13.4 second 1/4 for your 'stockish' R33. (A how to guide).

[rev210]

2rismo,

fair enough mate. I think hasty generalisations are not fair too. I think I could have qualifed my statement a little.

R33 GTST's:

*Run the standard turbo? Don't expect the aftermarket BOV to help performance.

*Run an aftermarket intercooler and standard turbo? 'As above'. The extra air is far from pushing the std BOV's abillity on an R33. Test it yourself using a g-meter, I would glady bet you a beer that no aftermarket BOV will do anything but put the accelleration backwards and at best not change it.

*Have a serious T88 34D pushing 2bar?

Go buy an aftermarket BOV that can take it.

I really have no 'beef' with properly applied aftermarket BOV's, it's just that application on an RB25DET is not often till you reach beyond 500HP @ motor. know of one with 509PS with the standard valve intact HKS intercooler and a GT30 turbo with lovely on/off throttle response.

[Jay95R33]

After reading 2rismo's post, now my eyes are hurting along with my brain !!!

But it makes sense.

On the deflating the tyres thing, that might actually reduce the rolling diameter even further (axle will be closer to the ground), but I'm sure it would be mm we're talking about LOL.

I think I've got a headache now

[crooser]

4.3:1 LSD diffs can be had from R33 GTS Type S's and transplanted.

Possibly other non turbo models but not 100% sure.

i experienced a noticable loss of acceleration going to 4.11 when

the old one developed a whine.

[Doctor]

I have noticed positives and negatives for both types of valves.

External - More responsive throttle but in high rpm applications over fuels when changing gears therefore hurting power. Takes the turbo a little while to recover.

Stock valve - Drivability is much better ie not as jerky. Tends to open too easily ie half throttle. When I put on my intercooler is sounds like it shits itself when you let it off, due to the extra volume of the intercooler and bigger turbo.

Doc

[GTS-t VSPEC]

I must admit that the external BOV made my car slightly more responsive, but I didn't have any of the problems associated with the car stalling etc. that many people do. I do think that they are best used once you have aftermarket management, so that any over fueling issues can be handled.

See'ya:burnout:

[Guest INASNT]

Thanks for posting this thread rev should help alot of people get better times!

I agree with you about atmo venting BOV's, i just took off my Blitz ATMO BOV when i put my new cooler on and went back to the stocker, what a difference it made, car wouldnt cough and sputter between gear changes and is so much smoother to drive with the stock BOV in place. If i was considering running more than 20psi with a bigger turbo then an aftermarket BOV would be beneficial otherwise its just a hindrance!

[GTS-t VSPEC]

INASNT,

It does seem strange that everyone gets different experiences with atmo venting BOV's. I never had any problems with coughing or spluttering, but many people do, and so going back to stock is a good decision. I'm not sure what the other factors are which contribute to the issue, but it worked better on mine but not on yours, strange.

See'ya:burnout:

[Guest INASNT]

i really knew the difference as when i got the car new it had the Blitz 1 blocked off and running with the stocker, then (dont know why) i got the stock 1 blocked off and blitz 1 unblocked, then vise versa again when the cooler went on as the blitz 1 annoyed me so much.

[rev210]

the standard Vs other BOV is an interesting issue. I think that testing with a g-meter or something could determine the merits pretty easy.

[Steve]

I think it would be worth setting up the BOV properly too, as well as a comparison between different types. Alot of people have huge dramas with aftermarket ones causing stalling and backfiring, and some (like myself and GTS-t VSPEC, etc) have had nothing but good results - from a seat of the pants perspective.

Maybe its time a performance mag got off its butt and did an article? Or has anyone seen an article on this before?

[GTS-t VSPEC]

I thought that Martin Donnon metioned this in HPI, in one of his collumns, saying that external BOV's are much better, I'll try and find the article tonight.

See'ya:burnout:

[rev210]

I have read an article (could be hpi?) testing showed that the aftermarket ones did absolutely nothing to improve performance, test on a supra I think.

[slip]

Another thing to take into account with cars that have the same modifications, but different rwhp and 1/4 mile times (apart from drivers and dynos) is the monday/friday car phenomenon. With 2002 model roadbikes which are built to very exacting specs, you can have 2 bikes on the showroom dyno with a difference of anywhere from 0-5rwhp generally. Just another factor to take into account.

