MFI type T.B.’s & Motronic

[duckmcf]

Hi Everyone,
I was just wondering if anyone’s experimented with individual throttle bodies on a 3.2 Carrera (Motronic), perhaps with something like the Bosch HFM5 Mass Air Flow System that’s on http://www.911chips.com/HFM1.htm and a pair of S cams....

I must admit that I’m not thinking of going down this path, it’s really just a thought that’s struck me while doing research for my first 911. I guess Mr. Anderson’s book is getting my brain ticking over with a lumpy idle... ;-)

[village idiot]

$2700.00 Holy Cow!!! similar items can be bought for far less. Split Second sells universal kits for a third of that, although you don't get the cute carbon fiber airbox.http://www.splitsec.com/

[duckmcf]

Yes,
On the surafce it appears a bit steep, but given that it's a bolt in part made of carbon fibre with a BMW M3 spec MAF sensor it's probably about right....

[PorscheGuy79]

It may or may not be priced right but regardless the real questions is if these things give as much or any significant gain over stock. There has been some discussion. You have to ask is the juice worth the squeeze?

[Bobboloo]

I sent Steve Wong an email aways back asking this very question but got no reply. I also posted in the rebuild forum with no reply.

I guess it's uncharted water.

I have an extra Motronic brain and an extra MFI induction I want to put on the 87' Carrera motor in my 73'. I contemplated mounting the MAF meter inside an MFI airbox and mounting a filter cone on the outside but I have no idea if this would work.

Also wanted to know if Steve could program a chip to work with MFI induction and all the other Motronic goodies minus the MAF.

[asphaltgambler]

Check www.pro-flow.com They sell a mass air conversion for bosch/motronic equipped cars.

You would still need chip tuning to maximize the potential.

[JeremyD]

or http://www.promax.uku.co.uk/maf_kit911.htm

But if Steve Wong is putting his name on it - it will be done right

[Carrera3.5L]

Hmmm, that motor on Steve's website with the HFM5 kit installed sure looks familiar...

I plan on trying some more radical cams (rather than the 20/21's in there now) in the somewhat near future with the HFM5 kit on the dyno just to see the difference. Probably won't pass the visual inspection (carbon fiber airbox isn't stock on a 911?) and most certainly won't pass the actual emission tests.

Summer project, have to finish my Yellowbird bumpers first.

Ralph

[duckmcf]

Hi Ralph,
I'm new to 911’s but I've dabbled with in-line sixes, single 4bbl / vs. triple Webers and hot cams. Over the years my experience has been that if you significantly pep up the cam you need a throttle body per cylinder (eg. DCOE’s, IDA’s or MFI) and as near to the intake port as you can otherwise it’ll idle very poorly.

My understanding is that a single throttle body feeding a large plenum chamber with hot cams will still give good top end power, but the drivability will be impaired due to the very low vacuum that the hot cams will induce.

I'm not sure if this is the case with Porsche's flat six, but I thought I'd mention it anyway.


PS The in-line six that I used to have was an Aussie Chrysler Hemi SixPack Charger. It was a 265ci “Hemi” six that came from the factory with 3x45DCOE’s and put out 300hp in 1972...