SWB Quattro Project

[Jamo]

Well this is it, I have no idea on my head, it's ported but how well I don't know. I've asked a few people and they only want to work on a "fresh" head so for now it's staying

I seriously doubt we will have these issues as these elitest 3 have welded exhaust ports and big extra flow which seems to be the issue.

[Thuppu]

Making me nervous that my WG will be too small

You're not alone with that feeling.

On the other hand, I shouldn't have problems as my head propably flows like a stock one.

[Jamo]

Thanks for the pick me up JP! Walked away from the car this week to have a break.

I remember you changing to the 60mm but considering the size difference between the gt42 and gt35 I thought a 44 would do be fine. The more I am looking into it the more others are having the same sort of problems. Like you we want to be able to run spring pressure right to the red line.

2 x 44mm's will not fit in mine either the single 60 is the way to go!

Making me nervous that my WG will be too small

[Billman]

1. The valve is 44mm the opening is 42mm
2. We proved on the dyno and on the logs the wastegate was fully open at 3700/3800rpm
3. lol good try

I had to

Lift becomes irrelevant beyond 15mm due to the design of the seat and valve. A hole will only flow so much before it achieves choke doesn't matter how high you lift it beyond that

As a reference point a 42mm opening has surface area of 1385.622mm2 divide this by circumference of circle (131.964) = 10.5mm

So at 10.5mm the valve has enough lift to allow maximum flow through the hole so even at 15mm it is already overkill.

A 42mm hole with nice valve angles will flow 130cfm @10" pressure drop. The exhaust ports on the head flow 124cfm @10" each if I go back in my records compared to 88cfm @10" of a standard cyl head. Doesn't matter how nice a 44mm wastegate it is it just isn't going to work. Whereas a 60mm wastegate would flow 250cfm @10"

I just wish I'd done these calculations before, worked on the assumption it would be ok because on a ported stock 34mm wastegate there was no problems with the smaller frame gt30 turbo, then again we can only learn from it.

Anyway putting all that aside Mr Hamish the good news is I've done some measuring and a 60mm wastegate dimensionally is no more in height than a stock one and there is enough space diameter wise to mount it. If you wish to plumb it back into the downpipe it would have to be into the top elbow of the downpipe. Alternatively I've got enough space to squeeze a 2.25" pipe through which will either join further down the exhaust rather than the downpipe with a slip joint or just run a separate silencer for it and kick it down to the ground.

If it goes off topic and you like make a new thread for it:

How much can the stock WG flow on a stock head/turbo setup and it can hold spring pressure to the redline?

[G60Rallye]

Thanks for the pick me up JP! Walked away from the car this week to have a break.

I remember you changing to the 60mm but considering the size difference between the gt42 and gt35 I thought a 44 would do be fine. The more I am looking into it the more others are having the same sort of problems. Like you we want to be able to run spring pressure right to the red line.

2 x 44mm's will not fit in mine either the single 60 is the way to go!

[Jeffer]

Its starting to get a little bit annoying this car!

Keep at it Hamish. I've reached that point several times...

I also changed from a 44 to a 60 mm WG. I wanted the spring pressure to be 0.8 bar just to be sure that if anything fails it would be within limits.
Now it works like a charm.

(btw; I couldnt fit 2 x 44 mm's in my engine setup.... Only 1 x 60 mm)

Good luck!

[G60Rallye]

The 44mm lifts a good way up, I dont think Tial would have designed it to limit flow due to lack of lift? 60mm is the way forwards I just need to decide how to get back into the downpipe. Could go back into the downpipe higher up or come around the front of the manifold and then under it and join the exhaust just before the driveshaft. I will have to eye it up.

[JP]

My turbo seem not to have an issue with the stock wastegate. Running 1.8 bar and having 60% N75 DC on stock spring. Turbo has an 65/75 turbine wheel and 0.70 turbine housing.

