100 cfm more with anular and downleg boosters can't beat AFR

[TT5.9mag]

It depends on the booster. I’m very green on these boosters, but what I’m finding out is the better boosters are a SLIGHT CFM air reduction.

Which, comes back around to the old saying “not all airflow is good airflow”.

If a slight reduction in air flow cleans up distribution, allows less total timing (within reason...in my opinion no way will a chamber that runs at say...35 degrees will ever run at 28 degrees if everything is perfect...you may get down to 32...maybe), reduces required MJ sizing and such, then I consider that an easy thing to give up and a win.

Because of the way most engine dyno’s measure power, a booster change may not show up in anything but the BSFC number. On an inertia dyno, that lower BSFC number will translate into higher HP numbers.

On the other side of the coin, you can atomize the fuel too much and lose power right quick. A heated intake manifold, engine temps for catalytic converters and such will atomize the fuel too much and drop power.

I have at least 6 carbs that are getting annular boosters this year. It may suck hard on all of them. I hope not, because that’s going to cost me an arm and a leg.

So am I (green) but I just ordered a custom built CSU blow through 750 spec’d for my new big block by Kevin and he is doing annular boosters on all 4 and I will be testing it soon. I learned so much about airflow from that Darin Morgan webinar that my head is full. It’s changing a lot of how I used to think of these things.

 

[Mattax]

Got it. Thanks. I’ve heard they do reduce flow quite a bit. But I have no data to support that. If you’re interested I have a 3310-6 center here with no choke horn and radiused entries I could send you for testing. It just came off my big block for a CSU blow through. I’ll send it to you if you’d like. Just send it back when you’re done and post the data.
View attachment 1715678734

Thanks, but Gosh no! At one time I had good access to a chassis dyno, but not now. I don't know if Atco will be open this year but sitting around all night for maybe 2 runs is not effective testing. Nor is it much fun. After three hours waiting I got a run. If I stayed I might have got another before closing - or maybe not. I was told Friday nights were even more crowded. I'll try Cecil or Maple Grove this year even though they are further drive.

I *think* Mark W has posted some flow restriction info on one of the forums he frequents. He has been able to do a lot of testing and measuring.

 

[Hysteric]

Hey Mattax.

Are you still running the same combo that you and Bruce discussed here: Update on Dyno Results - Part 2, Fuel Curve

Also are the secondary downleg boosters stepped or plain?

 

[Mattax]

Hey Mattax.

Are you still running the same combo that you and Bruce discussed here: Update on Dyno Results - Part 2, Fuel Curve

Also are the secondary downleg boosters stepped or plain?

LOL. Basically Yes same hardware but tweaking the carb. That dyno session where I tried three different springs along was pretty helpful. I'll dig up the missing screenshots if I can.

However there are two changes that likely affected the combustion.
One is that the engine had 340 cast iron exhaust manifolds, but since 2016 has custom headers.
The other is a change in timing curve.


No skirts onthe downlegs

 

[Hysteric]

Why the LOL?

What is your cranking comp?

 

[Mattax]

What is your cranking comp?

Checked cold, with 4 compression cycles, 170 psi

 

[Mattax]

""Are you still running the same combo that you and Bruce discussed here: Update on Dyno Results - Part 2, Fuel Curve"

I'll dig up the missing screenshots if I can."
Here's the datalog with the black spring.

Next is the plain and yellow springs

Finally the dynometer results of all three springs.

You know Shrinker still makes my head hurt!

But I know its good for me and each time maybe I grasp things a little better.

 

[Hysteric]

Thanks for posting that Mattax.

Ahh.....Shrinker, I wish he was still around to answer all my questions. I tell you what I did do and it helped me understand what he was always trying to get us to understand but we were to dense to grasp. I dug up every thread Bruce ever posted on I could find and categorized every topic he discussed with associated key words with in threads and grouped them together under their relevant topics. When you review all the info you begin to get an idea on what he considers important and you begin to understand why. Also as you go you pick up stuff from other extremely knowledgeable guys like Tuner and pieces of the puzzle come together.

