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The mkiv Supra Owners Club

Urgent NA-T Help needed~!!


bluedrag

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hi guys if your reading this im hoping you can help my plight,

i have recently finished assebling my NA-T conversion and took it to the tuners to get a link installed and tuned, i thought all would be fine but it isnt.

the tuners have come across the boost running away on the tune (overboosting) and they dont want to keep running it above 4500rpm in case something goes bang.

my question is has anyone ever come across this issue? and if so how did you fix it??? aparently relocating the wastegate can fix the issue somewhat so that it draws more of the exhaust flow, however it is another cost which i really cant afford at this stage

 

any help on this would be greatly appreciated

 

fyi this is the kit i bought

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemVersion&view=all&item=200680024171&tid=896847711010&ssPageName=ADME:X:CPSCTOB:US:1123

 

thanks in adavance

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The kit you have linked is no longer available mate but if it is one of the cheaper kits then the wastegates don't get a good rep at all. The springs inside them can be the reason for your overboost. I'd recommend a good quality one to hold the boost properly and avoid causing any real damage at a later stage. Make sure your oil feed and drain kit is good quality as well, that's another component you really don't want to go on you

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hey Style the wastegate itself has already had the spring replaced, aparently the issue is that where the wastegate piping runs off the manifold because its almost going back the oposite direction of the gas flow it cant build up enought back pressure to flow to wastegate hence the reason for over boosting, just wondering if anyone else has had this issue and whether they found a cheap fast solution to it?

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Reason for over boosting is lack of wastegate bypass

Causes are either sticking wastegate/ not big enough wastegate (unable to flow enough gas past the turbo)

 

Rarely any other reason tbh

 

Even if you have a bottleneck in the wastegate pipe , as long as the pipe itself isn't tiny

Then under 400bhp you shouldn't really have any issues

A fully open wastegate should be as if that pipe is open ended

 

Get a bigger or better quality wastegate and try again :)

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ok guys this is a link to a auction by the same people everything but the turbo is identical in this auction.

http://www.ebay.com/itm/IS300-SC300-GS300-2JZ-GE-2JZGE-T4-Turbo-Kit-W-Turbonetics-Hurricane-7868-Benita-/170946857125?pt=Motors_Car_Truck_Parts_Accessories&hash=item27cd3a08a5&vxp=mtr

hopefully u guys can tell by looking but i really need a cheap solution as its already costing me more than i anticipated to get it tuned

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Is say possibly the 40mm wastegate may not be upto the job

I'd go bigger 50mm at least , I run a 60mm but I think a 50 should bypass enough to stop boost creep on a turbo the size your running

At around 400bhp

Maybe check the wastegate you have is moving freely and the diaphragm is ok

Use an airline to open the wastegate to check its opening

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  • 2 weeks later...

ok thanks for everyones help i have discovered that the clowns who i got to plumb my wastegate into my downpipe only drilled a 16mm hole and welded a 40mm pipe over the top =( not what i expected from an exhaust specialist shop, however problem has been found and am now getting it done properly by a friend who makes manifolds etc

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