boost level after fitting enhancer

[diabloam]

Hey all, who has fitted these to their car, just fitted mine that I got from promaxmotorsport (pleased with them as they very open and helpfull), big difference to car, although I notice that before full boost would be 9-10psi, I am now seeing 14-15 at full boost. Spoke to promax to see if I should change the setting on it but they said since car is standard the overboost protection will cut in before it gets likely to damage anything, so it should be fine as it is. Whats everybodies experience of these enhancers when they fitted them and does everybody agree that this is a safe amount to run on a standard car. 15psi equates to 1.034bar (above ambient pressure). Anyway any opinions welcome, thanks all

 

[Diver944]

I had one on mine when I first got it and it's a wonderful, simple little device that is the best 'bang for the buck' you can do to our cars. It's main function is to delay premature opening of the wastegate and thereby reduce lag, but it 'can' also be used to adjust the peak boost attained if you have an accurate boost gauge - not the in-dash gauge.

If you turn up the boost too far and are still on the factory chipset then you will hit overboost as it protects your engine from destroying itself [] You may want to get your car tested on a dyno to make sure of the exact boost level and that you are not running dangerosuly lean or maybe you could turn it down a little to be safe. You may also find that in winter it will hit overboost much easier due to colder denser air, so be prepared to turn it down a little over the cooler months.

Overboost feels like the car has violently hit the brakes and can be quite unnerving if it happens half way through an overtaking manouvere. It will reset itself after a few minutes of gentle driving or by stopping and switching the ignition off/on

 

[944Turbo]

I think you might not have standard chips if you are hitting 15psi, so be very carefull, I think a standard 250 car trips at not much over 0.85 bar (1.85 on in dash guage) Do you have an additional guage?
Tony

 

[sawood12]

There seems to be a wide and varied experiences of people with boost enhancers ranging from Paul (Diver944) who had no probs to Hilux who has had problems. My guess is your experience with it is likely to depend on how good your wastegate is and the stock boost control system. If it is working fine then I guess you are likely to have no problems.

The thing I noticed when I installed my DPW is just how fast the boost picks up and this is what you'll get with the BE. This means the stock boost control system will need to react very quickly (i.e. instantaneously) once the BE pops open. If for whatever reason it isn't reacting instantaneously then you could very well be getting boost spikes. Only half a second delay or so could easily mean the extra 0.15 bar or so it takes to trip overboost at the rate the boost picks up. This is just my guess based upon the different experiences people seem to have with them.

I thought the BE was adjustable as Paul has hinted. It might be worth checking this out and winding it down as it could very well have been fiddled with at some stage and you don't know what setting it has left the factory at.

 

[diabloam]

Yeah I thought the maximum boost should stay the same, and before I would see about 0.8bar on dash guage and around 9-10 psi on secondary guage I have fitted. After fitting the boost enhancer boost defo comes on quicker which I was expecting, however it now rises to 14psi or so on my gauge and pretty much maxes out gauge on the dash, however over boost does not seem to come on at all at this setting. I am convinced the chip set is standard as when I got the car it had full service history and every receipt for anything that went on the car. The only non standard things being a non standard gear knob (which i have replaced with an original), cup 2 wheels and some stainless sill trim panels and there was receipts for them so I reckon if had non standard maps there would be details for them. So not sure whats going on. Andy at promax said it should be fine if its standard as the over boost should cut in and the anti knock sensor should see if the car is getting detonation from the extra boost. I only had an hour to fit and take it for a wee spin before I went back offshore to work so need to play with it more when I get back home. I aint sure what to do, I have a air/fuel ratio gauge but havent fitted it yet as need to get a oxygen sensor first. I really dont want to melt a piston or anything so am wondering if I should be backing this down, I know the BE is meant to come set at a little before 10psi (0.8bar or something), but we all know boost is addictive and car was pulling brilliantly and if I thought I could get away with this I would love it. I aint sure I understand how it is seeing 15 psi as before it was fitted I seen a pretty much factory standard 0.75-0.8bar above atmosphere so know wastegate was working fine, so unless I am getting a prolonged boost spike, not sure what is happening. Can I leave it as it is and assume the overboost and anti knock will look after me. To be fair I probably need to give it a long blast in fourth or fifth to see of that level of boost is consistant, and I aint just getting a spike as I go up the gears. Not sure how to progress here? p.s. the car is an 86 plate 220bhp version not the later S version!