So either:

1. That wastegate has a big 44mm opening but can't flow enough.

2. The spring is very strong and cannot open with the current N75 DC

3. My head flows crappy so you have to provide me one for a head to head comparison

1. The valve is 44mm the opening is 42mm
2. We proved on the dyno and on the logs the wastegate was fully open at 3700/3800rpm
3. lol good try

Same problem I had with tial 44mm. Tial WG have not very big lift, you should first try to modify WG lift to have minimum 25mm ...
Lift is more important then valve diameter

Lift becomes irrelevant beyond 15mm due to the design of the seat and valve. A hole will only flow so much before it achieves choke doesn't matter how high you lift it beyond that

As a reference point a 42mm opening has surface area of 1385.622mm2 divide this by circumference of circle (131.964) = 10.5mm

So at 10.5mm the valve has enough lift to allow maximum flow through the hole so even at 15mm it is already overkill.

A 42mm hole with nice valve angles will flow 130cfm @10" pressure drop. The exhaust ports on the head flow 124cfm @10" each if I go back in my records compared to 88cfm @10" of a standard cyl head. Doesn't matter how nice a 44mm wastegate it is it just isn't going to work. Whereas a 60mm wastegate would flow 250cfm @10"

I just wish I'd done these calculations before, worked on the assumption it would be ok because on a ported stock 34mm wastegate there was no problems with the smaller frame gt30 turbo, then again we can only learn from it.

Anyway putting all that aside Mr Hamish the good news is I've done some measuring and a 60mm wastegate dimensionally is no more in height than a stock one and there is enough space diameter wise to mount it. If you wish to plumb it back into the downpipe it would have to be into the top elbow of the downpipe. Alternatively I've got enough space to squeeze a 2.25" pipe through which will either join further down the exhaust rather than the downpipe with a slip joint or just run a separate silencer for it and kick it down to the ground.

[Jamo]

Maybe this is why I haven't seen this issue with turbosmart wastegates?

[nervas]

Same problem I had with tial 44mm. Tial WG have not very big lift, you should first try to modify WG lift to have minimum 25mm ...
Lift is more important then valve diameter

[G60Rallye]

Its irrelevant comparing other engines realy. We proved on the dyno the gate is wide open and still it cant bleed enough gas to hold boost.

[Billman]

My turbo seem not to have an issue with the stock wastegate. Running 1.8 bar and having 60% N75 DC on stock spring. Turbo has an 65/75 turbine wheel and 0.70 turbine housing.

So either:

1. That wastegate has a big 44mm opening but can't flow enough.

2. The spring is very strong and cannot open with the current N75 DC

3. My head flows crappy so you have to provide me one for a head to head comparison

[JP]

I went and took mine for a test drive last night straight after and unfortunatelly was met with the same results 1.8bar of boost and still climbing. Have spoken to owen developments at length this morning and spoke to jeffer aswell who appeared to also have the same issue with being unable to hold boost with a 44mm wastegate.

Conclusion we have come to is that the cylinderflow on the 3 heads in question is so great in the lower to middle rpm band that the wastegate is physically not able to bleed it of enough to regulate boost and as boost starts to creep it continuous to escalate like a self feeding system. Ironically all 3 cars in question have got the same headwork on them different turbo's, cams, intakes etc only thing in common is cylinderhead and wastegates. Guess it's good for me as it shows the true gains of the head especially as Owen Developments use the 44mm to support 700-800hp 2ltr engines with no problems. Unfortunately a pain in the butt for both me and G60Rallye as we both have to change our manifold wastegate downpipe setup.

My saving grace is I went with a screamer pipe so not as horrible as it could've been.

So the options are either to run 2 x 38mm wastegates, 2 x 44mm wastegates or 1 x 60mm which I feel is going to be the easier to plumb and fit in the long run.

[JP]

its a hts 3582 with a tial mvr44,

[Thuppu]

What is the turbo and wastegate setup?