Ducman82

I went and checked mine while running for pulse.. Then remembered I'm running sequential.
All -6, aeromotive bypass regulator..

GregBBRD

Keep in mind that the Bosch system is only opening two injectors on one side, at the same time....not all four.

victor25

True, there are 2 firing controls, which fire four injectors at a time. But thats no where close to sequential, and using optimum firing times synced with valve openings.
What is the HP gain with a well tuned sequential I wonder???

Ducman82

from what i can tell from what i have done, idle to low end seems to be an improvement.

GregBBRD

Doubtfully very much......12.5 to 1 is 12.5 to 1.

Although virtually any engine with a carburetor will make less horsepower when converted to fuel injection.

danglerb

I wonder if this is due to;

A) Charge air cooling by evaporation of the fuel.
B) Fuel being evaporated more fully.
C) increased mass of the "air/fuel" in the intake.
D) Something else.

GregBBRD

I'll ask my local DTS dyno guy. It is an interesting question.

BC

The theory on this from A. Graham Bell is that a properly tuned sequential motor will net 5% power increases if (IF) the duty cycle is below 70%.

danglerb

Makes sense that as duty cycle goes towards 100% there is no difference, but what about as duty cycle gets below say 20%, isn't that also a big mismatch with the air flow?

How is sequential timed anyway relative to the stroke/cycle?

Carl Fausett

I've been asked how loud the injectors are when using our Billet Fuel Rails, batch firing, and with no fuel dampeners in the system. Answer: not very. In this video, the 928 is running 40 pound injectors (twice normal size), no fuel rail dampeners, and I have removed the supercharger so you don't have to try to listen over that.

If you listen close, you can just barely here the "click click click" faintly of the injectors firing at idle. I did this indoors, so it would be as loud as possible. If it were outdoors, and of course if the hood was closed - it is completely inaudible.

I apologize I didn't shine up the motor before the video. Those fuel rails were installed in 2009. Same ones we have been making and selling for 4+ years. The intercooler is new, and wrapped in masking tape so we don't scratch it while we work on the Stage III kit. Just in case your curious.

GregBBRD

It is really great that you are so convinced that what you are doing is so correct.

The real test will be if you take your car, this next year, to Bonneville with your same "high volume" fuel rails, no dampers, and batch firing.

I'm guessing there will be changes.

Speedtoys

..enjoy the piston melting events every 600rpm starting at 1200, then 1800, and the fiercest at 2400, and so on...a street car might take that abuse for a little while..with a little boost..but..

Greg..do we agree?

SeanR

No, larger volume equates less need for damping. Aren't you guys paying attention?

ptuomov

The undampened rails are not guaranteed not to work with out old ECUs. It's just that it's not guaranteed to work. The undampened rails may very well work with some injector sizes, hose "give", etc. But they may give problems in some seemingly similar configurations.

My view on carburetors:

I don't think there are many (any?) high-budget racing series in which unrestricted fuel injection is allowed and in which anyone is competitive with carburetors. Once you put a real budget behind development, the fuel injected car is quicker -- at latest by the first time you have to turn the steering wheel.

The American muscle car people are making more power with carburetors than with EFI. There are a number of reasons for that. My guess of the reasons is the following:
- Carburetors have been developed for a century for these applications, and the technology is basically fully developed to its potential. In contrast, EFI products are in their infancy in these applications.
- People building big V8's understand carburetors very well while don't really understand EFI
- At least on a stationary dyno, carburetor vaporizes fuel earlier in the intake tract than port fuel injection, absorbing the heat and increasing density early in the intake tract, which will increase power.

If the muscle car people would fully use the flexibility that EFI gives for making intake manifolds, instead of installing injectors on manifolds that are designed for carburetors, and then experiment on injector spray patterns and injector placement as much as they have experimented with carburetors over the decades, I doubt we would see carburetors making more power in the muscle car applications.

Ketchmi

It has been my experience that early fuel injection gained considerable mid range torque vs. carbs but properly setup carbs had a good peak horsepower advantage. Balancing your a/f ratio over the entire rpm range with a carb is not the easiest thing to do and if you were a competitor, you had to adjust the tune for every different track and weather condition. If you get a chance, watch "Pro Stock" racing...still running carbs and no power adders while turning 6's in the quarter with 1200+hp and 500ci. Max hp carb setups are like a 2-stroke engine with a very narrow but extremely efficient powerband. The Weber 40's on one of my Fiat Spiders don't smooth out until 4k rpm but then again the cams don't come on until 4.5k rpm so it doesn't really matter. (1.8L w/200 flywheel hp NA) Current FI with fully sequential tuning capabilities easily takes the cake in all ways.

As far as Carl's setup, you overzealous naysayers are forgetting one little thing that you have all mentioned at one point or another. He is not street driven and will only see the harmonics you are referring to once during a run. At higher rpm and longer duty cycles the pulsing is reduced and you have all admitted it. Do you see a car on the salt dropping below 5krpm once it's moving? Oh, wait...none of you have ever actually been on the salt have you? Put it to bed guys, if he burns it down then he burns it down. It's racing, it happens all the time and frequently on the salt. I can only imagine the joy you guys will feel if that happens...

Two years ago I got the chance to help a team from England run their Skoda on the salt for the first time. The smashed the record for their class while barely knowing how. Their first time out and they increased the record by 11mph, turning an average of 227mph with a 2.0L VW based engine and front wheel drive. The things they encountered and overcame are what racing is all about. A local team tried last year to beat their record and failed horribly by bad configuration changes and losing an engine at 200ish due to an oil filter coming off. It happens. At least the local team didn't have a small group of guys in the background cheering the failure like some children on a playground.