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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Fri Jan 19, 2018 3:48 pm 
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Vehicle: MY09 SH Forester XT Premium

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Bram wrote:
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As it may turn out I just might. I'm acquiring a built 257 with billet crank, forged pistons/rods for 5k.
i'll upgrade the 4EAT and do E85.

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Mar 08, 2018 11:28 am 
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I Say: Plan for tomorrow,Live for TODAY!
Vehicle: MY12 XT

Posts: 118
Location: Sydney
FOZVF34 wrote:
Tossing up between putting in a set of pistons in order wind up the boost or go E85 Flex Fuel tune with the stock internals.
It's a tuned EJ255 VF34 about 220kw. I can't boost it anymore safely without better pistons. E85 tune should be safe with the high octane knock resistance.

Bang for buck I guess.


I am curious to know what boost you are running..... I have been looking at VFs for a while to determine their limits.
A VF34 is (460cfm at 18psi, 250-325whp, Bolt-On) - which is 186kw - 242kw atw. I think if you are close to 18psi, pistons will not make much difference.
The link below shows that the stock engine is ok till 400whp - 300kw atw.
http://www.superstreetonline.com/how-to ... gine-tech/
I think you are limited by your turbo..... E85 will get you close to 240kw with your current turbo and mods.

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Mar 08, 2018 12:15 pm 
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I Say: Car mods are like OddBodz, you got to collect them all! -------------------------------------
Vehicle: MY05 STi swapped sled

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nomads64 wrote:

The link below shows that the stock engine is ok till 400whp - 300kw atw.
http://www.superstreetonline.com/how-to ... gine-tech/
I think you are limited by your turbo..... E85 will get you close to 240kw with your current turbo and mods.



400whp is a bit of a stretch for stock ej25. There are some that have done it, but its far from what would be concidered reliable. And even the definition of reliable is questionable. To some tuners in the states, reliable is like 2 years at that power. Tuning a stock ej25 upto 400whp, and it not instantly grenading =/= reliable.

Also that link you used is hardly a shining case for getting 400whp out of a stock ej25. Infact if you actually read it, 2 out of the 3 performance workshops interviewed stated that to make 400whp with a EJ25, atleast pistons are needed. Only one workshop said it can be done on a stock EJ25.

Also, not one of those 3 shops said anything about doing headstuds to achieve 400whp. Is this because they know the engine will crack a piston or spin a bearing before that happens. :dontknow: :lol:

And lastly, are we talking American WHP, or actual WHP? Because I dont think they are always the same thing.

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Mar 08, 2018 12:48 pm 
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I Say: Plan for tomorrow,Live for TODAY!
Vehicle: MY12 XT

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Yes - You make some very sound points, not disagreeing at all. I was mainly referring to the combinations and limitations. The link should be used as input, decisions on whether you agree will be completely up to you and based on other factors (my disclaimer).

The research I needed to do has sometimes been contradictory, sometimes complimentary. Upgrades need to be considered as a whole, not just one piece at a time. Pre-planning to get the best bang for your buck is a must, without the 'bang' of the engine giving up.

I was just trying to show that it is the turbo that is currently the limiting factor, building up the internals and expecting more power may not be possible if the turbo is blowing flames instead of air.

Also that the internals can be pushed up to 400whp ( american ) by some tuners, which means there is head room in the stock before having to upgrade internals.

Reliability is yet another factor, everything WILL break in time, that will come down to the weakest link and driver behaviour !

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Mar 08, 2018 1:21 pm 
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I Say: Car mods are like OddBodz, you got to collect them all! -------------------------------------
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100% agree about turbo sizing.

There is this notion in the Subaru (more specifically forester) world that VF series turbos are large-ish turbos. But in reality they arent all that large. If you break it down into 5 different sizes or turbo, then it makes visualising it a bit better. Eg : Very small, Small, medium, large, very large. 5 broad sizes of turbos right. Now lets assign some horsepower figures to those 5 sizes. Lets say that turbos capable of 200hp are very small. Turbos capable of 400hp are small. Turbos capable of 600hp are medium. Turbos capable of 800hp are large, and turbos capable of 1000hp are very large. Well if you apply that logic to Subaru turbo sizing then VF series turbos fall somewhere between small and very small.... And its not unreasonable to do it this way when you consider we now have 1000hp capable EJ motors getting around these days.

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Mar 08, 2018 2:08 pm 
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I Say: Plan for tomorrow,Live for TODAY!
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Nice to have a non-argumentative discussion !

