Divided vs undivided, 2 gates vs 1

Right so I've been reading on Supraforums, mkivsupra and several other Supra-related websites and the amount of contradiction between '2 gates being superior to 1' followed by 'no it's not it's more hassle more cost more to go wrong for just a tiny bit quicker spool' I'm kinda losing my mind. I want to get this sorted once and for all before wasting money on two gates and an incorrect manifold.

Ideally yes I would love a divided manifold and turbo alongside two wastegates, but on a 600-700hp street car, can the boost not be adequately controlled via just one wastegate? Sean from Titan Motorsports seems to think it's impossible to control boost on a 6466 divided, with divided manifold and ONE gate, he says you must have two gates to prevent boost spikes and to prevent the pulses interfering with each other.

So, my question is can you run a 6466 dbb with a divided housing, on a twin scroll/divided manifold with just ONE wastegate controlling boost? I don't want to know if it's more/less efficient than using two, but can it be done in a way that isn't going to cause horrendous boost spikes or surge?

Thanks in advance!

One of the many links I read: http://www.mkivsupra.net/vbb/showthread.php?319063-Twin-External-Vs-Single-External-Wastegates

The HKS manifold is divided with a single wastegate flange. I think the SRD manifold comes like this too, and Whifbitz probably offer it as an option.

Jamesy's car uses the full T04Z kit, and is supposed to be very quick and responsive from what I hear, so is Sean from Titan Motorsports saying that this is impossible?

There seems to be a lot of myths and BS pedalled around the US forum by supposed respectable traders

This is probably the best thing you are going to read today, hopefully you're answers are inside.

http://www.supraforums.com/forum/showthread.php?672553-Hks-full-race-t4-exhaust-manifold-test-results

Read the results correctly, they are quite surprising

The HKS manifold is divided with a single wastegate flange. I think the SRD manifold comes like this too, and Whifbitz probably offer it as an option.

 

Jamesy's car uses the full T04Z kit, and is supposed to be very quick and responsive from what I hear, so is Sean from Titan Motorsports saying that this is impossible?

 

There seems to be a lot of myths and BS pedalled around the US forum by supposed respectable traders

Yeah that's what got me even more confused. Why would SRD sell a single gate manifold if 1. It's impossible and 2. It's worse than twin gates?!

My mechanic tells me to ignore all the crap the Americans say, as most of it is 'do it the way everyone does it or it's the wrong way' supposedly! I'll message James, I'm sure he can shed some light on what a single gate is like. I remember you saying that you're using a single gate too? Are you going for a divided manifold/turbo?

This is probably the best thing you are going to read today, hopefully you're answers are inside.

 

http://www.supraforums.com/forum/showthread.php?672553-Hks-full-race-t4-exhaust-manifold-test-results

 

 

Read the results correctly, they are quite surprising

Wait, so a single gate makes MORE power than two?! Well, I think my mind is firmly made up!

We have two cars running 6466 gen 2 on divided manifold and single HKS 60mm gates, no problems at all

The yanks usually use a 50mm gate which may be where the problem is.

There may be an argument to say a twin gate, true divided setup will spool faster and provide better boost control. To be honest, it's way beyond my limited knowledge. But there are plenty of single gate divided manifold setups working very well on cars all over the world.

I've always understood divided with a 60mm single gate is the way to go

Wait, so a single gate makes MORE power than two?! Well, I think my mind is firmly made up!

I have the HKS manifold, single gate and divided manifold. It is a nice piece of kit. I'm sure Paul also did something that showed twin W/G were better and did aid spool and that he was stopping sales of the singles as they didn't sell ?

Lee likes the reliability of one and generally recommends a 60mm gate ( I think )

I've always understood divided with a 60mm single gate is the way to go

Only as in it simplifies the installation, and costs less. I doubt a single gate outperforms a twin gate setup overall.

We have two cars running 6466 gen 2 on divided manifold and single HKS 60mm gates, no problems at all

 

The yanks usually use a 50mm gate which may be where the problem is.

Right well in that case I'm definitely going for a single gate to simply things, keep the cost down and to keep the heat down. Bloody yanks and their theories

There may be an argument to say a twin gate, true divided setup will spool faster and provide better boost control. To be honest, it's way beyond my limited knowledge. But there are plenty of single gate divided manifold setups working very well on cars all over the world.

That's exactly what I've been lead to believe. A true divided turbo/manifold setup with two gates outperforms the same setup except with one, however it costs more, weighs more, more to go wrong etc.

I have the HKS manifold, single gate and divided manifold. It is a nice piece of kit. I'm sure Paul also did something that showed twin W/G were better and did aid spool and that he was stopping sales of the singles as they didn't sell ?

 

Lee likes the reliability of one and generally recommends a 60mm gate ( I think )

Well he sells manifolds with single gates, so I doubt that's true. If it is he wouldn't still sell them. I like the idea of having increased reliability and cheaper costs by using one than all the hassle of having two just for that tiny bit quicker spool. I'm VVTi anyway so that's gonna help a load too!

HKS did twin wastgate very early on then went back to single gate

I've gone twin on mine as spool is hugely important to me. I'm still running my autobox currently so pushing the power isn't my primary concern either.

