E85 Pistons .. such a thing ?

[Butters]

So I am sure many have experienced E85 passing the rings and flowing into a catch can.

I am looking at engine build options and the car will be full time E85.

 

I've been reading(dangerous I know) about gas porting and the impact on ring seal.

I also saw on a piston manufacturer video they have specifically designed the gas ports with E85 in mind and reducing passing into the crank case.

 

So does anyone have experience or knowledge on this ?

 

In my own experience of E85(running it 15 years now) multiple cars, regular street driving, i've not had huge amounts in my catch can.

My latest setup really does though and at all power levels.  Two different tuners have told me this is very normal but it's new for me.

The compression test on this engine is the same as my other.

 

 

 

[r32-25t]

There’s no such thing, it’s a marketing ploy to try and sell more pistons to suckers 

[GTSBoy]

Eugh! Luck of the draw, I reckon. All the possible variables probably come into play wrt how any given engine (built or factory) will go in this area. Piston material, piston-bore clearance, ring pack specification, all the possible choices that might be made about coated piston crowns and skirts and how hard the ignition timing is pushed and so on (which all then reflect onto the thermals of the piston and how close it ends up running to the bore wall, etc) will likely have an impact. And the problem is, unless you have probably hundreds of near identical engines under your belt, each with only one or two differences from another, you'll struggle to pull the statistics out as to what is causing the performance differences.

For mine, if I was worried about trying to deliberately build an engine to minimise this blowby, and specifically with E85 in mind, then I'd ponder whether it was wise to build it to run really really tight piston-bore clearances, like, as tight or tighter than anyone thinks is sensible, and put anti-friction coating on the skirts (as insurance), and possibly coat the crowns to minimise the heat they pick up, so that they will be less likely to use up all the clearance given to them cold, and other such decisions directed toward keeping the gaps as close as possible. And then....probably still a lottery, because maybe there's something else which is more dominant.

[tridentt150v]

Would Total Seal type 2 piece rings help at all?

[joshuaho96]

I suspect the problem with E85 is mostly cold start related. If you're doing short trips and your engine has generous P2W clearance for high power it's going to be way worse. MotoIQ did a feature recently where they tore down an engine that was almost entirely fine but short trips + E85 caused some chaos with the piston rings and ringlands below the top compression ring: https://motoiq.com/e85-can-mess-up-your-engine/

One thing that would be very cool to see I think would be dual fuel feed where you only have E85 injection in parts of the map where the higher octane and cooler burn will help. I suspect this is too impractical though as Ford didn't seem to pursue any of that despite publishing this slide deck on it: https://www.energy.gov/eere/vehicles/articles/e85-optimized-engine

Cold start E85 isn't great and it only gets worse as you up the ethanol content and drop the temps.

[GTSBoy]

1 hour ago, joshuaho96 said:

One thing that would be very cool to see I think would be dual fuel feed where you only have E85 injection in parts of the map where the higher octane and cooler burn will help

Almost a reversion to WMI.

[Murray_Calavera]

I know Nelson Racing Engines like to do dual fuel/octane on demand for their monster street cars (2,000+ hp)

https://nelsonracingengines.com/blogs/nelson-racing-engines-projects/69-camaro

Wish I had the money for a NRE built car, they are works of art!

[Butters]

3 hours ago, joshuaho96 said:

I suspect the problem with E85 is mostly cold start related

Nar it's when you are on it.

I had a clear catch can ... ok it was a coke bottle on the dyno and on a powerrun a good 50ml would appear.

Doing the school runs , car cruises etc I get almost nothing in the can(its a proper one now)

One night of roll racing and its half filled, nearly a liter of e85.

[joshuaho96]

4 hours ago, Butters said:

Nar it's when you are on it.

I had a clear catch can ... ok it was a coke bottle on the dyno and on a powerrun a good 50ml would appear.

Doing the school runs , car cruises etc I get almost nothing in the can(its a proper one now)

One night of roll racing and its half filled, nearly a liter of e85.

That just sounds like too much cylinder pressure making for more blowby. Is it still a problem at lower boost targets?

6 hours ago, GTSBoy said:

Almost a reversion to WMI.

Pretty much yes, but E85 fuel systems seem to be a lot more straightforward than doing WMI "correctly". I talked to Nostrum and they stopped trying to make WMI aftermarket kits due to the sheer cost involved.

[Butters]

12 hours ago, joshuaho96 said:

That just sounds like too much cylinder pressure making for more blowby. Is it still a problem at lower boost targets?

18 hours ago, GTSBoy said:

Yep in all combos this motor has done it since going on e85. 

 

From 

Stock turbo, stock injectors, 14 psi 300 rwhp 

to 

G35 turbo, 1650cc, 28 psi 780rwhp. 

 

And everything in-between. 

[joshuaho96]

6 hours ago, Butters said:

Yep in all combos this motor has done it since going on e85. 

 

From 

Stock turbo, stock injectors, 14 psi 300 rwhp 

to 

G35 turbo, 1650cc, 28 psi 780rwhp. 

 

And everything in-between. 

I genuinely find it hard to believe that you wouldn't have blowby issues just in a different form running comparable boost on pump gas. The pistons/cylinder walls don't know the difference when the engine is warmed up unless you're actually getting liquid fuel splashing down the cylinder walls. It's also possible depending on how your catch cans are hooked up you wouldn't see anything despite a lot of contamination during cold start. Factory PCV has two very different flow paths depending on vacuum vs boost. Mahle basically calls out the exact same thing MotoIQ did in this press release and suggests that their PVD coated piston rings and a finer bore finish will help with the issue: https://www.mahle.com/en/news-and-press/press-releases/mahle-piston-rings-for-flex-fuel-engines-512

I would focus on reducing P2W clearance to the absolute minimum necessary if you can open up the bottom end. I would not recommend going crazy with the gas porting of the compression ring. Too much pressure really accelerates ring wear which is maybe fine for a dedicated big money drag car that only needs to do a few passes on the runway before getting torn down for rebuild. Most likely the most you want to do is gas ports on the sides of the piston and even then only as much as you really need. The less P2W clearance you have the less of this you need to do to begin with. Obviously the danger here is if you actually need that clearance when you're making 780 whp then bad things will happen.

[Butters]

Thanks, you are correct in saying I don't want a one shot motor. I am looking for 50k-100k of life over 5 + years.  The current motor is 150,000ks and 30+ years , did rest for 2 of those though haha. 

 

A couple of extra points as your point about your blowby on petrol.  As what you say makes sense to me. 

I really didn't get any U98, it was also run 14psi, stock turbos 270rwhp.

I did wonder about injectors but I have had both stock and bosch. I also have had 2 different ecu's 2 different tuners. 

One spent a bit of time putting in fuel cuts to minimise excessive e85 when not needed. 

 

And to be clear, i don't get any real oil either. 

Here is a pic from draining catch can, this is basically one single 2,3,4 pull Roll race run.  All E85

After a night, the bottle would be half full. 

 

 

 

[Ben C34]

Pending where the catch can is mounted will determine what it actually catches that you end up seeimg.

Cans that are in a hot spot don't collect much liquid as it boils off with the heat. Cans in a cooler spot condense more and you see more liquid as a result.

Another variable to ponder....

[Butters]

I purposely mounted it in the wheel arch , with cool air over it to collect as much as possible.

My catch can is plumb back to intake, to keep everything legal.  I want as little in the intake as possible.