200R4 Trans With Stage motor

[Two Lane]

Originally posted by 4timesT
So how is it possible for the chip makers out there to program more fuel into the chip at WOT as they all claim? If it's static, then there's no more room to grow unless you raise the fuel pressure.

________________________________________________

And some call that "tuning" (through the FPR), to allow pushing a (too small) injector BEYOND a 100% DC.

As others have stated over & over again on dozens of threads,
with today's chips from today's custom chipmakers, that "technique" is no longer necessary, thankfully.
_________________________________________________

An 85% DC at WOT sounds good!



HTH

 

[HighPSI]

Originally posted by 4timesT

Going by an Accel/DFI chart for maximum injector opening time before static operation, at 5000 rmp the injector has an 11.2 ms max opening time before going static. With a 25-30 ms being the commanded WOT pulse width, then even a stock injector on a stock car is static at that point even if it's firing in batch fire mode once every crank rotation (22.4 ms total time). So how is it possible for the chip makers out there to program more fuel into the chip at WOT as they all claim? If it's static, then there's no more room to grow unless you raise the fuel pressure.

Is the 11.2 ms maximum for a batch fire or a SEFI? On a batch fire, the injectors fire every crank rotation. This means the pulse width is half, twice as often. On a SEFI (orB2B FAST) the injectors get pulsed twice as long, every other rotation. The reason a SEFI idles better than a batch fire with very large injectors is because it gets to pulse twice as long, thus more stable at small pw's.
FWIW: A FAST B2B idles very well, even though the injectors aren't in sinc with the valves. This is because of the bigger p/w.

A chip can only be commanded so much fuel, then it goes static. usually, ther is some room to grow, this is why you can command more fuel.

4timesT: I am curious, who are you?

 

[ijames]

As for the pressure drop being mostly around the valve seat area, then why is it that exhaust reversion can be seen up the intake runner and even the plenum on an engine with alot of overlap? The pressure drop I'm talking about is due to the valve opening and the piston's downward travel sucking the mixture into the cylinder. It's quite substantial otherwise the cylinder would never fill, irregardless if the engine is n/a or turbo aspirated. The reason why gases move is that they travel from an area of high pressure to an area of lower pressure. The pressure difference across the injector can't remain static during the intake phase.

Eric covered most of your questions on duty cycle. With the stock ecm in sequential mode each injector fires once every two revolutions of the engine so there's 20 msec between firings at 6000 rpm so any attempted injector pw greater than 20 msec at 6000 rpm results in a static injector (ideally).

I didn't say that the exhaust reversion didn't reach the plenum, I just tried to say that since I believe that the smallest port cross-section is at and just under the valve, that's where the greatest pressure drop will be when the reversion occurs. When the piston starts downwards, yes it will cause the cylinder pressure to drop and this will suck in air-fuel. However, think of the extreme case where the intake valve is tiny and the bowl under it and the port to the manifold plenum are huge - the pressure in the cylinder will be low, the pressure just behind the valve will be the same as up in the plenum since there's virtually no restriction so virtually no pressure drop even though we have flow, and all the pressure drop will occur right as the gas moves through the tiny valve orifice. That's an extreme case, but in most heads (at least according to porting books like David Vizard's which is an excellent read, by the way) the valve curtain area at low to moderate lifts (including shrouding), and the bowl area just under the valve are the big restrictions compared to the port runner up by the intake manifold flange and the intake manifold port runner. Porting out the runners to the max doesn't get much extra port flow because they weren't the restriction anyway, and the bigger you get them the slower the port velocity so you want them to be somewhat big but not excessively so (how's that for a waffling sentence? ). That means that starting with low pressure in the cylinder, the pressure in the bowl will be substantially higher and the pressure in the intake manifold runner where the injector exits will be a little higher, and up in the plenum it will be a little higher yet. What's "substantially" relative to "somewhat"? If each drop were equal the pressure in the bowl would be 1/3 of the way up from cylinder to plenum and the injector exit would be 2/3 of the way up. Guessing, based on memories of head porting texts and diagrams of port flows, velocities, and pressure drops, I'd say the pressure in the bowl is maybe 1/2 to 2/3 of the way up from cylinder to plenum, and the pressure at the injector exit will be at least halfway from there up or 5/6 of the way from cylinder to plenum. At the extreme example of intake valve opening halfway to bottom dead center, 25 psig boost in the plenum, 35 psig pressure in the cylinder when the exhaust valve closed, and 8:1 compression (and thus expansion) ratio, the cylinder pressure will be (35 +15 psia) / 4 = 12.5 psia. The plenum pressure is 25 + 15 psia = 40 psia, and my estimate of the injector exit pressure is 5/6 * (40 - 12.5) + 12.5 = 35.4 psia or about 20.4 psig. That's 4 psig less than the boost pressure but remember the unrealistic starting condition. In reality, as the piston moves downwards and flow starts, the cylinder is alway filling as the piston drops and the minimum pressure is much greater than my example. I can't "prove" any of this but I would be surprised if the injector exit pressure dropped as much as 1 psi through the intake stroke. Even 2 psi only makes 55's look like 55*sqrt(45.5/43.5)=56.2's, a 2% change.

