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traqrat wrote:
That’s only for ECUs with M1.3, as I think that M1.1 doesn’t have learning mode (i.e. not as sophisticated) I am not completely sure on this and will have to look it up to refresh my memory. I was thinking about this and rules while back but completely forgot about it…
Igor
badboypolar wrote:
[quote]Patton wrote:
Acutally you are correct. It is documented that fuel pressure robs horsepower. I personally don’t think that a FPR should be "banned" as people who travel to different tracks at different altitudes may want it to keep it running at a certain spec. And honestly they aren’t really that expensive.
My opinion is that some things like this that don’t really matter, and should be left up to the person if they want to use one or not.
Again I forget that the point of Spec is that all cars remain equal with little difference. I have to remember that.
Thanks.[/quote]
Sounds like the feedback that I received from a race engineer that it appears that increasing the fuel pressure well beyond what the injectors were designed for can actually suppress the spray pattern. Clarification of the above post. I don’t know that fuel pressure robs HP but leaner generally gives more HP at the expense of torque and richer visa-versa. The increase in fuel pressure above resulted in the injectors actually putting out less fuel (a/f ratio dropping) and in some instances would make more HP depending on where you started at with optimal a/f ratio. It’s different for every car.
erupert66 wrote:
[quote]badboypolar wrote:
[quote]Patton wrote:
Acutally you are correct. It is documented that fuel pressure robs horsepower. I personally don’t think that a FPR should be "banned" as people who travel to different tracks at different altitudes may want it to keep it running at a certain spec. And honestly they aren’t really that expensive.
My opinion is that some things like this that don’t really matter, and should be left up to the person if they want to use one or not.
Again I forget that the point of Spec is that all cars remain equal with little difference. I have to remember that.
Thanks.[/quote]
Sounds like the feedback that I received from a race engineer that it appears that increasing the fuel pressure well beyond what the injectors were designed for can actually suppress the spray pattern. Clarification of the above post. I don’t know that fuel pressure robs HP but leaner generally gives more HP at the expense of torque and richer visa-versa. The increase in fuel pressure above resulted in the injectors actually putting out less fuel (a/f ratio dropping) and in some instances would make more HP depending on where you started at with optimal a/f ratio. It’s different for every car.[/quote]
a common mod to an E30 is to swap the injectors to the ford 5.0 injectors. I believe they flow more and have 4 holes to spray rather than 1. I know what the rules say but this could be a tech item to look at.
nasaregistrar wrote:
The injectors that came on my car look just like Accel brand injectors. I know that most Accel brand will work with our year cars. So it is not hard to swap out injectors and not be able to tell. Accel also has different lbs rates so a person could go from 19 to 21, 23, 27, 31 lbs very easily.
Wow, more stuff here than I ever wanted to know.
However, to stop blatant "rules bending" there is always the dyno test. And we all have a great deal of knowledge to correct-before-the-next race, note-in-the-logbook tinkering that is going to occur. I’d better go plug in my trunk light…
The great part about this discussion is that we’re giving Carter, Mike and others good data from which to close rules loopholes.I can only imagine an engine that is being built here in Atlanta that will be pushing the envelope. But, that car is far from being completed.
Now, what is the horsepower specification?
Fire up the dyno and let’s go racing.
Regards, Robert Patton
I just finished my car complete with a new exhaust based upon the rules as published at the first of the year. I would prefer to wait until next year to impose a spec exhaust which I still believe is not necessary. Adjustable fuel pressure regulators are not necessary either just as wide band O2 sensors. If we can’t mess with cams and ECUs, then why mess with the fuel? Just leave the car as stock as possible regarding the engine. The suspension I understand.
Question regarding dynoing for that 6% hp gain.
The engine in my 318is (M42) was overheated and warped the head and pistons. So the machine shop had to clean up the head and took off .007 inch to get the head straight and had to go over .50mm pistons because the pistons where out of spec (.41mm out of spec; piston to cylinder wall). So I’ll have to run an FPR to get the correct fuel rate. However I have NO idea what that might do to my hp figures. And the M42 has adjustable cam gears which can also help gain power which I was planning to utilize.
I am just worried that I will not be allowed to participate if I’m over the 6% hp rule.
jlevie wrote:
This is correct.
I had an A/F ratio meter on a carbureted race car but am not planning to spend the time or money putting one on a stock fuel injected engine.
Carter
badboypolar wrote:
[quote]Question regarding dynoing for that 6% hp gain.
The engine in my 318is (M42) was overheated and warped the head and pistons. So the machine shop had to clean up the head and took off .007 inch to get the head straight and had to go over .50mm pistons because the pistons where out of spec (.41mm out of spec; piston to cylinder wall). So I’ll have to run an FPR to get the correct fuel rate. However I have NO idea what that might do to my hp figures. And the M42 has adjustable cam gears which can also help gain power which I was planning to utilize.