 

[andyslade]

I ran a boost enhancer on my 86 turbo that i owned a while agut of the box the overboost protection would cut in when accelerating hard in 4th gear.So i adjusted it until this no longer happened.Then it ran fine,bringing the boost in much faster than standard.
If the overboost protection cuts in when overtaking,this can be very dangerous,so i suggest you set it up so this does not happen!
Regards,
Andrew.

 

[Fen]

My BE made sod-all difference until I tweaked it to get as much boost as I could before the overboost protection cut in. In this case it should be OK, assuming the overboost works, which I imagine it will be as it would run virtually no boost if it was faulty. You will blow your head gasket in a few months though if it's original as it will be brittle from all the years of heat cycling and the extra boost will tip it over the edge. It's not the end of the world when you do though and it's worth having a new one in there. When mine blew that was the start of the slippery slope, however...

 

[pauly]

Assuming there's no boost enhancer fitted, how do you turn the boost up or down ?.

 

[Fen]

You don't. Or rather you can't, unless you meddle with the plumbing in some other way to achieve the same result.

 

[pauly]

ORIGINAL: Fen

You don't. Or rather you can't, unless you meddle with the plumbing in some other way to achieve the same result.

So just over 2 bar is either due to chips or an optimistic gauge ?.

 

[swright]

ORIGINAL: pauly

ORIGINAL: Fen

You don't. Or rather you can't, unless you meddle with the plumbing in some other way to achieve the same result.

So just over 2 bar is either due to chips or an optimistic gauge ?.

Thats what id like to know too as mine shoots past the 2 bar mark.

 

[Fen]

Chips don't change boost without some mechanical means of assistance be that a boost enhancer type device, a manual boost controller, shimmed wastegate or a bleed valve. I'd suggest optimistic boost gauge - there isn't a lot between 1.82 and 2.0, especially on a gauge as sparsely calibrated as the in-dash one.

 

[diabloam]

Well mine now shows dash gauge maxed out and my other gauge showing 14/15psi, whereas before I seen 1.75-1.8 bar on dash gauge and 9-10psi on other gauge. No overboost protection cutting in and car pulling brilliantly, really wish to leave leave it like this. So whats the consensus view, should I adjust it back in or chance it. My car has covered 92k so am I right in thinking a head gasket is probably looming on the horizon at some point and am I just charging quicker towards this by leaving boost enhancer as it is. Can handle a head gasket going i just dont want to hole a piston by running too lean. Maybe should find an O2 sensor and stick that in with my air/fuel ratio gauge. As an aside, can i fit most O2 sensors in my exhaust or do I need the proper porsche/bosch item, who has one fitted?. Also whats the bung like to get out, I take it it needs some prolific heating to shift it?

 

[Fen]

You should not do any damage leaving it as-is, but try extended full throttle in 4th or 5th to check if it kicks in as you do not want to find it for the first time when you're alongside a 40-footer with someone bearing down on you from the other direction. Also use V-Power or similar as you get a lot more boost before the protection kicks in.

The "overboost" protection is actually a (single, between cylinders 2 and 3) knock sensor and the electronics don't actually care how much boost you're running so long as they don't pick up detonation.

You can use whatever sensor your gauge is happy with if you fit an AFR gauge, but the bung in the exhaust as standard is not in the right place (it gets too hot for 5-wire sensors) and you really need to get a collar welded on under the front seat area. Remember it's stainless if you do go that route.

