My new engine was recently completed and the dyno showed a 40 hp drop with the flame arrestor in place.

Fresh air without flame arrestor: 620 hp @ 5400 rpm (pulls 620-630 hp all the way to 6300 rpm )

With Gaffrig 3" x 10" arrestor in place: 580hp @ 5400 rpm

Engine is 548ci tall deck, 9:1 compression, 6.385 rods, 345cc merlin iron heads, cam is solid tappet 256/[email protected] (dry exhaust) 1.8 rockers, Holley 4150 850 cfm on Dart single plane intake

Since 40 hp per engine is significant, what's the best way to get cold air directly to the carbs and still be coast guard legal?

Do I have enough carburetor?

the way to tell size on carb is to hook up a vac line run at WOT and it should read 0 or maybe 1 inch but anymore it means the carb or flame arrestor is to small

I've never seen a flame arrestor cost 40 hp try the carb size deal then another flame arrestor

I never tried it on the dyno, but with this motor I PICK UP 75-100 rpm and almost 1mph with the K&N filter ON!!! I know, I know....but I am being honest.

I did not beleive it either, but I made 6 passes at wot, everything consistent (I did not even change tabs or trim) and each time it confirmed the increase/decrease. Some people think I am crazy, but I am telling you what I saw.

Also, that is the 4" K&N which is probably starving the motor a little. They did not hav the 8" when I ordered it. Try a 4" K&N (automotive will work) on the dyno and see what turns up....I'd be interested to hear the results.

Last year I had my 461 on the dyno, and was disappointed in the results. I had a Gaffrig flame arrestor on it. We took the flame arrestor off, and bingo, we jumped considerably. I don't remember the exact figures withourt getting the pull sheets, but I think it was around 20 HP. I then bought the biggest K&N that I could fit under my hatch.

Well........I know a guy who took his Gaffrigs apart & pulled all the screen door stuff out of them........They will not function as flame arresters any more...but they look the same to the Coasties

WARNING !!!!!!!!!!!!!!!!!! Do not try this at home !!!!!!!!1

Ooopsss....to clarify...I made passes with the K&N on then off (open carb). 3 times each, all back to back withine 30 seconds of eachother. Same results each time. WITH the K&N I picked up 75-100 rpm. Maybe it's just my motor combo, but I saw what I saw. Apparently the filter reduces turbualnce enough to help, is what I take from that. Straight, easy flowing, clean air.

They do not sponsor me either(yet...hahahaha), so I am not just saying this. Plus, most the race car guys I know use K&N, and we do also. I beleive my testing more than some magazine article!

Goodluck, many different opinions on this one!!

It could be that 20 hp is about right for the arrestor's effect alone and the other 20 hp was from the fresh air plumbed from outdoors instead of drawn from inside the dyno room. I'll check to see if that's the difference at the shop.

Still, it is good to know that fresh air and the right flame arrestor can make such a difference.