Case in point Bruce posted this about engine tone:


This is a 417 cube Cleveland through the mufflers. The engine makes over 780hp with a 1042CFM SmartCarby on it. It is regular street driven, its not a race car. It makes 300hp at the wheels in top gear at 60kph( 37mph our speed limit). It runs at 40kph (25mph)in top gear (manual not auto) without snatching and pulls away with WOT. It passes noise laws and passes emissions. The engine was first built with a Dominator on it and it didn't have this sound, it was dull and bassy. It made similar power but had less response, used far more fuel and couldn't pass emissions.
Listen to the sound how it changes from the burnout and the RPM before the launch and compare it to the sound as it goes down track. You can hear the other car, its a dull bass sound (conventional). The sound in the burnout and pre launch is smooth and snappy, the sound during the run is sharp and supersonic. We have chassis dynoed it with pipes on pipes off etc it makes no difference it kills your ears.
During the run the sound is a sharp hard crack, Its got this crack at basically all revs when under serious load. That is the sound of supersonic flow when the valve opens. Engines that make that sound (you have to correctly identify it compared to an exhaust resonance) are usually really good efficient engines. They make high power from little fuel. Engines that sound dull and more bassy are making high levels of CO with high levels of unburnt HC and some unused O2 in the exhaust. Basically they could be better.

And then I found this from Tuner recently and the pieces come together:

Blair's chapter on mufflers and the mathematics in it (the math in the book is available in a software program from SAE) is very useful if you are at all interested in the future of motor sports in general and track public relations, the general public's opinion of hot rod cars. I know some people would rather be loud than fast, but there is no good reason to be loud, and this is particularly so when it is possible to use the sound energy to increase the power output instead of aggravate people. He explains how the mufflers can be band-pass filters and how to use acoustics to cancel the peaks of select frequencies which a particular engine emits. Sound energy lost out the tailpipe is energy that could be used in the engine for something useful. Within Blair's work is solutions to design of systems, intake and exhaust, which utilize the acoustic energy and gas dynamics to improve engine efficiency. For instance, the speed of sound, hence the reflected wave, is different in CO2, CO, H2O, etc, and in a running engine all those exist in varying quantities in (what we usually think of as merely) air flow, when in fact it is not simply air, it is a varying mixture of gasses, each with significantly different characteristics

They say we stand on the shoulders of giants and we most certainly do, but to get up to those shoulders is a long and arduous climb. I'm still climbing but I hope to someday enjoy the view from all that hard work. Anyway sorry to divert from the topic at hand.

 

[Hysteric]

Checked cold, with 4 compression cycles, 170 psi

I think part of the issue is you don't have enough compression for the cam you're running but I think you already know that. Have you thought about advancing the cam to build more cylinder pressure? It's free

Another thing that has occurred to me is the vacuum spivy is very close to the booster so maybe it could be affecting the air flow nearest the booster? Could that be causing a change in fuel distribution. Also as the airflow is faster in that area is that affecting the vacuum response to the vacuum pod. Just thinking aloud here.

 

[Mattax]

I think part of the issue is you don't have enough compression for the cam you're running but I think you already know that. Have you thought about advancing the cam to build more cylinder pressure? It's free

Probably right. I had thought about whether advancing might help but that got rotated to a back burner. I really spend time building an engine that will let me drop into a more stock SCCA autocross class. Really never thought I'd still be running this engine! Those headers and the timing changes did make it fun to drive so no regrets.

Another thing that has occurred to me is the vacuum spivy is very close to the booster so maybe it could be affecting the air flow nearest the booster? Could that be causing a change in fuel distribution. Also as the airflow is faster in that area is that affecting the vacuum response to the vacuum pod. Just thinking aloud here.

I suppose its possible but wouldn't the volume of air effected be pretty small compared to a notch or spivy on the booster itself?

