In anticipation of of a Gtec1 arriving I have fitted a boost gauge and a PRV*. I fitted the gauge first and took the car out for a spin. It was showing 0.8bar with quite a rapid drop off to 0.5bar after 5k rpm. I then fitted the PRV on a low setting, and took it for a spin. This time it was 0.75bar but it held a lot longer. I adjusted it and tried it again. This time it was 0.95 bar and still held very well and pulled very strongly. My quesion is, should I back the boost off 0.8 bar again until I have the new chip fitted?

* I know the question of PRVs is contentious, but I had suspected my EBV to be causing a stutter/hesitation on boost having ruled a few other things out, and it would appear I was correct as it didn't hesitate once on boost on either run.

Also, can anyone tell me what the purpose of connecting the hose between the the connections on the EBV is? Just to stop atmosphere or underbonnet air flow to affect the ECU?

Its always best to err on the side of caution, but 0.95 bar isn't particularly high

Even a standard EBV should allow close to 1 bar with a gentle drop-off to about 0.7 bar at the redline

the way I look at it is that you're not really going above the standard boost levels, so you should be OK.

Its always best to get your fuelling checked once you have the G-Tec fitted - different cars react differently to havig the extra fuel - some handle it perfectly, some don't

Yeah that was my plan Nigel. I had a Gtec1 on my previous coop, and whilst that was absolutely spot on for fuelling, delivering 1.1 bar with the standard EBV, I'm still going to get this one checked. I'm unsure whether to get a different EBV and run the car with that or stick with the PRV.

It sounds a possibility to me that your actuator rod could be too long, If your base boost is about 0.3 bar that would add strength to the theory.

Holy Cr#p maybe that's what's wrong with mine!

OK, so my Gtec1 is on the car and the Air/Fuel meter is showing that everything is as it should be. For this first run I reconnected the Fiat EBV to see what readings I was getting. It's overboosting to 1.2 bar, but taking a while to reach it as if it's not as snappy as the PRV. It's then settling at 1.05~1.1 bar until I get past 5k rpm then falling off fast to about 0.5 near the redline.

I noticed that the boost seemed to hold a lot better with the PRV installed running at 0.95 bar without the chip, so my question is should I reconnect the PRV with a setting of 1.05~1.1 bar and be happier with the quicker spool up or allow the car to sort itself out via the EBV? Is the car deliberately backing off the boost higher up the range?

Cheers

With the EBV it should be falling to around 0.7 bar at the top end, so I think your actuator arm is too long. As the boost is always acting on the wastegate with the EBV it will take longer to spool than a PRV, which holds the pressure back then releases it all at once. Same applies at the top I think which is why it drops off more than it shoud. (that's a theory so please correct if wrong)

I think screwing the wastegate rod in a good few turns will improve things with the EBV, then you can keep the safety features it offers as well.

Hmm, I'm not sure I want to start playing with the wastegate when it's running ok with a PRV... Any other opinions on EBV/PRV?

EBC

shortening the wastegate should bring the EBV closer to the same level of performance the PRV offers, wthout changing the way it runs with the PRV on at all. If I'm wrong, then just change it back to the length it was at to start with.

That's what I'd do

I'd love to, but what with a new rad, new bumper and other bits and bobs this month it's not viable for a couple of months.

Bad idea, it's a recipe for chronic overboost.

Stick with the PRV, or use your EBV and use the PRV in parallel to kill the overboost.

EBC's do nothing to resolve the contentious issue with the PRV install anyway.

It's not

Well, it could be if you shorten it too much, but as long as you test it and make sure it doesnt overboost even at high revs, it will be good. I'm only talking about shortening it so you get the proper correct boost levels with the EBV, not actually raising the boost this way. Far safer than using a PRV.

I think you said:


How exactly will you be doing that without raising boost level?

One of the chronic shortcomings of inferred boost control is there is no absolute measurement of pressure at any stage.

Your ECU has no idea what boost is being generated and it's guess work via TPS, load and AFM measurements is going to be even more vague once you start messing with actuator preloads.

Brewster says he has 0.8 bar boost and 0.5 bar high up with the standard EBV. that is 0.2 bar less than it should be, indicative of a wastegate rod which is too long as the fuelling is spot on. Reduce it to the CORRECT length should not make it overboost, if it does then there is a problem elsehwere.



By clamping the wastegate tightly shut at lower boost resulting in quicker spool up, in the same way that a PRV does. As long as it can open far enough to vent all the exhaust gases it needs to at high revs and doesnt spike too much then the tighter the better. This is NO DIFFERENT fuelling-wise than using a PRV.

You got strange low boost levels with your EBV's?
I get (on 99octane) 1.4-1.5bar maxboost and 1bar at 6000rpm (0.95bar now with racecat).
I use the Novitec chip and std EBV control.

Sorry to hijack but how important is it that you connect the 2 pipes on the bottom of the stock EBV (as shown in the how to guide) after you have fitted a PRV?

Ask as previous owner fitted a PRV and has just left the old EBV with the top hose connected and other 2 pipes open to the air..........

Yeah, that was my second post on this thread boonman and I'm still unsure unless it's as I guessed and is to prevent underbonnet air flow from sending conflicting signals to the ECU?

What is the standard set length for the wastegate rod? Just curious....

DBP

got a spare one lying around here, it's screwed on with 16 full rotations, dont know whether that's correct or not. you should have to pull it a bit to attach it to the wastegate or it will be loose and leak exhaust gases when it should be holding them in.

Hmm.... I'll check this out - engine was "replaced" by Fiat dealer 4 years ago before I bought the car, it's not as quick as my previous 20VT (both running Gtech1) - thanks!

DBP

have you got a boost gauge? you'll need one to be able to set it correctly on your own, you dont want to adjust it too far.

Thanks Mattw

Next step, whip out the clock and fit the famous boost gauge, then check boost, confirm suspicions that it's boosting low - then I can have a look at the actuator arm... don't worry, no cowboy stuff here - I also run a 'grale with slight mods and 1.2 bar - but it's easy there, as it's already got one! I've already checked the pipes, so I suspect a leak elsewhere in the system.

I just love turbo cars!

DBP