See through carburetor and high speed camera

Daleandee said:
I worked in auto parts for a numbers of years and one way that the Holley Carb got a bad rap was from dem good ol' boys that came in and bought an 850 CFM double pump for their wore out 283 chevy ... then came back a few days later wondering why it didn't make another 200 HP and had black smoke pouring out the stock exhaust. Trying to explain the results before the sale was found to be worthless because them boys couldn't be bothered with facts from some stupid counter sales guy ... :dunno:
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I don't need no big block to run 850cfm! That 600cfm is for sissies!
 
bluerooster said:
What about the old Hilborn injection? Dirt simple.
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I changed from circle track to drag racing one summer and ran an alcohol dragster with Hillborn injection on a big block chevy. Similar to the picture below. IIRC the class could run a blower on gas, carbureted or injected on alky.

I had sprint car customers using Hilborn injection on their small blocks.

As you said, dirt simple.

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Not my dragster but very similar to what I had. (man, I was young, dumb and fearless...) And yes, I got hit by debris coming off the tires.
 
SoonerAviator said:
I don't need no big block to run 850cfm! That 600cfm is for sissies!
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Funny thing is all those folks who want the biggest carbs possible are hurting their performance, meanwhile with EFI a bigger throttle body doesn't hurt you since you don't need that vacuum signal to the carb.
 
Ted said:
Funny thing is all those folks who want the biggest carbs possible are hurting their performance, meanwhile with EFI a bigger throttle body doesn't hurt you since you don't need that vacuum signal to the carb.
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If the throttle body is too big it can have some of the same characteristics as a carburetor that is also inappropriately sized...

Since you bring up vacuum signal to the carburetor, Weber’s will often exhibit drivability problems when you use the largest chokes for a given carburetor. Same thing as what you’re describing, there just isn’t enough vacuum to make them work right, particularly at low throttle openings.
 
mondtster said:
If the throttle body is too big it can have some of the same characteristics as a carburetor that is also inappropriately sized...
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That may be true, although I've never seen it in a practical sense. It's certainly far less sensitive than carburetors.
 
Ted said:
That may be true, although I've never seen it in a practical sense. It's certainly far less sensitive than carburetors.
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It depends on driving style and application of the engine. Too large of a throttle body or carbs will typically result in a light switch type throttle response. That’s commonly fine when driving like most Americans do - in a straight line. Too big on an engine meant for a road course or autocross can make what may seem like a good performing engine very challenging to drive well.

Or in the case of stationary engines, it may make a governor very hard to get set up so it won’t surge.
 
mondtster said:
It depends on driving style and application of the engine. Too large of a throttle body or carbs will typically result in a light switch type throttle response. That’s commonly fine when driving like most Americans do - in a straight line. Too big on an engine meant for a road course or autocross can make what may seem like a good performing engine very challenging to drive well.

Or in the case of stationary engines, it may make a governor very hard to get set up so it won’t surge.
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Right, I get those aspects. Too large will mean that a very small throttle motion results in much airflow change. But with EFI you don't necessarily have the vacuum signal issue that messes with mixture control, since with EFI you have a number of other tools you can use to help regulate fuel vs. airflow.
 
Ted said:
Right, I get those aspects. Too large will mean that a very small throttle motion results in much airflow change. But with EFI you don't necessarily have the vacuum signal issue that messes with mixture control, since with EFI you have a number of other tools you can use to help regulate fuel vs. airflow.
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Yes, I addressed that as well. My point was that EFI is not the absolute solution many people purport it to be. You can create just as much of a tuning and drivability headache with EFI as you can with a poorly set up or mismatched carburetor.
 
mondtster said:
Yes, I addressed that as well. My point was that EFI is not the absolute solution many people purport it to be. You can create just as much of a tuning and drivability headache with EFI as you can with a poorly set up or mismatched carburetor.
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That's definitely true. And most of the people who just want a simple carburetor instead of new-fangled EFI mostly think EFI is a pain because they end up with those sorts of driveability headaches/issues. :)
 
Thinking about large (modern) throttle bodies and drivability; one project that I recently worked on had too large of an electronic throttle to be able to reliably use air flow control for idle (needed that big throttle due to supercharger and close to 800 hp at the wheels) - so the engine calibrators decided to flow enough air to cover any idle torque loads, fuel for that amount of air flow, and control torque and RPM with ignition timing. Those beasts would be almost at full operating temp within a couple of minutes of starting, even at idle, even at -20c... certainly the best remote start warmup performance that I have ever experienced, and I could always hear it start from my hotel room in the morning to verify that it was actually running!
 
