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Old 11-30-2001, 12:50 PM   #26
Section 8
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Oh quit playing favorites.

He wrote it in black and white (in this case blue and light blue).

First Shiv said that he NEVER said that, now he is saying that he was mis-quoted. I can go to the link and see that he in fact typed exactly what Larry quoting him as typing. (Pulling such a short excerp out of the post might be a concern for losing context however.) If he would just put the ruler away and explain EXACTLY what he meant by the statement (again if necessary, if he feels that there was enough information there in the first place. That of course if for the reader to decide, not the author.) this would be over with already. Enjoying some celebrity has some problems, one of which is that every post has someone, somewhere, who probably remembers it.

Shiv is an asset to the board, but sometimes I think that he gets himself into more work by fighting with people, than just explaining something again, maybe a little differenty, so everybody understands EXACTLY what he meant. Then he would have more time to drop a few more tidbits around the board.

Greg
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Old 11-30-2001, 01:46 PM   #27
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Quote:
Originally posted by LUME
Allwheeldrift,

RFPR increase pressure with and increase in pressure, this is correct. But remember your manifold pressure is below atmospheric at idle (vacuum), and it INCREASES as power increases (ie, the throttle plate opens, and pressure increases to higher absolute pressures.... ie lower vacuum). So RFPR do work for NA engines, you just have to source them correctly (I've used one on a 600 cc na cycle engine).
--Roy
Yes, at idle you'll have more vacuum because the throttle plate is closed, but at WOT your manifold preasure will drop as the RPMs come up since the filter, intake tract, throttle body, etc become more and more of a restriction. You will be able to keep your idle and part throttle fuel preasure closer to stock, but under WOT it's going to be worse than a regular FPR. Compared to a regular FPR, under WOT a RRFPR will deliver proportionally more fuel in the low-mid RPM and less in the high RPM which is the opposite of what we'd like.
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Old 11-30-2001, 11:52 PM   #28
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Quote:
Originally posted by 8Complex

Kevin Thomas - Are you running the stock pump now without any mods on the car? That sounds just like a weak pump.
I do have mods. I have a JC Sports intake, 2.5" custom exhaust piping and a dynomax muffler (2.5"). I am running really lean between 5k-6k rpm according to my Jumptronix air/fuel meter. The voltage drops all the way down to 0. Yikes! Even with +50 (Apex-i S-AFC) from 4500-6000rpm, it doesn't help at all. Fuel pressure holds steady at anywhere between 38-48psi. It doesn't drop off at all. I want to remedy this situation because I'll probably be anywhere between 70-120 shot of nitrous to the XT6. I can't allow for any variation in my air/fuel ratios at all.


wcbjr (Charlie),

Thanks for the help. I'll be trying that pump out. But before I order it, is there any reason you picked this particular pump? I know you can't be sure it fits but does it fit an Impreza? Do you know of someone with it installed, have you gotten one yourself or anyone else here? I am just one click away from ordering it so if anyone got good feedback on this pump, then I'll just order it. If there is a slight modification needed to make it fit, my shop should be able to handle it. Thanks!
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Old 12-01-2001, 12:40 AM   #29
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Kevin,
Revision over in the Midwest forum is having the exact same problem. You should get together and figure that one out. On his RS we didnt think it was likely fuel supply issues, but beats me if I know what it is.
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Old 12-01-2001, 01:12 AM   #30
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Quote:
Originally posted by Section 8
Oh quit playing favorites.

He wrote it in black and white (in this case blue and light blue).

First Shiv said that he NEVER said that, now he is saying that he was mis-quoted. I can go to the link and see that he in fact typed exactly what Larry quoting him as typing. (Pulling such a short excerp out of the post might be a concern for losing context however.) If he would just put the ruler away and explain EXACTLY what he meant by the statement (again if necessary, if he feels that there was enough information there in the first place. That of course if for the reader to decide, not the author.) this would be over with already. Enjoying some celebrity has some problems, one of which is that every post has someone, somewhere, who probably remembers it.

Shiv is an asset to the board, but sometimes I think that he gets himself into more work by fighting with people, than just explaining something again, maybe a little differenty, so everybody understands EXACTLY what he meant. Then he would have more time to drop a few more tidbits around the board.

