L28 Dyno run after new exhaust

[Whittie]

 

The dotted lines are from the last tune, the only difference this time was the exhaust!!

 

Went from a stock header 2.25" system to mandrel 6-2-1 tuned length extractors and a 2.5" highflow exhaust

 

Power is not that massive but the torque is HUGE, pulls like nothing else!

 

Here is a bit of a write up about the car now its finished, including spec list and some pics:

 

http://forums.hybridz.org/showthread.php?t=141631

 

**EDIT**

Just for clarification, this is wheel numbers, not flywheel as i know the graph says

[ktm]

How can the new torque and HP numbers cross at one RPM and the old numbers cross at a different RPM? They both should cross at the same RPM.

[Whittie]

Should they?

 

Why is that?

[ktm]

Unless I am missing something, torque and horsepower when plotted on the same vertical scale must cross at 5250. Things get a little odd when torque is on one scale and horsepower another.

 

Saying that, your original curves are plotted on the same vertical scales as your revised curves. Torque and horsepower for both runs should cross at the same RPM if the scales are the same.

 

Notice that on your latest run the curves cross damn close to 5250. Converting Nm to ft-lbs indicates that your torque and hp are on the same scale. On your latest run, the curves cross at 5250, at ~167 hp and ~ 167 ft-lbs (227 Nm).

[JIM73240Z]

yep. something is amiss. torque and hp ALWAYS cross at 5250. it is a math thing.

 

jimbo

[ozconnection]

I'm happy for you that you found increases in midrange torque. That really makes the car 'fun to drive' and really responsive to your right foot. Well done on your upgrade.

 

Those torque curves look a little erratic IMO. I had graphs that looked like that when there was wheelspin on the chassis dyno. It's just so difficult to interpret curves that look like that and what to tune/correct with engine calibration to 'smooth' things out a little.

 

Post some sounds from your tailpipe here so we can have a listen please. Better still, strap a small one to the arse of the car and take it for a spin so we can listen to it properly 'winding up under load'

 

Cheers mate.

[datsun723]

is your L28 stock otherwise?

[Whittie]

here is an incar vid of last weekend. So obviously before the tune, but still with the new exhaust.

 

After the tune it sounds much deeper but otherwise very similar.

 

and no the zed is not stock

 

L28, 60 thou over bore, flat top pistons, shaved deck and head, head port, triple 45 webers etc etc. read the link i posted to my write up and just scroll down for the full list

 

http://au.youtube.com/watch?v=CJn4M5SktwY

[PalmettoZ]

here is an incar vid of last weekend. So obviously before the tune, but still with the new exhaust.

 

After the tune it sounds much deeper but otherwise very similar.

 

and no the zed is not stock

 

L28, 60 thou over bore, flat top pistons, shaved deck and head, head port, triple 45 webers etc etc. read the link i posted to my write up and just scroll down for the full list

 

http://au.youtube.com/watch?v=CJn4M5SktwY

 

 

Hey Whittie-

Good driving skills, you worked your way right to the front there. How did you end up ? Car sounds really good too.

[TimZ]

Unless I am missing something, torque and horsepower when plotted on the same vertical scale must cross at 5250. Things get a little odd when torque is on one scale and horsepower another.

 

Saying that, your original curves are plotted on the same vertical scales as your revised curves. Torque and horsepower for both runs should cross at the same RPM if the scales are the same.

 

Notice that on your latest run the curves cross damn close to 5250. Converting Nm to ft-lbs indicates that your torque and hp are on the same scale. On your latest run, the curves cross at 5250, at ~167 hp and ~ 167 ft-lbs (227 Nm).

 

You're almost there - the 5250 thing is a conversion specifically for torque in lb-ft and horsepower. If you convert both torque plots to lb-ft then you will find that they do have the same value for hp and torque (in lb-ft) at 5250.

[ktm]

Duh. The 5250 is specific to torque in ft-lbs and power in horsepower. Thanks Tim.

[Whittie]

Hey Whittie-

Good driving skills, you worked your way right to the front there. How did you end up ? Car sounds really good too.

 

Cheers

 

Well the event was regularity. The aim of the game is to post a time and then repeatedly do that time over and over. You score 1 point for every 1/100th of a second you are away from that time, lowest points at the end of the day wins. So, in terms of regularity, I lost

 

But in terms of what counts: Fastest Z (of 8 on the day) and 3rd fastest in the field behind an evo 9 and my old mans TT supra

[Globerunner513]

That sounds like a endurance racer i talked with. He told his team that who ever posted the fastest lap time of the day had to buy dinner for the whole crew. Basically ensuring that they endured, first and foremost. Interesting concept.

[Whittie]

Globerunner, that is exactly what regularity is about.

 

However, within our field of about 8 z's we have a tendancy to take things a little serious basically its the only way to race in a pack without a full race licence and log-booked car.

 

So for me and the other zed boys we take it as a chance to just have a bit of fun and none of us take it too seriously in terms of regularity or fastest time, just as a good way to race with people we respect as drivers.

 

When i want to go fast i go to sprint days. Infact i have a sprint event tomorrow so it might be a chance to see if i can go one better than last time. I will be sharing drives with my dad and we will be swapping cars so i wont get a super fast time in 1 run. I will however be able to truely guage how much faster the car is now than it was

[zxtman]

FYI ... just so that we all know, the exact number is 5252

[Sideways]

How can the new torque and HP numbers cross at one RPM and the old numbers cross at a different RPM? They both should cross at the same RPM.

 

I know im late on this and maybe its been answered by now (though i did see a couple others asking), but check the scales.

 

Hp is on the left, torque is on the right. They are set to different scales.

[katman]

Uh, 30+ ft-lbs increase with just an exhaust system change? That don't pass the giggle test. You have a 'tater stuck in the pipes of the old system?

[Sideways]

I see a 20 pound increase, fwiw.

[fhptom]

When I do my DE events consistent lap times are the only thing to gauge whether or not you are hitting your marks every time. I like the concept alot and it gives you a goal when you are out there with cars of much greater HP and cannot keep up in there pack.

 

Tom

 

Good video of some nice Z cars also.

[TimZ]

Uh, 30+ ft-lbs increase with just an exhaust system change? That don't pass the giggle test. You have a 'tater stuck in the pipes of the old system?

 

Look again - the graph is in Newton-Meters, not lb-ft.

 

20Nm is about 14.7 lb-ft.