critics tell me where I could have done better here??
Post up the dyno data, not much to go on there.
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Re: BBC output overview.

Post by David Vizard »

Warp Speed wrote: Wed Oct 17, 2018 9:55 am Unfortunately, David obviously doesn't want a technical discussion. He only wants to make technical statements....?
Any questioning of his views is taken as an attack on his intelligence, and is rescued by the faithful. Hard to progress that way........imo

That being said, I have NEVER seen a full radius intake seat be better on the intake side on a running engine......
EVER

I'm out
Comment:-Unfortunately, David obviously doesn't want a technical discussion. He only wants to make technical statements....?
Just read what my original intent was here. Since I won't have the time to construct a volume 3 of my BBC book I stated that I would pass on what ever I found time for to ST posters. These were not up for discussion but simply a way for me to share MY FINDING without too much interruption. With all the hold ups I am getting it would save time for me to actually write the book. Again Warp, thank you for your encouragement!
So your statement is right but somehow you have made what I am giving ST posters here a negative deal.

Question - will I ever be able to do anything positive in your eyes?

Comment:-Any questioning of his views is taken as an attack on his intelligence,

When we met at Charlotte at the recent road course event I believe I made it clear that anything tech that I put forward and is disagreed with should not be taken up with me but the dyno that delivered those results. (I don't have an opinion - I have a dyno)I guess that did not support your low opinion of me so was dismissed.

As for me assuming it is 'an attack on my intelligence' I have got to say NO. That, I suspect is how you re-act and that is why you appear a little on the closeted side posting and take cover behind a Non Disclosure deal. An attack on my intelligence is responded to typically by a stream of numbers and tests that support my claim. The beauty of not spouting opinions is that you don't have to prove one way the other whether or not you are intelligent only how well informed you may be. The two are not the same.

'and is rescued by the faithful.' How petty -sounds like a comment from a school kid - give me a break!!

' Hard to progress that way' Sure is and posts like this simply stop me from supplying the tech stuff that many have been waiting for - that seems a little thoughtless ........imo And I am so glad all of this is simply that ---- an opinion.

That being said, I have NEVER seen a full radius intake seat be better on the intake side on a running engine......
EVER

Thank you for letting us know the limit of your experience.

I'm out Really? Well we will see on that one!
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Re: BBC output overview.

Post by In-Tech »

I don't know shit about fock<<<<<<spelled incorrectly for the forum, quote from ozark tv show, still makes me chuckle. :lol:

As far as A-B-A testing, when trying new things like 5 cams and 3 intakes per cam change, you learn some things. Cutting seats will only tell you so much without valve event changes to match. bleh I don't want to ramble
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: BBC output overview.

Post by WeingartnerRacing »

Let me put on my waders because there is a lot of crap here.

One you can get perfect round seats with a traditional seat and guide machine using the full form of the cutter. I do it all the time. No single point cutter machine are not always great. You mentioned Afr and I have gotten heads from them that are not at all round. My data backs it up. If I could post pics I would but why.

Radius seats on intake have been proven by many people and companies to not to make more power than sharp angles. Only looking at your data and ignoring many opposing one doesn’t make yours right.

I think you just wanted to write and people to just lap it up like in a book. This is the Internet it doesn’t work that way.

You sound like a salesman on Facebook when you say things like only I have so and so data or tools. I use to think that way then I realized that whatever I was thinking there was a good chance someone else had and then done it.

I thought Of the smartbaord before they were invented.
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Re: BBC output overview.

Post by David Vizard »

gruntguru wrote: Tue Oct 16, 2018 10:05 pm Hi David. I am sure I can speak for the majority here in saying the following


I look forward to every post you make. Your vast experience in this field and your passion for passing on that knowledge (whether by selling books and seminars or FOR FREE on forums like this) are legendary. I bought my first David Vizard book nearly 50 years ago.

Imagine my disappointment when I find a new post from David Vizard and it contains none of that. Responding to haters and fools is a waste of your VERY VALUABLE time. Please ignore them.
Hey grunt,

Thanks for the opening line of your post. I like to believe you are right though so often it seems not to be the case.

As for looking forward to my posts thanks again. I often think that 'vast' is overused but if 61 active years and still going is vast then I will take it as intended - thank you.
And you are right I do have a passion for what I do. That is why I typically work 7 days a week. After spending time with me so many tell me I am one of the happiest most contented people they have ever met. I put this down to the constant fun I have from my work. I have told many that if it was not for race cars I would be a worthless item on this planet.

As for the next part of your post I am trying as hard as I can to pass on the bulk of an entire book to ST members but some folk don't seem to like that.

Imagine my disappointment when I find a new post from David Vizard and it contains none of that [tech).

I totally understand and agree with your sentiments here. Unfortunately I cannot stand for injustices and this tends to divert my train of thoughts.

Responding to haters and fools is a waste of your VERY VALUABLE time. Please ignore them.

I could not agree more. Seriously would you like to volunteer to keep me more focused??

Thanks,
DV
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Re: BBC output overview.

Post by David Vizard »

In-Tech wrote: Wed Oct 17, 2018 1:27 pm I don't know shit about fock<<<<<<spelled incorrectly for the forum, quote from ozark tv show, still makes me chuckle. :lol:

As far as A-B-A testing, when trying new things like 5 cams and 3 intakes per cam change, you learn some things. Cutting seats will only tell you so much without valve event changes to match. bleh I don't want to ramble
Exactly my point put into far less words.
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Re: BBC output overview.