[rob77]

I found that about 2 weeks after fitting an apexi twin chamber bov that the car run far richer(started back firing on 80% of gear changes) and had less power than before. Having removed it and reconnecting the std bov and reseting the ecu the car runs leaner and of course feels that tad bit quicker.As per my mod list below, I still have the stock turbo, cooler and ecu, but running 0.8bar of boost. I think if I go for an aftermarket bov I'll go for an atmo/plumback so I get the psccchu and it doesnt run so rich. I've also found since putting the HKS pod filter on the stock bov does sound much louder when it vents.

[2rismo]

A lot of the problem with backfiring is to do with the cars being AFM'd. The air is already measured and an appropriate amount of fuel supplied by the injectors when all of a sudden, the BOV lets it out into the atmosphere. The fuel is already there so with no air to mix with, it goes *pop* and backfires. Aftermarket ECU's tend to deal with this better than the factory Nissan item.

I haven't had any problems with backfiring (Power FC) since fitting my BOV but i know a lot of others with AFM'd cars do.

On the stalling issue, I had this problem innitially because the valve was gooped up and wasn't shutting as quickly as it should be, thus releasing all the nice vaccuum required to keep the motor running. Lubed the brass valve and prob went away.

[Steve]

I do believe that alot of the problems associated with atmo BOVs is due to poor setup and/or maintenance - I bought a brand new turbosmart type 2 and had nothing but good experiences, no backfiring and a percievable increase in accelleration due to loss of lag on gear change.

[rev210]

I think with the aftermarket BOV, one needs to actually 'test' the accelleration objectively. Seat of the pant's is only good as a guide with modifiactions that produce a fairly dramatic effect, I doubt the BOV change will yeild any more than a very slight performance increase, certainly one not able to be easily detected. More often than not it is a placebo effect that is 'felt'. I am certainly guilty of falling fowl of the 'placebo feel' and it is a trap for everyone who likes to have a go at road tuning. Without a stopwatch or some other measurement device claims of improvement are difficult to back up. These days I try my best to avoid seat of the pants evaluations, or at least cross reffernce it with something else.

To sum up I guess if you are heading down the mod path, with a small budget, on a stock gtst, I would reccomend that the BOV be placed in the cosmetic list, or at least at the lower half of your performance list below thermo fan and pulley changes.

[judd]

I still cant figure, last nite i ran a 12.9 @104mph in my R and all the other gtst at eastern creek ran 14s. my friend has 94 GTST, PFC, Bov, Front Mount, boosted 1 bar, Turbo back hks exhaust, 265 Ggrid2 tyres, air filter (cold air) and he ran a 15.2, 14.7, 14.9? launches were ok. i think the time gate could be out? Ur Ans: Rev?

and ur car must be accellerating faster than my R. we are both at 104mph.i have exhaust, airfilters, rest is std. launch at 4500rpm

[rev210]

judd,

I can drive ok but, 2.1 60ft isn't world beating.

My car is just faster fullstop. The meeting before I had ran a best of 13.8, without the lightened flywheel and with over 100kgs in the boot (work stuff). On the meet of the 13.4 I ran several 13.5's making the car very consistant.

I have seen many a car (not just skylines) poorly setup, with more performance gear than you can poke a stick at and they run slower than even some completely stock vehicles.

Matching each component to the purpose is the best approach to going quicker. I'd say your mates vehicles are victims.

I have tried to set up my car with 'efficiency' style mods that compliment the broad power band of the stock setup and provide time saving through faster build up of revs and spooling on the turbo, something a dyno does not measure (yes there are performance aspects a dyno doesn't measure).

Geez if I had 265's I may have already got a 12.

BTW, ask Rhino what to do to your 'R' to get a 12.4.

[GTS-t VSPEC]

Judd,

It took me many weeks in the 14's before I managed to get my 13.5. It was primarily driver related, and I didn't change the car setup during this time. Last run I was consistantly in the 13's which goes to show when you learn how to drive the car, the car will perform consistantly.

Keep practising, make minor adjustments to suspension and you'll easily knock a few tenths off your times.

See'ya:burnout: