BC

Hey Blown. Thanks for coming over. When I am able to tune, I will be able to do as you suggest. So you are talking about a lean burn high advance situation?

BC

Thanks for contributing. I think I am running quite lean right now, and may up the fuel pressure as well, though with the 02 loop connected, it will still attempt to get to stoich.

I am surprised by your comments on the bosch pumps, as I was under the impression that these in-line pumps immerse the windings (copper) IN the fuel. That, I understand, was going to be risky with ethanol.

blown 944

that is correct. I do not use the o2 input on my car though, so that may pose a problem for you unless you have the ability to set specific parameters in your ECU. Other wise it will constantly be pulled back to stoich. I'm not at all familiar with the 928's.

blown 944

They don't immerse the windings in fuel. There is an o-ring at each end keeping the fuel away from any electrical parts.

Podguy

From the one I took apart the interior is full of fuel.

morsini

Ethanol has less energy density than gas and that's why you get fewer miles per gallon.

BC

Hmmm. I'll have to research that some more. My number still passed, but they were higher than I expected, even with no cat. Cat is going on today for passing grade and getting the car registered properly.

BC

There is a five page thread in OT/PC about "energy density" and some very technical discussion of why energy density is not the end-all be-all determinate factor when talking about the efficiency of a fuel in a SI (Spark Ignition) IC (Internal combustion) engine. I wish to not get too far down that path in this thread.

This is simply a "Does it work in a 928 longer term" thread.

BC

Ah. Ethanol is supposed to keep the combustion process much cooler - part of the reason its able to withstand so much cylinder pressure and timing advance. I do recall now that NO is a function of combustion temps.

svp928

Yes, unfortunately, higher temps increase the nox, thats what EGR systems are supposed to help with. Screws up everything else, but helps with nox. I don't believe the 928 ever had EGR, but running ethanol without any other changes should result in lower temps, as Brendan suspected.

BC

There is some question as to whether the increased mass of burnable fuel in the chamber may somehow, while the combustion temps initially are lower, actually increase the temperature, and lengthen the amount of total heat. I'll try and add links when I am not so blocked at work.

Podguy

The 78 and I think 79 CIS US cars came with the EGR. I know because I just took the manifold off a 78 engine and had to free up the valve. Kano was great to get the value freed up. Although I am looking for something that can stand the heat and keep the valve working. Kano makes a high temp graphite lube but you have to buy a large quantity.

Fabio421

Brendan,

I just found and purchased some Bosch 36lb low impedence hose barb style injectors today for my E85 turbo project.

By the way, that piece of 928 fuel tank I've had soaking in a mason jar of E85 since 12-26-10 is still perfect in every noticable way.

BC

Hey Fabio -

Be careful on the size of the injectors and fuel pressures if you have to have the car smoged - I am going through a steep learning curve right now with the e85 and about stuff I thought I already knew.

First, I want to thank NeilH who came through in the clutch for getting me an air-box top which the ****-like smog individual where I have the retest refused to even retest the car without. That hurdle overcome....

I still failed the test today - even though I put the cats on. Very good shape cats are on the car as of today and I have VERY VERY low HC and NO numbers, but EVEN HIGHER CO numbers now.

This is on NEW 24lb injectors, and higher-than-stock fuel pressure, which I have had to raise in an attempt to cure a (what I now believe is a different) problem with being lean on transition between 2-3k.

But the 15mph test, which he does at 1800 rpm failed the car with very high CO. The 02 sensor loop SHOULD be correcting that richness at that load, but it is obviously NOT or unable to because of the minimum duty cycle on the injectors with my higher fuel pressure.

What I will do is reduce the Fuel pressure to below stock, and then go back and retest.

What I know from this now is that its nearly impossible to run E85 on a stock older car and get what you need out of it without an aftermarket ECU or a complete retune. You cannot, from what I can see, do this on the stock ECU since you would need to do it with fuel pressures and injector sizes (which amounts to rejetting a carb blind)

You need a specific, measurable, and repeatable way of changing the tune to suit the very wide range of usability with E85, and the stock systems simply cannot do it. You need lean idle, very rich transitions, normal cruising, and fat pig rich acell. And the timing needs to be drastically changed to suit the operating parameters. How could the car be operating so poorly and seemingly lean on transition and below 3k, but on this test its pig rich at low speed, near idle, cruise?

Wish me luck.

neilh

Brendan, glad to help with the air box cover, but sorry to hear the smog results.
if you recall that 84 Auto euro i did the refurb on also failed smog, several times - CO was way to high - and so was NOx. i had new cats installed ( the ones on the car were punched out!) , loaded it with lowest octane I could find and took it for a hard drive in 2nd, got those babies real hot, went to test. CO passed fine, NOx was still way out and it failed again. Not sure what this tells you - but I did eventually ship the car out of state to my daughter - where they don't have a smog test!
Good luck - let me know if I can help you further....