I don't really buy in to the 'more to go wrong' ethos, as it's hardly a huge complication. If I get 200-300 RPM of spool, I'm happy... that, and going single is a HUGE investment anyway, and the price difference was negligible once everything is said and done. For reference, I'm using a Whifbitz twin WG manifold & Turbosmart wastegates. And the weight? If I want to save the weight of the extra bit of pipework and the additional wastegate, I'll go jogging once a week

An extra wastegate is hardly a concern to reliability, but equally the difference in response will likely be minimal unless you're running a huge turbo. Switching to vvti will likely reap a much more noticeable gain if spool is important. The yanks, who once dismissed vvti out of hand, are now mad for it.

An extra wastegate is hardly a concern to reliability, but equally the difference in response will likely be minimal unless you're running a huge turbo. Switching to vvti will likely reap a much more noticeable gain if spool is important. The yanks, who once dismissed vvti out of hand, are now mad for it.

Project for the future, I've spent all I've got getting it this far

Someone please explain to me how 2 gates aids spool cause i`m struggling to get that.

Someone please explain to me how 2 gates aids spool cause i`m struggling to get that.

Not spool, controlling boost

Well he sells manifolds with single gates, so I doubt that's true. If it is he wouldn't still sell them. I like the idea of having increased reliability and cheaper costs by using one than all the hassle of having two just for that tiny bit quicker spool. I'm VVTi anyway so that's gonna help a load too!

Just for you Jack

We stopped making the single wastegate kits because everyone was going with the twin wastegate version and the price difference was so minimal it wasn't worth selling 2 different kits. The twin wastegate setup provides better boost response and boost control over a single wastegate version, when we tested them back to back many years ago we gained about 300rpm in spool up time switching from single wastegate to twin wastegate.

 

 

Thanks

Paul

Spool occurs with the wastegate closed Unless your wastegate is creeping open at the wrong time, the amount or type of them shouldn't matter squat. And if it is creeping open, fix that instead of hiding it by halving the gas flow to it.

I would be very interested to see suppliers/manufacturers debate the claims they make about their manifolds. The link earlier comparing the Fullrace manifold with the ancient but we'll designed HKS manifold is very interesting.

IIRC it's to do with the fact they're completely divided, rather than the fact there's two wastegates

Well a divided manifold is supposed to stop exhaust pulses interfering with each other, mainly on 4-cylinder engines from what I recall. You need a divided turbo housing as well to get the most benefit. Didn't think it was an issue with an inline six though?

When we started producing our own turbo kits many years ago we started off with a single wastegate version. We tested this back to back against an HKS one and it increased spool up by 500rpm, which is a lot! That's just down to the design.

We then tried a twin wastegate design and knocked another 300rpm off the spool up time.

So from there we decided to sell our kits with the twin wastegate setup. Cost wise it's not much different to a single wastegate as a smaller one is cheaper to buy than a big one, i think it's something like £50 off the top of my head. Wastegates don't tend to go wrong so reliability shouldn't be effected and the latest Turbosmart wastegates are so small weight doesn't come into it either.

We still sell the single wastegate manifold on its own as some people want them but they very rarely sell, pretty much all of our sales are twin wastegate.

I think the problems people might be having in the USA with the latest billet turbos is probably boost creep due to poor manifold design. The turbos are flowing so much air that they then show up weaknesses in the manifolds, wastegate not big enough or just the way the wastegate is mounted to the manifold. Take that billet turbo off and put an old school turbo on and the issues go.

Hope that helps.

Well a divided manifold is supposed to stop exhaust pulses interfering with each other, mainly on 4-cylinder engines from what I recall. You need a divided turbo housing as well to get the most benefit. Didn't think it was an issue with an inline six though?

I think it's also to do with preventing back pressure in the manifold, something an inline 6 surely still produces being an engine

When we started producing our own turbo kits many years ago we started off with a single wastegate version. We tested this back to back against an HKS one and it increased spool up by 500rpm, which is a lot! That's just down to the design.

We then tried a twin wastegate design and knocked another 300rpm off the spool up time.

So from there we decided to sell our kits with the twin wastegate setup. Cost wise it's not much different to a single wastegate as a smaller one is cheaper to buy than a big one, i think it's something like £50 off the top of my head. Wastegates don't tend to go wrong so reliability shouldn't be effected and the latest Turbosmart wastegates are so small weight doesn't come into it either.

We still sell the single wastegate manifold on its own as some people want them but they very rarely sell, pretty much all of our sales are twin wastegate.

 

I think the problems people might be having in the USA with the latest billet turbos is probably boost creep due to poor manifold design. The turbos are flowing so much air that they then show up weaknesses in the manifolds, wastegate not big enough or just the way the wastegate is mounted to the manifold. Take that billet turbo off and put an old school turbo on and the issues go.

 

Hope that helps.

Wow, lots of useful information! I think, for now, a single gate will be the way to go. If it gives me any issues, I can add another one

I'm with bignum and Ian here. I can't understand how a wastegate configuration aids rpm's relation to spool. A properly operating single wastegate will be closed just like twins would be until the turbo starts to spool and will only open at the pressure it's set to. If the answer is down to the fact that the gate creeps open then surely the tune is out?