 

[diabloam]

Fen- When you say under the seat area, do you mean along where the exhaust has already turned horizontal and is running along bottom of the car, could I buy a bung off ebay (seen them on there) and just get somebody to tig weld it in and screw sensor into that, does it matter that this is fairly far down stream from turbo etc. Also as an aside, and I know this is a bit sad, but I would like to fit a dump valve that vents to atmosphere (I love the noise on my pals volvo T5). I know one on our cars recirculates the air but has anybody fitted one that makes the noise (cue boy racer jokes, lol), I might be 30 but often act like I am a seventeen year old in a corsa a lot of the time, lol. To continue with my boost level question I will probably take it for a blast and hold it in fourth and fifth when I get back home (week or two) and see what it is like then. Also I stay on scottish isles (Isle of Lewis) and highest octane fuel I can get locally is standard 95 ron unleaded (although ambient temps are often low, lol, which should help), would it help if I used an octane booster and which does everybody recommend, thanks all

 

[sawood12]

I've installed my O2 sensor bung just after the bend in the pipe where it turns horizontal. I put it there because if it was further down the pipe i'd be worried about condensation forming as it is moisture that kills these sensors. Ideally you should also try to angle it such that the sensor tip is slightly downhill so if any condensation does form it is likely to drip off the tip rather than drip into the small hole at the end of the tip. unfortunately in the location I have mine there was not enough room for that so mine is maybe just off horizontal at a slight upright angle. Also the wire loom was not long enough to have it much further down. Not ideal but i'm hoping that not much condensation will form in that area due to the higher temps. The sensors are consumable items anyway and even in an ideal installation will require replacement.

Just need to install the rest of the kit now!

 

[Fen]

ORIGINAL: diabloam

Fen- When you say under the seat area, do you mean along where the exhaust has already turned horizontal and is running along bottom of the car, could I buy a bung off ebay (seen them on there) and just get somebody to tig weld it in and screw sensor into that, does it matter that this is fairly far down stream from turbo etc. Also as an aside, and I know this is a bit sad, but I would like to fit a dump valve that vents to atmosphere (I love the noise on my pals volvo T5). I know one on our cars recirculates the air but has anybody fitted one that makes the noise (cue boy racer jokes, lol), I might be 30 but often act like I am a seventeen year old in a corsa a lot of the time, lol. To continue with my boost level question I will probably take it for a blast and hold it in fourth and fifth when I get back home (week or two) and see what it is like then. Also I stay on scottish isles (Isle of Lewis) and highest octane fuel I can get locally is standard 95 ron unleaded (although ambient temps are often low, lol, which should help), would it help if I used an octane booster and which does everybody recommend, thanks all

Yes. I put mine roughly as far back as the stereo with the cable secured in the corner between the inside of the chassis leg and the bulkhead/floor (I should have said passenger compartment rather than seat area). It sounds like mine was a bit further back than Scott's as I had enough room to get it angling about 10 degrees downward.

I can't say I have tried octane booster, but I am in the same boat as you in that 97 is as much as I can get here and my Mini is mapped for 99 so if/when I get to the point of tracking it I'll need to run booster. Of course the available brands will be different here in any case.

Atmospheric dump valves are not a great idea on the 944. The air flow metering (flap type AFM) has already "seen" the air and therefore computed fuel requirement for it before the dump valve dumps it. With a recirculating that's fine as it gets dumped back in to the inlet downstream of the AFM, so it still gets used for combustion. With an atmospheric one the air is dumped to atmosphere so is no longer in the engine. The result would be excessively rich fuelling as there is less air to mix with the fuel than the engine has measured. How long that rich situation lasts, or how much difference it makes I don't know, but regardless it's not a desirable thing to have happen on a regular basis.

It's a taste thing, but personally I didn't like the noise mine made (which I was running with a MAP sensor so there was no issue regarding fuelling) and I put up with it only as it was a big dump valve and it made plumbing easier having it vent to atmosphere.