I am just worried that I will not be allowed to participate if I’m over the 6% hp rule.[/quote]
9.3.1.5. Block
9.3.1.5.1. A maximum of .020 (.5mm) overbore is allowed.
9.3.1.5.2. Compression ratio may be changed only within the tolerances affected by resurfacing for trueness and within factory tolerances or as allowed by these regulations.
No one gets a pass on an illegal engine because the engine was junk to start with. If yours is now more than .5mm overbore, it’s illegal.
Carter
Exhaust update:
We are looking at a specific size pipe, specific bends at specific parts of the exhaust, and specific glasspack silencers. We are discussing it with a couple of tuners (for home installation) but any good exhaust shop should be able to do it correctly.
And we will have templates to lay on the pipes to quickly and easily check the cars at impound.
And again, built (old and new) cars will be fine for some time.
Carter
Carter wrote:
[quote]Exhaust update:
And again, built (old and new) cars will be fine for some time.
Carter[/quote]
Good to know since I need to get my exhaust system made next week and I’d hate to have to go out and buy something new again. Any particular reason to do this? There’s only a couple choices on pipes and the rules spec "exit in the stock location" so there’s not a whole lot of options. Basically pipe diameter and choice of muffler. In a totally stock system w/out even a header, I can’t imagine that any of these variables can produce more than a 1-3% delta.
Is that worth worrying about?
Carter wrote:
[quote]
9.3.1.5. Block
9.3.1.5.1. A maximum of .020 (.5mm) overbore is allowed.
9.3.1.5.2. Compression ratio may be changed only within the tolerances affected by resurfacing for trueness and within factory tolerances or as allowed by these regulations.
No one gets a pass on an illegal engine because the engine was junk to start with. If yours is now more than .5mm overbore, it’s illegal.
Carter[/quote]
I fully understand the rules here and am following all the rules to the "T" so that I am 100% legal. If the engine was junk, I would not have used it. But it is rebuildable according to the rules. The overbore is .5mm so I will be okay with that. If this engine goes, I’ll just buy another and start over. I don’t want to be illegal in any area.
I am not trying to bend, push or test any rules. I want to build a car that is legal with no problems. I just want to race with NO problems. So please do not think that I am trying to test any rules.
Above all, I just want to race, fairly and legally, with no problems. That is why I am asking questions, so that I do not run into problems with my build. I also have a very detailed build diary and log of the build with receipts so I can try and avoid problems.
Also with the exhaust, I plan to use a streetable exhaust as I will be using this car at other events other than NASA, some of which require a 92dB compliant exhaust. Which is why I would like to use a regular muffler. Will the exhaust template be flexiable for this? And for those who will be running the 318is that will need to have a different exhaust because of a different engine?
Thanks,
Daniel
Daniel and all:
I want everyone to feel comfortable asking any questions and am glad to hear that you are being so meticulous with your build. It sounds like you will have a well-built car.
When you wrote "…had to go over .50mm pistons…" it read as if you had gone over .50mm pistons, not that you had used .50mm pistons, thus my reply.
Regarding your exhaust questions, yes, the 1.8L engines will have a different spec exhaust than the 2.5L cars. We’re communicating with several tuners and will come up with a program that is in the best interest of the racers, long-term. I appreciate you asking about the noise limitations and giving us more information for this project.
And it’s not just the peak hp or torque numbers that are the concern. It’s where the torque and hp are available. Have a close look at the dyno sheets from Mid Ohio, that are posted in the gallery on this site. The curves are very different and we know that the exhaust is affecting this.
I want my car to be just as fast as the other cars…but no faster than the other cars.
Carter
Carter, if Jim Pantas has his new dyno at CMP I will test the Taxi Cab and let you know the before and after numbers to see if there is a mid-range difference.
Regards, Robert Patton
Carter, I am all for the spec’ing of the pipes, but I’d strongly suggest leaving the mufflers to be free. Some tracks have really asinine sound restrictions and it will only get worse as time goes on. Without proper testing of whatever muffler you propose, it is bound to cause problems.
Mike and I have been discussing the exhaust situation for several days, along with some professional BMW tuners. According to the information we have received from them, the bends, and the positions of the bends, are not as critical for tuning, as is the tube size.
Plus, we have to make sure the exhaust system we choose passes sound regs at every track, in every state.
Therefore, we have decided to keep the existing exhaust rules. During the '07 season, we will do some testing and will revisit this issue late in the season.
While the exhaust is not an expensive part of the car, we want to get it right the first time.
Mike has completed the few and minor changes to the Rules for this season and we should have them posted this weekend.
Carter
How about this one question: will the required exhaust likely be a single or a dual pipe system? If I know that much I have a better chance of building it right the first time.
How about sharing the optimum system with the rest of us. Such as pipe size, number and muffler type. Those of us getting ready to build a system would love to know.
Thanks,
Michael O.
