Thanks that clears it up.

is it making the ports smaller that helps or is it the latter opening timing?

any pics of the custom sleeve?

I think both have a benefit . The later opening also helps with turbo spool as it allows a more concentrated pulse from the main ports .

The custom sleeve idea belongs to someone else so I am reluctant to show it here .

no worries just curious on what has been tried.

A question on tuning... Can 16psi be run on high octane without ethanol? if you run really rich and retard the timing?

This is mainly a question for flex fuel tuning for SC where you can’t change boost with ethanol content.

It's always about massflow ....not boost .
That said , my thoughts would be .... it might be ok for a couple of runs on a cold day .......... but one day with heatsoak etc etc ....zoom zoom -boom!

Thanks again it's great to have the opinion of someone with experience.
So are you going to chase more power?

Brett, This observation is on a system w/upgraded seals, porting and whatnot. Recognizing systemically that "Everything affects everything.", in your experience does the above observation hold for a non-hardened, i.e, stock, boosted rotary? Or do the apex seals become a weak link at some point prior to the diminishing power return to boost increase ratio as described? :dunno:

Thx.

Great question ! What I'm experiencing only manifests itself at elevated mass flows and the dropoff in power/psi is sudden and dramatic . I said way back at my first dyno that it was like hitting the wall ..... well 2 years and heaps of improvements later ...it still is like that but at a lower rpm and lower boost level but similar power.
For a setup that isn't targeting maximum whp (and can't reach 400+ whp anyway) the dropoff you see is not nearly so dramatic . A greddy setup for example will just drop away gradually (till the turbo runs out of puff) but if you don't have high octane fuel , will detonate at relatively low boost/flow if conditions aren't right.
And the weakness of the engine is only exposed if you detonate ...which is why I'm ramming high octane down peoples throats these days . Running high octane will do much more for saving the engine than any modification you can do inside it .

Brett,
I've understood that tuning for and running E85 requires installation of larger injectors. Beyond that...
- What, if any, other hardware modifications are required, or a good idea, to run E85?
- Can a tune be generated to run premium (93 oct.) and E85 within the same tune, e.g. premium (0-8 psi.), and E85 (9-12psi)? Or are separate tunes required for each fuel type?

Thx.

You definitely need enough injector but how much depends. But I run E85 and 93 on the same tune, it has been that way for a couple of years and the car runs great, I would never go back to just a 93 tune.

9K,
- Thanks for chiming in. Re: running 93 & E85 on the same tune... Good to know. E85 stations are not as abundant as I'd like. So, good to know that I could run E85 w/ more boost, yet run 93 at reduced boost (when no E85 station around), on the same tune.

- What injector flows are you running: P1 / Sec / P2?
- W/ the above injector flow capacity, what max. PSI are you tuned for?
- Did you make any add'l hardware mods specifically to run E85?

Thx.

Well, not on the same tune, I have to run E85. I just have blues in the P2 location, all injectors were brand new and flow tested.

And no I did not make any hardware changes.

9k,

• Can you explain what you mean by "Well, not on the same tune, I have to run E85." when you said earlier "But I run E85 and 93 on the same tune,..."?
  
• So, if I understand correctly you're running:
  - P1: R (290)
  - Sec: Y (380)
  - P2: B (???)
  If so, what are your blues flow tested at?
  
• W/ the above injector flow capacity, what max. PSI are you tuned for?

Thx

Yes, if I run 93 only it's pig rich. Drivable, but not ideal. And yes, that is my injector setup. I'd have to look for the numbers, I bought the injectors new from Five O motorsports and I asked for flow rates at 60psi when I ordered them. Not having enough fuel has never been an issue on my setup.

jcbrx8 .... I'm pretty sure 9krpm didn't mean to say E85 and 93 "on the same tune" .

But with what I do and recommend you can run on the same tune .

I do my tune for E28 (1 part E10 to 3 parts E85) and run at full boost on that . If I can't get E 85 anywhere close , I'll just put E10 in there and reduce boost to below 10psi. This works fine , but the on E10 it does run very rich under boost . Not too rich to cause any hesitation though so it's fine. So it can run just fine at lower boost on any combination between E28 and E10.

I thought you ran E30 ?

I do, mixed with 93, :lol:

and it's more like E30ish, it varies at the station I use.

Talk about confusing the issue !

My bad, and it is, I have had people ask me where I get E30 from...........

Found the below Exx Octane calculator:
Calculate Ethanol % of Mixture

Used it to generate the below matrix showing the resulting Exx and Oct. when the given % E85 is added to a 12 gal fill-up of 93.

For clarity... what Exx and Oct are we targeting: ~E35 @ 95 Oct ...or ~E60 @98 Oct.?

https://cimg5.ibsrv.net/gimg/www.rx8...ea56743b6f.jpg
Note: This is a course approximation table as E85 octane levels generally fluctuate, 100-105, ...in addition to seasonally, and the table assumes 10% Ethanol contain in the 93 fuel as well.


Thx.

I suggest E29 which is 1:3 or E35 which is 1:2 .

I would do more research on actual octane levels ...It is known widely that octane does not follow a calculated result as that table suggests .

Also : that table assumes 93 has 10% ethanol in it .

Got it. Thanks, Brett.

Yes, I am aware that E85 Octane level fluctuates (100-105) and also seasonally. So, just set content to lowest level, 100, to generate a course approximation to generate a quick table. And that's accurate (for me ;-): the 93 around here contains 10% Ethanol.

Good points: I'll go back and note such for anyone else that may view it.

I was actually refering to the non linear relationship between ethanol % and octane . Those tables (including the one 9k posted) appear to assume a linear one .... which undervalues the effect of ethanol at lower percentages.
Some light reading :
http://www.speedperf6rmanc3.com/cont...%20Article.pdf

Note the as tested octane rating for E50 vs those in above tables
https://cimg9.ibsrv.net/gimg/www.rx8...332222b519.png


In the conclusions from that study :

"non linear relationship between ethanol % and octane." - Aah, I missed that nuance.

"light reading". - :lol: Brett, you got jokes. ;-)

Good info. Thx.