2.5 Sport Evo air meter

[bclemente]

Hello,I´m thinking of fitting the air mass meter and cams from a 2.5 sport evo on my 320iS,before I go to the rollers and fit a chip.Does anyone know if there are any drawbacks to this?Also can I change the twin pipe layout of the exhaust into a single pipe ,I´m trying to save some wheight.Any advice would be helpfull.

[Jeroen]

Hahaha well I don't know the exact answers that's why I didn't reply. But I don't think the 2.5 AFM provides extra intake air flow, believe it's the same size.

Also... there are many S14 specialists around (especially in Germany) that can give you the right advice regarding cams. The 2.5 cams don't have to be better than a good setup from Schrick for example. The 2.5 cams might even perform less as they were intended for a 2.5 bottom end!

If you really want to improve, go for a dedicated set of cams and combine it with a CF airbox and replace the restrictive AFM by Alpha-N. Then you will make big jumps in terms of torque and power.

See for examples: http://www.kk-automobile.de/produkte/motoren/e30/01.htm

As for the exhaust... you need flow there as well! So reducing weight doesn't measure up to the reduced flow through the exhaust system. Something that will work: a dedicated stainless sports exhaust system.

[Hannes]

Well, I know close to nothing about it, but I think a single pipe exhaust setup does not necessary entail reduced airflow. See: http://e30m3performance.com/installs/in ... t/exh1.htm

Hannes

[Jeroen]

Hmmmm.... interesting!

[bclemente]

Thanks guys,you I have somewhere a BMW magazine that says that the 2.5´s mass meter has a wider intake port and was used on the six cilinders like the 635 csi,M5 e28... the problem is I can´t find the magazine as I keep all magazines I buy for future reference but there are so many of them and they´re all in boxes about 30 of them with 15 years of info,but unorganized,plus I wanted a few comments on the subject.I want to keep the mass meter ´cause I plan to supercharge it in the future,that´s why I´m thinking of ordering the mass meter+injectors from the 2.5 from Turner Motorsports.As for the exhaust,going to one pipe I will increase the bore by,let´s say,10 mm to compensate flow I´m willing to sacrifice 1 or 2 hp if I can save about 20 kilos cause I´m thinking of going to a bike exhaust fabricater and have the mufflers done in carbon fiber.I have a supersprint complete system and the whole lot wheights about 30 kilos mostly because of the twin piping.

[Jeroen]

Ah ok, there's some more info making things clearer, thanks!

[hardtailer]

Thanks guys,you I have somewhere a BMW magazine that says that the 2.5´s mass meter has a wider intake port and was used on the six cilinders like the 635 csi,M5 e28... the problem is I can´t find the magazine as I keep all magazines I buy for future reference but there are so many of them and they´re all in boxes about 30 of them with 15 years of info,but unorganized,plus I wanted a few comments on the subject.I want to keep the mass meter ´cause I plan to supercharge it in the future,that´s why I´m thinking of ordering the mass meter+injectors from the 2.5 from Turner Motorsports.As for the exhaust,going to one pipe I will increase the bore by,let´s say,10 mm to compensate flow I´m willing to sacrifice 1 or 2 hp if I can save about 20 kilos cause I´m thinking of going to a bike exhaust fabricater and have the mufflers done in carbon fiber.I have a supersprint complete system and the whole lot wheights about 30 kilos mostly because of the twin piping.

The AFM (air FLOW meter, not MASS) has the same dimensions in all S14's, the only difference is in the spring tension inside (under the black cover) the AFM. So it does not flow better, in fact probably less, as the spring tension is higher in the 2.5 AFM...
What the magazines are on about is the bottom half of the air filter housing. That had a bigger inlet diameter on later models (215/220/238 PS) and apparently also on some 320is'es. Have a look at the same site as the link above and look for the engine modifications he did.

To keep the same flowability you need (at least) the same cross sectional area of the twin exhasut when you swap to a single one. search the forum on s14.net (use 'single pipe exhaust') and you'll learn all about it.
before understanding all that I would not 'just increase by 10mm' because the subject is too easy to understand that you would need to go the 'trial and error' route. That would be a waste of time, effort and money.