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Discussion Starter #1
Hey SF,

I've seen there's another SPA manifold thread active right now, but I didn't want to hijack it, so I'm posting a separate thread. I've been looking at exhaust manifolds for quite a while now and was going towards the SPA cast manifold, as it seems a great option for both spool and power, and has been proven in a lot of builds. But recently I've found out that SPA make the same manifold but in a twin scroll option for the 2JZ, as seen here:

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Now, as far as my knowledge goes, this is the only twin scroll cast manifold on the market for the 2JZ. And I've been wondering how it would perform compared to the single scroll option. Would the spool/response be better, as seen in tubular manifolds, and would the top-end be affected at all? Currently looking at the 6870 Gen 2 turbo, I would be stuck between the 0.81 A/R single scroll housing on the single scroll SPA mani, and the 1.00 A/R twin scroll housing on the twin scroll SPA mani, now I've seen this option exists. Does anyone on here have experience with this SPA version or maybe has seen some results with it? Any input would be very appreciated!

Thanks.
 

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I would imagine with a twin scroll housing that it would spool a bit harder than the open design. I can't imagine there would be a downside. No experience with this product.
 

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I'll start by saying that am the biggest proponent of the SPA manifold. But with a 6870, I think I would go tubular unless a hard hitting setup is what you're after. The SPA runners are short for great spool-up and mid-range, but that has got to limit top end HP a little, if max HP is what you're after.

Al
 

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Unfortunately the SPA twin scroll isn't really effective as a twin scroll, and that's apparent just from the pictures. The whole purpose of a twin scroll is to separate exhaust pulses so a 'collision' doesn't happen and the JZ's firing order makes that an easy 123 vs 456 as far as operational cylinders. But in order to get this benefit the WG merge cannot be so close to the turbo flange. The 'collision' will easily occur in the space above the wastegate and the benefits of this vs a proper dual WG twin scroll manifold will be significantly reduced as a result.

Other twin scroll, single gate manifolds such as the later HKS manifolds get around this issue with physical distance down runners to a WG flange - by the time a given 'collision' is in play the exhaust that would be affected is through the turbine housing already.

That said, T6Rocket is spot on about a 6870 being a big ass turbo for a SPA manifold, but it has been done. If you decide to go with a SPA manifold with that 6870, that would be an excellent candidate for a SPA open T4 manifold + Sound Performance QSV + Twinscroll 1.00 housing on your turbo. But I would carefully measure before ordering the turbo or the QSV as that may be too big of a turbo to fit over a QSV with the SPA manifold.

If it were my build, I'd run a tubular T4 divided manifold with twin wastegates on the twinscroll 1.00.
 

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Discussion Starter #5
Thanks for the replies fellas.

Hi Wreckless, that's a very well thought out post, helps a lot with most of my questions. I appreciate it a lot. Yes, the 6870 turbo is a big boy turbo for a cast manifold, but I've seen that the SPA manifold usually does better on the top end compared to other cast manifolds out there while still having excellent spool/response, so that's why I originally thought about using it. A lot of the points you made about the twin scroll SPA version are very valid.

I should probably add that my build is gonna be 3.4L stroker / 9.0:1 cr / built head with Kelford 264/272 cams etc. so I'm not sure if the SPA manifold isn't overkill to begin with. I really want to hit full boost before 4k RPM and still pull hard to redline, but with the said build it might be achievable even with a good tubular manifold. I think something like a PHR S23 manifold and the 6870 1.00 A/R might be the best middle ground for both spool and power... Would you consider it being a more optimal setup all-around?

Best regards.
 

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Thanks for the replies fellas.

Hi Wreckless, that's a very well thought out post, helps a lot with most of my questions. I appreciate it a lot. Yes, the 6870 turbo is a big boy turbo for a cast manifold, but I've seen that the SPA manifold usually does better on the top end compared to other cast manifolds out there while still having excellent spool/response, so that's why I originally thought about using it. A lot of the points you made about the twin scroll SPA version are very valid.

I should probably add that my build is gonna be 3.4L stroker / 9.0:1 cr / built head with Kelford 264/272 cams etc. so I'm not sure if the SPA manifold isn't overkill to begin with. I really want to hit full boost before 4k RPM and still pull hard to redline, but with the said build it might be achievable even with a good tubular manifold. I think something like a PHR S23 manifold and the 6870 1.00 A/R might be the best middle ground for both spool and power... Would you consider it being a more optimal setup all-around?

Best regards.
I think it's important to set your priorities honestly - I would even take some time with a notepad and think about it. Too many people start a build and want some (number) whp and want it to spool by (number) RPM at the latest without planning for whether the spool or the power number matters more. Then trying to split the difference they build a combination trying to make that 'sweet spot' happen but instead just suffer a mix of non-optimized parts as a result. Think about the drive you want to take with that car and what's really going to matter on that drive - and more often than not for most pleasure driving the spool threshold matters more, and only if you're going to do lots of street digs/half mile or similar competitions does the raw HP really matter most.