Two Lane - yes, that's the definition of static. If you want to read ad naseum discussions of this look back in the chip section.

While I'm typing, I'm going to get on a little soapbox about incomplete jargon - batch really just means firing all of the injectors at the same time, and sequential means firing them one after another. However, in the TR world, probably because of useage in the ecm code and the Accel DFI, batch seems to mean not only firing all the injectors at the same time, but also once per engine revolution. The timing relative to cylinder #1 TDC is set at startup and then remains the same as long as the crank sensor is sending pulses, since the injectors will fire on the first crank sensor pulse on cranking which will either be #1, 120 crank degrees after #1, or 240 crank degrees after #1. Likewise, in the TR world the phrase sequential mode means not only firing the injectors in order synchronized to each cylinder by a cam sensor in addition to the crank sensor, but also firing them once per every two engine revolutions. As Louie Andersen would say, "That's not right!". Okay, I feel better now .

 

[Eric Stage I]

Thank you Carl. Someone needs to rename this thread

Eric

 

[NJTurbo]

Man,

And to think i just wanted to now about how many guys are running a 200R4

 

[Trbobuick]

400 with a gear vendor o/d unit.

0/d will be controlled by the DFI's TCC output circuit.

 

[Reggie West]

Ijames, I know about the fuel pressure issue you brought up. But now let me ask you this, when the intake valve opens for a particular cylinder a huge pressure drop occurs as the air gets sucked in by the piston and it rushes past the valve and into the cylinder. At the same time the injector fires. So the relative pressure inside that intake runner when the valve opens up is lower than when it's closed. The injector is not seeing the 25 psi of boost you're talking about.


This has been a wonderful discussion but I have one simple question.

How can there be a noticable pressure drop in a manifold that is pressurized by a turbocharger? The entire purpose of a turbo or other forced induction system is to " push " air into the cylinders.
Not let the cylinder pull the air in a motor that is normally aspirated.

 

[NJTurbo]

Originally posted by Trbobuick
400 with a gear vendor o/d unit.

0/d will be controlled by the DFI's TCC output circuit.

Interesting set-up please e-mail the juice on that.

 

[Two Lane]

TurboMaster, Your Wish Is Our Command!!

http://www.gearvendors.com/racing.html


HTH

 

[ijames]

Can we hijack a thread, or what?

How can there be a noticable pressure drop in a manifold that is pressurized by a turbocharger? The entire purpose of a turbo or other forced induction system is to " push " air into the cylinders.
Not let the cylinder pull the air in a motor that is normally aspirated.

Well, first the theoretical answer that anytime there is flow through a non-zero restriction there must be a pressure drop. There will be a small pressure drop between turbo and intercooler, a large drop across the intercooler, a small drop from intercooler to throttle body, a drop there into the plenum, and then more drops into the cylinder. The goal is to make each drop as small as possible consistent with whatever velocities you need in that region, but no drop ever reaches zero. I agree that in an intake where you have a pretty large plenum (not large enough for some but that's a different thread ), pretty large intake runners, and then port runners that start out pretty big and then taper down to the bowl under the valve you won't see much pressure drop between plenum and bowl - that was my point responding to 4TimesT (for lack of a better name), that you won't see enough of a drop at the head end of the manifold runner to affect the apparent injector flow rate.

