Has anyone switched from a carb or carbs to the Holly 4500 EFI system. They clam it works just fine on all bracket racing apps and would be more consistent, but I can't find anyone that has done it.
The next question since most of us run leaded race gas, which will kill an O2 sensor, is it feasible or even possible to switch to unleaded? I do believe I could get away with 110, but I run 112 just to make sure. Any input on the leaded vs unleaded race fuel?
Never ran that system, but have had EFI on my race car since 1988. Many different systems, the latest being the new Holley stuff, which has been on there for about 8 years now.
The leaded race fuel will kill the wideband sensors, no doubt about that! The cheaper Bosch sensor usually lasts at least 100 passes, the good NGK sensor easily double that, but the price is also double, so it's a wash.
A good carb is just as consistent as a good EFI tune. Most EFI systems have really good data recording built into them though, and can control fuel and timing without additional boxes.
Again, have never used nor seen that Sniper system, but if it uses the HP EFI ECM, then it should have the same data recording capability as the HP and Dominator ECM systems.
I’ve looked at these and been wondering if it will work with alcohol. Love my carb but still thought about it.
Thanks guys. I am trying to sort out the real deal from all the marketing. It doesn't seem like there have been many pure bracket cars or pipe racks converted. If someone could tell me that it is more consistent, which I think it has the potential to be, then I would try it. All the EFI mfg seem hung up on HP not CFM which confuses me and I haven't found anyone that gets pure built drag cars. I did find out that there is unleaded race gas that should work in a 13:1 motor.
Another question I have that none of the mfg can answer is how a EFT motor follows the weather. If the ECU adjusts the mixture for weather changes, then will a conventional weather prediction be accurate? If I find out anything I think is real, not hype I will be happy to post it if anyone is interested.
I don't think you'd want to run it where it makes its own adjustments. You're introducing variables.
From people I've spoken with, I've gathered that EFI can be really great for consistency on the throttle stop but there aren't significant improvements to be made wide open over a carb or mechanical injection.
The man that can give you all the answers minus the marketing is Tommy Keeter at KPE Racing in Wichita Falls Tx. He has been doing the holly efi for awhile now on blown and aspirated engines and has a deep knowledge of it. He's your man
I'm running one on Q16 in a Super Comp Dragster, so far so good. We got a few races on it last year, we were going rounds in learn mode. I'm no computer guru and I'm in learn mode as well as the efi. The last day of racing there was a shootout right off the trailer and a points race. We didn't win but were in every round all day. We dropped a pushrod in the final and shut off after the launch. (the other car in the final had a Dominator efi on E85) we were having a good time with all the naysayers.
No matter how many times you paint over a shadow it's still there.
There you go. It can certainly be consistent, don't you think.......
As I stated before, been racing with EFI since I bought my car new in 1988. Never ever raced with a carb!
You really can not over-size a throttle body for EFI. Too large can make part-throttle response a PITA, but unlike a carb, you do not need air speed to draw fuel out of the bowls.
I run a 1550cfm TB on my 750ish SBC, it can be larger, I do draw a slight vacuum at the top of the gear, but since I slow it down for 10.00 Index Racing a lot, I don't need any more power. When I put a restrictor plate on it it really draws a vacuum!
Do not be concerned with leaded race fuel and the wideband sensor. Keep a spare, they are pretty cheap. Cheaper than running the wrong fuel for your engine and hurting it!
I do not run in closed loop, I do not want it to try to make changes, that is what shoe polish is for. If you run closed loop, limit it's range so it can't screw with the power too much.
As far as closed vs open loop: My intention is to use closed loop for as long as it takes to get my tune correct. It certainly makes the process quicker. Then start taking control away from it until it has none. I may find that letting it make changes (small ones) is beneficial for being able to predict what the weather does. But I don't trust it that much currently. Plus, if you ever have a sensor start going south, it can cost you a round or worse if you are giving it a bunch of control. We will see.
Foxtrot Juliet Bravo
What fuel pump are you using with it?
How much fuel pressure does it have to have?
So in speaking with vendors, some of which don’t have a clue, and most not completely knowledgeable of how Pro/Super Pro racers set up their cars, here is what I have found out to be some of the hurdles.
If you are running a SLE, or even going up against the chip before launch, and you are running closed loop, when it hits the chip is will of course dump unburned fuel into the exhaust system. This makes the system think it is lean, (don’t ask me why, but that is what they all say happens) so it will add fuel. When you launch you will be rich. To negate that you could be in open loop until a specified RPM, say you launch at 4500, you could be in open loop until 4700 and then it goes into closed loop assuming you don’t drop below that at the shift. That sounds reasonable, but most vendors don’t know if that will really work and are afraid of it. I would assume you would have to develop a good enough open loop tune to get you on the converter.
One vendor I spoke with did understand using prediction software and how running open loop vs. closed loop would change the scale of the weather prediction software. However, they had no actual experience and couldn’t really tell me how much. I assume as many suggest, once you get your tune, you could run open loop and the car would react just like any other with weather prediction. Sounds reasonable, but if you have a good carb, and tune, isn’t it doing the same thing, and what would you gain? But it seems to me if you could run closed loop and always be on your target stoichiometric (AFR) value of the consistency/weather scale would be way smaller, hence the car could almost be running the same number all the time.
