Look at it this way. Turn your garden hose on, just barely, and note the the amount gpm that comes out. Now turn it on full and note the gpm. The opening didn't change, but the gpm increased proportional to the pressure. That's what was happening with your fuel flow.

To get 8 mpg, your pressure was way over spec. That's the mpg I got with the Mikuni on the 1/2 bp-1/2 sp in the widebody, during the winter with long warm ups, and short hard trips. On the highway I was getting 22-23 .

Yaw carbs arevirtually non-exsitant for the gerneral public anymore, it's worth some cash.

 

Mine is mounted over the two smaller holes on the manifold. I believe those would be the secondary ports, but I don't think that matters. Don't the primary and secondary ports on the manifold both go to a corresponding intake port on the housing?

 

Primary ports are the 2 center ones, secondaries are the outer ones and are larger than the primaries.

 

dont knock it till you try it..
these little boogers have some kick

 

Amen to that, they definitely have some kick in them

 

I would think that they would max out quite early. So off the line you'd probably have "some kick" because the velocity is really high with such a small barrel so fuel atomization would be good... but once you maxxed it out you'd be screwed.

So I guess if you are never exceeding 40-50kph you'd be alright, lol.

Jon

 

I'm less pessimistic, haven't seen Robert build anything which "didn't" work yet

 

Why would you expect high performance from a carb that was set up specifically for good fuel economy? If it can hit the mpg goal, then great. If it can give enough of a kick to still keep the car somewhat fun, even better.

You've got to give credit to anyone who is trying different things with/to/for these cars. Get on with that tuning so we can see some real results already...

 

Take a vote, who would sacrifice 10hp for 10+ mpg?? You'd get a few, it could turn that old 7 from a pleasure vehicle to a daily driver.

 

If I were you I'd order up the 1-10psi gauge from Billy at ReSpeed. He did his research and found a gauge that's very accurate (~1%-2.5%) for tuning low fuel pressure. It's expensive (I think I paid $50-$70), but it's well worth it. Other low quality gauges can be off 10%+.

 

I just put the regulator on and dialed it to 2lbs. I'm currently waiting on USPS to deliver something, but after that I'm going to warm up the engine and advance the timing a bit.

Then I'll be heading on a 60 mile round trip to test it out (40 interstate, 20 highway).

 

The regulator didn't work. It reads "0" on the gauge between the regulator and the carb no matter what I dial it to. I'm going to take it back and get something else I guess.

Fill up my tank when I returned and got 16.524 after switching to the 50 idle jet and advancing the timing a bit. That's going 65-70 on the interstate and 55-60 on the highway. I had about 40 miles on the tank at that point in-city-driving with the old idle jet/timing, so it might go up a bit more than that.

so 40 in town, 40 interstate, 20 highway and about 8 misc somewhere for a total of 108.2 miles on 6.548 gallons.

I'll probably be putting another 120ish miles on it thursday and friday to test it more. I'll post more gas slip numbers after that.

 

What kind of regulator did you get? A lot of them are very cheap and poorly made.
Show us a pic of it if you can.

 

And the only gauge that's going to read correctly at these misiscule pressures is the one from www.re-speed.com

I could site a whole bunch of references for you, or you could just take my word on it... Good luck...

 

It was what I could afford. The cheapo spectre 1-5 or 1-6 from autozone. Oreillys sells one that looks identical with a mr gasket sticker on it. I can either try that or return this piece of junk I have and save up for something better.

I did notice the mr gasket comes with metal adapters, while the spectre model comes with plastic.

 

I'm sure the gauge I have isn't accurate, but at least it's showing that I have pressure. Even if that pressure does seem to bounce up and down 1/4 of a pound randomly. :P

 

I got 16.8 MPG on my last tank. freeway, traffic, and plenty of spirited driving on that one too..

 

You guys need to give up on this. I average 18-20 mpg on my 13BT streetport at 8psi. The last Nikki I built was for Jeezus. I think he already posted 30+ mpg. I don't know what you guys are expecting here, but I highly doubt your ever going to get the "advertised" results.

 

Thats exactly the one I told you not to get. Its crap, restricts flow and is highly inaccurate. Go to jeggs or summit and get a decent one.

BTW I have a RB Dellorto 48 DHLA and it gets 17 city and 25+ highway. Theres also no downside to power with it.

 

I got over 18 with my Sterling (jetted for racing, not economy) coming back from Deals Gap. Plenty of spirited mountain driving counted in there too, and averaged over 80 on the freeways. But we took a lot of backroads too, just to break things up a bit.

I bet I could get 22 or so if I was driving with economy in mind, and really making an effort (without swapping jets). It would never work though, I have no self control when it comes to the application of the throttle. When you feel those secondaries open up, it's like you just can't help yourself...

But for those who say you should give up, I say no way. Everybody started somewhere, you guys are just actively participating in the R&D... It will be interesting to see how high of mileage you can get to....

 

I think you need to reseach "Hypermileing". This is what Jeezus did to get the results he posted with his Nikki.

 

Interesting. I don't think I'll take it *that* far, but I've certainly reconsidered my driving habits. My wifes Nissan gets a solid 30 mpg at all times, but I think I know one of the reasons why now. Unless you smash the pedal to the floor and hold it the transmission never gets above about 3k. Most of the time it's around 1.5 and shifts around 2 to 2.5.

I may have to try that and some other things, but I think going 60 on the interstate here would be murder. Speed limit here is 70 and most people go 85 or 90 at all times. They don't really have a concept of yielding or slowing down for slower traffic. Even at 70 it's scary. :P

I would say I could take the highway instead to get places, but my wife thinks the interstate is too slow at 75. Chances are she would never go for it...even if it saved money.

 

Get a proper regulator on there and fix any ohter issues so we can get some real world results....with regular driving

 

for all the haters and non believers out there, i have bad news for ya!

there are now 22 kits on the road and fuel economy reports are great..
funny how there are always the non believers out there, same thing happened with my 12A turbo that made 680 rwhp in '99, nobody online could believe it made that much power, but the local guys that witnessed the beast in action knew what was up

with all the nikki carbs worn out the 1bbl carb kits are a fresh new alternative fuel friendly carb kit that offers out of the box improved of low end performance, better starting and great fuel economy


i have customers that go to extremes for maximum fuel economy. a few examples would include taller tires, installing a GSL_SE tranny for the taller 5th gear, vacuum guages installed to monitor while driving, mixing fuels, 1bbl carb kits.
here is some pics of a recent customer that stopped by the shop to show off his 1bbl carb kit. he averages over 900 miles a week commuting in his rx7 fyi

 

me want one