Ok i have posted a couple posts about my emissions woes. The HC limit here is 150 my 85 rx7 was around 600-650. CO% limit is .5% and mine was 2.5-3%. So the emissions inspection station suggested it was the carb but wouldnt actually diagnose it properly because they are scard of rotory motors. I brought the car to RP performance and asked them to look at the car and rebuild it if necisarry. Well they just rebuilt it and that set me back $300. They told me it wasnt that dirty or anything (which kind of peaved me). It ran the same after i got it back from them, still smelling like unburned fuel at stop lights. SOOOOOOO i decided to mix 1 part denatured alchol (1 gallon @ home depot $8) to 7 parts gasoline. I PASSED. Now i CANT say for SURE if it was the denatured alchol or not since i went into the station with a freshly rebuilt carb BUT from what the shop (RP PERFORMANCE) told me about the carb not really being so dirty I think its logical to say this denatured alchol really does work. THANKS rx7club.com!!

 

$300 for a rebuild? Well glad you passed your emissions.

 

Yes sir. $300. I had much higher quotes from other shops too. I know someone on here will rebuild it for like $150 but i needed it done asap and this is my daily driver. Im just happy it passed cuz my tags expired today.

 

Isnt that bad for the engine though? I would think alcohol would make it burn excessivly hot. Im kind of curious about this, especially if they bring emissions back around here.

 

it probably isnt the best thing BUT its already exists in gas......just smaller amounts. Its purpose? TO control emissions. THere are some cars the use E85 which is 85% gas or 85% ethynol i forget. Ever see a ford with FFV on the side? Thats one of them. Im more worried about the fact its a strong solvent and used to clean metal and my car is old.....so any rust in my gas tank will probably end up in my fuel filter. I only did this to pass emissions, its not something i would of done under any other circumstance. try it at your own risk. DO a search on it. I found severl posts on ppl who used it with success and none on ppl using it and having problems.

 

Thanks, ive just never heard of it before is all, sounds kinda cool, something to remember if i need to pass the test

 

I would guess that since alcohol burns hotter, it would help in burning up all those
carbons that all that fancy emissions stuff tries so hard to do. Denatured alcohol is a very clean burner too.

 

ah! WHo said they do it for $150?

 

c mon guys hes talking bout the carb.....at least i think...

 

The methanol gag is encouraging. Last try I made with the red 83 gave HC of 670 at idle. So I added 10-15% methanol to see if that cleans it up. I might re-route the airpump output past the ACV direct to the cat as someone suggested, before I go for another $40 test.

B

 

Ahem...

 

Alcohol also doesn't have as many BTU's/liter, it also has a different Air-to-Fuel Ratio. Basically Stoic for alchol is around 8:1 AFR vs gas which is 14.6:1. Thus when you add alcohol, but keep the same volume of liquid fuel the same the excess air ratio (Lamba) increases. So basically adding alchol, besides burning cleaner, also causes the engine to burn leaner. Burning leaner lowers HC and CO emmissions, at the expense of increased NOx emissions.

Be aware though that adding alcohol to a gas tuned engine that you will lose power, and depending on the level of tune (BMEP) you may crest the hill into detonation. Its not realy something to worry about on a NA rotary, but turbo guys could be in danger. Also be aware that alcohol is a bit more caustic than gasoline, and will eat away at basically everything in the fuel system, if the concentrations are high enough. Just be sure to change the gas for fresh gasoline when done.

BTW, a rumor I've heard is that with strait alcohol -- if tuned for it of course -- is that you can get a rotary to pass the sniffer even without cats...

 

Detonation? I thought alcohol was 100 octane. In fact, the standard.

B

 

Higher than that actually.... but the fact stands, if you run a highly boosted turbo engine lean it will detontate on C16 or pump gas. C16 just alows you a bit more playing room with AFR and timing.

Doing what cableguy did, running 7:1 gas/alcohol changes stoic from 14.6 to around 13.6. so at idle what is around 12.8:1 seems much closer to stoic than before.