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Ted said:
That's definitely true. And most of the people who just want a simple carburetor instead of new-fangled EFI mostly think EFI is a pain because they end up with those sorts of driveability headaches/issues. :)
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My experience has been that the same people who avoid EFI will make an equally big mess of trying to work on a carburetor. But wires and computers aren’t involved, so they have that going for them.

I think it takes an equally abstract mindset to excel at tuning either and make them work well.
 
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Matthew Johnson said:
Thinking about large (modern) throttle bodies and drivability; one project that I recently worked on had too large of an electronic throttle to be able to reliably use air flow control for idle (needed that big throttle due to supercharger and close to 800 hp at the wheels) - so the engine calibrators decided to flow enough air to cover any idle torque loads, fuel for that amount of air flow, and control torque and RPM with ignition timing. Those beasts would be almost at full operating temp within a couple of minutes of starting, even at idle, even at -20c... certainly the best remote start warmup performance that I have ever experienced, and I could always hear it start from my hotel room in the morning to verify that it was actually running!
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That approach isn’t uncommon in recent times, even in situations where there may be adequate control over a throttle body.
 
mondtster said:
That approach isn’t uncommon in recent times, even in situations where there may be adequate control over a throttle body.
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Usually, it is ignition timing for the initial torque change (since it is effective on the next cylinder firing) then change air & fuel flow to get ignition timing back to a place where it can be used to quickly change torque again. This was just an extreme example of that sort of control since the throttle plate control wasn't precise enough at idle airflow.
 
Matthew Johnson said:
Usually, it is ignition timing for the initial torque change (since it is effective on the next cylinder firing) then change air & fuel flow to get ignition timing back to a place where it can be used to quickly change torque again. This was just an extreme example of that sort of control since the throttle plate control wasn't precise enough at idle airflow.
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Things are changing, it is becoming more common to see unusually high manifold pressures at idle and other inputs being adjusted to keep idle speed in check. It may not be universal but it is certainly not a unique approach.

It is definitely an interesting example of a different approach to a problem. It reinforces my stance that good tuning requires much more critical thought than most believe.
 
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mondtster said:
Things are changing, it is becoming more common to see unusually high manifold pressures at idle and other inputs being adjusted to keep idle speed in check. It may not be universal but it is certainly not a unique approach.

It is definitely an interesting example of a different approach to a problem. It reinforces my stance that good tuning requires much more critical thought than most believe.
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I totally agree, and that goes for most automotive systems (and likely most aircraft systems as well). My personal specialties are vehicle dynamics and brake controls development, but I see a lot of the same sorts of creative problem solving in the engine, transmission, steering, and driveline calibrations as well.
 
Zeldman said:
I changed from circle track to drag racing one summer and ran an alcohol dragster with Hillborn injection on a big block chevy. Similar to the picture below. IIRC the class could run a blower on gas, carbureted or injected on alky.

I had sprint car customers using Hilborn injection on their small blocks.

As you said, dirt simple.

AhmDI4uwdX1kAyfxk6eDjjSKSC1QFmOrog7EFVzLJACTZEkCc_aUPZa_QquQVGuod12z7PzvnqcDNT7a0gJQ4WYc-f0


Not my dragster but very similar to what I had. (man, I was young, dumb and fearless...) And yes, I got hit by debris coming off the tires.
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Do you use hearing aids now?;)
 
Zeldman said:
I do have hearing loss in the upper range, like the range my wife talks in.....:lol:
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I'm sure somewhere there is a study that proves that years of marriage causes a condition in men known as selective hearing increase. :dunno:
 
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