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Gas? Fuel? What is it? *EA82T Performance Thread*


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#1 WJM

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Posted 24 January 2004 - 11:35 PM

Its the thing that burns!!

Well, it burns when some 42,000 volts jumps a gap and ignites it...well, it will ignite it PROPERLY when the fuel is mexed correctly with the air, and the volts jump that gap at the correct time. The more correct it is, the more power you make...or more MPGs you get.

So here is the deal, US spec 87 octane will ignite and burn faster than US 93. And 89 doesnt ignite quite as fast as 93, but burn faster than 87. In my owners manual, its recommended that 91 or higher is used...thats for a stock turbo engine. Well, for ALL EA82 engines for that matter.

So here is the deal...detonation/knock/ping/pre-ignition is the ignition of the air fuel mixture before the volts ignite it, OR the volts ignite it, and the burn completes way too soon...such as before the piston passes the TDC position. Ideally, you want to draw in the mixture, then have it compress...but before the piston reached TDC, the volts jump, igniting the mixture, the piston compresses the burning mixture to accel the ignition, and as the piston gets to TDC, the explosion has it greatest forces as the piston starts on its way down, and the mass presure is now there to push the piston down the PROPER direction...and not before. You can still not have knock and it be at max pressure before the piston starts down. Power loss there.

So now, its up to the timing. Too much and you loose power, MPGs, and engine life. Too little, and you get incresed emissions, less MPGs, and more engine life than with too much timing. Just right, and you've got a little choice of ranges...one for max MPGs, and one more max power.

In order to get max power...you need to have the proper fuel. Engines are tuned to run on certin fuels. After readgin this page several times, and seeing real life results with regards to intake ari charge temp, different fuels run thru my 9.5:1 turbo engine, and seeing other stuff happen...I firmly belive what is said about the fuels in the great ole USA.

http://www.spdusa.com/new_page_4.htm

Now that brings me to the point. 93 is fine for the average mostly stock EA82T. Ive ran one with semi-racing cams, and it boost crept to 15~17psi, and not a peep of detonation, even with 25deg BTDC. All of this with no IC either. Just the most open'est intake and exhaust possible. No octane booster either.

So if you all take the time to read that...i think it applies to our tuning situation with these engines as well.

Since the Dyno Day, ive been running nothing but 100 octane competition fuel, unleaded. Where i used to have to back off in the high end due to detonation, I now lay into it all the way to redline. It now no longer detonates under the 10inches of mercury vac adavnce, and it pulls like...like...well, A TON in the low end of things. Pure power from 2000 to 6000 now. Were as before, it was only 2400 to 4200, and even that was tricky, i could not use WOT. Now I can.

For a stock EA82T bottom end...with proper timing adjustments, and other mods, I think that the engine would greatly benefit from using this fuel. Especially under high boost situations, high load at low engine speeds, and in warmer operating conditions.