Totally agree again, there is lots of info out there, consuming it and making the right decisions is the magic!

The US sites have a lot about turbos and sizing, this link was really useful for my purposes, as it shows what was out there, compatibility, and sizing for Subaru turbos.
https://forums.nasioc.com/forums/showth ... ?t=1141476

Right-sizing a turbo for what you want it for, along with the right supporting mods and never forget the tune !
A simplistic guide......
Very small - quick spool, early power, runs out of puff very quickly in the mid-higher rev range.
Small - quick spool, early power, runs max boost for a little longer, then runs out of puff in high rev range.
Medium - slower spool, higher mid range power, better ability to hold psi at higher rev ranges.
Large - Slow spool, high pressures until redline !

It all comes down to understanding the efficient range of the turbo:
1) what is the max psi it can hold at redline ?
2) spool up time - this can be limited by stock header/up-pipe, exhaust and intake.

Supporting mods would need to consider the free flow of intake - larger straight through intakes (so it needs less effort to suck in that air to compress), the sucking consumes energy, looking at inhibiting anything that can slow the air down (i.e. intercooler, deletes), obstructions consume energy. Along with exhaust, headers and up-pipe to the turbo, then the exhaust, pushing out the exhaust consumes energy.

Most people forget that the easier it is to inhale and exhale, the more kw will be free to put to the wheels - that is your not wasting power on sucking the air in and pushing the exhaust out ! I liken it to trying to run by breathing in and out through a straw, it needs to breathing in freely and breathing out freely, otherwise you struggle ! The bigger the input and output, the easier it is. But don't forget it has to be balanced to get the best result.

The most important is what you are using it for, a daily drive will have different requirements to a track or drag vehicle.

An example is that I am at the upper limit of my VF52, and consider it a safe limit for my stock internals. the next upgrade stage for me is a much larger step, bigger turbo with upgraded internals.

Well, not entirely true - I have an upgraded billet wheel for the VF52, but that will only give me a slightly quicker spool, no power gains, just a little quicker in getting to max power. It should make it a little quicker though, as max boost will kick in earlier.

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VF-52 with Lava blanket, 11psi WG Spring, Company23 EBCS, 3" Mishimoto CAI, PSR Intake, Ceramic Headers & UP Lava wrapped, Ceramic DP, Large TMIC, GFB BOV, Grimmspeed AOS, 3" TBE, F&R Whiteline HD Anti-Sway bars, DW65C, ID1050x, Exedy HD Clutch, DBA F&R T3s - Pmu NS400S, Short shifter,Pitch Stop Mount, KiddoRacing 18psi Tune for E85(FF Shifting & Launch Ctrl)-220kw atw


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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Wed Apr 04, 2018 7:35 am 
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I Say: I JUST WANT QUICKER SPOOL UP WITH MORE TOP END
Vehicle: MY09 SH Forester XT Premium

Posts: 29
Location: Sydney
I am curious to know what boost you are running..... I have been looking at VFs for a while to determine their limits.
A VF34 is (460cfm at 18psi, 250-325whp, Bolt-On) - which is 186kw - 242kw atw. I think if you are close to 18psi, pistons will not make much difference.
The link below shows that the stock engine is ok till 400whp - 300kw atw.
http://www.superstreetonline.com/how-to ... gine-tech/
I think you are limited by your turbo..... E85 will get you close to 240kw with your current turbo and mods.[/quote]

Going off a KPA reading of 210ish via the Bluedriver App. I think it's around 15-16 psi.
I'm going to stay with the VF34 for the foreseeable future. It's operating range is where most of my RPMs are. Bigger turbos on an automatic city driver wouldn't be enjoyable IMO. Low - mid range is what I need.
E85 will give 30kw over the usable rev range with the advanced ignition timing, and a bit more boost if the tuner feels that way. Shouldn't be shooting too hotter air at that rate.

