nick
Junior Member
Posts: 11
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Post by nick on Apr 10, 2020 20:03:24 GMT
A couple of years ago I had fitted an alloy fast road head, had the inlet manifold polished & ported and have enjoyed the improvement in power/response so far. I am now thinking of my next improvement options and wanted to ask your thoughts on what I might expect if I change the manifold from the standard to a DWM tubular exhaust manifold.
Will it improve the performance of the car, if so by how much and will I notice it.
Is the improvement in performance worth the additional costs involved considering I use the car as a daily driver.
Many thanks
Nick
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Post by frankenhealey on Apr 10, 2020 20:26:48 GMT
A couple of years ago I had fitted an alloy fast road head, had the inlet manifold polished & ported and have enjoyed the improvement in power/response so far. I am now thinking of my next improvement options and wanted to ask your thoughts on what I might expect if I change the manifold from the standard to a DWM tubular exhaust manifold. Will it improve the performance of the car, if so by how much and will I notice it. Is the improvement in performance worth the additional costs involved considering I use the car as a daily driver. Many thanks Nick Denis Welch should know the improvement from their own kit.
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Post by healeyneil on Apr 10, 2020 21:18:58 GMT
I would suggest that, having improved the ability of the air/fuel mix to get into the cylinders, and therefore combust, to not improve the ability of the exhaust gases to escape would be a bad idea. Now, what you do to help control the under bonnet heat is another story. My view is that ceramic coating is best, wrapping is a cheaper option, but some don't like it.
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Post by dougie on Apr 11, 2020 0:48:08 GMT
I would suggest that, having improved the ability of the air/fuel mix to get into the cylinders, and therefore combust, to not improve the ability of the exhaust gases to escape would be a bad idea. Now, what you do to help control the under bonnet heat is another story. My view is that ceramic coating is best, wrapping is a cheaper option, but some don't like it. My question is why didn't you make the exhaust/output upgrade when you improved the incoming air/fuel as mention above when you added the new head? It's like taking a super model out for dinner, having a wonderful time and when she invites you up to her room you kiss her on the cheek and say "not tonight, I've got an early morning meeting".......Doh... My guess is you have 10-15% of untapped performance with all things being equal. Given my own experience with my vintage racer, I was amazed with the top end HP gain I achieved when I worked with an exhaust/motor engineer to design a specific header system when completing my lastest race motor build. After this exercise, I found a few suppliers that make a very good street performance header system. I recommend the following unit and have it ceramic coated. www.ahperformanceparts.co.uk/austin-healey/big-healey/Exhaust-Systems-EXS190-EXS246/EX-MANIFOLD-SS-performance.aspx#.XpETmWRKgy4
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Post by healeyneil on Apr 11, 2020 7:01:37 GMT
Dougie, I seem to recall reading something about cracking with stainless steel manifolds, or possibly I imagined it! I take it you haven't had any problems there? I will be in the market for a manifold soon
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Post by dougie on Apr 11, 2020 20:20:51 GMT
Dougie, I seem to recall reading something about cracking with stainless steel manifolds, or possibly I imagined it! I take it you haven't had any problems there? I will be in the market for a manifold soon Yes, I cracked or burned through my original "mild steel" ceramic coated headers I had raced with for over 10 years. It was time for them to be replaced. The newly designed system was a big increase in performance. Here's what the old ones looked like, poor scavenging at high rpms.
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nick
Junior Member
Posts: 11
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Post by nick on Apr 12, 2020 18:57:59 GMT
Thank you very much for your replies, much appreciated.
It sounds like ceramic coating is the preferred option and if I can get anything like a 10-15% improvement I will be very happy with it.
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