Now here are my recommendations for an EA82T user in search of more power (basic low budget power that is):
Run the highest octane pump fuel you can find...usually 91~94 at any gas station. Ya know, that Premium stuff.
MAF adapter from expressautoparts.com
APC or equivilent 3inch ID cone filter to stick on that adpater, right on the MAF (or flapper door style on the 85-86 turbo cars)
*NOTE: on 87+ turbo cars, that assy mentioned above will fit perfectly in the spot of the factory airbox, if a 1985/1986 "MAF" to turbo pipe is fitted to the 87+ system. I did this on my RX. YOu should rotate the assy toward the front of the car 10 deg with all the pipes/hoses underhood warm, so they wil flex some, and begin to rest in thier new positions. END NOTE*
Open the exhaust. Atleast make sure that you have a ture 2 inch ID flow from the downpipe back, and a glasspack/cherry bomb or some kind of stright thru muffler is fitted. Its is recommended that a Subspeed, or Skipster stlye downpipe is found, and 2.5 inch exhaust is run back, WITH a 3 way universal cat fitted ofcourse. We want to make sure there is a future enviornment for our children to drive SUBARUs as well, dont we?
The turbo crossover/up pipe assy is in DIRE need of better flow characteristics. No solutions have been made at this time. R&D has started.
Fuel system: its just fine stock, as long as the fuel system is clean and everytihng is working properly. Make sure to check fuel pump, injectors, pres. reg., and Evap system is all working properly and within specifications. I've ran a gallon of Laqure thinner thru both cars, and it worked wonders for clearing crap out. People think I am crazy for that...Oh, change that fuel filter when you do that.
Cooling, water and oil: Flush the system properly, and use a new rad if the current one is in question. a good one can be had for around $100 at any auto parts store, or online. *NOTE: Use a 180 deg T-stat!! END NOTE* I have not had a problem with hot oil...YET. I have not had a clean run during the summer time to record temps. It would be recommended that under hard driving conditions, an oil cooler be fitted. I have a source for the thermostaticly controled sandwich adapters.
OIL: MOST IMPORTANT!! Run a known good synthetic oil I run Mobil 1 10w-30. I have not tried Castrol, Valvoline, or any other. All I know, is that I trust AMSOIL, Mobil, Castrol and Valvoline, although my preference is Mobil at this time. DO NOT RUN CONVENTIAL MOTOR OIL IN THESE ENGINES! Especially 20w-50 in the wintertime, I lost an engine and a on separate occasions turbo to that. DO NOT RUN FRAM OIL FILTERS, they will come apart internally due to the high heat of the oil. They are made of cardboard and glue, while Wix/NAPA Gold filters are all metal construction. Use OEM SUBARU filters when in doubt. i change my Mobil 1 and NAPA Gold filter every 4k miles, and the oil is not black...its still clear and not far off from looking like it was just poured into the engine.

Overall: Use only OEM SUBARU parts, especially with the gaskets. EXPECIALLY HEAD GAKSETS! Use the OEM Turbo head gaskets. Ive never had a problem with those. The NAPA ones...they blew in 4 days. Use NGK plus, an Accell coil is recommended, I use Beck Arnley plug wires, dont use the NAPA Beldon or Mileage plus wires. NAPA Echlin Cap and Rotors are good to use, I used BA this last time...it was in stock!

A BOV is HIGHLY recommended. I have mine rigged to recirculate, instead of venting to the atmosphere. It keeps the turbo spooled between WOT shifts. Most impotantly, it increases turbo life. When you let off the gas when the turbo is spinning (anytime the engien is running), the turbo is pushin air into the engine...when the throttle closes, that air that its pushing has no where to go, except back out the way it came...there for it puts the compressore in a nid, it wants to reverse, while the turbine on the exhaust side is still going farward being driven by the exhaust output...so, it binds it up. Bearing score'ing happens. Life of the turbo is decresed with each shift, or closure of the throttle plate. With a BOV/ABPV fitted, it allows the air to escape, instead of letting it attempt to reverse the turbo and bind it up. A BOV/ABPV opens when the throttle plate closes and creates vacuum, and that vac. from the intake manifold opens it. Boost pressure alos helps open it.

I think Ive convered everything....it too late to tell now. Experts: Have at it! What did I miss?

Newbies: Read on!

Everyone: Feel free to chime in suggestions, Im always open!

#2 Danbob99

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Posted 25 January 2004 - 12:23 AM

wow, thats a heck of a post. I also second your opinion that the octane of fuel really does make a diffrence in the performance of the car, i've heard the stories, read the statistics and now why it shold theoreticaly work, and in my car, it does seem to also. I've never run any super high octane fuel, only what i can get from the pump, but i may have to try it soon. I have read several articles that dispute this, and say that the octane does not make a diffrence, that you should run what the manufacturrer suggests so that it matches your ignition timeing and prevents detonation. I had a really good one that would have had me convince, if it werent for my past experiences wth bad gas(in my car. ;) ) I will try to find them, and post them.

