Turbo Wastegate Mod

[ajb1967]

Hi guys,

Just thought tha some of you would be interested in a mod i had done to my 1990 SE.

I toyed with the idea of fitting a BOV but when my car was in the garage the techie suggested he do something else instead which would be better.

Anyway,since i did not do the work myself but have seen what was done the following is a short description.Forgive me if my expalanation is not as technical as some of the experts here.

We changed the spring in the wastegate to a stiffer spring and then drilled a hole in the other side of the wastegate valave and then ran a hose from there to the inlet manifold and also to a valve system which replaced the stock valve sensor in the relay ccompartment in the boot.This now has a manually adjustable valve which we can adjust from 0-2.0 bar as we wish.At the moment i have it set at about 0.8 bar.We then added a fuel boost valve into the fule system and linked this up to the new turbo "sensor".

Result is that due to the fact that the wastegate does not open at all until the set 0.8 bar is hit that the turbo lag has been very much cut down as well as the fact that the system incorporates a sort of automatic BOV system.We dynoed the car afterwards and found that at 0.8 bar that the output was 325 BHP.Running at 1.2 bar output rose to 410 BHP.(I have figures if anybody is interested & i will take some pics of the system.Total cost of this mod was in the region of 600 UKp so not excessive.

I also had a new exhaust system hand built which is much more free flowing then athe stock lotus one (never new how much the baffler weighed !!!! ;-) ) .Anyway,this is a lighter stainless steel version and was handbuilt and mounted on the car for 250 UKP.Two small Quicksilver mufflers were added in since otherwise the noise was excessive ;-)

The whole system does have one down side.Due to the fact that the amount of fuel being put in to the engine and the variable wastegate option large blue flames come out of the exhaust when you come off the throttle from high revs ;-) Some people may like that but it is an added bonus/disadvantage anyway ,depending on how you view it.

I am running the non-stock chip by the way.

Ayway,all that said and done the car is much faster,with a much lower "lag " on the turbo and it spins up to 0.8 bar under 3000 rpm ;-)

If anybody once some more info feel free to ask and i will do my best to provide a reasonably sensible answer .

Adrian

[mr.oogieboogie]

pics of this mod would be good, what chip are you running.

all the best

[davegtst]

600 pounds? seems a bit much. What is this fuel boost valve? Is it just an adjustable pressure regulator?

[SE Owner :-D]

There is nothing wrong with blue/orange/red flames coming out of the back - we love that!

[davegtst]

From reading that again there is no bov at all you have just modified the wastegate actuator and fitted a manual boost controller. A bov releases presurised inlet air from the plenum,chargcooler etc so in theory it keeps the turbo compresser wheel spinning quicker and reduces lag. A wastegate diverts exhaust gases from the turbine straight down the exhaust so you can control how fast the turbo spins, if you didn't have a wastegate you would overspeed the turbo and it would soon go pop.

[ajb1967]

@Dave,

You are correct in your assumption ;-) As i said,forgive my sometimes less than technical explanation. ;-)

It is a manual boost controller.

I only got the car back yesterday after extensive garage time (3 weeks) so am still finding out how well/worse it drives in relation to what it did before ;-) I will take some pics though since the system itself is good and as far as i know is the same type of system used on rally cars

Adrian

[Dermot]

Adrian,

I would be interested to see your A/F values especially at WOT. The fuel boost value will raise your fuel pressure if i have understood what you have done. When the car goes into open loop you could be getting excessive fueling as the car is running of fuel tables calibrated for the stock fuel pressure. I would also be interested in your stored BLM values.

Further, the ECU is also going to try and fight with your manual boost control to try and take control. Remember the ECU is is still reading the MAP sensor and trying to control it for a give RPM and TPS and then deliver the correct fuel.

Be very cautious...

[Quicker]

+1 - this is one of the issues we have, unless you reprogram the ECU, or remove it entirely with standalone systems, you end up in a funny state of the ECU trying to compenstate for the adjustment being made outside of it's control.

careful careful.

You put down get numbers!

[ajb1967]

@Dermot,

I get where you are coming from but the guy who did the mod for me is a very experienced raceing driver/mechanic and he has checked all the values and said they are within acceptable parameters.

I will run the car for a couple of weeks and we will see how things go.

One of the issues is though that the turbo is going to get a lot hotter using this system.He says it is not a problem but that i could do with more engine cooling.I will have to have a little think on how to do that.If anything i will mount some cooling fans where now the engine cover grille is and do the same sort of thing i saw on a Golf with a Bently GT engine which was midmounted.Instead of letting the air flow naturally ,i can then give it a hand ;-) Not a particularly difficult job i think.Plenty of places to get current from around there and buildinga frame to fit where the grille is now should be easy.Mount the fans and then just run them off a variable fan speed circuit linked up to an engine bay temp sensor :-) What do you think ?

