Anyone get $58 or $60 code to run well in a 730 with a 2 bar map and a large cam? I’m not talking huge, but something in the range of 230* or so at .050 in a 350 (the heads that are being used have biggish, 200cc or so, somewhat sloppy intake ports, so I suspect that idle vacuum will not be great no matter what). What, if any issues do you run into and how do you deal with them?

Anyone have a useful bin to start with?

For that matter, while I’m at it, does anyone have a good ecu or xdf for the $60 to use in tunerpro?

 

Hows 230/245 @ .050, .535/.540 lift on 114lsa 112ica ??

Its coming really close. Below 2,000rpm absolutely blows, but I got most of the 2k+ ve worked out and spark. Need to take a hair more out of ae, and some work under 2k but i'm optimistic.

This is $60 code

-- Joe

 

230/245 ,544/,576 112 cam with $58 in a 730 but with 415cui and no problem........oh 9.0:1 in comp

/N.

 

GTA, I’m not sure that yours is a great example… your 415 makes that cam act like it has probably 11-16* less duration at .050 then it would have in a 350.I would hope that setup is actually quite streetable and fairly easy to tune. Any idea how much vacuum at idle you have?

Joe, yours is a better example of what I’m trying to do… so what’s the problem below 2000rpm. Is it an issue with trying to get an accurate tune down there with too low a map signal (what is your idle vacuum?) or is it just that you haven’t spent the time to get it right?

How big injectors are both of you using?

 

I'm at 60kpa at idle @900 rpm

/N.

 

You wacky Europeans and your metric system…

Is it really that high??? 60kpa translates to 17in/hg, which is almost stock. I have no expectations of seeing anything close to that in my 350, I was figuring somehere in the 12in/hg range IF I get really lucky (that is if I end up going that big, which is the reason for the thread)

 

My MAP reads 60 kpa, but my vaccum gauge is 10-12in/hg......

(N.

 

huh... something is not adding up there, or I'm not converting right...

 

60kPa = 0.60 bar

 

Don't forget that vacuum isn't the same as absolute pressure.

I'm sure Mark knew that and just spaced it, but for anyone else reading along who might be a little rusty...

Vacuum is referenced to atmospheric pressure, whereas MAP is absolute, i.e. referenced to zero pressure. So,

29.9 in hg (atmospheric) - 12 in hg (vac) = 17.9 in hg (MAP) = 61 KPa (MAP)

 

in/hg of VACUUM
Here's the math;
100kpa = 1bar = 29.53in/hg
60kpa = 17.72in/hg or 12.2in/hg of VACUUM
Remember vacuum is measured from atmosphere (or bar depending on your system). So take your measure of atmosphwere, which with US is 1atm or 29.92in/hg and subtrace the 17.72 to get your vacuum. Which happens to be 12.2in/hg . Don't take 1bar and convert to in/hg and then vacuum, it doesn't work that way. The vacuum gauges with psi for positive pressure and in/hg for vacuum are based on 0psi/0in/hg at 1atm. It's hard to remember since 1atm is so close to 1bar.

 

Your table is incorrect. 0bar would be 29.92in/hg, not 29.5
The person that made that chart either forgot, or wasn't even aware of the difference between atm and bar.
The chart start-end should be this;
in/hg- 29.9 ... 0.4
bar- 0 ... 1

 

I'd assume that chart was intended for automotive tuning, and while you're correct that it's not quite right, I wouldn't get too bent out of shape over foks here who mentally round off one atm to 1 bar (100 KPa), instead of the 101.325 KPa that it actually is. (same reason for the difference between the 29.5 and 29.9 in Hg figures quoted in English units). From a PROM tuning standpoint, it's a very small error, and it seems kind of understandable given how the VE tables are arranged.

Obviously if you're studying for engineering finals, or working in industry you have very good reason to be concerned with the difference, and probably don't appreciate people trying to pollute your brain with approximations.

 

I idle around 57-60 kpa, and shows around 11-12hg on the vac gauge. The math is right.

Mark, hoe much overlap you looking at? I'm at 9.5 degrees.

-- Joe

 

97kpa ignition off
55kpa 900RPM idle

236/242 @ .050 113lsa

 

Heh, close, but not even that… 2am and no sleep for a LONG time leads to stupid confusion on my part… thanks guys.

So all of you are running $58 or $60 at such low idle manifold vacuums? Do any of you have it tuned well so it’s happy at idle? How big are your injectors?