ultimatejay

iTrader: (1)

So if you work at a machine shop then jets and chokes would be easy to make. Also, all you need is a couple of jets and you can drill them out to the desired size and if they get too big you just solder them shut and start all over again- very cheap. You can also get a used IDA for a very good price. But too each is own. Good luck regardless. I don't know how you can get any cheaper and simplistic than a carb set up, especailly for a pport.

peejay

The EFI setup was $75 for the computer, $60 for the wiring harness, and the rest was free or pre-existing stuff. The fuel pump did cost me quite a bit but that was before I knew about the Ford truck pump. I think I paid $200 for the Subaru turbo pump. But this pump is good for about 500hp at pressure, so it's more than I'll ever need

An IDA, I'd be looking at $400-500 for a used one, plus I'd have to make a new intake manifold, one that tapers because I don't think they ever made a 40mm throttle body IDA and my runners are 40mm. All that is time that I do not have. Nationals are on the 21st.

Tapering while curving is difficult to do without introducing a lot of flow problems. IDAs also don't have chokes, so driving when cold would be impossible or at least extremely difficult unless you tuned it so rich that it sucked.

You do not drill jets unless you like failure. Jets aren't just holes, they are metered orifices. Even nicking the jet with the screwdriver will ruin it, I'd hate to see what a scratchy nasty drill bit would do. Even properly doing it with a reamer would leave the inlet/outlet of the orifice horrible and irregular for flow.

Part of my job is making Holleys work good on engines that really should have something better. I know tuning carbs.

Trust me, there is just no way you could get a carb half as good as EFI on an engine with such variable intake vacuum and airflow. On EFI the P-port runs *smoothly* and doesn't even brap. In short it has the idle and low load runability of a stock engine. That translates to something you can enjoy on the street any time you want. But, quite honestly, I'm bored with it and want to do something different, so it'll go back on the shelf.

Whizbang

so whats the plan for the 21st then, pete?

j9fd3s

iTrader: (3)

i'm using a weber on my P port, cause i already own it. just to rebuild it, and put the jets in it that the comp book says i'm supposed to have was $200.

by the time i buy enough jets to have it running half as good as efi, i could have bought the TWM throttle body...

peejay

That engine sitting in your shop!

I need to get in sometime early... if I get there at nine then it's time for me to turn around and go home, I'm an old man need to get to bed before 10

Whizbang

we can figure a time. i can get there at like 530 if needs be. or we can arrange for other plans

peejay

It was 95 degrees and crappy all day today, and the A/C belt on my VW was slipping heinously, so I tried to tighten the belt after work. Clearly, the design of the tensioner arrangement is a form of punishment, possibly for something from WWI. I made no headway on it whatsoever. (note that the A/C compressor is what drives the *alternator*, and the A/C belt drives the water pump... so that belt is kinda important!)

I felt a need to accomplish something yet still had the energy to do it. Hmm, let's bash our head against the ol' brick wall. I happened to have my (now fixed) laptop with me so I went to the Mazda, plugged everything in, and started it.

It started without starting ether. Huh? That's unpossible! So I attacked the existing map with a vengeance.

Basically I richened it *everywhere*. As it turns out, a rough idling rotary is much harder to get the idle tune right than a rough idling boinger. You can tell when a crackly V8 is "right" at idle, but a rotary just bucks and stutters no matter what. (The O2 reading is useless because of all of the raw air going through) I mega-richened everything.

Then I drove it tentatively on the street, preparing to just drive around the local block. Hey, it pulls! But now I see that when it's pulling in certain conditions it's incredibly lean. (This after I enrichened everything a bunch) So I stopped at the BP on the corner to get four gallons of yummy $3.85 87-octane, since I have no fuel gauge and the last time I dumped in 2 gallons of fuel it had, er, 16 ounces of 2-cycle oil in it. So it may have been getting a wee much oil Richened up the areas where I noticed it cutting out lean before, and turned the idle down some more, since after clearing the plugs out by driving it, it was idling around 1900 instead of 1500.


I think part of what was faking me out was that the old 6-port based maps I was using were a standard 20KPa-100KPa map. I made a generic new map based on a 50KPa-100KPa map since this engine *never* sees below 50KPa. It idles around 60-65 though and the power brakes do work. But, a 50-100KPa map is going to be a lot flatter looking than a full-range one, and so a lot of the troubles are in the "low" parts of the map.

So really now it's just a matter of tuning now that I know what direction to take.

It seems to have stopped leaking coolant, too

And without air filters, it's, uh, LOUD. Not as loud as an open exhaust on any rotary, but definitely a lot louder than when it had a GSL-SE engine.

The corner seal springs for my next 6-port came in today as well. Now that I have all the pieces parts for it, I want to hang on to running the P-port for just a little bit longer.

peejay

110psi compression cold and hot, even pulses all around.

Running up to 85% duty cycle on 680cc injectors at 55psi base pressure instead of 43psi. (Thanks Alex, for bringing that up. I'd forgotten that Mopar uses a higher base pressure)

Whizbang

running better then?

ultimatejay

iTrader: (1)

That's some good compression. So lets see some vid of this puppy in action?