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waynef

Continued Boost...how to maintain?

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Ok turbo question here.

In normal circumstances the Turbo will boost for approx 15 - 20 seconds then revert to normal. However on the track it became noticable that when driving at high rev range speeds continously the boost seemed to just not be there. At 120mph the car normally buries you in the seat on 5th upchange. Normally on quick stints, however when on track and staying at a constant (6000rpm +) boost seemed non existent. Only to return when on the low rev section of the circuit (twist corners).

Another thing I noticed was oil temps getting near 90 degs, on the road they never exceed 60 degs. Would it do me any harm to install either a race type oil cooler in series to the others (perhaps at the rear) or to install cooling ducts from the front direct to the front oil coolers?

Any answers on how the track Esprits overcame these boost issues would be appreciated.

Waynef

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Wayne,

I think Markus' ECU upgrades will help on the boost front. Best to send him an email. I think he's changed the over boost conditions to provide the extra boost in the higher revs. see www.pukesprit.de for more details.

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Hi Peter

I'm running chip no5 at the mo. Car is running spot on in normal conditions its just prolonged high rev/speed driving that causes the situation.

I already use Marcus at PUK but thanks for the info.

Am going to look at the oil cooler mod though and potentially situate it at the rear for max airflow.

Waynef

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Well I can put my hand on it after an hour of track time and its cold to the touch...so I believe so.

I'll try and be more specific, the ECU will allow over boost for a limited period on boost, my question is can the car be set to boost continuously, or for longer? Road use its absolutely spot on as there is never a situation to keep the throttle on full for more than 15 secs or so. On the track though totally different.

Thanks

Waynef

Would I be right in saying that if I adjusted my midrange and got the Turbo to boost from higher RPM's that this would overcome this problem.

I'm wondering now if I should fit a dump valve to allow quicker throttle response on off power and back on again, thus increasing mid range response but getting the car to boost at higher rpm say from 5000rpm?

Is there a different solenoid controller or is this simply a case of adjusting wastegate and a rolling road and dyno testing?

Waynef

Edited by waynef

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The reason your boost drops off after time is that the stock turbo in conjunction with an uprated chip will run the turbo outside it's designed operating range ie. higher RPM's. While this is OK for short bursts, after sustained boost periods the excessive RPM's causes the manifold air temperatures to rise significantly, reducing the air density etc. and hence the power drops off. The way around this is to fit an uprated turbocharger unit that allows the same amount of boost, but at reduced RPM's..........this will generally also unfortunately increase turbo lag, but can be minimised by a decent low drag bearing assembly.

Phil

98GT3

Edited by 98GT3

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Hmmmmm....ok but i'm running a Garett Airesearch T56 with .60 compressor already.

It could be because in order to get over the strict limitations of noise control I put my stock exhaust back on...could this be choking the Turbo?

Thanks 98GT3

Waynef

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A standard exhaust could potentially limit boost and also introduce a certain amount of lag into the system, but not cause the boost to drop off. It will cause the turbo to run extra hot though..........do you have FreeScan? if so, it would be interesting to see a log of sustained boost and to observe the MAT etc. Increasing the capacity of the chargecooler would be a good thing to do for starters..........

Phil

98GT3

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Hi Phil

That is an option i'm seriously going to look into, however the annoying thing is that you can not use a race exhaust on pretty much most of the UK tracks on trackdays as they set db limits of between 98-105. My race exhaust as measured at Castle Coome is 112db and thats after having it packed.

Looks like I am in a difficult scenario as I guess its impossible to have a road car set up for ultimate track performance????

I am going to do the chargecooler mod though and introduce an extra oil cooler nearer the sump (rear of car).

Waynef

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Wayne, you might consider a dual box system, adding on a second straight though silencer coupling on to the exit of your present and running across the back - added for track days only - that may well do the trick without strangling the exhaust gases.

Phil

98GT3

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I use 2 3" magnaflow xl's

straight thru, no restriction

and absolutely no noise :lol:

u can see details on my website if interested


chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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Hi Ragingfool Do you have any piccies please of your setup?

Also what DB's are you running?

Very interested to see this. And 98GT3 I was looking at an actuator type valve that fits central to the downpipe (skyline boys use this) that allows at the flick of a switch a silenced exhaust to become freeflow. Problem is that most tracks have Db sensors all over the track so no good in my case.

Thanks again

Waynef

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One other thing you could consider is fitting up a water/methanol injection system. By spraying a fine mist of water/methanol into the intake at WOT and say above 5000 RPM you can drastically reduce your intake temperature and also help reduce the risk of pre-ignition or knock. Just a thought.

-Graham

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A water/methanol injection system needs to be carefully thought out and installed correctly. Otherwise you risk loosing power. Water vapour has no calorific value and it displaces fuel vapour. In Jap applications you have more scope to up the boost and ECU’s with adaptive spark timing can advance the ignition.

Where you inject the water/methanol is also important it has to be before the MAT sensor otherwise the ECU will not sense the cooling effect.

I system triggered by high boost may be worth considering, however if you don’t have knock at max boost then I don’t think you would gain very much for the cost. Money best spent on other areas.

PS. I agree with Phil's comments regarding Wayne's track behavior. It is classic turbo theory, discussed on my site. I would also worry about your gearbox oil temp.

Edited by Dermot

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pics on my website with part #s and prices

dB? same as stock

Edited by ragingfool35

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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For the last few years I've by-passed the stock waste gate controller and have used a manual controller. I set the boost to about 20 PSI and it works like a champ. I got tired of messing with the ECU controlled waste gate, you didn't know how it was going to perform from one day to another under similar conditions. I should add that I have an upgraded turbo, the blue race chip, and a free flow exhaust system. I also use NOS on occasion for the extra rush.

Pete

90 SE

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Hi Dermot

Hope all is well...Your exhaust is still performing well except I can't use it on track lol.

Your comments on the Gearbox have now got me thinking. Is there such thing as a gearbox oil cooler? On the turbo front do you think it would be worth looking at potentially changing the cams to improve mid range and boosting higher?

Could you send me some links to the specific pages you are on about failing that if your up for a beer this week one evening maybe we can hook up again.

Thanks

Waynef

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Mike S has a transmission oil cooler on the GT1 rep, details here

http://www.lotusespritgt1.com/engine.html

It's a different box however, not sure how you'd fabricate it into the UN1.


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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Hi Wayne,

You are always welcome. Email me.

I did some research on the bits needed for a gearbox oil cooler. As Bibs says Mike S has fitted one to his UN1. It looks fairly straightforward and can be set to be triggered once the temp exceeds certain value. Next time on the track you should stick some thermal sensors on the case to record the gearbox temp. I got some from Mocal in different heat ranges. That will be very informative.

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