Lawnmower Carb on a 302 V8… worth the watch

[unclebilly]

[911boost]

Pretty cool. I thought I recognized some of the places he was driving as well at at the end when he showed the map of the route I was right...

Lots of higher level thinking and tuning going on there. I would be curious to see it on a dyno.

I will say the "heater" he used in the winter is insane.

[LWJ]

That is just awesome.

And, he is a super cool guy (aside from the janky heater)

[pwd72s]

If anybody actually comes up with a flux capacitor, it'll be this guy!

[red 928]

Why not just adjust the throttle linkage
on the stock carb to only open
1/4 of the way

same result and easier

[unclebilly]

Originally Posted by red 928

Why not just adjust the throttle linkage
on the stock carb to only open
1/4 of the way

same result and easier

Actually not the same and he explained why.

The smaller carb better atomizes the fuel at wide open throttle than a larger carb does at 1/4 throttle. This is due to the smaller carb maintaining high vacuum at wide open throttle whereas the normal carb can’t / doesn’t. The hard 90°s on his intake assist with fuel atomization by increasing turbulence.

[mattdavis11]

Anyone notice the chain? I guess it's to keep the motor with the frame when that one barrel carb twists the motor mount out.

[beepbeep]

Sorry, I call BS on this. There is very little difference between part open larger throttle and fully open smaller throttle for given lambda. Both will maintain similar vacuum so any differences will come from potential fuel mixing gains, which will both be worse compared to port injection (which is worse than direct injection).

Now if he could put some magnets on that fuel hose....

[pwd72s]

Originally Posted by mattdavis11

Anyone notice the chain? I guess it's to keep the motor with the frame when that one barrel carb twists the motor mount out.

An old trick from the muscle cars days...kept the torque twist from hurting engine mounts.

[aschen]

skimmed through it at lunch, I am 0% suprised a tiny carb can run a big engine well, not much different than a big car with a low throttle position. I am not all that familar with lawnmower carbs but I assume that is sized for enough cfm for 20hp or so, you can get down the road on 20hp but 5 would be a struggle.

The most impressive part to me was whipping up a wireless smartphone app and hardware to PID the AFRs. Amazing what tools are available to the home gamers these days but a custom layout PCB and phone app is still pretty involved I would think

[masraum]

That's so cool.

I somewhat miss the days of tinkering with a V-8 (it's been >30 years). I'd like to have something to tinker with, but most stuff that I'd be interested in has gotten ridiculously expensive.

[masraum]

Originally Posted by aschen

skimmed through it at lunch, I am 0% suprised a tiny carb can run a big engine well, not much different than a big car with a low throttle position. I am not all that familar with lawnmower carbs but I assume that is sized for enough cfm for 20hp or so, you can get down the road on 20hp but 5 would be a struggle.

The most impressive part to me was whipping up a wireless smartphone app and hardware to PID the AFRs. Amazing what tools are available to the home gamers these days but a custom layout PCB and phone app is still pretty involved I would think

Maybe even more. I think my zero turn mower has 27hp.

[masraum]

Originally Posted by pwd72s

An old trick from the muscle cars days...kept the torque twist from hurting engine mounts.

I thought it was also so that if/when the motor mount did let go, the motor was still constrained.

[masraum]

Originally Posted by beepbeep

Sorry, I call BS on this. There is very little difference between part open larger throttle and fully open smaller throttle for given lambda. Both will maintain similar vacuum so any differences will come from potential fuel mixing gains, which will both be worse compared to port injection (which is worse than direct injection).

Now if he could put some magnets on that fuel hose....

Gotta have the molecules lined up! Orderly gas is powerful gas.

[Por_sha911]

The real secret as to why this works is he has a cool collar purchase on Pelican back in 2004

[svandamme]

Originally Posted by beepbeep

Sorry, I call BS on this. There is very little difference between part open larger throttle and fully open smaller throttle for given lambda. Both will maintain similar vacuum so any differences will come from potential fuel mixing gains, which will both be worse compared to port injection (which is worse than direct injection).

+1
It's an exercise of no results.
Fuel economy with a V8 by restricting max fuel suck is BS because the car is heavy and the damn engine has to much rotational mass.
he's wasting to much of his little carb on keeping the big engine spinning
That's the main reason it runs smooth at all.. it has a lot's of rotational mass

[red 928]

Originally Posted by unclebilly

Actually not the same and he explained why.

The smaller carb better atomizes the fuel at wide open throttle than a larger carb does at 1/4 throttle. This is due to the smaller carb maintaining high vacuum at wide open throttle whereas the normal carb can’t / doesn’t. The hard 90°s on his intake assist with fuel atomization by increasing turbulence.

and you bought it

[svandamme]

Originally Posted by red 928

and you bought it

utter nonense that his air with fuel already in it will atomize better on that 90 degrees

It probably will make the fuel slap against the outside wall and be less atomized then if it was a straight shot to the heads.
Fuel is heavier then air and change of direction it will want to continue straight. EG hit the outside.