Waste Gate On Standard Manifold Vs Waste Gate On Turbo

[Dose Pipe Sutututu]

^ top setup, it's looking real sex

[WYTSKY]

I've also got the gate off the housing.

Had both the manifold and housing sent off ( can't remember the place but its about 120km out of Melbourne ) and coated inside and out to reduce heat as my last manifold cracked. It actually does seem to work, it's still bloody hot, but you could brush past it for half a second and not get burnt whereas before a quarter of a second and you were smelling burnt flesh.

holds 18-19psi dead flat, I normally put a "heatshield" over the top of the gate so you can't see it. You can see the weld just before the gate is no where near as good as the weld joining the gate to the housing... that's the difference between a pro doing it and me and my mates still no leaks and has been a few years now.

[r34unit]

I'm all done fabricating my set up

I also cut out the divider on the inside of the manifold

[M@&k]

Any more experience with running the gate off the turbine housing at 90 degrees (i.e. similar to WYTSKY above)? Thought I've seen pics from Stao at Hypergear with similar ~90 deg exit path off turbine housing.

It makes sense to me to have the gate entry in line with flow as per pics of Scott's work earlier, but having it come off at around 90 degrees seems a bit easier for packaging the gate when using the stock exhaust manifold.

Interested if others have also had success with wastegate situated as per Adam's (WYTSKY) above?

[scotty nm35]

You will find it hard to get a definite answer, as there is no right and wrong, just varying wastegate flow. If you are running high enough boost you will probably never know the flow is restricted anyway.

At such high gas speeds you need to imagine the exhaust flow is water, as it would act very similar. Would you expect water to flow well out of a 90 degree outlet? Or would it rather go past into the turbo as it is easier...

[M@&k]

Yeah, point taken. I guess at some point of boost (or perhaps more accurately engine flow) the back pressure at the turbine inlet would become high enough that the wastegate becomes the path of least resistance and starts flowing. The question then is at what boost level does this happen... it depends I know

I would imagine that for a smaller turbine and housing A/R the back pressure would be higher making flow through a 90 deg outlet more likely for a given boost level. Perhaps for a given boost target if you go for a larger turbine and larger A/R housing the need to have a smoother transition into the wastegate becomes more important?

I agree that a smooth transition into the wastegate would be the most efficient for any application. Just curious if it would be possible to get away with something less ideal if it helps to package the gate and outlet piping.

[scotty nm35]

You can buy some very tight steam pipe bends, there is no reason to use straight pipe to make it easier, other than to get out of die grinding so much. It is obviously a lot easier to get the die grinder into the rear housing than the manifold for internal smoothing.

[hypergear]

Ok. Some feed backs with results:

OP6 Standard high flow profile. + Stock exhaust manifold Internal and externally gated result with wastegate fitted to factory exhaust manifold:

Gain of 25kws based on same boost level.

ATR43SS2 stock exhaust manifold, internal and external gate. With external gate fitted on rear housing:

Solid red = internal gate

Dotted red = external gate

Overall gain of 5kws.

So in summary based on using factory exhaust manifold.

The gain over internal gate by fitting external gate on factory exhaust manifold in this case is: 7.24%

While the gain over internal gate by fitting external gate on turbine housing is: 1.5%

In conclusion. If you are considering fitting an external gate to a factory setup, Then fit it to stock exhaust manifold.

[boostn0199]

Very interesting results.

[scotty nm35]

So in summary based on using factory exhaust manifold.

The gain over internal gate by fitting external gate on factory exhaust manifold in this case is: 7.24%

While the gain over internal gate by fitting external gate on turbine housing is: 1.5%

In conclusion. If you are considering fitting an external gate to a factory setup, Then fit it to stock exhaust manifold.

All it proves is the external gate flowing better made more power. So obviously, the wastegate doesn't simply drop the manifold pressure... It allows more airflow in the top end once the turbo becomes a flow restriction. That is the belief I have always held, and is why I don't like the 90 degree wastegate entries, or square edge protrusions in the turbine housing.

Get in there with a die grinder Stao.

[hypergear]

The manifold of a Rb25det could be significantly different to a M35 Stagea which should be more modernised.

There is a 15 KWs gain just by swapping stock exhaust manifold to some thing properly made. The restriction on it is before the entry of the turbine housing, of where three collectors merges into one. By adding an additional collector at that point reduce excess heat, and pressure as what we can see in the change in upper power and torque curve.

The overall gain of this modification have made a difference of 31kws, with a final result of 376rwkws that is some thing that no one have ever made using turbine housing mounted external gate setups on standard Rb25det exhaust manifold. This is also my first attempt, there are few things that could be done improving upper rev range torque.

Scotty: it is probably worth while making a jig and properly fabricate stock RB exhaust manifold in similar manner to what I've done. With proper external gating setups, the factory exhaust manifold could be performing at same level as some of the popular aftermarket high mount setups.

