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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > UK > UK Technical Forum > 335i - Dual Cones and Forge Diverters



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      01-19-2011, 07:44 AM   #23
335i E92
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Drives: 335i E92 SE
Join Date: Mar 2010
Location: Manchester

Posts: 686
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Quote:
Originally Posted by doughboy View Post
Picked this one back up again.... after promising to change the springs on the 19th November, I finally got round to it yesterday!

After fiddling with the JB3 it was as good as ever on the forge diverters with stiff yellow springs, but it still wouldn't run lag-fix mode without over boosting (i think) and dropping the boost off if you were heavy with the right foot. It got much smoother and more predictable after a week or so, I think the forge DVs are a little sticky when new and cause over boosting / spikes until settled in.

The yellow springs are meant for 15psi+, but on the Dyno, even on map 6, the car never exceeded 14.5psi as logged by the JB3. Anyhow, I wanted to check it with softer green springs meant for up to 15psi, so i put them in yesterday.

The effect theses things have at part throttle is so profound, much more than you would ever think.

Immediately it felt flat on map 4, much more laggy and a more gentle throttle response.

So on with map 5, (same as 4 but with lag-fix on) HOLY MOLY! It an absolute beast, the throttle response early on is just as sharp as with the yellow springs, but it doesn't drop out if you over do the throttle, it just keeps on going!

2nd gear, DTC on, from about 2krpm, a nice slug of gas to about 2/3rds and bam! off she goes, wheels spinning up, then at 4.5k it just wips into the red line as if i'd hit a patch of ice! Seriously quick.

Fast as fook! I still can't fathom why a boost divertor has such an effect on part throttle performance.

Got my AR decat downpipes now, they're getting fitted on 31st Jan.
Mike

I remember when i posted my original review of the Forge DV's and people were sceptical that they were having such an effect on throttle response. Just glad someone else can now confirm the same!!

I still stand by my conclusion though that they're a finicky upgrade and for me required far too much tweaking to deliver the desired results. (which i never managed to achieve with a straight forward remap) It was either too laggy on the softer spring or ran in to over boost on the harder ones, playing with the shims didn’t help either.


It's just so difficult to find that sweet spot between lag & over boost with a straight forward remap as you can't control the various peramiters like you can with the JB3. I actuually think the Forge DV's best suited to somthing like the JB3 as you can (as you've demonstated) find that perfect adjustment.


Great to hear you've cracked it anyhow.

Can't wait for the DP review, can't tell you how frustrating it is watchin mine gathering dust in the fricken garage!!

H
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