gemellocattivo.com

11-10-2007
If you google it, there are a lot of variations out there.

What I did was built a venturi meter. I took about a 4" pipe then a 4"-2" reducer followed by a section of 2" pipe and that forms the venturi. When air flows through, the diameter change causes the pressure to drop proportional to the square of the flow velocity. You measure the differential pressure, you know the pipe ID and you can calculate velocity and volumetric flow….or you can just plug the numbers in on this web site and it will do the math for you:
http://www.efunda.com/formulae/smc_f...meter.cfm#calc

The 4” pipe needs 2 pressure taps. 1 for the venturi attached to the reservoir end of the slat manometer, and one to measure the vacuum you are testing at attached to the standard manometer. The 2 inch pipe needs 1 pressure tap and connects to the end of the slant manometer. I used 6 pressure taps, instead of 3 with the second set of 3 just 180 degrees around the pipe and T’d to the first set thinking there could be uneven flow distribution and I’d get a more repeatable result by measuring in multiple locations.

I bought a cheap manometer for measuring the test pressure, but a bent plastic tube a a ruler will do just fine too. The pressure in the venturi in pretty low, so I made a slant manometer (plastic tube, a ruler, and a little reservoir) and played with the angle it sits at until it was exactly 10 times the reading on the standard manometer.

I’ve got 2 5hp shop vacs to make the vacuum and I control then with 2 electric fan speed controllers.

The second way to calibrate is using orifice plates. I made .75, 1.25, and 1.75 plates and the math for what they should flow is here:
http://www.efunda.com/formulae/smc_f..._flowmeter.cfm
They have the flow coefficient at .7 as the default, but everything I found said .62 so that’s what I used and the number matched the venturi calculation.

This set-up is good to 200cfm before the slant manometer runs out of numbers. A smaller pipe, like 1.25 or 1.5 would give better low end resolution and a bigger pipe more top end flow. I chose the 4”/2” combo because the range fit this project well.

11-11-2007
Not yet. It shipped last monday (10/5) and they said within 9 days, so it should be here by wednesday. I can't wait to see it!

11-12-2007
I decided to just have at the head a bit. The way Ferrari shaped the ports seems a bit odd to me. The smallest section of the port by far is right at the valve guide/stem section where you least want an area constriction. After seeing that and know my plan was for oversize valves, I figured there was no harm in grinding a little.

I like to just grind a little at a time so the head goes on and off the flow bench a lot, but that lets me catch mistakes before they are very serious. I got it about ½ way to where I think it should be with just a rough cutter finish, but the high lift flow is up quite a bit.

The low lift flow is more about the valve job than the port. At valve lifts up to .250”, the exposed area around the valve seat is less than the smallest part of the port making it the limiting factor and the point of highest velocity. Above .250” the valve is an obstruction, but the port is where velocity is highest.

All that said, here’s where I am:

Lift…….Flow (at 10" H2O)
.05”…….21
.10”…….48
.15”…….71
.20”…….89
.25”……103.5
.30”……110
.35”……113
.40”……114.5
.45…….117
.50”……118

11-13-2007
still no engine so I played with the head a little more tonight
lift......flow
.05.....25
.10.....51
.15.....74
.20.....91
.25.....105
.30.....113.5
.35.....117.5
.40.....120
.45.....121.5
.5.......123.5

It's doing pretty good up around .400 lift.....but the stock cams I'm hoping to keep are only .350 lift and I'm running out of ideas. flow area wise, the valve is out of the way by .300 lift, but it's obviously still acting as quite an obstruction. I think I'm going to play with how the seat meets the combustion chamber a bit more I guess and take some careful measurements to be sue I've got the port the way I think it should be. After that the only think left it to go to a bigger valve I guess and just make everything bigger, up to now the seat ID hasn't change, so all the flow gains also represent velocity gains and I'd hate lose all velocity since that is key to low rpm performance.....I need to think some more I guess.....

11-14-2007
I think with the bigger engine I'm going to have enough hp without boost, but I'm not ruling out boost. Right now, the heads are flowing enough to make 550+ hp I think, and that's just over what the boosted 3.0 was doing. If I can get to 120-125 from the heads at a reasonable valve lift it should clear 600....so about 5 more cfm to go.

The valves in these heads are 28.5mm, a honda 1.6 with identical bore and stroke runs 31mm as standard and 33 in the R versions. That tells me I should be I should be able to open things up a bit more if required. A 31mm valve is 18% more area…I really want to stay as small as I can though to keep the velocity up.

11-14-2007
The engine has arrived!

Pics to when I get home.

11-14-2007
here it is in all its (oil covered) glory.

11-14-2007
There was no way I could have the engine sitting here and not at least see if there was any real hope of getting it in the engine bay.......

11-15-2007
No, I don't think so. It's already set-up to accept 10.5" wide wheels and at least 285 tires und the stock fenders. That should be enough I think.

11-15-2007
It will, but not much and no more than I already had with the supercharger stuff I had in there. the supercharger stuff was all mounted on top of the engine and it still handled well enough to win it's class at several autocross. this weight will be carried about 12" lower on average, so it should be a bit better. 100 lbs is really not enough to worry about, it's only a 3% weight change and it's coming between the axles.