Greg
I'm not sure what the confusion is here. I never said that the stock injectors could only support 170hp. If I did, I'd have a heck of time explaining how my Minnam turbo'd 2.5RS made a dyno proven ~250hp a couple years ago with stock injectors.

shiv
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Old 12-01-2001, 04:45 AM   #31
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Shiv,

Do you think you might have time to address Midwayman's questions? I know that I personally, would feel better about the issue of Tuning an NA 2.5RS motor if we knew a little more as far as what the engine will require, or even perform in a 'safer' range with... and I think your opinion would carry a lot of weight.

Thanks,

-Dean
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Old 12-01-2001, 05:02 AM   #32
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Originally posted by Midwayman
Kevin,
Revision over in the Midwest forum is having the exact same problem. You should get together and figure that one out. On his RS we didnt think it was likely fuel supply issues, but beats me if I know what it is.
Thanks for the response Midwayman. I'll check out Revision's problem(s) in the Midwest forum today when I go to work. I'm not one for trying to figure to many things out. WCBJR responded to my question via ICQ and it was enough for me. I ordered the Mustang Walbro fuel pump just before posting this. Hope it works.
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Old 12-01-2001, 06:11 AM   #33
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Kevin, Please note that the XT6 most likely uses a 31 GPH external pump. Anyway thats what the Turbo sedans and wagons used in 88, and 31GPH is likely going to be plenty for 145 HP. I put on a 60GPH external pump by walburo but its a BIG thing, and with my getto mounts its the lowest thing on the car.

If you want I can find a pic of it, and get any info you want about it. I will say that the stock FPR hates that ammount of flow though.
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Old 12-01-2001, 07:48 AM   #34
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Originally posted by XT6Wagon
Kevin, Please note that the XT6 most likely uses a 31 GPH external pump. Anyway thats what the Turbo sedans and wagons used in 88, and 31GPH is likely going to be plenty for 145 HP. I put on a 60GPH external pump by walburo but its a BIG thing, and with my getto mounts its the lowest thing on the car.

If you want I can find a pic of it, and get any info you want about it. I will say that the stock FPR hates that ammount of flow though.

Well....er....you are about 1.5hrs to late. I already ordered the Mustang pump. Don't forget that I'll be using anywhere from a 75-120 shot of nitrous in the future. Thanks for the heads up though.
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Old 12-01-2001, 09:13 AM   #35
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Originally posted by XT6Wagon

If you want I can find a pic of it, and get any info you want about it. I will say that the stock FPR hates that ammount of flow though.
Oh...this would be great. Thanks!

BTW: What can I expect with my stock fuel pressure regulator with all the extra fuel flow?
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Old 12-01-2001, 12:42 PM   #36
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I'm not sure what the confusion is here. I never said that the stock injectors could only support 170hp. If I did, I'd have a heck of time explaining how my Minnam turbo'd 2.5RS made a dyno proven ~250hp a couple years ago with stock injectors.
THATS THE WHOLE POINT!

Somebody misunderstood someplace, instead of denying something that was understood differently than you said (which in the persons mind who read it is truth), just explain it again how you mean it!

Don't forget that it is always possible to make mistakes.

If a person adheres to strict engineering principals, then the stock injectors can only support 170 HP. I would say that the confusion came from the formula for how much HP stock injectors can support in a post somewhere with the formula, without a disclaimer about changing other fueling parameters changing the equation, or running a little closer to the edge than engineers design for. It was probably posted with the disclaimer implied, and some of the people understood it as such, others didn't.

Greg
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Old 12-01-2001, 02:14 PM   #37
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Shiv,

We know you are not denying that you can run get almost 250 HP from stock injectors in a turbo by (1) increased duty cycle (2) higher fuel pressure (3) using different numbers for the BSFC that a turbo runs vs NA.

But you clearly said for NA the injectors were sized for 170 hp, and I did not misquote that. So, now it becomes an issue of semantics and whether you actually meant they can only "support" 170hp or not, even though you said they are sized for 170hp. So, I have been acussed of misquoting the "tuning God" in several places on the board. Maybe there are some times when the context is an issue?

i.e., In an NA application, people are getting 20% gains in power with intake, exhaust, cats, pulleys or cams, whatever. Accounting for an increase in duty cycle in the NA car, or maybe a high flow high pressure fuel pump they obviouly can support more than 170hp. That might not have been the context you were using the statement in, and if so, I understand your frustration.

