Safe boost pressure....

[Nick Mann]

my mates vr4 is running 16psi and is running great

Mine has been set at 1.3 bar in the past and was a tad rapid. At the time, I said it was running great too. A year or so later and the turbos were dead though....

Plus the supporting mods helped - custom exhaust turbo back, fuel pump & fpr, ARC intercooler, piggy back ecu etc.

I wouldn't touch that kind of boost level in a standard car without checking wideband and knock. TBH most standard VR4's would be hitting fuel cut well before that anyway.

[steelie600]

my car hits fuel cut at 15psi, si ve set my boost at a conservative 12 psi, and my afr is almost 14:1 across the board except bleedin cruising at 80-90 where its a crap 9!!!

[AlanDITD]

Eh. you get 14:1 on boost and 9:1 on cruise? Or did you just type that backwards?

[steelie600]

no according to my af meter im gettin 13.7:1 at full boost and wot which i dont understand either after reading other posts, ill plug my scanner in and try again gimme 10 mins

[steelie600]

Right been out again with scanner on and probe up the exhaust

afr at wot is 10.9 cruising 12.6 lambda is 1.06 most of the time except for very high revs when it does drop to 1 but the most alarming thing is the hydrocarbons up at 600 ppm rising to 900ppm at high revs. Which says to me its over fuelling like hell. Ahh well best get savin!!!

And this afr guage is going back to halfords in the mornin

[AlanDITD]

If your using a narrowband, which i assume it is being bought from halfords, there a waste of time, about as accurate as a blind man in a darts compettion.

[steelie600]

yup its a narrow band alan, im going to get me money back and get a wideband from demon tweeks. If in doubt break the snap on scanner out!!!

[Turbo_Steve]

Demon Tweaks!!!! Are you made of money!!?

Have a look at Innovative and PLX devices and the like.....especially if you're considering an ECU.

[Davezj]

VR4-Fan, you haven't mentioned what AFRs you're running?

steve just read through the thread and thought this was the case.

doesn't this VR4-Fan chap tell us in other threads he can only get crap fuel where he is form 95 octane at best but sometimes lower.

from my test with 95 octane fuel and WOT, the ecu pulls the timing to the absolute max to try and kill the the pre det/knock you will be getting.

and that is on staock boost, auto, PFL.

i assume that ecu pulling the timing to try to negate knock, will adversley effect performance.

please correct me if i am wrong on this one.

massive aside:-
By the way i hope VR4-fan had the TCL swithed off when trying to do his 1/4 mile runs.

[Turbo_Steve]

Dave, I believe he runs ultra-high octane fuel for his drag runs (105 or similar). Not sure how it stacks up against UK fuel...this was the source of some debate.
That aside, yeah, 95 RON is bad.

[elnevio]

Dave, I think the Dominican Republic use MON, not RON, and it's quite possible that he has been using a 99/100 RON equivalent fuel. MON is several 'point' lower on the scale, as it were.

And as for TCL? Well, at the Pod in June, I inadvertently left it on for one of my runs. The TCL one was in fact my second fastest run, and the difference in 60' times between that run and my fastest one, was just one ten thousandth of a second! That's right, 0.0001 seconds difference!