bhvrdr

There you can see those particular mods didn't do anything for performance with the slightly better air being during your modded run.

I had the identical experience with the 91eff and ported manifold without any exhaust mods.

Fore58

Actually the air down here in south Florida is somewhat very tricky regardless what you see on the forecast as far as DA. That⁸ can change in an instance without being recorded at the time you are running. Also, you just don't know when the car actually pulls timing. Quite a few variables. If I stand correct, mods work with good air also as opposed to stock. Those time slips are very close to the same DA. The only difference was that 11.29 run was done in much warmer weather conditions. And I have run 11.29@121 in stock form in much cooler air but the DA still around the same. Since that time I could not duplicate that run. But after those few mods the car was able to pull back that 11.29 which was a relief. When I go to the track I compare my car with the other C8s. One young guy had a C8 Z51 best run was 11.60 around 117mph almost every pass.....then another Z51 managed 11.55 around 118. I later spoke with the younger guy. He was trying to figure out why my car was going much faster than him. I eventually told him that my car is slightly modded. He tried again with an ok launch but his result was the same as far as trap speed. All of my runs and theirs are on YouTube. Even my wife said my car is faster. But she doesn't know about the mods, lol.
Having said that I truly believe that those guys would probably be running the same numbers as my car if they if fact had the same mods.

Note: I haven't been to the drag strip after the Halltech Intake installation.

bhvrdr

You always go by density altitude.

There was only a 3 degree Fahrenheit difference in weather both days but your modded run was in more favorable conditions.

You actually have a great comparison there. Your launch was almost identical!

It shows no significant improvement from the mods.


I had those same mods and had identical results as you. No significant difference.


And obviously the human body couldn't feel the difference between .2 mph so always take subjective impressions with a grain of salt. The objective numbers don't lie

64365coupe

My first pass ever in my z51. Ported the intake myself and soler throttle body. That’s it.

Fore58

[QUOTE=64365coupe;1606674391]

Thanks for your confirmation 64365coupe. I actually remembered that run. I guess I will see you again around October.

bhvrdr

What was the da and trap? Yes in good air bone stock cars are going 11.0 at 124.mph. I couldn't do better than 11.1x at 124mph bone stock due to 1.8 60 foot



https://www.corvetteforum.com/forums...-1-4-mile.html

64365coupe

[QUOTE=Fore58;1606674451]yes! Too hot now. I did a lot of work and now have to wait to see what it did. I think milling made the biggest improvement so far. You can actually feel the difference. Will find out in October I guess.

Fore58

Bhvrdr
To the point, myself and my C8 friends are not a bunch of rookies at the drag strip. Been doing this for over 30 years.....cars and motorcycle. I just want to remind you that we very seldom get negative DA down here in south Florida. When we do have even close to negative DA I just can't make it to the track on that particular day. 64365coupe was very happy with his time that he had presented with a time slip.....meaning there were some improvements with the mods that he installed himself on his C8. I was there with him that day. And the youtubes that you have presented is not a comparison to the c8s at Bradenton Motorsport. The real world is to run the C8's at the same track same day. That way DA wont be a factor for all of the C8s. Having said that, the slight improvement to my car is a great satisfaction ......mods work.

bhvrdr

I never said anything about your experience. I said the slips you provided showed no performance improvement from your mods right? That's not in dispute is it?

on your modded run you picked up 24.07mph in the back half. The stock run you picked up 24.63mph in the back half in worse conditions!


You did a great comparison with an almost identical launch!

I did same day controlled condition before and after testing with identical mods and had identical results as you did. Nothing significant

The other person then posted one single slip with no date on it or trap speed so obviously we'd want that information to see if similarly other bone stock cars are running those times in that air. That one video was mine in Palm Beach running 11.1 at 124mph bone stock.

Fore58

Bhvrdr

Are those numbers from a draggy or Palm Beach drag strip? Once again the DA did not make a difference in those two runs. If in fact you keep doing your DA calculation that way my car will be doing 10.50 by the time it's all said and done. There's no negative DA there.....not even close.

bhvrdr

Do you mean the DA was a bit better for your modded run but wouldn't likely have made a statistical difference? I agree. Neither were your runs statistically different right?