Next, the real purpose of a turbo or blower is to increase the density of the intake chage so when the same fixed volume is drawn in, there will be more air-fuel mix in the cylinder. Each kind of blower has a different set of side effects, however. With a supercharger the exhaust system is nominally at atmospheric pressure just like on a normally aspirated motor, while the intake manifold is at boost pressure, so at the end of the exhaust stroke the residual cylinder pressure is near atmospheric and the boost does help fill the cylinder. That's why supercharger heads have small intake and big exhaust valves; the intake side doesn't need any help and the exhaust needs all the help it can get. Also supercharger cams have little or no overlap because during overlap the intake charge can blow right through the cylinder and out the exhaust. On a turbocharged motor the exhaust manifold pressure will be somewhere between the boost pressure and maybe two times that. People have measured exhaust manifold pressure of 35-40 psi on stock TR's with 20 psi boost. Bigger, more efficient turbos with less restrictive exhaust housings and turbine wheels help that a lot but even with a 70-something turbo on a GN1 headed motor with big roller cam Todd King measured exhaust manifold pressures between 25 and 30 psi with 20-25 psi boost (my memory is a little foggy on the exact numbers but these ranges are correct). A crude way to think of this is that the closer the two pressures get the longer it will take to spool up the turbo. All of that means that the minimum cylinder pressure is greater than the intake manifold pressure and so the boost really doesn't help push the intake charge into the cylinder. A turbo motor behaves like a normally aspirated motor with some exhaust backpressure, which is why our choices of valve sizes are about the same as a normally aspirated motor. There will always be a little flow from cylinder back into intake manifold when the intake valve opens (unless it's real, real late with a very custom cam and the net is probably worse than letting the reversion happen, at least according to Vizard) because the residual cylinder pressure will be about equal to the exhaust manifold pressure and that's higher than the intake manifold pressure. A turbo cam also doesn't want overlap, but for the opposite reason than with a blower: exhaust will flow from exhaust manifold back through the chamber and into the intake manifold.

Everyone understands that it takes power to turn a supercharger with a belt, but lots of people still think that a turbo gives you "free" horsepower. The truth is that having to exhaust from the cylinder into that high exhaust manifold pressure takes a lot of work, and costs horsepower compared to exhausting to atmospheric pressure. The power that goes into overcoming those pumping losses is power not available at the rear wheels, just like the power that went into driving the belt on a blower. Turbo systems are usually more efficient than belt-driven blowers and so can make more peak hp, but it's never free .

 

[Larry]

IM switching to a 400, however- I want to keep my stock shifter! Is that possible? If so- what mods are neccesary?Thanks Larry

 

[4timesT]

Hi, bet ya missed me.

Cal, I'm someone you've met at E-Town a few years ago when Lazaris and I were still friends. I'm not a troll and I've not been booted from any BBs. So don't worry, I'm not here to cause trouble. I don't believe in giving out my name on the internet, but that's just me. I don't know if anyone recalls about 3 years ago when one of the BB's younger members scanned and posted his driver's license on the board. Myself and other's told him what an assinine move that was, but he didn't care. To each his own.

Anyway, besides being a Buick aficionado I also have a soft spot for Mustangs, had 4 of those too. I bring this up because I like reading Mustang magazines. Information is alot more plentiful in the Mustang world. I would like to direct those who have posted in regards to the drivetrain HP loss, IJames and others, to the newest edition of 5.0 magazine (Jan 14, 2003 issue). Check out page 54, the right most column (in black). Not unlike myself, others have doubted the HP percentage loss that is commonly attributed to the drivetrain. And these guys have alot of experience building, testing and racing many fast cars. I just picked up this issue tonight and figured you fellas might like to see what these guys think about this topic. Yeah I know, their talking about manual transmissions. But lets look at IJames's argument that due to the increased acceleration of the torque converter in a higher HP motor vs a lower HP motor there is a greater loss of HP between the flexplate and the rear wheels, then the same principle applies to a stick car. Granted, a converter filled with fluid is quite heavy, but a stock Mustang cast iron flywheel, clutch and pressure plate assembly is no light weight by any means. I disagree with the article about one thing though. I don't believe a mustang loses 35 hp due to drivetrain loss, certainly not a stock one. Once Ford corrected the advertised HP for the 5.0 in 1993 to 205 net HP, I find it hard to believe that a 3300 lb car w/3.08 gears could get into the mid 14s at 95 mph, as most Mustangs with a decent driver could do back then, with only 170 RWHP.

