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The mugen ones probably didn't run one because no-one had really thought of using them on turbo cars at that stage I dont think.

BOOSTBOY I *think* that having the bov to stop the air going back through the turbo and stressing the compressor is prolly benificial. I believe thats the main reason most new factory turbo cars have recirc BOV's so it doesnt damage the turbo, something about shockwaves when the air tries to get back through the turbo or something.

But yeah when I drive my car hard, the BOV is open for 0.5 seconds, keeps all the air moving the the right direction, doubt very much pressure would drop much in my piping as my bov has only a 19mm inlet, and the turbo hopefully wouldn't slow down much at all.

However, you know your shit so I might give it a try without the BOV hooked up, hell I can even record what my boost guage does so I could do an experiment and post videos of my boost guage action with me caning it.

Disconnected my BOV today, Im gonna have to say I agree with you BOOSTBOY. I will take some videos of my boost guage recordings this week and we can compare to see which is actually better.

The only concern I have with not running a BOV is the stress that the air surging back through the compressor causes. Some people recon that this can cause significant damage to the bearings and stuff over time, especially at high boost, what are your thoughts on this boostboy?

The only real reasons manufacturers run BOVs is for NVH issues.  Without it, the compressor flutter sound is very hard to shut up, even with the standard airbox etc.  

With the bov, the air released is recirculated within the inlet tract and due to lower than atmospheric pressure within the inlet, the recirc'd air is never released to atmosphere.  

Without the bov, the reversed air has nowhere else to go but out the inlet and the noise it makes goes with it.

As for turbo longevity, i seriously doubt it makes enough difference on these small turbos at low pressures.  Many will argue though but i havn't run one for a long time and haven't had a problem.  HKS doesn't run one on their GT-R drag car.  Most of Aus's fastest VL turbos dont run them.  Indy cars dont run them.  I guess that's saying something...

Just to add to it - GTR700 runs a bov..

Indy cars make the same power that the GTR700 makes out of half the capacity

Yeah, there are arguments for and against them - that's just my opinion, im happy to hear others!  :)

[quote author=HyperBlade link=board=ForSale;num=1127525144;start=0#2 date=09/28/05 at 12:05:31]Ha i missed that bit, Gecko you over here (from nzhondas ) to get another T2?  ;) [/quote]

Maybe

[quote author=BOOSTBOY link=board=ForSale;num=1127525144;start=0#11 date=09/30/05 at 15:20:48]Hope that makes sense - it works in practice - i used to have a blitz valve on my SR20DET and now run none and it is noticeably more resposive...[/quote]

I doubt you'll find anyone that'd say that a car with a BOV is going to be more reponsive than one without, but AFM cars definately seem to run smoother without them since your dumping all that air that the car thought it was going to be getting..

[quote author=BOOSTBOY link=board=ForSale;num=1127525144;start=15#17 date=10/02/05 at 17:58:48]HKS doesn't run one on their GT-R drag car.  Most of Aus's fastest VL turbos dont run them.  Indy cars dont run them.  I guess that's saying something...
[/quote]

All of those cars change gears in under half a second, probably more like under 100th of a second. There would be hardly any chance for compressor surge.

Not having one on a road car will damage your turbo significantly quicker over time than having one, simple as that..

[quote author=bigelboe link=board=ForSale;num=1127525144;start=15#19 date=10/04/05 at 11:21:09]Indy cars make the same power that the GTR700 makes out of half the capacity [/quote]
huh? indy cars put out ~850hp out of a 2.65L turbo v8.  gtr-700 is 2.7L twin turbo and 2 less cylinders. "Current power: Greater than 1 Megawatt (~1,350 BHP) at over 3.0 Kg/cm2"

i didnt know 2.65 was half of 2.7

All of those cars change gears in under half a second, probably more like under 100th of a second. There would be hardly any chance for compressor surge.

Compressor surge is a different thing all together.  

Not having one on a road car will damage your turbo significantly quicker over time than having one, simple as that..

How is it 'simple as that'?  Tell me why...

Ill just add to this, most standard T2's i have seen blow the turbos, have done it after the 200,000k's mark.

And they generally have other things going wrong, eg no filter, head gasket going.

Sorry about the indycar thing, I got confused between indycars and the turbo F1 cars, they were 1.5 litre turbo engines making like 1500BHP in qualifying trim, not sure whether they ran BOVs or not.