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Restrictions of running a cast t4 manifold


Parry_10
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Will a cast/log style manifold ported and the wastegate hole machined out to 40mm with a 44mm wastegate make 700hp? I know DanDan made 621hp on stock cams. A guy on supra forums made 800hp on a cast manifold. If not if anyone has a decent second hand tubular t4 manifold for sale for cheap let me know.

 

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Hey Chris,

 

I'd have no reservations about the cast manifold depending on your intended turbo choice and what you are trying to achieve. I don't think I am at "the limit" by any means. I have a Greddy intake to go onto mine and was also thinking about trying a 6766 but the car has taken a bit of a back seat in preference to working on the house lately.

 

I would make sure you port the manifold and open the wastegate port right up with very long smooth transitions into it from the main part of the manifold. I would also make sure you join the wastegate dump tube back into the downpipe, keep all the wastegate piping very smooth with no real turns, make sure the downpipe is 4" (and ideally the exhaust), and don't go silly on the turbo A/R - the spool will be very fast anyway so you don't need to choke things up. Back when I first did it, my 0.81 A/R 6776 was spooling faster than Jamie's 0.68 A/R 6776 (tubular manifold) and making more torque and power at the same boost.

 

What turbo are you planning to use and what is this for - road use, drag racing, track use etc?

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Will a cast/log style manifold ported and the wastegate hole machined out to 40mm with a 44mm wastegate make 700hp? I know DanDan made 621hp on stock cams. A guy on supra forums made 800hp on a cast manifold. If not if anyone has a decent second hand tubular t4 manifold for sale for cheap let me know.

 

Discuss...

 

There your answer mate :D

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Hey Chris,

 

I'd have no reservations about the cast manifold depending on your intended turbo choice and what you are trying to achieve. I don't think I am at "the limit" by any means. I have a Greddy intake to go onto mine and was also thinking about trying a 6766 but the car has taken a bit of a back seat in preference to working on the house lately.

 

I would make sure you port the manifold and open the wastegate port right up with very long smooth transitions into it from the main part of the manifold. I would also make sure you join the wastegate dump tube back into the downpipe, keep all the wastegate piping very smooth with no real turns, make sure the downpipe is 4" (and ideally the exhaust), and don't go silly on the turbo A/R - the spool will be very fast anyway so you don't need to choke things up. Back when I first did it, my 0.81 A/R 6776 was spooling faster than Jamie's 0.68 A/R 6776 (tubular manifold) and making more torque and power at the same boost.

 

What turbo are you planning to use and what is this for - road use, drag racing, track use etc?

 

Hi dan,

 

Well I was thinking of not joining the wastegate back into the downpipe and having a screamer pipe. The exhaust I will be custom making 4inch from turbo all the way back. I also have a greddy intake which I have port matched etc and a q45 throttle body. I have got hks 264/272 cams and ti springs and retainers and plan on running a 7500rpm limit. The car is mainly for street use, I really want to make 650-700hp and saw you made 621hp on stock cams just dont want the manifold to start becoming a restriction for me. I think I will go with a precision 67mm billet journal bearing turbo as the manifold will give me quick spool anyway. I think I can safely open up the wastegate port to 40mm like you did without getting to close to the edge of the casting.

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I think you might be pushing it a bit. And your fuel setup is way overkill lol

 

But, if you plumb in an EGT probe into a #6 you should be able to keep a gauge on the EGT's - and let the Syvecs control it

 

Haha I had to go with the same fuel set up that was on the car before because I bought all the lines twin filters etc so it was just easier and ive over specced on pretty much everything to be honest but hopefully that will pay off and it will be a great car and produce good figures. Thats what im worried about Johnny is the manifold restricting me I really want to hit 700hp all the parts I have are more than capable of it so I would hate the manifold to be the only restriction!

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Haha I had to go with the same fuel set up that was on the car before because I bought all the lines twin filters etc so it was just easier and ive over specced on pretty much everything to be honest but hopefully that will pay off and it will be a great car and produce good figures. Thats what im worried about Johnny is the manifold restricting me I really want to hit 700hp all the parts I have are more than capable of it so I would hate the manifold to be the only restriction!

 

Well, I'm sure there's some maths that can work it out - might be worth asking someone like Chris Wilson?

 

Or I know a kit you could buy lol

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Well, I'm sure there's some maths that can work it out - might be worth asking someone like Chris Wilson?

 

Or I know a kit you could buy lol

 

Yeh more hours of research I guess, I am going to be making up my own kit mate. Im even considering making a custom tubular manifold.

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I bought an SPA cast manifold from USA- the same one Frederic Aasbo has fitted to his GT86 2JZ drift car. The runners are larger than the Treadstone cast manifold, but it did cost a little bit more- worked out at £350 delivered + tax. I would be willing to sell that for a good enough offer as I ended up fitting a Sinco Customs steel tubular and so never even fitted the SPA manifold!

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I bought an SPA cast manifold from USA- the same one Frederic Aasbo has fitted to his GT86 2JZ drift car. The runners are larger than the Treadstone cast manifold, but it did cost a little bit more- worked out at £350 delivered + tax. I would be willing to sell that for a good enough offer as I ended up fitting a Sinco Customs steel tubular and so never even fitted the SPA manifold!

 

What was the reason you never fitted it? Have you got a link for more information on the manifoid. What power did the drift car make? I already have a cast manifold lined up but wouldn't mind looking at others for research.

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A cast one will spool quicker and cost is nothing compared to a whifbitz scroll manifoldit will just be my own time and labour to make the cast manifold as good as it can be. Plus if it pays off and I make good power 650 mark I think a lot of people will be screwing they paid 1200 for a manifold and a cast one costs 200 and will spool quicker and is as reliable as you can get.

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