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SP250 exhaust manifolds

Posted: Thu Sep 19, 2019 2:20 am
by TWF
Hi , Is anyone currently manufacturing exhaust manifolds for the SP250 ? Regards ,Terry .

Re: SP250 exhaust manifolds

Posted: Thu Sep 19, 2019 7:18 am
by Marcel Renshaw
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.

Re: SP250 exhaust manifolds

Posted: Thu Sep 19, 2019 10:48 am
by silverdart
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.

Re: SP250 exhaust manifolds

Posted: Thu Sep 19, 2019 11:17 pm
by Fossil
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

Re: SP250 exhaust manifolds

Posted: Fri Sep 20, 2019 2:50 pm
by gc0700
Robert Grinter does list a stainless manifold on his web site, see https://www.robertgrinter.co.uk/styled-7/styled-28/

Re: SP250 exhaust manifolds

Posted: Sun Sep 22, 2019 7:48 pm
by Sonus
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.

Re: SP250 exhaust manifolds

Posted: Mon Sep 23, 2019 8:51 am
by daimlersteve
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

Re: SP250 exhaust manifolds

Posted: Wed Oct 09, 2019 5:12 pm
by Reedweaver
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...

Re: SP250 exhaust manifolds

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

Re: SP250 exhaust manifolds

Posted: Sat Oct 12, 2019 6:54 am
by daimlersteve
Things have moved on regarding extractors. Look up "Pipemax " computor program
Steve