Hymee

iTrader: (1)

I'm posting this information on behalf of Wildcard, who recently transferred to a remote part of this country where there are no speed limits on the open road. Wildcard has limited internet acces, and agreed for me to tell his story.

Before he left for "the territory", there were a couple of mods done to his car. Firstly it had a custom made exhaust: Headers, highflow cat, midpipe etc. All mandrel bent, all custom made from exhaust ports to tips.

The supercharger was removed before the trip, as we knew it wasn't quite ready, and also to the remoteness of Wildcard's posting along with the regions high ambient air temps.

But something else was fitted prior to the trip. We put on a Racing Beat Ram Air Duct.

Apart from all that, and a K&N Panel Filter, everything else was stock.

Wildcard has reported earlier about his problems on the trip - bad fuel economy, serious overheating problems, lack of top end speed. It got that bad that he seriously considered swapping the RX-8 for some Chevy powered V8 muscle.

His top speed he could achieve was only 215km/h or 134MPH.

I had some long serious discussions with him about it. I suggested taking the ram air duct off, and putting the factory VFAD back in. The next thing I know, I got a short email saying "I'm keeping the car!", along with the following picture as an attachment:



Wildcard had infact taken the ram air duct out and put the VFAD back in. The immediate result was his top speed increased by 20km/h to 235km/h or 146MPH.

But one problem remained: the engine wouldn't rev past 7250 RPM. VDI perhaps? Yep, he checked the DVI valve, and the vacuum hose had come off somehow. (VDI being the valve that connects the two long runners "together" for the "variable dynamic intake"). The result: Revved like he remembered it always did, right to redline. Plus he picked up another 5km/h top end speed.

As far as I know, this information has been supplied back to Racing Beat via the sales channels it went through to get here.

I hope you all find this interesting.

Thanks once again to our fearless test pilot!

Cheers,
Hymee.

PS - Fuel consumption had also returned to expected levels.

edit: Removed reference to overheating issue in relation to back to back tests. Overheating was earlier a problem in 40+ deg C ambient temps, but these were not encountered at the time of the test, or since.

rxeightr

I am to assume the RB Ram Air was not fitted with the RevI Intake?

This is an interesting observation. During normal daily driving, my RevI & Ram Air combo nets me ~ .5 mpg better than stock. It appears to have a detrimental effect at autobahn speeds.

olddragger

iTrader: (3)

Too much air?
olddragger

WantedTwo

iTrader: (4)

Kinda hard to see out the wind shield with the hood up.

swoope

iTrader: (5)

what are the ambient temps???

beers

Nemesis8

iTrader: (3)

Was the VDI vac line off the whole time until he saw it was loose? Also, I think the larger REVi intake would have helped. The panel filter drop in does not have the same surface area.

r0tor

iTrader: (1)

hmm... i wonder if he hit the speed for the airflow to choke in the individual ram air runners

rotarenvy

it could make more power with the std filter so the limiting factor was the ram air-duct not the filter.

Mazdastrib

And that has what to do with this thread?

Gomez

That's correct. RB Ram Air with a stock intake.

Gomez

Look again.

That ain't the hood.

It's the inner rim of the steering wheel.

Gomez

Average daytime temp in that neck of the woods exceeds 30Deg C.

Hymee

iTrader: (1)

http://www.bom.gov.au/climate/dwo/ID...8.latest.shtml

About 90F for those blokes using funny numbers

Cheers,
Hymee.

Hymee

iTrader: (1)

Since the size of the panel filter in the RX8 is about 30% bigger than that found in 5.7 Chevy LS1, I have never believed they presented a restriction. Unless they are dirty of course.

Also, when you look at the maths relating to rolling resistance, wind resistance etc, top speed is more or less releated to power in a "cubed" relationship. I.e. A small gain in power is only going to give tiny speed gain, but a large gain in top speed means a substantial power gain has been found. A good read can be found here: http://www.pumaracing.co.uk/topspeed.htm

Cheers,
Hymee.

Gomez

Mostly I provide conversions for them, but sometimes I like to make them work for it, Hymee....

We never see the Yanks post anything on this forum in metric!!!

zaglo6204

ask & you shall receive. maybe.

QBallz

All this really shows is that the VDI is important, which Dyno's have been showing for awhile.

Hymee

iTrader: (1)

We always new the VDI was important. I think you missed 80% of the story.

In some ways I am really amazed at the responses to this post.

Cheers,
Hymee.

Gomez

I was always a little concerned at the amount of the grille area that the RB Ram Air duct took up...if that's what you are alluding to.

A fair amount of air reaches the radiator via the lower opening sub-bumper level though. The overheating that Wildcard experienced could possibly be explained by the fact that the duct is located at the high pressure area on the front of the car. It's at this point that the air splits and goes either under the car, or over the top.

It seems apparent that the opening behind the grille becomes increasingly important to cooling as speeds rise.

Gomez.

Hymee

iTrader: (1)

Gomez,

I'm amazed at the somewhat disbelief posts and even the almost nochalent responses. I guess it was QBallz reply that tipped me to say something. I'm thinking along the lines of what Revolver posted (you know where).

Cheers,
Hymee.

Nemesis8

iTrader: (3)

For more air entering the front grill, why not hollow out the OEM grill diamonds then. I think the wall of plastic is there to only cover up the bumper brace, right?

Japan8

Aww Hymee... you can't just say that and not let know what was posted or point us towards the post.

Temps... they could be a factor or the factor. VDI and SDAIS control... hmm. I wonder what would happen with the stock box and no VFAD or RB Ram air -OR- RB intake and no VFAD or RB Ram air. I'd like to see those results as well...

Hymee

iTrader: (1)

Here is what I eluded to:

https://www.rx8club.com/showpost.php...8&postcount=27

As for the temps being a factor - he re-tested in the same locality. I even posted the weather details for that month so you can see how stable it is.

Cheers,
Hymee.

timbo

MazdaSpeed doesn't offer anything in the induction area, apart from a sports air cleaner. Does that not tell us something?

Hymee

iTrader: (1)

I remember Wildcard "de-blanking" a number of those diamonds, but many of them are there to cover up other non-aesthetic looking things.

Cheers,
Hymee.