Well, it's not the fuel pump.

OK, maybe not the fuel pump. I also have an underdrive pulley. I'm just thinking that my numbers aren't really any better than Matt's considering the additional mods.

I assume Mike has the Weather station module or whatever for his dyno, or that could be it as well. It was damn near freezing when we ran my car.

I am just trying to understand the numbers if possible. Maybe we will never know, but thought it might be worth discussion. :P

I think a street race is in order.

Dyno numbers are good for comparing before and after mods on the same car when all other factors are constant. Comparing between cars, because of many different factors, is asinine and pointless.

IBI'llstreeraceyoutodeath.

That's how I solve all my issues :lol:


Dean, like Scott said I do have the same Fuel pump, so it's not that, nor can we blame it on the color. Also, I am catless with Gruppe-s headers.

It was very cool when we ran my car....like 55 degrees, and I also had my 18"x 8" Rotas with meaty Falkens on. :cool: That could be a big part of it.

That was my point, not that the fuel pump doesn't make a difference. I actually thing the fuel pump is a great idea, as it makes the car safer if nothing else. Cheap insurance against running lean.

And I agree with Aaron, we can't really compare, but that doesn't stop us from doing so. ;)

And I was just wondering if any of my other mods might be contributers to my numbers? I've always heard that rotating mass affects real world HP and torque numbers. (flywheel, clutch, underdrive, wheels/tires)

Colder plugs are supposed reduce detonation(?) and thus allow more power to be made???

Mike said something about the fuel pump increased pressure allowed for lower injector duty cycles...

I was just throwing those things around as possible discussion points as to whether they or the weather might impact dyno numbers.

All our cars Rock.

I devoured many Audis, Porsches, a Lotus and a race car or two at Thunderhill, and am still hungry. I want my DMSes back from Oh-Canada... :)

Exactly. "Stage 2" and up can benefit from one step colder, especially before tuning, as I understand it.

Dean...

Your tire: 235/40/17 = 24.4" diameter or 225/45/17 = 25.0" diameter

Matt's tire: 245/40/18 = 25.7" diameter

Matt's car probably makes more hp and torque than yours based on the tire gearing difference alone, nevermind the loss from turning 28lb 18" wheels.

Yes, Dean, rotating mass and tire gearing both make a difference in at-the-wheels power. The pulley is practical negligible, the flywheel makes a difference, the wheels really help, and the tire size gets you another 5% or so torque to the ground compared to Matt.

Oh, and "colder" plugs really are physically colder under hard conditions. They absorb less heat from the combustion cycle, which makes them less hot when that cylinder is on the intake or compression stroke, and they cause less pre-ignition. The downside is they foul more when you aren't getting high EGTs. Tuners pretty much universally think that's a good tradeoff, as long as you aren't fouling them so bad you get misfires when you do go WOT again.

225/45-17s actually. Stockers with street tires were on. So no gearing advantage to speak of.

nos.

You still had shorter, lighter wheels/tires than Matt, just not as much as 235/40s would be.

If the effective gearing changes that are due to the tire diameter changes the horsepower that a dyno reads, then the dyno is not very good at reading horsepower. Actually dynos do not measure horsepower anyway - hp is just a calculated number based on torque and rpm. The dyno reads torque and rpm and then calculates hp from those two inputs. There should be a place to enter the tire diameter in the dyno's computer so that the difference in effective gearing does not change the hp, because changes in gearing just do not change horsepower (except in more extreme cases where the frictional losses change).

Also as far as rotating mass is concerned, if the car accelerates slow enough while it's on the dyno, the mass becomes a negligible factor. The faster the car accelerates on the dyno the more the mass will make a difference in the WHP. If a load-based dyno holds the car at a certain RPM and reads torque then the mass makes no difference.

Because of these and other factors, such as run-to-run variability in dynos and automobiles in general, it is silly to speculate about small differences in two diffent cars' HP as measured on a dyno. The dyno is a tool for tuning and should be used with extreme caution during bench racing.

I doubt Mike said this, because it's not true. The pressure regulator on the fuel rail determines pressure at the injectors, not the fuel pump. The only way a fuel pump becomes a factor is when it runs out of flow capacity, then the rail pressure will drop, and then bad things start to happen.

Speaking of Fuel rails. When depending on mods should they be installed on a wrx?

I've never seen a tuner that calculates and enters tire diameter on a dyno per run. I'm willing to bet Matt and Dean were dyno'd with the same settings.

Furthermore, dyno's are easily +/-5hp from run to run, let alone from car to car on different days. i.e. It's ridiculous for Dean to be trying to figure out why he made more hp than Matt. My post regarding the tire sizes was an attempt to demonstrate that Dean's speculating on things that probably make no repeatably observable difference, while he's ignoring things that are known to have more of an effect on numbers.

In reality, I would say anything +/-20hp on a dyno is pretty much similar enough to write off as "the same". On the track the faster car between Matt and Dean will be based on the driver, not the dyno'd hp. Trying to figure out vf39 vs. vf43 based on the data in this thread is a waste of time. According to the data and the margin of error involved, the turbos are equivalent. Same goes with all the rest of the differences between Dean and Matt's cars.

