Common sense backs it up. I can’t believe all of this searching around for the right ECU BS. If the car makes 168 hp at the flywheel stock then it will make any where from 142 to 152 at the rear wheels depending on the dyno, day, etc. The rule of thumb for every dyno shop I have ever been to is around 15% loss for drive train drag. I thought this was going to be a fun class to race in with bascially stock cars. All of this talk of tweaking the ECU, over writing it, fuel pressure regulators ad nausea is taking the spirit out of this class for me. Protesting missing covers behind the headlights stuff is ridiculous. I’d be more worried about welded diffs which is legal and more expensive than whether a little air was getting through the headlights to the air filter producing maybe a half a horsepower. Big deal.
Dyno Runs At VIR
What is up with all this ECU stuff? According to the math, a car with 205/50/15 tires, 3.73 diff, and a 6500RPM limit will only go 120 MPH anyway. That seems to be what most people are running. Once again, anybody going much faster than that is cheating.
Even if the cars are limited to a certain top speed, that’s not really a factor in a race. We spend very little time at top speed. What’s important is how quickly the cars gets to the top speed, or to any speed.
We will have more and new tech checks at Summit Point this month and the names and numbers will be shared with the group.
Carter
Proeagles wrote:
That’s in 4th gear. With overdrive you can go over 120. One of the SE racers (at least) as experienced the limiter at Road Atlanta (and maybe elsewhere).
Proeagles, I’m not going to say whether someone is legal or not, but it is fairly commonly accepted that factory hp numbers are not always right. Plus, they are an average of many motors; if you have a good one and you build a motor that maximizes everything, you will get a little more power. That coupled with a dyno that gives strong numbers, maybe it could happen. I don’t know. I also don’t know you from Adam or whether you’re racing, but at the track I don’t think you’ll find these issues. This is internet discussion talking about what we need to watch for. Patton is simply pointing out what people can do; what we need to keep an eye on.
Carter, I agree top speed limiters won’t affect lap times much, but try making a pass into 10a at Road Atlanta when you lose your juice at the black flag station. I have not experienced this personally, but it’s not hard to imagine someone driving away as you pull out of the draft for a move.
JM3$W
I am gonna have to chime in here because I do have experience building m20 motors, I have been involved with several kp motors and ITS motors , Let’s get one thing straight 164 hp or 160 at the wheels is NOT easily accomplished! The highest whp ITS motor I have ever heard of was 168, and that motor would never be legal for spec 30, Hell it was probbally barely legal for its. Your average kp motor with a mild cam and headers are struggling to put 160ish at the wheels.
I will be watching this issue closely , I would love to build some motors for you guys!
B digel GTS 3 black and blue #112
Proeagles wrote:
Proeagles, You are obviously more knowledgeable than I am about the gain one may experience with a missing headlight cover and a ram air intake fabricated to take advantage of said air. My point is, this is not a legal modification. The benefit of it is irrelevant. I choose not to protest anyone at RA and probably never will. I need to keep reminding myself this is supposed to be fun and relationships are more important than a $9.00 trophy.
Proeagles wrote:
Proeagles, You are obviously more knowledgeable than I am about the gain one may experience with a missing headlight cover and a ram air intake fabricated to take advantage of said air. My point is, this is not a legal modification. The benefit of it is irrelevant. I choose not to protest anyone at RA and probably never will. I need to keep reminding myself this is supposed to be fun and relationships are more important than a $9.00 trophy.
mskeen wrote:
[quote]Proeagles wrote:
That’s in 4th gear. With overdrive you can go over 120. One of the SE racers (at least) as experienced the limiter at Road Atlanta (and maybe elsewhere).
Proeagles, I’m not going to say whether someone is legal or not, but it is fairly commonly accepted that factory hp numbers are not always right. Plus, they are an average of many motors; if you have a good one and you build a motor that maximizes everything, you will get a little more power. That coupled with a dyno that gives strong numbers, maybe it could happen. I don’t know. I also don’t know you from Adam or whether you’re racing, but at the track I don’t think you’ll find these issues. This is internet discussion talking about what we need to watch for. Patton is simply pointing out what people can do; what we need to keep an eye on.
Carter, I agree top speed limiters won’t affect lap times much, but try making a pass into 10a at Road Atlanta when you lose your juice at the black flag station. I have not experienced this personally, but it’s not hard to imagine someone driving away as you pull out of the draft for a move.