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Internally Stock EJ255, VF34 Turbo, Motec 500HP internal fuel pump, Hyper-flow TMIC, Full set of lightweight under drive GFB pullys, 3" TBE, GFB recirc valve, GrimmSpeed AOS, Baffled Catch Can, CAI, MAF Pipe, Turbo blanket, Auto Trans-cooler, ECUTEK tune, F & R Gen5 GT brakes, SS lines, master cylinder brace.. (Power? No idea, it's fun though)


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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Apr 05, 2018 2:52 pm 
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I Say: Plan for tomorrow,Live for TODAY!
Vehicle: MY12 XT

Posts: 118
Location: Sydney
Going off a KPA reading of 210ish via the Bluedriver App. I think it's around 15-16 psi.
I'm going to stay with the VF34 for the foreseeable future. It's operating range is where most of my RPMs are. Bigger turbos on an automatic city driver wouldn't be enjoyable IMO. Low - mid range is what I need.
E85 will give 30kw over the usable rev range with the advanced ignition timing, and a bit more boost if the tuner feels that way. Shouldn't be shooting too hotter air at that rate.[/quote]

...... 210kpa is 30psi...... Are you sure? you maybe blowing fire already. I think you should check...
Also - you will need larger injectors - would recommend IDC 1050X - you will need more fuel, I noticed that you do not have them in your signature.

If you want to get an idea of what power you are putting out, have a look at Virtual Dyno. It works out the ATW power. It uses the weight of the vehicle, acceleration and mass moved over time, gear ratio, with some drag coefficients. From a physics and maths perspective, it is sound and accurate. You then add the logs for the input, wham, you have a result. At least it will give you a ball park.

Have a look at the Virtual Dyno post I put up in this forum.

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VF-52 with Lava blanket, 11psi WG Spring, Company23 EBCS, 3" Mishimoto CAI, PSR Intake, Ceramic Headers & UP Lava wrapped, Ceramic DP, Large TMIC, GFB BOV, Grimmspeed AOS, 3" TBE, F&R Whiteline HD Anti-Sway bars, DW65C, ID1050x, Exedy HD Clutch, DBA F&R T3s - Pmu NS400S, Short shifter,Pitch Stop Mount, KiddoRacing 18psi Tune for E85(FF Shifting & Launch Ctrl)-220kw atw


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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Apr 05, 2018 3:01 pm 
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The pressure reading is absolute pressure, so you have to remove 1 atmospheres worth of pressure to get the amount of boost.

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 Post subject: Re: Pistons & boost or E85 Flex
PostPosted: Thu Apr 05, 2018 3:32 pm 
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I Say: I JUST WANT QUICKER SPOOL UP WITH MORE TOP END
Vehicle: MY09 SH Forester XT Premium

Posts: 29
Location: Sydney
nomads64 wrote:
Going off a KPA reading of 210ish via the Bluedriver App. I think it's around 15-16 psi.
I'm going to stay with the VF34 for the foreseeable future. It's operating range is where most of my RPMs are. Bigger turbos on an automatic city driver wouldn't be enjoyable IMO. Low - mid range is what I need.
E85 will give 30kw over the usable rev range with the advanced ignition timing, and a bit more boost if the tuner feels that way. Shouldn't be shooting too hotter air at that rate.


...... 210kpa is 30psi...... Are you sure? you maybe blowing fire already. I think you should check...
Also - you will need larger injectors - would recommend IDC 1050X - you will need more fuel, I noticed that you do not have them in your signature.

If you want to get an idea of what power you are putting out, have a look at Virtual Dyno. It works out the ATW power. It uses the weight of the vehicle, acceleration and mass moved over time, gear ratio, with some drag coefficients. From a physics and maths perspective, it is sound and accurate. You then add the logs for the input, wham, you have a result. At least it will give you a ball park.
**************************
Hey mate.
You had me confused for a second. I had to retrace how I came up with that number.
The KPA reading is above atmospheric pressure. So minus 100KPA (assuming I'm closish to sea level) is
110KPA - 16PSI.

It was tuned by the previous owner at MRT. I don't have an opinion of them myself, but others say they are quite conservative in their tunes, however less so with the price.

Yes injectors will be a must. The ones you mentioned are getting good reviews.
Froozenboost.com have a reasonably priced water to air intercoolers what i'm interested in.
They add a fair bit more weight though.

Someone was selling their Kelford R199-A Camshafts on here somewhere for $500 or so.
It never ends though. I want to keep things simple.

be_oh_be .... yes exactly. Silly me still wrote the full amount.

Cheers

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Internally Stock EJ255, VF34 Turbo, Motec 500HP internal fuel pump, Hyper-flow TMIC, Full set of lightweight under drive GFB pullys, 3" TBE, GFB recirc valve, GrimmSpeed AOS, Baffled Catch Can, CAI, MAF Pipe, Turbo blanket, Auto Trans-cooler, ECUTEK tune, F & R Gen5 GT brakes, SS lines, master cylinder brace.. (Power? No idea, it's fun though)


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