Guess the horsepower this 454 made!!

In reply to Robbie:

Ill volunteer to do it for the challenge car if someone donates an itb manifold for a small block ford.

Dusterbd13 wrote: By my math, if you put 1 carb per cylinder, you could have a 440hp 454 with itbs..... For about 96 bucks. Carbs are 12 bucks on ebay....

Mower carbs don't have accelerator pumps, driveability would be awful.

EDIT:Also, is there any video of the dyno run? I imagine it sounds pretty bad.

Dusterbd13 wrote: In reply to Robbie: Ill volunteer to do it for the challenge car if someone donates an itb manifold for a small block ford.

I always thought the GT40 lower would be a perfect start for an ITB manifold. 8 perfect holes in a line. Nice flat plane.

Easy to machine a matching flat flange, and then 8 90 degree bends, 4 in each direction (if you want to run side drafts). I always wanted to do twin motorcycle carb banks...

If you promise to do it I will buy an eBay gt40 lower and mail it to you.

I volunteer to make the matching adapter plate to weld the intake tubes to.

BrokenYugo wrote:

Dusterbd13 wrote: By my math, if you put 1 carb per cylinder, you could have a 440hp 454 with itbs..... For about 96 bucks. Carbs are 12 bucks on ebay....

Mower carbs don't have accelerator pumps, driveability would be awful.

I know of a half decent tiny cheap carb that has an accel pump.

I bought an honest to God Japanese built keihin pd18 carb for a Gy6 50cc scooter last month for $23. The 20mm version can be had for not a lot more, or the not quite as nice Chinese made version for under $15.

Driveability problem solved, still in challenge budget.

And this was the year grm decided that lawnmower carbs were perfectly acceptable alternatives to a holley 850, as long as your had enough of them.

Now we just need to make 24 chainsaw motors with a single 4 barrel!

Bruce

This needs to be in a Lemons race.

I LOL'd at that pic. This is re-goddamn-dickulous. I love it.

mndsm wrote: And this was the year grm decided that lawnmower carbs were perfectly acceptable alternatives to a holley 850, as long as your had enough of them.

double pumper? psh. Try octa-pumper, or dodeca-pumper.

Doing some down and dirty math, I came up with a volumetric efficiency of ~32%. lol.

Robbie wrote:

Dusterbd13 wrote: By my math, if you put 1 carb per cylinder, you could have a 440hp 454 with itbs..... For about 96 bucks. Carbs are 12 bucks on ebay....

This is amazing and needs to be tried. Maybe even make a manifold with 12 of em for the WTF factor.

This is GRM. It needs to be done to a Jaguar V12. Or a rotary.

Knurled wrote:

lrrs wrote: What hp tecumseh did the carb come from ? Going to guess if from a 8 hp motor, the 454 would only spin to 2000 loaded, and say about 55 hp.

You're really close. 60hp at 2500rpm. I am shocked that the lawnmower carb could move 60hp worth of fuel!

That is a lot of fuel form a little carb. Flow rate is not everything if you run under say 5000rpm. I can squeeze 180hp out of a y block with a single 97 stromberg.

Dusterbd13 wrote: By my math, if you put 1 carb per cylinder, you could have a 440hp 454 with itbs.....

Unfortunately, it doesn't actually work that way. A closer approximation is that this carb/manifold flowed enough for 7.5hp per cylinder, which sounds much more reasonable. Feeding each cylinder individually would only offer a limited amount more power per cylinder.

On the other hand, if you built a single manifold for all 8 of them to feed...

And while not possessing nearly the 'shock' value, it probably would have been more informative to their cause if they had simply stuck it on a moderately larger single cylinder engine than a huge 8 cylinder engine.

This is, like, the Kaleco of GRM threads. Awesomely sick and wrong.

Next year's special class. Lawnmower carbs. As many as you want. Highest placing car wins a lawnmower. I'll donate it.

In reply to mazdeuce:

Bonus points to anybody that can get them to open sequentially.

The linkage requirements would be so awful that I'd almost think it'd be EASIER to run them drive by wire. With some sort of momentary-on popper solenoid. Throtte control is how many carburetors are at WOT.

This is sillier than my idea for a "Big Bang" V8 engine, where all cylinders on the right bank fire, then 90 degrees later all cylinders in the left bank fire, then 630 degrees of dead time. I'm not sure what would be worse, the vertical shaking, the torque spike at the flywheel, or the cam drive "harmonics". Getting the firing order correct would be easy at least.

So, as I understand it, a restrictor plate works because air will not travel through it at higher than the speed of sound. So there is an absolute maximum flow rate for a restrictor plate.

So is it reasonable to assume that the airspeed through that lawnmower carb was approaching the speed of sound?

In reply to DWNSHFT:

It's not the speed of sound that is the restriction. Over something like .3 Mach, it takes more power to move the air than can be gained from mixing the oxygen in the air with fuel.

32mm restrictors cut you to roughly 300hp max. It's been maybe 25 years since I hotrodded lawnmowers, but I remember the carbs being far, far smaller than 32mm. If it was the carb's CSA that was the limiting factor, then 60hp is 20% of 300, so the venturi might be (16 squared is 256, divide by five is ~51, square root is ~7...) about 14mm - 9/16 in diameter.

Which sounds about right, actually.

Now, exhaust ports on the other hand, can go supersonic, and when they do there seems to be an effect where the act of flowing keeps the flow going. The problem is making exhaust ports that want to go supersonic in the first place.

TIL that I know enough quasi-useful trivia and can do enough headmath to calculate the maximum horsepower potential of a restrictive carburetor.

Now I want to contact the guy who did this and ask him what the venturi ID was, to see if my XKCD What If level of mathematical approximation was correct.

Wait, we don't know the answer. I need to know how many HP, not discuss what we think it is.

The answer is, almost as much power as the stock 454 in my '93 K3500 with TBI.

Knurled wrote: The linkage requirements would be so awful that I'd almost think it'd be EASIER to run them drive by wire. With some sort of momentary-on popper solenoid. Throtte control is how many carburetors are at WOT. This is sillier than my idea for a "Big Bang" V8 engine, where all cylinders on the right bank fire, then 90 degrees later all cylinders in the left bank fire, then 630 degrees of dead time. I'm not sure what would be worse, the vertical shaking, the torque spike at the flywheel, or the cam drive "harmonics". Getting the firing order correct would be easy at least.

I bet the linkage could be done mechanically. Design would be tricky but certainly not impossible. Fabrication shouldn't be hard.

I wonder what a big bang crossplane V8 would sound like, considering that a big bang I4 sounds kind of like a crossplane V8.

volvoclearinghouse wrote: The answer is, almost as much power as the stock 454 in my '93 K3500 with TBI.

Oh boo-hoo, some of us have to move a whole RV with that garbage!