JM3$W[/quote]
Michael:
I didn’t write my post correctly. I wasn’t trying to say that a top speed limiter isn’t important, my point is that pure, unlimited top speed is not a significant issue because the straights are not very long.
If someone has an ECU that has an electronic top speed limiter, and he swaps it with a stock/unmodified in any way ECU that doesn’t have that limiter, he will never be DQ’d by an official.
Carter
Mean while, back at the ranch…
Did anyone figure out what the problem is with the loss of HP? My dyno results are about like Carter’s. Perhaps even a little more extreme. I am trying a rebuilt AFM this weekend to see if there is a difference.
Mean while, back at the ranch…
Did anyone figure out what the problem is with the loss of HP? My dyno results are about like Carter’s. Perhaps even a little more extreme. I am trying a rebuilt AFM this weekend to see if there is a difference.
Carter wrote:
I did write my post correctly. I wasn’t trying to say that a top speed limiter isn’t important, my point is that pure, unlimited top speed is not a significant issue because the straights are not very long.
If someone has an ECU that has an electronic top speed limiter, and he swaps it with a stock/unmodified in any way ECU that doesn’t have that limiter, he will never be DQ’d by an official.
Carter[/quote]
At a track like VIR, if you’re competing for a top spot, having an ECU that limits your top speed is going to be a significant issue, and will guarantee that you will not finish on the podium.
I think Robert has a valid point that should be explored. I’ll throw in my experience, and give away one of my nuggets: You need a non-limiting ECU (like a 153 or a 173) to win.
Carter: Glad to hear your ruling on ECU’s - that’s the right call in my opinion!
-Vic
P.S. I’m selling a 153 ECU on ebay if anyone needs one.
I thought the older BMW 5 speed transmissions were 1:1 in 5th gear which is what I based the calculation on. I don’t have my manual handy and so I can’t verify that for the E30 cars. Does anyone know what the actual 5th ratio is off hand?
Proeagles wrote:
5th gear ratio on Getrag 260 is 0.81 . If you scroll down on this e30 specs page to the Manual tranny ratios section you can see other gear ratios as well (and other bmw e30 specs as well)
p.s. just saw that Michael already gave you an answer
That makes a huge difference obviously. I doubt that a 325 brick can pull 6500 rpm in 5th gear on most tracks all the way to 145+mph. I would love to try it however. I have never raced at a track with straights longer than Mid Ohio, Texas Motor Speedway, and Road Atlanta. My E36 325 JP cars would red line at those tracks in 5th gear with a 3:73 diff which worked out to something in the 135 mph range with my tire combination. My current Spec E30 car hasn’t even been into 5th gear yet at the two tracks around here (MAM and Iowa).
Proeagles wrote:
I agree. If a spec e30 car is hitting 145mph on any track in North America there is one word thatmust be uttered. Protest.
FWIW, from my G2X data logger which is GPS based, the fastest I have gone in my car was 122 at Reobling and 120 at VIR. As far as I know I do not have one of the speed limiting ECU’s in my 1990 325i.
I do believe that any one of the front running racers in SE30 would be at a disadvantage if they had a top speed limit of 120. For me, it is most likely a lack of experience and maybe a weak motor that makes me slower, not the ECU.
I know speedos can be wrong, but I’ve seen an indicated 127 mph on the back stretch at VIR. I’m far from fast, so I imagine others are seeing the same or higher.
Sasha
screwynewy wrote:
[quote]FWIW, from my G2X data logger which is GPS based, the fastest I have gone in my car was 122 at Reobling and 120 at VIR. As far as I know I do not have one of the speed limiting ECU’s in my 1990 325i.
I do believe that any one of the front running racers in SE30 would be at a disadvantage if they had a top speed limit of 120. For me, it is most likely a lack of experience and maybe a weak motor that makes me slower, not the ECU.[/quote]Ken,
My 90 has the 525 ECU
nasaregistrar wrote:
[quote]screwynewy wrote:
[quote]FWIW, from my G2X data logger which is GPS based, the fastest I have gone in my car was 122 at Reobling and 120 at VIR. As far as I know I do not have one of the speed limiting ECU’s in my 1990 325i.
I do believe that any one of the front running racers in SE30 would be at a disadvantage if they had a top speed limit of 120. For me, it is most likely a lack of experience and maybe a weak motor that makes me slower, not the ECU.[/quote]Ken,
My 90 has the 525 ECU[/quote]
Thanks for letting me know. I guess I should take a look and see what I have. I assume the 525 ECU has a speed limiter program in it?