Dan

#3 Myxalplyx

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Posted 25 January 2004 - 05:22 AM

Originally posted by WJM

A BOV is HIGHLY recommended. I have mine rigged to recirculate, instead of venting to the atmosphere. It keeps the turbo spooled between WOT shifts. Most impotantly, it increases turbo life. When you let off the gas when the turbo is spinning (anytime the engien is running), the turbo is pushin air into the engine...when the throttle closes, that air that its pushing has no where to go, except back out the way it came...there for it puts the compressore in a nid, it wants to reverse, while the turbine on the exhaust side is still going farward being driven by the exhaust output...so, it binds it up. Bearing score'ing happens. Life of the turbo is decresed with each shift, or closure of the throttle plate. With a BOV/ABPV fitted, it allows the air to escape, instead of letting it attempt to reverse the turbo and bind it up. A BOV/ABPV opens when the throttle plate closes and creates vacuum, and that vac. from the intake manifold opens it. Boost pressure alos helps open it.



Nice read! I'm absorbing and taking ALL of this in for future reference. :D I quoted the above info for a reason. I remember reading something from 'Skip' here on blow off valve from THIS thread.

Here is the quote, "ah actualy the Subaru engineers must have given thought to the problem that a blow off valve or By Pass valve is suppose to solve. (i.e. the boost pressure bouncing off a rapidly closed throttle plate and hitting the turbo's impellor thus slowing it down.) They did this by using a "dash pot"
Little known and not often mentioned devise slows the throttle closing just before idle and allows some of the boost pressure leak by the throttle butterfly. I have a Volvo By Pass valve unit fitted to my 87 5 speed turbo and it does help a little compared to the well adjusted dash pot. Newer cars use BPV's because they have higher factory boost pressures."

Comments?

#4 WJM

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Posted 25 January 2004 - 10:37 AM

Yeah, I remember reading that...I dont think it works anywhere near as well as a BOV. Ive also seen non Jap cars, and many other Jap, Euro and US cars with that little thingy on the throttle close stop.

Mine doesnt function at all, not on the RX either, to keep the throt. partialy open for a sec....

#5 Bishop

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Posted 25 January 2004 - 12:43 PM

Great post! I am reading all of this very carefully because I am in the process of rebuilding my 86 turbo wagon. Awsome stuff on the SPD WRX page too. Keep it up!

#6 Warp3

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Posted 25 January 2004 - 02:00 PM

A couple comments:

Now that brings me to the point. 93 is fine for the average mostly stock EA82T. Ive ran one with semi-racing cams, and it boost crept to 15~17psi, and not a peep of detonation, even with 25deg BTDC. All of this with no IC either.


Ok...now this begs the question: What were the figures I've heard about the boost levels of the EA82T in the past based on? I understand the posts I read were likely conservative numbers (so noobs don't go crank the boost and blow their engine then try to blame the poster), but several times now I have read the "14psi is the limit of the stock fuel system" rule-of-thumb. If you were running 15-17psi without detonation on pump gas with no IC and a stock fuel system, that would imply otherwise. Perhaps the person who "discovered" the "14psi limit" was running lower octane or had a partially clogged fuel filter or something?


OIL: MOST IMPORTANT!! Run a known good synthetic oil I run Mobil 1 10w-30. I have not tried Castrol, Valvoline, or any other. All I know, is that I trust AMSOIL, Mobil, Castrol and Valvoline, although my preference is Mobil at this time. DO NOT RUN CONVENTIAL MOTOR OIL IN THESE ENGINES! Especially 20w-50 in the wintertime, I lost an engine and a on separate occasions turbo to that.


This is one point I hesitate to follow on my RX...yet. I know that synth is definitely better (I've run synth in my 2.5RS since about 10k miles), but the EA engines are even more prone to oil leaks than the EJ engines and synth flows well enough that it will point out these leaks very quickly...lol

Now that said, if you are building a car for performance, you should probably just make the change to the better flowing oil, then fix any leaks that suddenly are made known to you, as they need to be fixed anyway...hehe

Personally, I'm sticking to high-quality dino oil for the time being (Castrol GTX 10W40) because I'm not at the point in the car's development where I want to be going around replacing all the seals and gaskets because there is now free-flowing oil all over the place...lol :)

As for the rest of your statements, I completely agree:
- BOV/BPV = good for turbo life
- Fram filters = crap
- Higher octane = good IF you have enough timing or boost to need it (otherwise you make LESS power)
- Intake/Exhaust flow are huge factors for power on any turbo car
- Cooling and fuel system should be in perfect condition before attempting to add any more power

#7 WJM

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Posted 25 January 2004 - 02:19 PM

Ok...now this begs the question: What were the figures I've heard about the boost levels of the EA82T in the past based on? I understand the posts I read were likely conservative numbers (so noobs don't go crank the boost and blow their engine then try to blame the poster), but several times now I have read the "14psi is the limit of the stock fuel system" rule-of-thumb. If you were running 15-17psi without detonation on pump gas with no IC and a stock fuel system, that would imply otherwise. Perhaps the person who "discovered" the "14psi limit" was running lower octane or had a partially clogged fuel filter or something?