Post by David Vizard »

WeingartnerRacing wrote: Wed Oct 17, 2018 1:30 pm Let me put on my waders because there is a lot of crap here.

One you can get perfect round seats with a traditional seat and guide machine using the full form of the cutter. I do it all the time.Must be a Sunun or the like not a Serdi No single point cutter machine are not always great. We had one at Ultra Pro that we sent back because of it,s short comings however current models seem pretty good now. You mentioned Afr and I have gotten heads from them that are not at all round. My data backs it up. Yes I have also seen that on a small number of heads I have had from them If I could post pics I would but why.

Radius seats on intake have been proven by many people and companies with their test criteria to not to make more power than sharp angles. Only looking at your data and ignoring many opposing one doesn’t make yours right. MT you are missing the point - why are my results different what did I do that they did not or visa versa?

I think you just wanted to write and people to just lap it up like in a book. Should I keep all the BBC stuff that I have not yet used in editorial and take it to the grave? This is tens of thousands worth of dyno tests??

This is the Internet it doesn’t work that way. Yes - apparently I am finding that out the hard way.

You sound like a salesman on Facebook when you say things like only I have so and so data or tools. I have not looked at my Facebook page in over two years. My road manager takes care of it. I will check into your comment and see where the problem might be.

I use to think that way then I realized that whatever I was thinking there was a good chance someone else had and then done it. MT - I have been responsible for over 40 patents so I think that there may be a likelihood of me thinking about something that has not been done before.

I thought Of the smartbaord before they were invented. So you missed the boat on that. Pity, you would have been able to fund your racing better. Money rarely makes a race car go slower!
DV
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Re: BBC output overview.

Post by RevTheory »

David Vizard wrote: Wed Oct 17, 2018 2:20 pm OK guys we have had our fling- can I now get back to posting my findings on hopping up BBC for those who might want to know. If your one of the yeses don't be the silent majority because I am getting close to fed up with all the negativity I am seeing.
DV
Yeah, please do. It's easy to get sucked into this kind of back-and-forth but I'd urge you to do your best to avoid the temptation.

I figured you had something up your sleeve as to the radiused seats so that's why I asked the question that likely crossed all of our minds when we saw them.

If I'm understanding you correctly, it's not that it caused a fuel problem by not having multiple angles present to shear it, it's the valve timing not being addressed to account for the increased reverse flow. Yes?

My wording is off a little today so hopefully it reads ok.
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Re: BBC output overview.

Post by David Vizard »

RevTheory wrote: Wed Oct 17, 2018 2:48 pm
David Vizard wrote: Wed Oct 17, 2018 2:20 pm OK guys we have had our fling- can I now get back to posting my findings on hopping up BBC for those who might want to know. If your one of the yeses don't be the silent majority because I am getting close to fed up with all the negativity I am seeing.
DV
Yeah, please do. It's easy to get sucked into this kind of back-and-forth but I'd urge you to do your best to avoid the temptation.

I figured you had something up your sleeve as to the radiused seats so that's why I asked the question that likely crossed all of our minds when we saw them.

If I'm understanding you correctly, it's not that it caused a fuel problem by not having multiple angles present to shear it, it's the valve timing not being addressed to account for the increased reverse flow. Yes?

My wording is off a little today so hopefully it reads ok.
In most cases yes it is the valve events off the required mark for a radius seat. Also if the intake is lower than the exhaust this can also present a problem by exaggerating the reverse flow increase at the worst time.

As for fuel shear I will get to that shortly when we get to some wet flow photography I did for Dart when sorting out test procedure.
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Re: BBC output overview.

Post by Frankshaft »

RevTheory wrote: Wed Oct 17, 2018 2:48 pm
David Vizard wrote: Wed Oct 17, 2018 2:20 pm OK guys we have had our fling- can I now get back to posting my findings on hopping up BBC for those who might want to know. If your one of the yeses don't be the silent majority because I am getting close to fed up with all the negativity I am seeing.
DV
Yeah, please do. It's easy to get sucked into this kind of back-and-forth but I'd urge you to do your best to avoid the temptation.

I figured you had something up your sleeve as to the radiused seats so that's why I asked the question that likely crossed all of our minds when we saw them.

If I'm understanding you correctly, it's not that it caused a fuel problem by not having multiple angles present to shear it, it's the valve timing not being addressed to account for the increased reverse flow. Yes?

My wording is off a little today so hopefully it reads ok.
It's a simple text. Do it for yourself. Cut the seat with the radius first. Test it. Remove heads from engine, disassemble heads. Use a single angle cutter say 60 degrees. You could use 58 too. That way you can test other bottom angles,night you start at 58. Cut the radius with the chosen bottom angle until it meets up with the bottom edge of the seat. Then use a 70 or 75 degree angle to blend the bottom angle into the throat. You can start with a 70, that way you can try something different, like the 75. Now you will have 4 distinct angles. Top cut, seat, bottom angle and throat transition angle. Reasemble heads. Seat depths are unchanged because you didn't touch the seat. You didn't change the anything else other than remove the radius. Obviously keep valves in order so they go back in same holes. Re run engine, note results.

Doing it how I described, allows to to try different angles. Now you could test a 60 bottom, and maybe a 72 throat transition angle. Then go to a 65 with a 75, that would be at least 4 tests you could do. Without touching the actual seat.
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Re: BBC output overview.

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OP, please feel free to start a V2 thread.

Thank you to the people that tried to save this thread.

Update: Chapter 2 thread viewtopic.php?f=1&t=55035
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