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SP250 exhaust manifolds

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TWF
Posts: 41
Joined: Wed Mar 09, 2016 7:10 pm

SP250 exhaust manifolds

Post by TWF » Thu Sep 19, 2019 2:20 am

Hi , Is anyone currently manufacturing exhaust manifolds for the SP250 ? Regards ,Terry .

Marcel Renshaw
Posts: 356
Joined: Fri Feb 12, 2016 8:44 pm
Location: Derbyshire

Re: SP250 exhaust manifolds

Post by Marcel Renshaw » Thu Sep 19, 2019 7:18 am

I believe Robert Grinter has the tooling for cast manifolds but hasn't had any made for a long time now due to minimum order problems at the foundry.

silverdart
Posts: 162
Joined: Sat Feb 13, 2016 10:49 am
Location: West Midlands

Re: SP250 exhaust manifolds

Post by silverdart » Thu Sep 19, 2019 10:48 am

Hi, I had a problem with exhaust manifolds. The triangular exhaust flanges tend to break off around the bolt holes. I solved the problem by cutting the complete end off where the neck is circular and welding on a complete new flange.
The flange is pre machined in EN8 steel and the holes are drilled and tapped in the flange which also I made thicker than the original.
The flange has a very small location spigot for alignment and I use a simple jig to position the flange for welding.
I have these fitted to one of my cars and they seem to perform well.

Dave.

Fossil
Posts: 417
Joined: Sat Feb 13, 2016 5:08 pm
Location: Helensburgh, Argyll

Re: SP250 exhaust manifolds

Post by Fossil » Thu Sep 19, 2019 11:17 pm

Terry

Stainless Exhaust Specialist of 9 Nunn Brook Rise, Huthwaite, Sutton-in-Ashfield NG17 2PD can supply stainless steel 4:2:1 exhaust manifolds and also stainless copies of the standard 4:1 manifold. They're not cheap but very good. I have had the former on my SP for over 10 years with no issues. Website easily located in the usual way.

Regards

Fossil

gc0700
Posts: 34
Joined: Wed Sep 21, 2016 8:29 pm
Location: Bury St Edmunds

Re: SP250 exhaust manifolds

Post by gc0700 » Fri Sep 20, 2019 2:50 pm

Robert Grinter does list a stainless manifold on his web site, see https://www.robertgrinter.co.uk/styled-7/styled-28/
Tim

Sonus
Posts: 191
Joined: Wed Apr 13, 2016 2:19 pm

Re: SP250 exhaust manifolds

Post by Sonus » Sun Sep 22, 2019 7:48 pm

gc0700 wrote:
Fri Sep 20, 2019 2:50 pm
Robert Grinter does list a stainless manifold on his web site, see https://www.robertgrinter.co.uk/styled-7/styled-28/
Wonder what the pipe length and diameter is for the free flow 4-2-1 system? The 'free flow' system needs to be tuned to the engine to be free flow or they might actually limit the engine more than the original design.

daimlersteve
Posts: 354
Joined: Wed Mar 09, 2016 11:20 am

Re: SP250 exhaust manifolds

Post by daimlersteve » Mon Sep 23, 2019 8:51 am

The primary pipe size should be no larger than 35mm o/d for a 2.5 engine . 300 Long to the first junction then 38 mm for 150 mm then 41 mm thereafter
If the pipe sizes are larger the length needs to increased as well

Reedweaver
Posts: 31
Joined: Sun Feb 21, 2016 2:20 pm

Re: SP250 exhaust manifolds

Post by Reedweaver » Wed Oct 09, 2019 5:12 pm

I had some manifolds from the same guy who supplies Robert Grinter last year. One of them was a bit of a pain to fit due to two pipes being too close to the bolts. I had to do a fair bit of messing around to get the b****r on. I did complain and I got the answer, well they fitted on the jig...

I think the sound has altered slightly as well, I no longer get as raw rasp at 3500rpm as I used to. Its there, but sounds more muffled than before imo...

Ian Slade
Posts: 468
Joined: Sat Feb 13, 2016 9:54 am
Location: Akrotiri Cyprus

Re: SP250 exhaust manifolds

Post by Ian Slade » Wed Oct 09, 2019 6:38 pm

I seem to remember that the 4.2,1 manifold will not exit the rear for the most effective tuned length and the first node point was about 4ft from the head
Owner since the 70's, Genghis is slightly to my left.

daimlersteve
Posts: 354
Joined: Wed Mar 09, 2016 11:20 am

Re: SP250 exhaust manifolds

Post by daimlersteve » Sat Oct 12, 2019 6:54 am

Things have moved on regarding extractors. Look up "Pipemax " computor program
Steve

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