I also had the same boost creep incident on my wagon...it detonated like heck cuz of the pump fuel, high compression, and high temps. It didnt rev any further. I would HIGHLY NOT recommend running more than 12 psi on a non IC system, especially without all the other factors checked out, clean fuel system, open intake and exhaust, high quality oil and a BOV/BPV fitted...

As far as max boost on these cars, i think that 14~15 is the max reliable limit for the turbo. As far as the rest of the engine...if its in great shape and taken care of in other regards, fuel, cooling, oil, i think it can handle 20 psi for a while....as long as it breathes correctly, fuel is delivered, spark is on time, etc. etc....But i ahve not fitted a turbo and done this yet, this is just a speculation.

As far as oil goes, thats really a personal preference. But face the fact, synthetic protects way better under pressure. I dont ahve any leaks....but i do have some kind of oil blowing out somewhere around the turbo, it may be PCV relate'd, or otherwise....but i dont have any physical leaks from seals...yet. Its been going for 19,000 miles now on synthetic, just did the 4k mile change friday morning.

Bottom line is that I would not run more than 12 psi on a stock turbo and intake/exhaust tract. With open'ness...and a proper IC-BOV/BPV setup, and a slighty better exhaust crossover pipe...14~15 is the max id run on a stock turbo...unless I had 5 laying around as extras, id run 17 and a very large IC core.

#8 Bishop

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Posted 25 January 2004 - 04:07 PM

In my 86, with no BOV, no IC, running 91 octane, and with mostly stock exhaust parts, I could only run 12psi of boost before detonation at between 15 and 20 degrees BTDC. You could cut back the timing, but you loose power throught the band. I am hoping to add a BOV and replace most of the exhaust parts and bump it up to around 14psi.

#9 Subarutex

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Posted 25 January 2004 - 07:20 PM

There is no point trying to push the stock turbo passed 14psi. Actually, i want to say 13.8psi. Thats where the stock turbo stops being effecient.

After that point, yes it will be pushing more pressure, but the actual volume of air will be less.

Spend the money, go out and by yourself a stock legacy turbo and a WRX downpipe and exhaust. Bolt it on to the stock crossover, the put the WRX stuff from the turbo back.

#10 josh long

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Posted 25 January 2004 - 07:27 PM

I thought the legacy turbo had a different flange from the up pipe, like the WRX one....?

Do you make an adapter flange?

#11 MaroonDuneDoom

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Posted 25 January 2004 - 08:37 PM

GOOD LORD I WANT AN ea82T AND A SEDAN TO PUT IT IN

the more i hear about the amazing options and tuning involved with the 82Ts the more i think that i need one.

#12 Subarutex

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Posted 25 January 2004 - 08:57 PM

As i understand it... the uppipe flange on the legacy turbo is the same as the stock turbo. Its the downpipe flange that changes to the WRX style.

Its not a matter of making a flange, its a matter of spending $30 on the NASIOC and buying a wrx uppipe. Then you cut the flange off, grind the plate smooth and weld it to the top of the existing uppipe flange.

Thats how I imagine it could be done. Once this is done, you could run a td04 (stock wrx), one of the many VF options... like VF22, 30, 34, etc...

The issue is tunablility now. Recently, it has been found you can modify a stock WRX injector to flow 740cc's. A very simple mod that all you need is a dremel. I just spent the better part of my evening seeing if this will work on our injectors.

Sad to say, it won't. Our injectors work by moving a needle back and forth. To open and close this little hole. I cannot forsee how hard it would be to widen this hole (but then it wouldn't be closed all the way, and fuel effeciency would be out the window) or to widen the hole and make the needle better.

