Karlos G

iTrader: (4)

Looking for one to use on an RX7 running a GT42...

Why are the bigger brands so crazy expensive, £710 for a Turbosmart 60mm for example?
Are the cheaper ones like Demon Motorsport (£95 ebay) worth a look or is the quality so bad it's just not worth it? Do the valve's not seat 100%, or are the springs weak and don't hold boost well?

All experiences welcome!

Rod-Tarry

Ive used the Turbosmart but changed it for a Tial which has been 100% reliable.

stevieturbo

They will work, but the diaphragm may not last as long as a proper brand. Springs are generally springs. Seats shouldnt be an issue really for the most part.

Just generally all parts used are cheap.

£700 is rather excessive though. DO you need as big as 60mm though, they are huge ?

Precision 46mm here is only £300
http://www.powermaxengineering.com/s...49&id=15211594

They also do a 66mm...which is huge. Powermax arent listing stock though, but can easily get them

Stolton

I think my mate runs one of those Demon motorsport ones on his Zetec Turbo and he says they are really good for the price..

xr2wishy

iTrader: (2)

i ran a demon sport one, so does qplaterst (dean), his did stick shut though and blew an engine, mine has been completely reliable, however i've had it stripped off many times and i check the seat hasn't degraded every time.
60mm is a huge one karl, 46mm would be far better suited.
i was looking to replace mine however as i just think it's a bit more security with a bigger branded item.

stevieturbo

I have seen one of the cheap Demon ones, and TBH it really wasnt that bad.

If it is exactly the same fitment as a more expensive unit, then I'd go ahead and try one. If it fails or causes problems, it's a simple job to replace with no further fabrication.

If you cannot find one that's a direct replacement for a more expensive unit, then it might be worth spending the money straight off.

xr2wishy

iTrader: (2)

if you are going to use a cheap one or an expensive one, you should have overboost protection setup in the ecu anyhow. that will cut the juice if the wastegate jams shut, which can happen if they get hot or just worn.

Karlos G

iTrader: (4)

Rod you don't say if you had problems with the TS one?

Yes we need a 60mm one, it's going to be running a GT42 which can flow for 700 odd BHP!!

Sticking shut is not good at all, how the fuck did that happen?? I thought creeping open would be the problem!! lol

stevieturbo

If you're only 700hp, then you certainly do not need 60mm.

DazC

iTrader: (1)

I agree with that statement. An RS500 T4 has a wastegate penny covering a hole of about 20mm and even when it's been ported for big boost it can't be more than 25mm yet that handles 500+ bhp.

I use a little 38mm gate on my turbo rated at around 400bhp and even finite little adjustments in duty change the boost characteristics dramatically. It has to be done carefully to get and maintain correct boost levels

clarke5700

If the Diaphragm splits or fails then the boost presure entering to act against the Force of the spring will leak past (i Actually had this happen with a turbo smart one on a friends starlet)

xr2wishy

iTrader: (2)

size of wastegate is relative to the limits of the turbo, if you're pushing it close to it's potential the wastegate will barely bleed any gasses off, so doesn't need to very large.
if you put too big a wastegate in then it can be too sensitive.

stu21t

i guess what the op means is being a large turbo it can flow a lot more than he wants it to so he needs a big wastegate to bleed off a lot of gas making the turbo do less.

dont all RX7s run massive turbos at relatively low boost and make big numbers?

Karlos G

iTrader: (4)

I see what your saying about it being sensitive with such a big WG, hadn't thought about that!
But it depends how much gasses the rotary produces, if they flow large amounts (more than the turbo will ever need to spool to the desired boost) then a big waste gate is needed, if on the other hand the GT42 needs say 90% of what the engine flows then a smaller gate will be needed....
A 60mm WG has been recommended by a tuner that has built many big power RX7's so I can only assume the advice is correct.

Rod-Tarry

I didnt have a problem but several reported bent shafts so I changed to a Tial. Didnt want to risk a problem. It worked fine on mine.

bigchez

aren't rx7 rotary engines massively fragile to big boost but run very well with moderate boost off a big turbo (ie, lots of air)? Therefore I guess a big wastegate could be used to quickly modulate (ie, dump!) boost pressure from a big turbo that comes in with a bang all of a sudden to keep it within limits?

all of that said, the size of W/G the OP suggested does seem like overkill.

andy escos

iTrader: (1)

what manufacturer makes a wastegate that uses a piston & not a diaphragm ,i seen them but can not remember who .