I will note that in re-searching for all your posts about the subject, I can see that at other times you have also stated that they can support 165-185hp. In your defense I have the following

Quote:
http://www.i-club.com/forums/showthr...threadid=59251

The stock injectors reach 100 duty cycle at 1-2psi of boost. Above that, you're just running lean. Hence, the 1650 degree EGTs at 7psi with stock 280cc njectors and 1500 degree EGTs at 12 with TEC-II and 550cc injectors.
That 1-2 psi represent about a 20hp gain before going static - HOWEVER, that is with higher fuel pressure and a different BSFC factor than NA, and represents going from 80% duty cycle to 100%. But at 80% duty cycle in NA and normal fuel pressure, then your first 170hp statements would still be what you meant, right? At least admit that you said it?

From the same thread

Quote:
I assumed the subject title, "piggy back electronics" only refers to electronics, not fuel pressure regulators

With 80psi of fuel pressure at 10psi of boost, you will get 27% more fuel flow. Essentially turning the 280cc injectors into 355cc injectors. Still only considered ideal for 210-240hp. Either way, injectors don't like to go static.
Going backwards with math, that would mean 165-189hp from the stock injectors, but at again, using the turbo BSFC numbers or the one for NA?

Then there was this...

Quote:
http://www.i-club.com/forums/showthr...threadid=56446

Stock MY99 injectors flow approximately 280cc/min according to the flow bench at RC Engineering. Perfectly sized for a 165-185hp car. Still too small for any turbo system. With 8psi of boost, my injectors went wide-open at 3500rpm. Even Imprezer's NA TEC-II'd 2.5 is brushing up agains the 80% duty cycle mark.
And this one

Quote:
http://www.i-club.com/forums/showthr...threadid=55405

Why do you say the stock 280cc injectors approach full duty cycle at 8psi when, in fact, they reach 80% duty cycle in N/A (no boost)?
Those last two confuse me because Imprezer's NA TEC-II car was making more than 170hp, yet you said he was only running 80% duty cycle. Certainly if you feel that peeps should not run over 80% duty cycle to be safe, then you need to stand by the math that gave you the 170hp at 80%:

Quote:
Inj. Size(lbs/hr) X Duty Cycle / BSFC = HP per injector.

280cc / 10.5 = 26.6 lbs/hr

26.6(lbs/hr) X .80(80%dutycycle) / .50 (b.s.f.c) = 42.6(hp per injector)

42.6 X 4(number of inj) = 170.6hp
But if 95% duty cycle is acceptable to you, them midwayman's math above is:

Quote:
Calculations:
You can set the duty cycle higher but that is not recommended. Since then the injectors are basicly stuck open.

Inj. Size(lbs/hr) X Duty Cycle / BSFC = HP per injector.

280cc / 10.5 = 26.6 lbs/hr

26.6(lbs/hr) X .95(95%dutycycle) / .50 (b.s.f.c) = 50.54(hp per injector)

50.54X 4(number of inj) = 202.16hp

But there are other key factors that can change the output, these things are Fuel Pressure and BSFC (Better the fuel the lower the number)
That brings up some NA injector size questions - the 2000+ ECU with MAP doesn't let the MAP voltage exceed 4.7-4.8V and so the injectors can only support as much duty cycle as the ECU allows, right? So, does the my99 and older hit 100% duty cycle more easily than the MY00+ when NA (not turbo) because the MAF sees more flow and opens the injectors more? Will the my00 ECU even let the injectors go over 85-90% duty cycle without hitting the wall the ECU puts up?

Larry
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PS: stop saying I misquoted you, I did "quote" you, and now I have more information to stop throwing out that quote at people.
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Old 12-01-2001, 03:48 PM   #38
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Quote:
Originally posted by Section 8

If a person adheres to strict engineering principals, then the stock injectors can only support 170 HP. I would say that the confusion came from the formula for how much HP stock injectors can support in a post somewhere with the formula, without a disclaimer about changing other fueling parameters changing the equation, or running a little closer to the edge than engineers design for. It was probably posted with the disclaimer implied, and some of the people understood it as such, others didn't.