Some people say there are other injectors that will work, but I am not certian which ones. I'm fairly positive that the main bearings in the engine will give out, before the limits of these injectors are taxed.

To get more fuel, take out the factory fuel pressure regulator, and get a rising rate fuel pressure regulator. I think a 1:1 one will work just dandy.

#13 josh long

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Posted 25 January 2004 - 10:31 PM

Is the stock fuel pressure regulator not rising rate?

I think this is generally how most stock turbocharged fuel systems work. It makes the ecu maping more simple.

#14 Subarutex

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Posted 26 January 2004 - 12:00 AM

actually, i'm pretty sure the stock is a rising rate. We just need to get more pressure out of it.

#15 WJM

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Posted 26 January 2004 - 10:14 PM

Welding that plate on makes the turbo sit higher...but not by much.

Since I am getting a TD04...I'll now need one of those pipes.

#16 scoobie steve

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Posted 27 January 2004 - 09:07 PM

All stock fpr's are 1:1, so that is for every pound of boost the fuel pressure increases a pound. A 2:1 will increase fuel pressure by 2 psi for every pound of boost. The TD04, vf11 and similar turbo has to be modded slighty to fit the stock up-pipe. Its easier to oval out one hole then it is to change the up-pipe flange. If you ask Dennis nicely he might be able to take a pic of his modded vf11 turbo. Any wrx downpipe will work, the HKS is $140 new. I have some real concerns about fuel. An inline pump and fmu would help. A cold start or AIC would work good and be inexpensive. Anyone ever have a wideband on these EA82t engines?

#17 WJM

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Posted 27 January 2004 - 10:00 PM

Buying race fuel sure gets expensive....expecially on the DAILY driver...

#18 RallyKeith

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Posted 28 January 2004 - 08:48 AM

I appologize but I don't have time to read the entire post to validate or invalidate everything you said, but from what I saw you are right on most of it, but I think you never talk about one of the single most important things. Let me start off by explaining something. You say several times that "the volts ignite it." No not really. The coil produces a voltage that is applied to the electrode of the spark plug that then arcs to the ground tip. That arc is very hot. The heat from that arc is what ignites the compressed air/fuel mix.

Now for that important thing..... Intercooling. The Octane rating of the fuel is actually what is called an AKI, Anti-Knock Index. The higher the number the more it takes to ignite. What happens in a turbo system is both simple and complex. Basically, the act of the turbo creating the pressure also causes a super heating of the air. Then as the air is compressed in the cylinder it gets even hotter. The problem that occurs is that the combination of the effects makes for a high enough temp that it ignites with out the heat from the spark. (This is actually how diesel engines work and why diesel engines run about twice the compression in the cylinders as gas engines.) So, the battle you need to win is that of not reaching all of these critical parameters before YOU want it to ignite, and there are two basic ways of doing that. One, by increasing the Octane rating (AKI) of the fuel to allow it to resist the higher combustion chamber temp, or add an intercooler after the turbo to reduce the combustion chamber temp allowing you to run the lower Octane fuel. An intercooler is like a radiator for air. It will cool the pressurized air coming out of the turbo to a level much closer to what it came in at. Just think about how hot the turb gets when you are using it. That heat is getting transfered into the air and that is bad.

So, while running higher octane will allow you to run higher boost levels while avoiding knock, so would just simply adding an intercooler.

Keith

#19 WJM

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Posted 28 January 2004 - 09:30 AM

I am NOT running higher boost presures. I am running 9.5:1 pistons under the FACTORY turbo setup.

Yes yes, I understand what you said about the spark/volts. I was just trying to put it simply.

The IC issue...I totaly agree. I am going to get one, no doubt. I will do a setup with it, and try pump gas again.

#20 RallyKeith

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Posted 28 January 2004 - 10:18 AM

Originally posted by WJM
I am NOT running higher boost presures. I am running 9.5:1 pistons under the FACTORY turbo setup.



Forgot about that. Still end up with the same effect as running higher boost. Higher pressure, and therfore heat, in the combustion chanber.