[scotty nm35]

If i was going to modify the stock manifold I would need to die grind it internally and smooth the entry into the gate. I just don't see the point of hacking up a manifold when I can weld the gate to the turbine housing and make similar power to a highmount, with better response. Your setup needs a little work imo, and a proper external gate housing, I am quite happy to help with ideas with you if you like as you seem to enjoy dyno testing as much as I do.

I have done this many times for RB's and VQ's, it is nothing new. Perhaps you should back to back one of my turbine housings to see any gains.

You obviously didn't believe the stock manifold could flow 430kw unmodified, but perhaps you are leaning more that way after your recent trials?

[Dose Pipe Sutututu]

well Stao, you still have my rear housing that Scotty modified.. why don't you pop it on a dyno and try it out?

[Guilt-Toy]

hahahahaa.. yeah pop it on a dyno and try it out.. its only a 15 minute job. lol

I am putting a 40mm ext gate on my stock manifold, its running a hks 2535 making 235rwkw with boost issues... going to go external instead of stuffing around with actuators. would like to see 250rwkw from this turbo on 98. maybe 280ish with e85.

[Dose Pipe Sutututu]

hahahahaa.. yeah pop it on a dyno and try it out.. its only a 15 minute job. lol

Not sure if you're being a smart arse again or not.. but do please tell me if you are...

Stao pulls and puts on turbos to his car like weekly, I'm sure swapping over a rear housing with one of his SS2 turbos whilst it is still on the car isn't that much of a deal to him.

So cut the bullshit.

[scotty nm35]

Unfortunately your rear housing is still an internally gated hypergear, modified to suit the external. There are still gains to be had over yours, with one of my external gate housings Johnny, as I spoke to you about. Hopefully the internal gate hole doesn't affect the flow too much.

One thing I need to talk to Stao about is his laser cut T3 spacer, it is much larger than the T3 flange, as he cut it to suit the gasket, not the flange. This means there is a 5mm+ square edge on either side of the flanges, right at the critical point before the nozzle.

I am only trying to show my results are real, and that the stock manifold flows fine unmodified. I am more than happy to share results and help others achieve similar power on the stock gear, I don't like people wasting money and introducing other issues (like melting heater hoses, clearance to the chassis rail, runners hitting the head, defects) by fitting of these aftermarket manifolds to a road car, which gain very little at this power level from my experience. No bullshit.

[hypergear]

Well, my claims are so far are supported by evaluation results. Cold side might be flow related, how ever the turbine end has every thing to do with pressure. I'm not going to get a 31kws gain from 5kws regardless of how smooth my screamer pipe is or how differently shaped of turbine housing might be, based on the same size. Beside exhaust manifold restrictions from RB has already been proved.

Details of the evaluation on exhaust manifold is at:

http://www.skylinesaustralia.com/forums/topic/261613-hypergear-hiflow-service-continued/page-298

Its is obviously much cheaper using factory exhaust manifold, If people can make big power from it externally gated off turbine housing then no one would be bothered going for high mounts. And we would be seeing plenty of results supporting it.

Scotty: If you are well to weld one for me free of charge, then I'll be happy to trail it and give you dyno feed backs.

Johnny: Unfortunately I'm not be able to trail your exhaust housing as the dump pipe of mine won't line up to your current (already been cut). Since you've got an external gate this exercise isn't very costly.

[scotty nm35]

Scotty: If you are well to weld one for me free of charge, then I'll be happy to trail it and give you dyno feed backs.

I have already spoken to you about working for free, or in this case losing money. My kids need to eat you know. Perhaps you can make me a turbo for free as a swap?

I was just trying to help you learn and further your development. Sticking your head in the sand to prove your point is counter-productive as there is always a better way.

I have no need to prove my theories any more as I already have dyno results on quite a few Skylines/Stageas to prove my setup works. Perhaps you don't think they are accurate... Why don't you head down to Edge for a run instead.

[blah_blah]

well Stao, you still have my rear housing that Scotty modified.. why don't you pop it on a dyno and try it out?

Unfortunately your rear housing is still an internally gated hypergear, modified to suit the external. There are still gains to be had over yours, with one of my external gate housings Johnny, as I spoke to you about. Hopefully the internal gate hole doesn't affect the flow too much.

Oh this is like de ja vu

Also thought about asking Scotty to weld on an external gate to my turbo housing, and he told me the same thing

Save money I spose lol

[hypergear]

I'm not in the business of doing welding related fabrication work, all arguments are purely technical referring to topic. I'm only in the process of finding the most cost effective way of creating the highest possible out put. And if my ideas have resulted in better output then it is far more effective then what had been done.

I only believe what I see based on solid results. So if some one claims Rb25det factory exhaust manifold on a stock spec engine is capable of flowing 400rwkws+ on E85 then I don't believe it till I see it. VQ25 results does not count.

The cold side has some to do with flow, The hot side has more to do with pressure.

Assume the amount of volume that is in side the turbine housing does not change, then pressure at any point of exist remains constant, which is why the shape of the housing based on identical volume has no affect in velocity of pressure discharge, As result, by high flowing a T3x turbocharger out of a R34 Neo makes no difference to, as if the same turbocharger was inside a .63 turbine housing made by whom ever.