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 Post subject: Ethanol tunes
PostPosted: Tue Feb 13, 2018 12:36 pm 
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Vehicle: 00 gt

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Location: HerveyBay
Most of this is hypothetical but I'll put it out there for some friendly banter.

I have an auto gt with the original tf035 with TH tune producing a suposed 120atw on the dyno at coffs. I understand if you really want to make power you add at least a td04 if not bigger and a full exhaust. I only have a 2.5 catback.

E85 tunes provide some great gains on big boost/ applications. Would you find any improvement on a 12psi application?? What about for a 2.5xt with a td04??? I wonder what size injectors/ fuel pump would be required on a low boost aplication?

If there is little to be gained from 98 to ?100 ron. Would there be much lost going backwards to a e10/95ron tune for the daily grind then swap to a 98 or e85 tune when you want..... the e10 price gets tempting when you are filling up on 98 for a foz that is nice but far from a rocket ship.

Yes just go stick a decent size turbo on would be a logical response but im just curious.


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 Post subject: Re: Ethanol tunes
PostPosted: Tue Feb 13, 2018 4:15 pm 
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Vehicle: MY08 XT (SH)

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Location: Brisbane
Not an "apples to apples" comparison, but i have a 4-speed auto with a VF46 turbo. On petrol it got about 150kw at 16psi boost.

For "slippy gearbox" reasons the E85 tune kept the boost at 16psi.

See the 20% (approx) gain across the whole usable rev range:-

Image

More expert commentators can probably talk about whether keeping things at 12psi would produce a lesser (but significant) gain than 20% or what you might expect.

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 Post subject: Re: Ethanol tunes
PostPosted: Wed Feb 14, 2018 3:56 pm 
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Vehicle: MY09 XT Premium

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Location: Australia
Slightly out of context but my old STi made 278awkw on E85 & 230awkw on 98 at the same boost. E85 makes a significant improvement across the entire useable rev range, as shown in Yowie's post above. I believe the turbo characteristics would still be the same (ie; TD04 falls off up top HARD), E85 won't fix that but it'll give you a proper kick when the turbo is on song.

You wouldn't need anything bigger than a 255lph pump with a stock turbo/motor but you may need to upgrade the injectors. I was running a 460lph and 1000cc injectors on the STi with a GT Pumps 3.5 turbo, on a built 2.5l.


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 Post subject: Re: Ethanol tunes
PostPosted: Wed Feb 14, 2018 5:11 pm 
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Vehicle: MY08 XT (SH)

Posts: 976
Location: Brisbane
JamesMR_ wrote:
Slightly out of context but my old STi made 278awkw on E85 & 230awkw on 98 at the same boost....


What was "same boost" in your case?

I note that the improvement is about 21% in your example and 22.5% in my example (or 20.3% if we go off my earlier 150kw baseline).

be_oh_be had a 13% improvement between his best 98 octane tune and his E85 tune on a naturally aspirated 2 litre:- viewtopic.php?f=77&t=57533&st=0&sk=t&sd=a&start=40

I wonder if there is a rough linear relationship starting with 13% improvement for NA, whatever whitfoz can get on 12psi, 20% (approx) for my 16psi and James' STI boost level then more again for other examples of similar engines running higher boost (on 98 then E85).

Obviously the sample size is very small and there are too many other variables, but it would be interesting to estimate the general trend.

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 Post subject: Re: Ethanol tunes
PostPosted: Wed Feb 14, 2018 7:10 pm 
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I presume higher boost pressures limit the amount of timing advance you can run without detonation. Therefore with a jump from 98 to 105ron tou can return to timing figures you would use with less boost???

So at 12psi there may be no significant gains??????


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 Post subject: Re: Ethanol tunes
PostPosted: Wed Feb 14, 2018 8:08 pm 
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Vehicle: MY08 XT (SH)

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Location: Brisbane
I don't know how directly this addresses your last comment/hypothesis, but my tuner indicated that the timing he was putting into my tune (at 16psi) was nowhere near the E85 limit.

In other words, he got to dial-in ideal timing without needing to balance it out with detonation-prevention (as opposed to what is required on a petrol tune).

Looking at your hypothesis again, it may be that with x amount of crazy boost pressure that the balancing of "ideal timing" vs "detonation-prevention" comes back into the tuning equation. Surely at 12psi you're also in the "can use ideal timing" club and can realise all the gains from it.

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 Post subject: Re: Ethanol tunes
PostPosted: Wed Feb 14, 2018 8:31 pm 
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Vehicle: 00 gt

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Location: HerveyBay
I understand what you mean... suppose we have to hope someone with tuning knowledge would want to share their wisdom...

I dont have the capability to look at my tune and see what timing i am running. Would be interesting to find out but i wouldn't be able to say if it was lots or not much....


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 Post subject: Re: Ethanol tunes
PostPosted: Fri Feb 16, 2018 12:12 pm 
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My STi was running 24psi on both E85 and 98RON to make those figures.

The original tune was with stock top mount and stock intake at 254kw. I had a Process West top mount and Process West 72mm CAI put on then re-tuned to 278kw at the same boost level.

A recent video I watched - https://www.youtube.com/watch?v=qq6GBhsSsgQ&t=132s
Stock K20A motor on US 93RON vs two blends of race fuel.


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 Post subject: Re: Ethanol tunes
PostPosted: Fri Feb 16, 2018 2:40 pm 
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Vehicle: MY08 XT (SH)

Posts: 976
Location: Brisbane
From that NA shopping trolley video - a 13% improvement between the basic (238hp) and the top race fuel* (270hp) [*non-ethanol presumably? i don't feel like looking up all the fuels they used]

So, it looks like 13% isn't a bad average gain for a NA engine when moving to a low-knock type of fuel.

---

James describes a 9.4% gain at 24psi boost. Perhaps that's an example of "x amount of crazy boost pressure that the balancing of "ideal timing" vs "detonation-prevention" comes back into the tuning equation".

ie the ""e85 performance increase back-of-an-envelope trend line" starts at 13% with no boost, goes to 20% with 16psi, peaks somewhere then tapers back down to 9.4% at 24psi.

Obviously the usual caveats about too many variables and too small a sample size apply.

As such, I wonder if we can assume that a 12psi boosted motor would enjoy a gain somewhere between 13% and 20%. I would bet closer to the 20% end.

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 Post subject: Re: Ethanol tunes
PostPosted: Fri Feb 16, 2018 2:54 pm 
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Vehicle: MY09 XT Premium

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Location: Australia
I have very little knowledge on the topic but from what I've seen on tuned STi's - 20% seems to be a good marker for an increase in peak power when tuned on e85 (compared to 98RON). This is keeping in the 230-320kw region as that's a very common power level for tuned STi's. Evo's seem to be the same but they tend to use more boost to get their numbers.

I wonder if, when looking at higher power levels (>500hp), if the % increase is roughly the same or if there's greater benefit on E85/race fuels as the power levels (boost levels?) increase.


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