And you gained more mph in the back half in your stock run right?

You went from 95.4mph to 120.03mph on the stock run picking up 24.63mph. this was better than your modded run.

But ​​​​​​we're not questioning there was zero significant difference here right? Even if you did a bit better in the back half on your stock run?

Fore58

I have plenty of time slips that records all type of results from the beginning to the end. Sometimes no matter what, the car picks up more at the back half or less. That's just the way it is at the drag strip stock or modded. Like I mentioned before, I have another setup now on my car and it's time to move forward....no need to look back.

bhvrdr

Back half improvement in the 1/4 mile is not "just the way it is". It's an indicator of power in the back half of course where launch is not part of the equation


If you gain more speed in the same distance (1/8 of a mile) it's helpful to know you have more power. You did a bit better stock but again statistically insignificant.

Your slips are awesome objective data showing no improvement from those mods. You actually did better power wise in the back half stock.

Fore58

The mods that I had is going to do that much at the back half. The only way to prove my little point is for you to show me some of your drag strip numbers.....not the draggy. Or you just pay us a visit at Bradenton Motorsport in October. Brooks is now renting our track on certain occasions since Palm Beach is gone. I am a guy of action most of time. If it's going to be an inconvenience to you then I understand. The red c8.....I saw that video almost 2 years ago. So if you are saying that stock is faster than mods, that is fine with me. But I know for fact I didn't waist my money

yell03

I don't think anything more than stock is required to run 11.2 if you get a decent launch z51 or non-z51.
My car is a stock z51 convertible which is heavier than a coupe. I have a AWE Track exhaust, but I doubt that is worth much if any power gains, however it saves about 38lbs.

I only ran one 1/4 mile on the street using my Dragy, it was a 11.48@121.65, but my launch spun, it was a lousy 1.92 60', the 1/8th was a 7.46@97.77.
I ran another 1/8th with a better1.82 60' on the street, still spun a bit, it was a 7.28@97.61. I ran out of room, but that should have been worth a 11.2x@121+ 1/4 mile.

On the street you will never get a 1.6X 60' like you can on a track, but I feel 11.2 is still possible on the street or track.

bhvrdr

That's not the only way to prove your point.

You actually did prove it extremely well. You have slips for it from your own car that show there were no gains. Your 60 foots on those both were within 1 thousandth of a second. You did great showing the data.

And I'd say dragy or vbox acceleration runs on the identical road from 60-130mph would obviously be A LOT more accurate and useful in comparing mods than a drag strip where variables from heat soak, surface prep and launch are going to confound things.

64365coupe

Dragy. 😆 I’m a drag strip guy for actual TRUE results.

yell03

Are you serious...

A prepped drag strip with unlimited traction compared to a Dragy which is giving you the same timing accuracy as the dragstrip, but showing what your car will really run on an unprepped street???
I think you have it backwards.

I have run at ATCO and Englishtown numerous times, waiting hours between runs.

bhvrdr

To accurately compare whether or not aftermarket parts are giving more power you would want to reduce confounding variables not add confounding variables.


I don't think there's any question that dragy and vbox are accurate to the hundredth of a second so now that we have an accurate timing device wed want to standardize runs.

To do this we'd take launch, track prep, lane, etc out of the equation.

you also datalog at the same time to take out other confounding variables like heat soak which happens at the track.


Then you know without a doubt what your car is doing performance wise so when you do go to the actual track you'll know what to expect. Road course track too which is why I run comparison data.


You can do these comparisons using 1/4 mile data by looking at back half (aka big half) improvements in mph to know if the car is making more power.

Obviously if I pick up 24mph in the last 1/8 of a mile versus 26mph on another run the car is making more power on the second run. Your track prep and launch are not confounding there.


Btw what was the date and da for your 11.1x run?

Fore58

Bhvrdr

Never ran a 11.1 at the track. The things that you are experimenting with your car is fine. But I would never do that on the streets. You have made your particular point with variables and calculations. It doesn't take a rocket scientist to know what's going on at the track. With a draggy I have no idea. You just keep on enjoying your experiment with your C8 whether on the track on with your draggy setup.