I think this is a good basic way to figure out what you got going here. The car is running 1.8 liters at normal atmospheric pressure which is 14.7psi. So, normally aspirated car that 14.7 PSI gets compressed 9.5 times to a pressure of 140psi. Now, normally in a turbo car the compression ration is only 7.7:1. So, when you take the 14.7 and add that to the factory 7psi boost to get 21.7psi compressed 7.7 times for a pressure of 167psi. So, in doing the math of 21.7psi with your 9.5:1 pistons you get 206psi. "reverse" the math and that is like running 12psi of boost. 206psi(your cylinder pressure)/7.7(turbo pistons)=26.7psi. And 26.7psi-14.7(Atmospheric)= 12psi. So, you are currently running on the edge where most people would say you need intercooling to be any more effective. Just some fun with math that may help you in the end.

Keith

#21 josh long

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Posted 28 January 2004 - 12:51 PM

Originally posted by RallyKeith
Forgot about that. Still end up with the same effect as running higher boost. Higher pressure, and therfore heat, in the combustion chanber.

I think this is a good basic way to figure out what you got going here. The car is running 1.8 liters at normal atmospheric pressure which is 14.7psi. So, normally aspirated car that 14.7 PSI gets compressed 9.5 times to a pressure of 140psi. Now, normally in a turbo car the compression ration is only 7.7:1. So, when you take the 14.7 and add that to the factory 7psi boost to get 21.7psi compressed 7.7 times for a pressure of 167psi. So, in doing the math of 21.7psi with your 9.5:1 pistons you get 206psi. "reverse" the math and that is like running 12psi of boost. 206psi(your cylinder pressure)/7.7(turbo pistons)=26.7psi. And 26.7psi-14.7(Atmospheric)= 12psi. So, you are currently running on the edge where most people would say you need intercooling to be any more effective. Just some fun with math that may help you in the end.

Keith



Let me be the first to say this is a very clear and concise post!

Thanks Keith

#22 NoahDL88

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Posted 28 January 2004 - 01:33 PM

just to set the record straight, just running a higher octane gas will not increase hp, its the advancing of the timing that increases the power and its the octane that allows the timing to be advanced.

#23 rallyruss

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Posted 28 January 2004 - 01:44 PM

I agree with what WJM has to say. some good point in there.
I also have to say that my intercooler is probably the best mod. I have done to my car. It adds power and safety to the system. so to back up Rallykeith ( wierd my dad is named Keith ) I think the intercooler shold be a little higher on the list of prioritys. might save money on all that race gas.
Tex I see you are verry facinated with getting more fuel. have you had troubles running lean? and I read about that injector mod. I dont fully trust what they are doing. our injectors are the pintle type. actually a simpler design with less problems.

noah, on a turbo car higher octane also alows higher boost.

#24 RallyKeith

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Posted 28 January 2004 - 01:54 PM

Originally posted by NoahDL88
just to set the record straight, just running a higher octane gas will not increase hp, its the advancing of the timing that increases the power and its the octane that allows the timing to be advanced.



I'm not so sure about that, but I really don't know. Timing is set in Degrees BEFORE Top Dead Center. Power is optimized by having the mix ignite at the correct rotation of the crank, usually a few degrees AFTER top dead center. So you see, you are firing the plug even earlier before top dead center to get it to fire at the correct time after top dead center because the higher octane fuel takes more and longer to ignite. I'm not sure how that effects power output. That is the one place I still need to learn.

Keith

#25 Nug

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Posted 28 January 2004 - 02:08 PM

I don't think I agree with Noah either.
More timing CAN increase power...up to a point.
Octane reduces detonation. Fuel with a higher octane burns with a higher stability, which is why it is used in engines with a high compression ratio, or with forced induction. It will also allow more timing to be run, but optimum timing can't be decided by octane. You can't simply crank the timing up until the threshold of detonation and exclaim that that is where the most horsepower is made. It can only be proven on a dyno.

Compression raises efficiency and therefore power, and forced induction adds power. Optimized timing makes power. Octane does not. Octane just allows this to happen without detonation.

Timing requirements also change with changes in compression, cam timing, and combustion chamber design. Two apparently identical engines might also require different timing for optinal horsepower output.

Next time someone dyno's a car, figure out where the timing needs to go, and then leave it alone.




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