Greg
Strict interpretation of the rule does not say that the stock injectors can supprt 170hp. It simply says that if you assume a certain BSFC and a certain max. desired duty cycle, ~170hp is all you're going to get. I don't see a need to insert a disclaimer about the effects of changing these assumptions. That should be fairly obvious.

Larry writes
Quote:
Those last two confuse me because Imprezer's NA TEC-II car was making more than 170hp, yet you said he was only running 80% duty cycle. Certainly if you feel that peeps should not run over 80% duty cycle to be safe, then you need to stand by the math that gave you the 170hp at 80%:
One way you can make more power in an NA car is to run it leaner. Or, increase mass air flow (intake, exhaust, headers, etc,.) while keeping stock duty cycles relatively constant. Also, Alex's NA TEC-II'd car was tuned for premium gas, allowing me to tune aggressive timing curves. This impoves the efficiency of the engine, allowing it to make more power with the same amount of fuel. The stock EFI mapping accounts for the lowest common denominator-- those who run cheap gas, with tons of carbon build-up, in terrible conditions with zero maintenence. There is plenty of room to make more power with stock injectors. Of course, this safety margin is compromised. This shouldn't be a surprise.

Also, regarding the RS with the stock Minnam turbo: That 250hp was made at stock fuel pressures. So yes, it is possible to make that hp with stock injectors-- even in turbo applications. BSFC goes super low and duty cycle goes to 100%. More often than not, the lower you take the BSFC, the more power the engine will make at the expense of knock thresold and EGT. Lean is mean.

Larry also wrote...
Quote:
That 1-2 psi represent about a 20hp gain before going static - HOWEVER, that is with higher fuel pressure and a different BSFC factor than NA, and represents going from 80% duty cycle to 100%. But at 80% duty cycle in NA and normal fuel pressure, then your first 170hp statements would still be what you meant, right? At least admit that you said it?
Higher fuel pressure?

and...

Quote:
Going backwards with math, that would mean 165-189hp from the stock injectors, but at again, using the turbo BSFC numbers or the one for NA?
Using a BSFC of .45 (which isn't atypical for a well-tuned NA car running good gas), the stock 280cc injectors are just fine for ~200hp. For most other cars, the same amount fuel will be used up before 180hp-- which is what I've said. FWIW, good race engines can run BSFCs as low as .35 in endurance racing conditions.

Still confused by all the hooha...

Sihv
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Old 12-01-2001, 04:43 PM   #39
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Yes, Im sorta confused but the whole uproar over the 170hp thing. Id never seen the direct quote before, but it all makes sense. Can we drop the who said what, and get back to solving the problem of delivering enough fuel to NA cars that exceed their injector limitations?

For the purposes of this execise, Im giving a BSFC of .475 since I doubt we are running the worst case .50 bsfc number.

Using dyno tests (184hp or stock +19 per SCC's intake and exhaust tests) at stock pressures. assuming 80% duty it gives us .46 BSFC assuming 85% duty its .49. Cutting that range in half is still .475
Starting to look like a good number, eh?

to support 200hp @ 85% duty with .475bsfc we need 48psi
to support 200hp @ 80% duty with .475bsfc we need 54psi

But enough theory... who knows the best FPR, etc to actually achieve this while still keeping idle pressures low.
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Old 12-02-2001, 04:53 AM   #40
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Kevin, I'd check to make sure that the pump you ordered is capible of being used externaly. Most internal pumps need to be submerged in a couple gallons of Gas to cool properly. If they don't have this they overheat in a hurry.

On the Stock FPR, I can't say for sure, but mine howls like I just shot its first born. Then again the injectors are not firing so that may account for a good portion of the problem. The big concern I have is that the stock fuel lines will be marginal for the high flow pump and will add to the stress on the pump.

Last, What size pump did you get.
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Old 12-02-2001, 12:04 PM   #41
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Well, I've managed to swap out my problem for another by replaceing my hot film MAF. Now it stutters at idle, but at least the lean run at WOT is gone.