PS, let's reflect on one more thing, quite a few bone stock TRs have run high 13s to very low 14s in the 98+ mph range. Although Buich rated the TR at 235-245 hp it's commonly accepted it was more like 260 hp. If we take into account a 20 -25 % loss (depending on who you ask) for the auto tranny, then we're talking 208-195 RWHP. I just don't think a 3600 lb brick will run those numbers with 200 or so RWHP. Auto LT1 F-bodies run 98-99 mph in the 1/4 bone stock and they have an advertised minimum of 275 HP and are quite more aerodynamic than our beloved TRs. Just some more food for thought.

PPS : May we all have a Merry Christmas and/or a Happy New Year.

 

[TurboDiverArt]

Originally posted by Two Lane
Aluminum is doubtful beyond 300-350 hp, according to some reports.

Carbon fiber shafts are mega-light & strong, far beyond aluminum.

They are in the $800.00 range & up.

____________________________________________

I'll send you some links on suppliers later...Right now, I'm being chased by housewives sent over to seduce me out of my GN by their husbands...one from NJ...whoops!! I meant NY!!

Gotta go!!

I don't know about that. Yes there were plenty or people that twisted AL drive shafts in the past. Hell, our own Richie Rezes toasted one years back. I don't know if they have changed thickness or what but there are plenty of people out there (not Buick's) that are going 7's with AL drive shafts. My friends 1000 HP, low 8 second Dodge had one. Naturally there is a weight difference with our cars as you can only get them so light with the stock frame but still, 1000HP and 1.1 second short times is pretty damn harsh on a driveshaft. I believe there is a vendor in National Dragster selling AL drive shafts guaranteed to 7 seconds. AL drive shafts have dropped in price considerably since the carbon fiber ones have come out. I think AL ones are in the $300 range now but don't quote me. Don't have a National Dragster in front of me but if needed I can look it up or so can any member of the NHRA.

 

[NJTurbo]

I am going to run Alum, i cannot see spending $900.00 on a shaft

 

[TurboDiverArt]

Originally posted by njturbo
I wondered were she went. 800.00 and up Holy S... MAN

Welcome to the stage II world Travis. Everything is more expensive. Get used to it bud especially if you are planning to rebuild your 200R every season to the tune of $1000+ unless you learn how to do it yourself. Let's not forget the toasted converters from all the heat you are producing off the trans brake. Getting ready to dump my 400 out and have it and the converter rebuilt. Something let loose in there and gotta find out what it is before next season!

 

[Buicksx2]

Artie,

No truer words were spoken. I had a hard time convincing my buddy Newman to go the 400 route, he wanted the 200 for street driving. I asked him how much street use is the car gonna see and he says some but mostly track on a trailer. I told him 400 is the wiser choice and he decided to go that route.

He's all excited now cause his motor is coming by end of week and he's got all his parts ready to put in so putting his puzzle together should start soon.

He's a pisser this kid Newman.

Happy Holidays.

 

[NJTurbo]

Art i hear you i just cannot see myself with no OD and that race shifter. I really want to have a sleeper, GNX dash and my stock consol. I know Rich mentioned he knows someone that runs a 400 with stock shifter that is a trick set-up. I guess i will grab a 200R4 build it and keep as a spare. That way if i blow it up i can just swap it out. It would be nice if Bruce WE4 chimmed in

 

[NastyGn]

Originally posted by TurboDiverArt
I don't know about that. Yes there were plenty or people that twisted AL drive shafts in the past. Hell, our own Richie Rezes toasted one years back. I don't know if they have changed thickness or what but there are plenty of people out there (not Buick's) that are going 7's with AL drive shafts. My friends 1000 HP, low 8 second Dodge had one. Naturally there is a weight difference with our cars as you can only get them so light with the stock frame but still, 1000HP and 1.1 second short times is pretty damn harsh on a driveshaft. I believe there is a vendor in National Dragster selling AL drive shafts guaranteed to 7 seconds. AL drive shafts have dropped in price considerably since the carbon fiber ones have come out. I think AL ones are in the $300 range now but don't quote me. Don't have a National Dragster in front of me but if needed I can look it up or so can any member of the NHRA.

Art you are correct. Not all alum drive shafts are made the same. You need to check with the Mfg on there specs to insure that it works. You get what you pay for.

I have an alum drive shaft on Nasty that works good with no problem. 1.33 60' with a 3650# car

Happy Holidays

 

[NJTurbo]

http://www.pstds.com/driveshafts.cfm

 

[NastyGn]

Try here, Mark Williams has a little more information on theres

http://emporium.markwilliams.com/prodlist.asp?catid=1005