When/if you hit 450awhp, then you might need fuel rails. The factory design is pretty damn good on our cars. Don't buy the stuff you might hear/read about certain cylinders going lean due to the fuel rails. There are plenty of people maxing out 800+cc fuel injectors on the stock rails.

I think you and I are agreeing here, but I came at it in a different way.

With statistical analysis you could detect small changes or differences, but the sampling size would be large - maybe like dyno'ing both cars 10 or 20 times.

The best practical measure of "real-world" horsepower at the wheels is to run the car on the dragstrip several times and watch the trap speed (not the ET). Trap speed is a good indicator of HP because the gearing, tires, and a relatively competent driver have little to do with it, but power does. Here again though, it takes a sample size of maybe 10-20 runs to see small changes.

So what I am hearing is that I need more stickers to have more HP than Matt. :rolleyes:

Exactly^ NOW POST THAT FOOTAGE OF THUNDERHILL!!!!!!!!!!!!

Just out of curiosity.... Did Mike measure the RPM at the engine or did he just use wheel speed? If wheel speed is used to determine engine RPM was it modified for each car or just left at some generic multiplier/ratio?

You can't leave it measured off of the roller speed for different cars, that would not work and would give some funny readings.

All cars are setup on the dyno, rolled, restrapped, rolled again than set at 3k in the gear being used to dyno in.

We do not use any weather correction, tried it once found the results to variable to uninstalled the contraption and threw it away. Our Mustang is configured off of one setting so cold weather will come into play as will hot weather (like real world, cars with cooler air make more power).

I hope this helps somewhat, personally I think the headers, uppipe and turbo are the differences.

Mike

So who has the biggest hp car on here...???? I bet i have yo beat as of this last monday....

Did you look at the first post, it's been updated recently.

There are very few people on this site that are into big numbers or quarter mile times. We've seen 110hp Miatas blow 600+whp Vipers away at the track... numbers are meaningless unless you've got the complete package to put it to the ground and around the corners.

That said, what are you running?

Biggest part of the package = Driver!

So what do you have? Bring it by and we can dyno it for you.

Mike

Well that said, i have multiple tunes for track and strip, pump gas and race gas... anyways what are the biggest numbers you,ve seen on here so far??

703whp on a AWD car at the moment on the cars previous tune at 640whp it ran 138mph trap.

Mike

DAYUM!!!!

was that a subaru??? or an evo maybe?? i checked out a couple 700 horse subarus this weekend pretty wicked high dollar builds...

What are your numbers, hoss?
This club tends towards road course, so dyno queens don't mean much except that a big check was written.

The wagon will go back onto the dyno after a fuel pump. Then maybe I'll finally have something to post on this thread.

This thread is not about who has the most really. It is more about tracking upgrades and for reference. Tyson and my basically "stock" WRX numbers are up here. So if you got something, feel free to post it.

Still waiting to hear what you have.

The car put down $$$HP/$$$tq the %%%was at 6300rpm....i can also say that all work was done by me in my garage...i dont believe in taking your car to someone and writing a BIG CHECK as someone on here said about me....so for an independently owned car thats not to bad for now...

No one said that specifically about you... they said that anyone can get big ass numbers by just paying for them, which is why big numbers aren't the end-all measuring stick for performance. There are plenty of slow cars with big numbers, and plenty of fast cars with small numbers.

How about sharing what you've done, where you dyno'd, how you tuned it, etc. Hell, you haven't even mentioned what car you have. If that 500+/500+ is on a C6 Z06, it looks like all you did was an intake and exhaust. ;)

I wish I had a dyno in my garage. That would be cool!

Except for all the motorheads constantly at your house trying to get some high-altitude maps dialed in. :lol:

Sounds like a great way to make enemies of your neighbors!!

Which dyno?

the car is a 05 sti....it was a dynojet roller dyno...tuning was done in socal

To reintegrate, come on guy tell us what you've got.

Dynojets read significantly higher than the GST dyno.

I think you mean reiterate and didn't he tell you what he has?

Mod list or BAN!!! :P

Nope, he still hasn't. He's claimed HP and told us it was on a Dynojet. I can ride a bicycle on a Dynojet and get 50 HP (53hp if I eat Mexican beforehand)

On a completely unrelated note (riiiiight), e-dick-swinging with dyno numbers is retarded. Have fun ripping off "killer 60 foots", and having a 1000 RPM powerband, that's what your rally-derived car was designed to do..... :rolleyes: :rolleyes:

It's obvious by your screen name and first few posts that you expect us to be impressed...sorry about that.

Who did the tuning down south, HM or Brainstorm or........?

Hey their is no reason to talk shit on me.....I in no way did on anyone else on here...Is this not a thread Called dyno numbers???? I posted what my car put down, so its automatic everyone doesnt believe me on a 500+ number....I guess thats what i get for talking to guys who race angainst cones for fun?? And Sybir quit trying to be such an E_THUG..