Then there is the fuel thing. Leaded fuel will kill O2 sensors. In talking with the Sonoco fuel guys they say if you are going to run leaded fuel, have an O2 sensor that you know is giving correct readings, pull it out, keep it in the trailer as a base line, save that base line tune so you can load it back in if you kill a sensor, and have two spares in the trailer. If you are running 112 or 110 Sonoco believes that their 260 GT Plus unleaded would work in a car approaching 14 to 1. But, again, they are not sure.
Is seems like this has lots of potential but there doesn’t seem to be anyone out there (vendor wise) that has enough experience to give me confidence. It seems like lots of trouble and expense for perhaps a season of headaches.
You are talking to the wrong people!
First of all, any decent EFI system will automatically drop out of closed loop once you hit a 2-step. You have NO control over that! If these "vendors" don't know that, you must be calling Summit or Jegs...........
Second, if you are trying to run your engine at Stoichiometric, you WILL be buying new pistons OFTEN!
Talk to people that actually know what they are doing, not BS you read on the internet!
Leaded fuel WILL kill wideband sensors, as I already stated, but that is just part of the cost of racing. You do not need a wideband sensor after the engine is tuned. People with a Racepak suffer the same issues with their wideband sensors, they don't stop racing when the sensor pukes do they?
There are many reasons to use EFI, but if you aren't up to the challenge and can't afford to pay someone to set it up and teach you, stick with a carb, you will be happier.
Pretty sure Pat Mcreary at Nyes Racing Engines in Muncie Indiana is running one on one of his cars.
The two step thing just isn't a problem with most decent systems. I can address it in my software if needed, which it hasn't been yet. Of course mine is popping and banging for other expected reasons I won't get into. LOL.
Don't sweat the open vs closed. It is most helpful to get you to your tune. Don R has been running it successfully and going rounds in closed loop. Your prediction software will go off of your history that you feed it. It's just a little different. The thing that concerns me is when an O2 sensor starts to go, is that going to cost you a round? So a lot of efi guys will only run closed until you zero in on a tune, and then go open at least while you are seeing similar weather. Sounds reasonable to me. But I would advise you do not try to talk prediction software with the efi guys. Most of them don't know nor care. If you ruin a sensor, you can always run in open, which you may be at that point anyhow. No sweat.
There is a bit of a learning curve to efi. I'm still learning steeply unfortunately. Some software is much more beginner friendly. The Holley deal sure is nice with the bolt on and not having to deal with welding in bungs for injectors on your intake etc. It's mostly contained, and the one that I have witnessed running was up and going really quickly. To be fair he was getting help from a really smart guy too though. So we all know it wasn't me helping! LOL. I just changed injectors and fuel pump, so I am lost all over again!
Foxtrot Juliet Bravo
Mike - Thanks, I wasn't talking to Summit or Jegs but to a couple of the larger vendors that come up on a Google search. So if Stoichiometric isn't a target, then what is? You are also right about sticking with the carb, I have a good set up but always looking for ways to improve if possible. Hopefully I can find someone that knows their stuff. Don't mind paying for the correct info, in fact, I would prefer the extra expense for it to be right. Thanks for the advice.
Typically .80 to .85 of the Stoich value of the fuel you are using is the "correct" A/F to target. Usually the higher the octane of the fuel, the higher the Stoich value, and the leaner you will run the engine for best power. Running your engine at Stoich at full throttle though is not going to produce best power, it will produce less power, more heat by being too lean, and probably detonation. A Stoich value is simply the "perfect" A/F ratio to run in which ALL the fuel will be burned completely. That is good for emissions, but not for power! All manufactures will publish their Stoich values.
For Sunoco 112 (Supreme, or Blue) my A/F target is 13.3. Sunoco states their Stoich value for Supreme is 15 which would mean to run it on the rich side for best power you should run it around 12.75 A/F. My engine didn't like that too much and runs best between 13.0 and 13.3 A/F. I run Sunoco Maximal between 13.5 and 13.8 A/F.
Don't be afraid of EFI, but if you know nothing about it see what people around you are using. If the few people using it are running Big Stuff, you may want to lean in that direction. If they are using Holley, then that's great! It is one of the easiest systems to use and you will find PLENTY of help on the Internet. They are all similar though, and anyone decent with EFI can learn a new one pretty quickly.
Thanks for the tip. I spoke with Pat and he is running one on his car and his daughters car. He seems to know what he is talking about. He spent a good amount of time on the phone with me and answered all the questions I had. I am now starting to believe that this is very doable and really not that big a deal. I am going to download the Holly software and play with it for a bit just like I did with the Grid and when I become comfortable with all the terminology I think I am going to try this.
I'm using the Holley dual pump at 60 psi running both sides full time on a bypass regulator. Needing another pump, regulator and if you have a racepak the 15 lb.sender isn't usable adds to the cost.
And I'm the last guy that should be using one (tech wise) but if I can do it, you can too.
No matter how many times you paint over a shadow it's still there.
I run the Holley dominator setup on my car. I run it in alpha n mode. It just uses throttle position and rpm. I ran speed density at first but found it hard to tune with the big cam and inconsistent vacuum. Learn allows the computer to make changes to your base map but you have to transfer them to make them permanent. You want to turn that off as soon as you can. I have the closed loop % turned down. With what we do I think it is best to limit what it can do.
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