I'll try cleaning the old MAF and see if that fixes the problem with it.
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Old 12-02-2001, 12:11 PM   #42
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Quote:
Strict interpretation of the rule does not say that the stock injectors can supprt 170hp. It simply says that if you assume a certain BSFC and a certain max. desired duty cycle, ~170hp is all you're going to get. I don't see a need to insert a disclaimer about the effects of changing these assumptions. That should be fairly obvious.
The previous post explained what I felt that happened to lead to this situation, in an attempt to difuse it. If you felt that it was what I was telling you to do, fine. As for being obvious, what is obvious is that not everybody knows things like that on a board that needs no credential to read. Some people still do not even see their car as a system, and are taking your words as absolute, then you are busy trying to clean up the mess when they retype them. The disclaimer can be as simple as 4 words. "...without changing other parimeters.".

I don't know exactly what the exact maximum would be for the stock injectors using strict engineering doctrin, I'll give you that, but it is not much over 170. However, strict interpertation of the rule says, that an 80% duty cycle IS the maximum. No engineer, that is the member of a society with an ethics code that will want to stay a professional engineer, will design a part to work at 100% duty cycle on a consumer product. Period. What you do to raise the output, is your own business, but it falls under "without changing other parimeters" and is not supported by the stock fuel system, and will cause you problems with people reading your posts, and quoting them in the future. Frankly I don't care if you do it in the future or not, but saying that you didn't say something in the future, then that you were misquoted, when what you really mean is "thats not what I meant", the whole while complaining about people, isn't very professional. Especially from someone who writes for a well known magizine in this community, not to mention being a vendor.


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Old 12-02-2001, 01:06 PM   #43
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Old 12-02-2001, 02:13 PM   #44
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Thanks Greg

Apparently Shiv couldn't find an "emoticon" for

:what got you panties in a bunch:
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Old 01-15-2002, 06:57 PM   #45
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Can we get back to the Question at hand..... which to overly simplify is:

What is the best solution for a "heavy duty" NA car that is pushing its stock fuel system's limits? Specifiaclly for the MY00 and 01
I don't understand all this mumbo jumbo. I just want to know what to buy.

I hope this gets us back on track.
PS shiv your input would greatly appreciated.
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Old 01-16-2002, 01:07 AM   #46
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I'd be interested in this as well :monkey:
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Old 01-16-2002, 01:32 AM   #47
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NEW ECU and bigger injectors (TECII, Haltec, Wolf, Link, etc...) like AndresRS01 monster NA car doing low 14's in Houston with a Haltec

Unichip and bigger injectors (Does Cobb still do this?)

Maybe the SDSEFI.com/eic.htm system, since you can adjust what level of vaccum/boost to have the extra injectors switch in, from -10 vacuum to +22 boost

Larry
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Old 01-16-2002, 03:06 AM   #48
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This is a very interesting post. I had no idea that the stock fuel system was stressed in so many ways. I'm surprised (probably due to my lack of experience with fuel systems) that the stock fuel system is only capable of 30 more hp then stock. From what I have read here I'm gathering that it is a good idea to get an EGT or A/F guage even when doing bolt ons. It seems that this issue is severly overlooked, but I'm assuming no real damaged has accured due to pinging since the stock ecu will retard the timing and therefore keep the hp within the stock injectors capability. Am I correct in my assumption? Thank you for this informative post.

-Chav
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Old 01-22-2002, 10:15 PM   #49
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Would this work? FPR and a SAFC and have a mechanic put on an O2 sensor that actully works.
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Old 01-23-2002, 01:03 AM   #50
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imprezive - Been there done that.

1) Boost fuel pressure much over 45-50 psi on a 2000+ Impreza and you start to see CE lights for catalyst efficiency below threshhold"

2) Boost fuel pressure much over 55 psi on that car and idle starts to deteriorate from too rich.

3) Use the SAFC on on that 2000+ to remove that extra fuel at idle and get a rough loping idle and a CE light for "low abs/barometric pressure circuit input"

4) Use the SAFC to add more fuel in the 2000+ and expect to see a CE light for "high abs/barometric pressure circuit input" when you hit about 34inches of mercury on the OBDII, and hit a fuel cut at 35.7 inches of mercury

Larry
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