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Old 03-11-2014, 08:01 AM   #21
Ed Wright
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

I used an Opti for a while. Not gutted. It can be done with the Opti electronics, although I nener tried it. Some of the Stocker guys are doing that. I now use an MSD dist with cam sync. I didn't find sequential to be the huge HP deal some make it out to be. Still, 5 to 7 hp is worth the effort. I had 2 cyls 9 & 10% lean, the rest were 2 & 3% off.
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Old 03-11-2014, 09:01 AM   #22
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

For reasons David mentioned, believe there is potential with sequential but not necessarily in the range we would assume.
Upper RPMs would be little gain unless all the legwork was done and then it may be minimal for the cost and effort. But consider what we pay for 5 HP..........
The greater benefit should be in low / mid range RPMs getting the car moving and to the 330. When foot-breaking the effort may be worth it making the car easier to drive.
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Old 03-11-2014, 09:12 AM   #23
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

My converter flashes to ~6200, my cylinder- to-cylinder air/fuel imbalance was a little different, but no worse, at 6000 than at 8500.
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Old 03-11-2014, 10:13 AM   #24
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Thanks Nick. I am truly blessed to do what I enjoy for a living.

As for a cam sync on an LT1, there are several ways to accomplish this;
1. Use a distributor body w no cap/rotor, remove seven of the reluctor teeth and use the remaining tooth as a cam position sensor.
2. Use a distributor with a built in cam sync like Ed suggested.
3. You can use the factory Optispark as a cam sync with the following modification- use some metallic tape (the silver, aluminum stuff) and tape over all the slots in the Opti disk. Then, locate a slot in that wheel that will generate a single signal somewhere between 130BTDC and 60BTDC (for a FAST system, not sure about others) poke the tape through this single slot in the wheel. This sounds kind of hokey but it works!
4. Fabricate a custom aluminum wheel that will mount to the Opti shaft and a bracket to hold a pickup.
All of these obviously assume the use of a crank trigger for a crank signal.

To clear the air on the sequential fueling question, I do believe that there is power to be found in properly utilizing Sequential fueling, but it takes specific testing to find this power.
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Old 03-11-2014, 10:40 AM   #25
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Here is a funny story...

When I first ran my LT-1 Stocker....I misunderstood how to enter the firing order when running bank to bank...

I entered the std Chevy F.O.

Engine sounded like a boat and ran worse than one....LOL

I discovered my mistake pretty quickly and moved on....

Was at my local track one day and heard an LT-1 Stocker drive by me and heard the same sound......I went over and asked the owner a few questions and told him I think he made the same mistake....firing order entered was not correct for bank to bank operation.....

I know most people go to a pro for a tune up and it is well worth the time and money to do.......I definitely regret not going that route with my LT-1
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Old 03-11-2014, 02:07 PM   #26
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Don't know how many of you follow the Engine Masters contest but the 3/14 issue of Pop Hot Rod has an article on the engine Jon Kaase won with this year. After reading it I decided I was overdue for a lunch visit so I went to the shop.
The engine was a Ford 409 4valve mod motor. One cool thing was the set of 16 tube headers, but the interesting part of the FI system was the injector location. I am only going to tell what is in the article since I don't know how much of what I was told is public but the injectors are about 1/2 way up the runner and pointing toward the plenum. There were several locations tried but this was what went to the contest. Jon said it was hard to tune and lower rpm was not smooth. I think the dyno runs were from 3500 to 6500 so you can't give up bottom for top end power since they average the numbers over the range. Made over 800 on VP100 but was tuned for 720 at the contest.
Not something that can be done in a Stocker but in Superstock it could be done.
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Old 03-12-2014, 09:10 AM   #27
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Have heard of and read a few articles on this.
Injecting fuel behind the valve may not be the best location for atomization and mixture. Moving injector up the intake runner may allow better fuel distribution in the air stream. Pointing the injector into the air stream would seem to force the issue.
Some high HP engines have two sets of injectors: at the valve and up in the runner.
Has anyone played with direct injection in a HP application?
Sounds like fun.
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Old 03-13-2014, 09:56 PM   #28
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Direct injection is being used this year by the Chevrolet factory teams at LeMans in their GT-1 Corvettes. There is a detailed story about it Engine Technology magazine, a British publication. If anyone's interested, PM me and I'll look for the back issue.

Also, USAC midgets use 4cyl engines with a 23 degree SBC head. They use a nozzle in the intake manifold, and drill a hole from the exhaust side of the head, into the intake port pocket, and call it a "down-nozzle". Every GM powered car in the class seems to do this. Kinzler does the drilling, and provides the the injection system, which looks like old mechanical Hilborns, but are fairly sophisticated electronic controlled units.
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Old 03-14-2014, 07:07 AM   #29
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

I had a sprint car during the 1980s . We all ran down nozzles then. That has been around forever. Was still mechanical back then.
The big deal, we thought, was getting all that methanol out of the intake and port runners, making room for more air. Takes roughly twice the methanol as gasoline, which = less air. The nozzles were aimed to shoot fuel past/under the intake valve when open. Thing about those older mechanical systems, there was no injector pulsing, as with EFI. Constant stream of fuel meant an intake bowl full of fuel when the valve did open.
Brodix, AFR, etc, sold/sell their heads drilled for down nozzles.
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Old 07-14-2014, 10:03 AM   #30
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Default Re: EFI, Alpha-N vs Speed Density fueling Strategies

Quote:
Originally Posted by pbp1 View Post
Jeff Dona runs his SS LT1 Firebird in Speed Density, Open loop and he has run his car in 1.015 to 1.095 correction without changing anything in his tuneup and the actual Air/Fuel ratio never strayed more than 2% from the target Air/Fuel ratio. This allows a racer to focus on other aspects of his race program without worrying about his or her tuneup every time the engine goes from the dyno to the track or from track to track. [/FONT]
I thought Open Loop meant there was no such thing as a target A/F ratio since no correction is present? Basically it's a carburetor, no? What if it is 65 degrees and 500' DA during Stock Q1 and then 80 degrees and 2000' going into E1, wouldn't you have to make some VE changes? My stocker runs Open Loop Speed Density, Sequential fire, and was deadly to the .001 second during Q1 and Q2 but lost 1 tenth in Q3 and another tenth in E1 at the Summernationals because it got hot on Saturday.

I guess what I want to know is what method is the most consistent for bracket racing? Predictable dial-ins? And not having to hook the laptop up before or after every pass to add/subtract fuel or guess on a fuel setting before first round?
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