Reply to "High compression and pump gas"

I would think piston design also plays into the effectiveness of a chambers design given the pistons opposing surface and its relation to quench and ability to create turbulence in the chamber. If an engine builder (not assembler) takes into account the design of the chamber in relation to the opposing surface of the piston being used, they would have a better idea of how to build in a quicker burn.

Since we are on the subject of naturally aspirated pump gas, lets see if we can bring up some pump gas cleveland headed examples.

This has probably been posted before, but they used yates intake modified for an injection system with procomp modified heads (yeah i know), and I would be interested to know what the volume was on the intake. my understanding is FPS reworks the whole head including chamber. While they do have a methanol injection setup on it, its still running on 91 octane with 11:6 compression. I'm not endorsing a knockoff, just interested in how they worked the head for this displacement motor. They didn't say what ratio of water/meth though or when the methanol is being triggered.

http://www.popularhotrodding.c...uild/ford_438ci.html

i went with my girlfriend to help her buy a mazda3 with their skyactiv direct injection engine which injects fuel directly into the cylinder. No dribbling of fuel here, and they are running 14:0 on euro pump gas vs 12:1 in the US on 87 octane. The other hidden advantage is they can pull/add timing on the fly with the ECU of course.

I know this is stating the obvious, but it seems largely the secret to a carbureted car running more compression is by matching a head to a displacement capable of holding a velocity with a given cross section and throat size so that the air moving fast enough to keep the fuel in suspension vs part of it dribbling down the runner into the chamber creating inconsistent burn. You open the valve up and you have a puddle waiting. you put too big of a head on an engine and you get puddling at low rpm, you put too small of a head on an engine you won't know if its a dud until you compare it to a similar cubic inch motor with a bigger head. Then add in all the other variables.

I assume this is the basis for injection systems on street cars for emissions, because you are placing the point of injection/atomization closer to the valve/chamber and directing it as well vs a carb, you are pretty much spraying and praying hoping to get even distribution through to each runner, no pun intended same reason low rpm improves going from downleg to annular boosters. better fluid atomization.