 

[Mattax]

Blair's chapter on mufflers and the mathematics in it (the math in the book is available in a software program from SAE) is very useful if you are at all interested in the future of motor sports in general and track public relations, the general public's opinion of hot rod cars. I know some people would rather be loud than fast, but there is no good reason to be loud, and this is particularly so when it is possible to use the sound energy to increase the power output instead of aggravate people. He explains how the mufflers can be band-pass filters and how to use acoustics to cancel the peaks of select frequencies which a particular engine emits. Sound energy lost out the tailpipe is energy that could be used in the engine for something useful. Within Blair's work is solutions to design of systems, intake and exhaust, which utilize the acoustic energy and gas dynamics to improve engine efficiency. For instance, the speed of sound, hence the reflected wave, is different in CO2, CO, H2O, etc, and in a running engine all those exist in varying quantities in (what we usually think of as merely) air flow, when in fact it is not simply air, it is a varying mixture of gasses, each with significantly different characteristics

That sure is a good and understandable summation of those long Speedtalk discussions with modeling of sound waves and gas flow.

Anyway sorry to divert from the topic at hand.

I think it fits in well with theme that tuning is more important than the size or device.

 

[Hysteric]

I've looked at your cams specs and from memory it was a crane but I can't find it anywhere? Also where is it installed?

That sure is a good and understandable summation of those long Speedtalk discussions with modeling of sound waves and gas flow.

Lots to digest. You said you changed the exhaust to headers so is it right to assume you retuned it?

 

[Mattax]

Hughes2430, [270/276advert.] 223/230@50, 504"/.515" 108 LSA
+ rhoads vmax lifters added long before the headers.
I'll have to see what the cam card says for install. Although I was there and helped on a little bit, I don't have the install notes.
What has bit me twice now is not having important build details like this and actual cc info. I will never do an engine again without cc'ing the heads.

I actually did really no retuning to speak of. When I go the car back with the headers I pretty much just used it. I had an opportunity before work really cranked up to get some datalogs, but then the LM1 flaked out (turned out to be the 9V battery connection). So that was that. it ran pretty well. I did try one step hotter spark plugs late in the year.

 

[Hysteric]

Hughes2430, [270/276advert.] 223/230@50, 504"/.515" 108 LSA
+ rhoads vmax lifters added long before the headers.
I'll have to see what the cam card says for install. Although I was there and helped on a little bit, I don't have the install notes.
What has bit me twice now is not having important build details like this and actual cc info. I will never do an engine again without cc'ing the heads.

I actually did really no retuning to speak of. When I go the car back with the headers I pretty much just used it. I had an opportunity before work really cranked up to get some datalogs, but then the LM1 flaked out (turned out to be the 9V battery connection). So that was that. it ran pretty well. I did try one step hotter spark plugs late in the year.

Since Shrinker hurts your head so much here's a thread where Shrinker was asked why the AFR showed leaner when they swapped to 1 3/4 headers.

"It didn't 'lean out the carb' The exhaust has allowed more flow through on the overlap of the cam thus depositing Oxygen into the exhaust and causing the WB to read inaccurate. And that's why its lost power now, its not as hot in the cylinder at the start of the intake stroke so vaporization is less and combustion efficiency has dropped.
Yes it will need larger jets either mains or PVCR take your pick. The reason for that is not that the carby has changed AFR, that it not possible unless your exhaust pipes managed to grab a spanner while you weren't looking and changed the jets
The reason is whenever the energy input of the cylinder is not sufficient to gas the fuel you have to put more fuel into the cylinder so that the light fraction of fuel that gasses easier, makes up a combustible mixture. Its the same thing as when your engine is cold and you have to enrich-en it with a choke. Pulling the choke on enriches the mixture so that the light HC's obtain a combustible mixture ratio with a cold environment.
A simple statement that has to be learned is" its not about the AFR of the liquid its about the AFR of the Gas". That's Gas as in the state of the fuel, not the slang gas as in gasoline."

Lots more to chew on!

 

[Mattax]

That's good stuff. That one doesn't hurt anymore. At high flow changes to velocity doesn't change AFR so the fuel to air ratio doesn't change.

The reason is whenever the energy input of the cylinder is not sufficient to gas the fuel you have to put more fuel into the cylinder so that the light fraction of fuel that gasses easier, makes up a combustible mixture. Its the same thing as when your engine is cold

This means the 'AFR' with best power curve using the cast iron manifolds may now be different using the headers. One more reason that shooting for a WBO2 reading is a bad idea.
Another thing is the drag strip run was made with the engine cold. This is pretty common with dragstrip runs. They never get heat soaked, and in this case it was dead cold.