Adrian

[wiseraven]

This mod sounds something like the Brodie Brittain Racing kit that was fitted to my SE when I got it. That worked by overriding the ECU's wastegate contro. It brought the turbo in 500rpm earlier and boosted to 1.1 bar. It was awesome, but it had to come off, because I was getting all sorts of stumbling problems, and the control box sat on the ALDL cable, preventing me from getting any diagnostics. I'm with Dermot regarding it fighting the ECU. The ECU will be trying to set the boost and fuelling, but will never be able to get what it's asking for. Although my problems turned out to be due to a fried ECU, I suspect that the kit was a contributory factor in its demise. The ECU would have been working much harder than normal, trying to correct for readings that it had no control over.

The "reduced lag" you're seeing is only because the turbo is active at a lower rev range, so it doesn't have to spool up as much. If anything, you need a BOV more now than you did before, because when you shut of the throttle from higher boost, you're even more likely to have excessive back pressure.

If I understand correctly, there's nothing you've had done (except for the fuel boost) which couldn't have been done with a revised chip, and that way, the ECU has full control of the parameters. With regard to the fuel boosting, I think you'd be better off fitting better injectors. You'd get better fueld delivery throughout the rev range, and the ECU learns their characteristics in closed loop mode, so when it's running open loop your fuel mix should still be correct.

I quite like the idea about the fans, but I'm not sure how effective they'd be. The vents are not near enough to the turbo to have the sort of localised effect you'd need. You'd also be disturbing the airflow over the rear wing, so it might have an effect on stability at speed. The vents at the top are in a low pressure zone, so there's already a tendency for the hot air to be pulled out. Why not try using the left air intake by the fuel filler? You'd need to make sure that you didn't get water on the hot turbo. I've seen a couple of examples where people have replaced the rear number plate surround with a mesh grille, although for that to be effective you'd need to modify (or remove) your boot.

Phil

[geoffsmith]

Be very cautious...

I agree. The MBC is pretty agricultural and as Dermot says the ECU will end up fighting it. I presume you normally have fuel cutoff at some level of overboost in your ECU (as it is the same as the Elans). If so, how have you disabled it to get up to 2 bar?

After I bought my Elan, I found it had an MBC and the ECU had been chipped to prevent fuel cutoff, but only after the wastegate stuck closed and I suddenly found enough power to smoke the tyres and clutch. I've ripped the lot out and put in an upgrade chip that ESM on LEC has developed as it retains the safety of fuel cutoff. (Another way of stopping fuel cutoff is to use a fuel cutoff defender which modifies the MAP sensor signal and can therefore run the engine very lean.) Inhibiting fuel cutoff is possible one sensor failure away from burning holes in the pistons.

[ajb1967]

Guys,

I have had a think about your comments and i can understand the ECU being overridden but for that then it will have to be getting a signal from the original wastegate controller (or am i wrong) .When we fitted this system i replaced the orginal electronic wastegate sensor in the relay box with this system and just removed the old system.If that is so then the ECU is not getting a signal anymore so should not be trying to comepnsate.

Am i wrong here ?

I looked at the fan set-up yesterday which i mentioned and it is an easy one.Although the vents do coll the engine bay if i put some high speed fans in there it is bound to help i think.

I have planned this for in a few weeks when i get back off the snowboard slopes ;-) When it is done i will post some pictures :-) and of course let yoy know if it makes any difference.I have found an ideal solution.My company ships computer parts and i have found a fan set-up which is normally used in 19" rack cabinets which when cut in 2 pieces fits that hole almost exactly.It already has a variable circuit and will save me lots of work :-)

Adrian

[Quicker]

I would be more worried about the fuel.

in closed loop - the car uses feedback from the O2 sensor - too rich cut back on fuel, too lean add fuel. At WOT (open loop) it uses maps to determine a preset mix. So there really is no intelligence to adjust to any changes you have made - that is why we have to 'chip' - which has changed the pre-sets to different values.

Installing a wideband is the only real way to measure the AFR - and you can log it along with your Freescan data and match the two data points to ensure that you never run lean.

Edited January 13, 2008 by Quikr

[fjmuurling]

Hello Adrian,

You are talking about the orginal electronic wastegate sensor in the relay box . As far as I know there is no such device (sensor) in the relay box. In the relay box in the boot there are three solenoids on the left side: the one on the left is the Boost Control Frequency Valve, the one in the middle is the Throttle Jack Vacuum Solenoid Valve and the one on the right is the EBPV Solenoid Valve. The ECU operates these solenoids ie is sending signals to them in which they operate the wastegate by means of pressure from the manifold and vacuum for the TJ and the EBPV. These solenoids are not sensors but only act as an interface between the ECU and the various actuators.

If I understood your posts correctly you removed/disabled the most left solenoid (the Boost Control Frequency Valve) so the ECU cannot control the boost anymore, however it still gets all information from the MAP, Baro, TPS etc sensors and so it will still be fighting against your manual boost controller.

I hope these thoughts above are of some help.

Freek