Guest escort_boy Posted May 30, 2005 Share Posted May 30, 2005 is there any advantage to running side drauights compared to a downie? Quote Link to comment Share on other sites More sharing options...
Jerm Posted May 30, 2005 Share Posted May 30, 2005 two 40mm DCOEs are going to be alot better than one Downdraught... and the fact that the air/fuel mixture travels in a straight line directly into the head allows better airflow... Quote Link to comment Share on other sites More sharing options...
lowlancer Posted May 30, 2005 Share Posted May 30, 2005 Sidies are better generally if you're running a harder tuned engine. No angle means better flow, like what jerm said Quote Link to comment Share on other sites More sharing options...
Draizuh Posted May 30, 2005 Share Posted May 30, 2005 Side draughts tend to be better for Crossflow engines where as downdraughts are for engines like V8s and v6's or early non crossflow engines. its all to do with the path that the Air/Fuel mix has to travel in to get to the bore for combustion. Quote Link to comment Share on other sites More sharing options...
Guest Eddie W Posted May 31, 2005 Share Posted May 31, 2005 Downdrafts don't work any better on nonxflow than on the xflow motor. They're ok for gt spec motors but sidedrafts will always work better on a vertical in line motor with the right mods elsewhere to take full advantage of them. The twin Dellortos on my Alfa are on a boxer 4 so they go staight in just like sidies on an upright motor. Lovely sound. Eddie Quote Link to comment Share on other sites More sharing options...
Jerm Posted May 31, 2005 Share Posted May 31, 2005 What kind of alfa do you have? My dad is into his alfas and is always telling me how great twin downdraught dellortos look and sound on those boxere engines Quote Link to comment Share on other sites More sharing options...
lowlancer Posted June 1, 2005 Share Posted June 1, 2005 There were some twin downdraughts for a 4G63 on trademe, but I missed em...damn Quote Link to comment Share on other sites More sharing options...
Guest Eddie W Posted June 1, 2005 Share Posted June 1, 2005 Hi Jerm, I've got 4x model 33s. 2x 1500cc and 2x1700cc ranging from '86 to '90. Do these qualify as " old school" ? One of the 1.7s is a '90 and is getting a Zender bodykit that I've repaired and is on 15" mags with 195/50s. It's also planned to get dropped 30mm and stiffer springs and shocks. The other 1.7 is also a ' 90 that I'm hoping to rebuild and supercharge. I''ve got another set of 15" mags that I'm cleaning up to go on it. Eddie Quote Link to comment Share on other sites More sharing options...
Guest Eddie W Posted June 1, 2005 Share Posted June 1, 2005 The two 1.5s have twin 36mm twinchoke Dellortos and the 1.7s have 40s. Eddie Quote Link to comment Share on other sites More sharing options...
Pushrod Posted June 1, 2005 Share Posted June 1, 2005 Hey eddie do you know anything about blanking of inlet ports and re drilling them and running down draughts possibly on a prexflow ????? Quote Link to comment Share on other sites More sharing options...
Guest Eddie W Posted June 2, 2005 Share Posted June 2, 2005 Yeah I've seen it done and even owned a head for a while. Never got around to using it though as you usually need to lay the motor over to use with carbs, with injection of course you don't have to go that far. The head I had was a Downton for a 1300 and was skimmed so much that the squish area of the chamber was starting to bow and I couldn't be bothered going to the trouble of welding reinforcing pins in it. It's done by fabricating the port and manifold shape you want ( usually they were both done as one piece), setting the head up in a mill to the required angle and cutting the hole then the manifold is pressed in and welded with the head preheated in an oven. Needs a fair bit of skill. Eddie Quote Link to comment Share on other sites More sharing options...
Pushrod Posted June 2, 2005 Share Posted June 2, 2005 Thanks for that I saw a picture of a 997 head with those mods on Broadspeed Anglia It's not something I could tackle though but seemed quite interesting Quote Link to comment Share on other sites More sharing options...
Guest Eddie W Posted June 3, 2005 Share Posted June 3, 2005 They got pretty good power figures but it's a lot of work. A few were used in single seaters. Eddie Quote Link to comment Share on other sites More sharing options...
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