100% honest 'full boost' before 4000rpm on a 6870 will require nitrous, regardless of manifold or your particular 2JZ build. IMHO at least, and based on every 6870 dyno I've ever seen.
If that 4000rpm spool threshold is what you're really after, I'd opt for a 6466 on a SPA cast manifold and I'd set up the rest of the engine accordingly for that powerband - GSC S1 or Kelford 260/260's, etc. If the power potential of the 6870 is what you're really after, set up the engine to max out that turbo's potential instead of kneecapping it in random places (e.g. going to small on the turbine housing) to make some arbitrary spool goal. In that case, the 6870 on the PHR manifold and the GSC S2's or Kelford 264/272's and a good aftermarket intake manifold would all be part of that build list.
 
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I think it's important to set your priorities honestly - I would even take some time with a notepad and think about it. Too many people start a build and want some (number) whp and want it to spool by (number) RPM at the latest without planning for whether the spool or the power number matters more. Then trying to split the difference they build a combination trying to make that 'sweet spot' happen but instead just suffer a mix of non-optimized parts as a result. Think about the drive you want to take with that car and what's really going to matter on that drive - and more often than not for most pleasure driving the spool threshold matters more, and only if you're going to do lots of street digs/half mile or similar competitions does the raw HP really matter most.

100% honest 'full boost' before 4000rpm on a 6870 will require nitrous, regardless of manifold or your particular 2JZ build. IMHO at least, and based on every 6870 dyno I've ever seen.
If that 4000rpm spool threshold is what you're really after, I'd opt for a 6466 on a SPA cast manifold and I'd set up the rest of the engine accordingly for that powerband - GSC S1 or Kelford 260/260's, etc. If the power potential of the 6870 is what you're really after, set up the engine to max out that turbo's potential instead of kneecapping it in random places (e.g. going to small on the turbine housing) to make some arbitrary spool goal. In that case, the 6870 on the PHR manifold and the GSC S2's or Kelford 264/272's and a good aftermarket intake manifold would all be part of that build list.
Wreckless are you moderator or mentor, damn man ! I wish I would of reached out to you before I built my car. I am learning the hard way right now re-doing my setup.
 

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May not be a big issue in the JZA80 chassis but my S362 hit the shock tower with a .88 A/R housing on the SPA cast "undivided" manifold on a GS300. The way the manifold pushes the turbo away from the motor is rather unappealing. Compressor housing is also way close and I had to push in that area a little bit for clearance.

254958
 

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Wreckless are you moderator or mentor, damn man ! I wish I would of reached out to you before I built my car. I am learning the hard way right now re-doing my setup.
LOL thank you dude - I'm just a guy that did it all the wrong way and worked in the performance industry long enough to see a lot of other folks do it the wrong way. Putting happy miles on the odometer matters most, all else is secondary! I'm glad I can share what I've learned and I'm glad that it helps out 🍺

May not be a big issue in the JZA80 chassis but my S362 hit the shock tower with a .88 A/R housing on the SPA cast "undivided" manifold on a GS300. The way the manifold pushes the turbo away from the motor is rather unappealing. Compressor housing is also way close and I had to push in that area a little bit for clearance.
Aristo engine bays are tighter and with the JZA80 it's still a tight fit with the SPA manifold + BW turbo. Pretty much anything larger than a T04S pattern compressor cover is too big to easily fit with the SPA manifold. The OG log manifold offers much better clearance for tighter engine bays. While it may not offer the peak HP that the SPA does, the difference is almost insignificant on smaller turbos like an S362. Seeing as you've already got the DP/IC piping etc all figured out there's no benefit to changing it now, but just in case anyone else asks...

Also, while there's only so much you can do with the stock MAFS still in play, I'd consider having a fabricator address your intake pipe. Expanding it to 4in just past the MAFS will make a difference in transient response and peak HP, and it'll look a good bit better too.
 

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Wreckless , the Cast Mnaifold route is one I am considering. In your experiance what are the differences in Characteristics between the Treadstone type Log manifold and the SPA one ?

I was considering the manifold this thread is about but find your comments interesting and not sure its really worth the extra for a "semi" twin scroll manifold.
 

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Wreckless , the Cast Mnaifold route is one I am considering. In your experiance what are the differences in Characteristics between the Treadstone type Log manifold and the SPA one ?

