New 4 Branch Stainless steel manifolds slant 4

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New 4 Branch Stainless steel manifolds slant 4

Postby edgoose1 » Sun Aug 18, 2019 6:08 pm

In the next couple of months a am having a complete exhaust system made in stainless steel for the Firenza.
Goughs of Nottingham quoted me £650 plus vat for a 4/2/1 manifold . The company local to me will make the manifold for £500 in stainless steel including vat. He will make it on the car as he does not have a pattern. If anyone is interested he can make another one at the same time.
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby VampireTigger » Tue Aug 20, 2019 8:27 pm

Is that just manifold or whole system? Where abouts is the guy based?
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby edgoose1 » Tue Aug 20, 2019 8:42 pm

just the Manifold , Nottingham
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby 1972nail » Tue Aug 20, 2019 9:09 pm

Which style is it? Janspeed (DTV race design) or HPF (DTV road design)?

The Janspeed design is really suited to quite a high lift cam and high compression big valve head, It's of little benefit and wasted on a mildly tuned car. Whereas the HPF design works best with the standard or fast road cam and a standard or big valve head either standard or high compression. It produces very noticeable low down torque however, it is a little more restrictive than the Janspeed once you get above 4500 RPM. The Janspeed adds little to the standard torque curve until you hit 4000 RPM.

The Janspeed style is also quite difficult to fit and requires the alternator to be swapped to the other side of the engine. If you can retain the alternator in the standard location you'll risk frying it!

Here's the stainless version of the DTV road manifold I fitted to my car.


Here's a photo of the much more complex Janspeed design
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby lord13 » Wed Aug 21, 2019 7:20 am

I had the Janspeed style one fitted to my HB back in the day, the complex design is to provide equal length primaries and secondaries to enable better extraction. The Idea/science behind it is that the exhaust pulse from cyl 1 will cause a depression that will 'pull' the exhaust pulse from cyl 4, and vice versa, the same for cyl 2 and 3, which is why they are paired 1-4 and 2-3 as firing (and therefore the exhaust) order is 1, 3, 4, 2, if they were paired in firing order the exhaust pulses would not be timed correctly. The size of the primaries and secondaries are also important as too large a primary would cause less of a depression, which is why the convoluted deign has smaller primaries than the more straight forward DTV one. This is also why it works best at a high rpm, it is tuned to extract the exhaust pulses at a specified RPM, for race use, where a vehicle will be 'on cam' as much as possible, i.e. flat out. It's pretty much useless for a road car apart from looking good in the engine bay. You should see the Chevette one, that is a wildly twisted piece of kit, more so than this.
The DTV style one on the other hand is a 'quick and dirty' style of extraction, going on the idea that the bigger the better to get the exhaust out as quick as possible. You'll notice it too has the 1-4, 2-3 primary configuration, again to aid extraction, but they are not of equal length. The larger bore of the primaries mean it is a more forgiving manifold and will be more versatile across the rev range but will not give a noticable 'punch' when the engine comes 'on cam' as the pulse timing is not so essential.
In my humble opinion, the DTV style one is the better for road use, and for maintenance, that janspeed one is a total *Bleep* to fit correctly, if you get it wrong its too low on the exit, the best bet is to fit the complete system ,front to back, loosely , and tighten it all up when it's exactly in the position you need it.
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby edgoose1 » Wed Aug 21, 2019 7:34 pm

He will make whatever i want. It was really to loose the weight of the rusty original manifold and tidy up the exhaust system
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby Fred Dukes » Thu Aug 22, 2019 5:49 pm

Paul Cullum and Steve Hammond had an stainless system designed and made for the 2300 the stainless 4 branch manifold was about the £500 you are looking at but that was a few years ago now I have the rest of the system which I will be putting on Flo come the day. The prototype was on Chalky which is owned by Chris Yearby -he is doing a restoration so the system is off at the moment. It may be worth getting in touch with him Carl and see if you can borrow the manifold for a pattern :?: He is maybe still abroad on holiday till after the bank holiday but if you pm me I can send you a contact no.
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby edgoose1 » Fri Aug 23, 2019 6:01 pm

Thanks Fred. Will see when the car is back.. Still about two weeks away at the earliest
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Re: New 4 Branch Stainless steel manifolds slant 4

Postby 1972nail » Fri Aug 23, 2019 9:01 pm

The Steve Hammond one is a modified Janspeed design.
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