therm8

Each car is equal because it's a rotary with the same engine management tune. Perhaps not so true of the production version. Otherwise gas mileage wouldn't differ so much from car to car.

Just as many variables at a track as there are on a dyno, the driver being the biggest one. Before and after dynos on the same car, same day, similar conditions, same dyno is about as scientific as you can get in this business short of ripping everything apart and putting it on an engine dyno. It will not say that your car will achieve the same numbers however (since every 8 appears to be a little different), but the gains should be similar.

DARKMAZ8

even still, the different flashes can't account for a 26whp gain. Trap speeds never lie. That's what I want to compare. If that guys car is really 206whp then he will trap over 100mph. If he doesn't than it's a dyno problem.

zoom44

gas mileage is so different from car to car-except for a few exceptions like tstat problems- because of the way the car is driven. period.

DARKMAZ8

Actually in the case of the 8 I would say yes. Drag racing high hp cars is a lot more difficult to be consistent than the 8. Launch the car at 7000rpm and make your shifts. It really is that easy. We're not talkin about a drag car here. Drag racing a 14 second car is not as scientific as you think. just be consistent with your shift points. imo any improvement on your trap speed will be worth documenting.

PoLaK

iTrader: (1)

I'm going to disagree with you there, have you taken the 8 drag racing or are you just talking out the ***? (no rudeness intended) You're talking about tenths maybe even hundreths of a second here, in addtion to track temps and how much sticky stuff is put down, that is no way to conduct any form of testing.

I ran 5 runs before I got 14.5 @ 94.55 all very different times the 4th run was a 14.7, 3rd 14.9 and the others were in the 15's.

DARKMAZ8

I'm talking about comparing trap speed. No, I havn't dragged the 8 on a track yet. I have extensive drag experience with various other cars. what were your trap speeds on your 5 runs?

DARKMAZ8

here's a link to a s4 n/a street port dyno:

http://www.rx7club.com/showthread.ph...05#post4300205

now tell me why the 8's dyno looks like this:

https://www.rx8club.com/showthread.p...highlight=dyno

PoLaK

iTrader: (1)

I only kept the 14.7 and 14.5 timeslips I was pissed about the rest.

14.703 @ 93.90
14.584 @ 94.55

Still man too many variables from a baseline done so long ago, not how you conduct an experiment. When I'm done it all I'll do another run to see but not for product testing.

ILIV48

I was thinking that Racing Beat has done engine Dyno work for Mazda so they will know the real figures for the US spec Renesis.

So in developing the intake they cannot give us all the figures of peak power etc because it may show that the 8 is not making the Mazda stated figures still and this will put racing beat in a spot of bother with Mazda. Especially as there dyno is an engine dyno so the old rolling road dyno excuse of that's at the wheels will not cut it!

Imagine they showed a before and after on the engine dyno with the before showing a figure down on the Mazda claim. Ouch!!!

Still I just ordered my intake, cannot wait until it arrives. :D

murix

DarkMaz8 is making a valid point and I think you are not understanding.

ET reflects traction, shifting, track conditions, experience, etc.

Trap tends to be stable and represent power the car is making. The only way you can really screw it up is if you are a really slow shifter, miss a gear, let off, or bog badly. On any clean run regardless of how bad your et is or 60' the trap should be reasonably consistent within a range.

Me personally, I pretty much take issue with every method of testing as to have certain incosistancies in the automotive industry. Everything is taken with a grain of salt and you make of it what you will.

murix

Try at least making the graphs of similar size before you compare a curve. Try to also verify what level of smoothing has been applied by the dyno operater.

Oh, and it might also help to try and use similar ecu tuning. That might just matter a little.

DARKMAZ8

Go check any other s4-s5 n/a dyno graph and find one that has dips. All the 8 dynos I've seen have significant dips in them. This is uncharacteristic of a rotary. I am a firm believer that the ecu goes into limp mode because the front wheels aren't moving.

PoLaK

iTrader: (1)

Since trap speed is dependant on horsepower, let’s assume that over the entire curve I made about an average of 6.5hp.

Now don't you think since that 14.5 run was done in 90+deg heat with a track temp of 100+ that there could be a difference of more then 6.5hp then trying to run it here in NJ in 70deg weather?

What about the difference in sea levels, and track compounds, general wear on my motor, wear on my clutch, the octane of gas I was using, tire ware, Do you see what im getting at?

This is the whole reason I didn't install the intake and exhaust at home, I knew the gains would be slight to moderate and I didn't want to use a stock baseline which I had from July of last year. I installed the intake on the dyno so that the rear wheels could stay in the same position on the drums, even that could create a variance of 3-5hp.

I'm not saying that a before and after track run would be a bad thing, but alone its just not accurate enough, nor do I have the connections to give me free strip days. I mean 6.5hp would net me what, about 1.5-2MPH trap speed assuming I could make an identical run, Its not easy not launching from 8000rpms.

Limp mode is a myth, but assuming it does exist even that wouldn't matter because it would be a control for the experiment since both intakes would be subject to it.

I've said it time and time again, a dyno doesn't show the exact number your making its useful as a before and after tuning tool and thats it.

DARKMAZ8

^^^Fair enough. I didn't realize that you were at a different sea level before.

PoLaK

iTrader: (1)

Like I said, I always like a **** in the wind, GF sure hates it though.

WinPeP 6 is the version DynoJet told me I need, googled it to no avail, shop owners?

therm8

The dips make sense with the variable length intake runners. When a port opens, it's associated runner is tuned for a higher rpm than the rpm where the port opens. The previous runner length was optimal for the rpm just prior to the new port opening. Therefore the car makes more power just before the port opening versus just after the port opening. Then power builds again to peak at the optimal rpm for the new port's runner length. Add another port, get another dip.

The flatlining at the top of the dyno curves is something else entirely, air starvation, fuel starvation, timing, or some other ecu shenanigans.

zoom44

1st of the dips are from port openings. not limp mode or any such thing.read what he said above^ second the 7dyno is smoothed or you would see more variation also. lastly on 8s that have been tuned with a piggy back those dips are less pronounced because of better air/fuel ratios. the stock tune makes the car go really rich as each port opens so there is less chance of detonation hence the drops in power. the piggyback tuned cars have leaned these spots out a little.

MadDog

^^^ What he said. Its called SDAIS, I believe.

-MD

zoom44

just noticed that 7 also has a piggyback tuning also. and they are all excited by the power number s on this street ported engine. who still believes this engien doesnt make more power than the old ones?

MadDog

Man, I wish I could see the graphs, but honestly, after starting this thread w/o the ability to share them... FOR THE LOVE OF GOD TELL US SOMETHING, POLAK! :D :p

PoLaK

iTrader: (1)

I can tell you that I made about 7-10 horsepower in the mid range 6-7.5rpm and 4.X horsepower peek and the AFR leaned out with the RB intake significantly.

Peek HP coulda been higher but due to the high wheelspeed the dyno gets spiky up around there, lots of up and downing.

But till i can see the graph again I can't get more specific.

dmp

...well, we KNOW it's not 'fuel starvation'... :D

therm8

From what I can tell, the intakes on the low and high power engines are the same, with the exception of the sdais and the vfad. I wonder, with the RB intake making 7-10 hp on the high power engine right where the low power engine peaks, and with the low power engine making slightly more power here than the high power, would the low power maybe see a bit higher gain around 6.5k-7.5k rpm?

zoom44

thats like saying the spare tire is the same as the regular ones except its smaller

therm8

I'm just saying the part that RB changed is the same.