 

[Hysteric]

This means the 'AFR' with best power curve using the cast iron manifolds may now be different using the headers. One more reason that shooting for a WBO2 reading is a bad idea.

Exactly. What's the AFR? Is it 12.7 -1? Is it that ratio everywhere in the chamber? Its 12-7 -1 but the spark plug has no deposits on it so it must be good and then you hear the unleaded fuels don't colour the plugs story so it must be true! No one ever talks about that and its implications so you're left to assume it must be because the WB tells you it is.

Here's something that Edward F Obert said in Internal Combustion Engines and Air Pollution, page 550. "This ideal picture, however must be adjusted to the fact that the mixture in the spark plug gap is never entirely homogeneous; very rich and very lean portions might be in the gap at the time of ignition."

This should ring a bell: "Its all about Homogenization and Vaporization" I wonder who said that

Another thing is the drag strip run was made with the engine cold. This is pretty common with dragstrip runs. They never get heat soaked, and in this case it was dead cold.

Very true. I usually leave early and get to the track before it opens the gates so usually the first run is cold as well. What was the differene in ET and MPH?

 

[Mattax]

Very true. I usually leave early and get to the track before it opens the gates so usually the first run is cold as well. What was the differene in ET and MPH?

Between not and cold ? Just one run and the car ran better than I drove. (in other words my driving wasn't very good)
Posted here
These runs were all on 215/70r14 tires similar to BFG all season Radial T/A. By launching from idle and squeezing it on I've generally able to avoid spin if the launch pad is sticky.

edit. Do you mean from previous exhaust and timing curve to the current setup?
Almost a full second and approximately 5 mph.

 

[Hysteric]

Between not and cold ?

I see you ran a 103.4 well done. . Also the most important question: What do the plugs look like?

These runs were all on 215/70r14 tires similar to BFG all season Radial T/A. By launching from idle and squeezing it on I've generally able to avoid spin if the launch pad is sticky.

I turned up to the track one afternoon to see this immaculately restored 4 door valiant which the owner was pulling the exhaust off before getting teched. Later on I see the car in the lanes and we start talking and he shows me around the car and it looks stock with 225 street radials and stock suspension. Opens the hood and all I really notice is the Airgap, a Holley 650 dp and headers. Didn't think much more about it until they pushed it to the line and it ran a 12.6 @ 105 from memory. WTF!

Anyway It turns out its a 318 with 11-1 comp a 218 hydraulic (268H Comp cams which only recommends 9-1) and ported 318 heads with 3.23 gears .The heads turned out to have been ported by the guy I take my heads to have flowed and he implied that the valves are really small i.e. probably stock. Turns out the owner is a tuner so he has a fair idea of what he's doing but this carb came from the guy Shrinker trained name Gregory. He went on to tell me that the smaller carb accelerates the car down the track quicker. There's more to the story but you get the idea.

Quite the over achiever, I wonder why.

 

[Hysteric]

Going back to this:

I would be inclined to go to a stepped down leg booster in both primary and secondary.

Maybe you could consider this idea: DOWNLEG BOOSTER INSTALLATION KIT - Allstate Carburetor

And experiment with different booster styles to see which your engine prefers. Its a lot cheaper than the booster tool.

 

[Mattax]

Those are some neat kits. Thanks. That opens options.
Didn't look at the plugs. You're right, but it didn't happen.

 

[Hysteric]

Didn't look at the plugs

Always look at the plugs! They tell you everything you need to know, especially what direction to go in with improving the burn.

I'll pm you something to look at that will help you understand this even more.

 

[yellow rose]

Going back to this:

View attachment 1715679663

I would be inclined to go to a stepped down leg booster in both primary and secondary.

Maybe you could consider this idea: DOWNLEG BOOSTER INSTALLATION KIT - Allstate Carburetor
View attachment 1715679664
View attachment 1715679665
And experiment with different booster styles to see which your engine prefers. Its a lot cheaper than the booster tool.

Do you have any pictures of the boosters without the threaded part in them? From the threaded end I mean.

 

[Hysteric]

No.

 

[rumblefish360]

No.

*

 

[Hysteric]

Are you still running the same combo that you and Bruce discussed here: Update on Dyno Results - Part 2, Fuel Curve

Do these plugs look familiar.