I was considering the manifold this thread is about but find your comments interesting and not sure its really worth the extra for a "semi" twin scroll manifold.
For 300-400hp the log manifold will likely spool a little faster than the SPA because of its reduced internal volume, but that also limits its top end performance significantly. Between 400-550hp or so there'd be little difference between the two performance-wise, with the possible exception of less boost creep from a 44mm WG equipped SPA manifold vs the 38-40mm WG on the log manifold.
Above 550-600hp the SPA absolutely smokes the log manifold with better overall flow and better runner design for top end HP and minimizing backpressure. If you were trying to set a HP record with a given turbo, the SPA is without a doubt the one to get regardless of your HP goals.

The original open-flange SPA manifold vs SPA 'twin scroll' manifold is anyone's guess, but my gut is telling me that the 'twin scroll' benefit will be minimal if anything at all because of the way SPA implemented it.
If they'd kept both sides totally sealed and went with twin WG's (one on either side) or at least did their best to completely seal the sides while the WG was closed, different story and I'm sure it would be well worth going twin scroll for that benefit. Looking at the pictures you can see how they kept things 'sealed' with the actual casting, only to create that open space right at the WG valve with the welded-on V-band WG flange adapter. Kind of a shame, really.

I also can't help but wonder if that divider in the WG port won't reduce WG flow enough to make boost creep an issue with some larger turbos. I really wish they'd changed the casting to run two 35-40mm WG's, one on either side of the scroll. That would truly be the best of all worlds for virtually any application below 800-900hp.
 

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Thank you for the reply.

Its very useful and confirms that I will look to get an Open SPA manifold as it seems the best option when looking for a cast manifold.
 

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Discussion Starter #13
Thanks for all the replies once again fellas. They really help out with making an educated decision.

I've also decided on going with the "normal" single scroll SPA manifold with a 45mm Turbosmart GEN-V wastegate and a 4" DP/MP combo. I think it's already solid enough considering it will go on a 3.4L stroker motor with a fully built head, etc. Should be a super nice street setup. After talking with my builder he's pretty much on the same page.

Only "pickle" left right now is turbo choice, originally I was set on the Precision 6870 Gen 2, but now, I have my eyes also on the Xona Rotor XR 9569S, after doing some research. They have some really trick stuff like their UHF turbine wheel, billet center housing, integrated oil filter, etc. In Precision numbering it's a 6869, so basically the same class as the 6870 Gen 2. I've seen some extremely impressive results from XR turbos, from Evos and Subarus to things like GT-Rs and Calvo Vipers. There's a certain Evo on YT that makes 1100awhp boost only on the 9569S and it has very impressive spool/response for a small capacity 4-banger motor. But for some reason I've not seen ANY results with ANY turbo from the XR lineup in the Supra / 2JZ / 1JZ scene. Not even the RB scene for that matter. There's a .81 A/R and .96 A/R single scroll options for the XR lineup, so those would fit nicely to the SPA mani. I guess someone needs to be a "guinea pig" sooner or later. Decisions, decisions...
 

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Thanks for all the replies once again fellas. They really help out with making an educated decision.

I've also decided on going with the "normal" single scroll SPA manifold with a 45mm Turbosmart GEN-V wastegate and a 4" DP/MP combo. I think it's already solid enough considering it will go on a 3.4L stroker motor with a fully built head, etc. Should be a super nice street setup. After talking with my builder he's pretty much on the same page.

Only "pickle" left right now is turbo choice, originally I was set on the Precision 6870 Gen 2, but now, I have my eyes also on the Xona Rotor XR 9569S, after doing some research. They have some really trick stuff like their UHF turbine wheel, billet center housing, integrated oil filter, etc. In Precision numbering it's a 6869, so basically the same class as the 6870 Gen 2. I've seen some extremely impressive results from XR turbos, from Evos and Subarus to things like GT-Rs and Calvo Vipers. There's a certain Evo on YT that makes 1100awhp boost only on the 9569S and it has very impressive spool/response for a small capacity 4-banger motor. But for some reason I've not seen ANY results with ANY turbo from the XR lineup in the Supra / 2JZ / 1JZ scene. Not even the RB scene for that matter. There's a .81 A/R and .96 A/R single scroll options for the XR lineup, so those would fit nicely to the SPA mani. I guess someone needs to be a "guinea pig" sooner or later. Decisions, decisions...
When my 6870 Gen 2 bit the dust, I contacted xona for options. They steered me away from their own product line, given my application, desired boost range, and power goals (1050whp+).

Having said that, I really enjoyed by 6870 1.00 AR, while it lived(a very short life). I'm running a twinscroll long runner BPA manifold, ported SD intake, 4" hot & cold side, and BC 276s. I was hitting peak torque at ~4800rpm on the dyno, @40psi making 960whp & 770tq, note that power was falling off after ~6800rpm, and I was overspinning it.
 
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