white_sandshoe Posted September 13, 2009 Report Share Posted September 13, 2009 I was thinking about the old American Graffiti movie, and that got me thinking about a scene in it where John Milner, the dude with the yellow hot rod, pulls in to take the restrictors out of his inlet and exhaust to prepare for a run against Bob Falfa (Harrison Ford) That got me thinking about a setup I'm looking to put together with a 2TG. I want to be able to lay down some decent power with twin side draughts and some nasty cam work. I was wondering what effect restrictors in the inlet and exhaust would have on the tuning of the carbs and if i could count on the reduced airflow to ease up the amount of fuel flowing, or if i'd have to re-tune the carbs every time i put the restrictors in... I'd like to think it's possible to have a setup where i'd drive down to the track, swap over a section of the exhaust to free it up, and possibly have some sort of slide in choke (smaller tube insert into the trumpet) which i could take out to free up the flow. What's people's thoughts on the technical implications especially in relation to fuel flow, taking into account the venturi effect they operate under... Quote Link to comment Share on other sites More sharing options...
styler Posted September 13, 2009 Report Share Posted September 13, 2009 sounds interesting... try a book called 4 stroke performance tuning by A.Graham Bell, besides all the other great info, he has a large chapter on carbies, how they work and how they can be modified to suit different applications etc... Quote Link to comment Share on other sites More sharing options...
towe001 Posted September 17, 2009 Report Share Posted September 17, 2009 Awesome movie. Number two was good but not as good. Milner just unbolted the cover to open up the side pipes. A GAS STATION--DEUCE COUPE John pulls the coupe out of the garage and wheels up to the pumps of the gas station. An attendant nods, looking at the roaring engine. ATTENDANT Took the header plugs off. Expectin' some action? John looks at him from inside the coupe and nods slowly. JOHN Yeah. Think so. There's some punk lookin' for me. ATTENDANT Why the hell do they bother? You've been number one as long as I can remember. JOHN Yeah...it's been a long time, ain't it? I'll see ya. Thanks. John drives the car out of the station and screeches down the street. But anywhat, you'd have to redo the carbies if there's a restrictor in the road of the intake. Think of it as a choke. I'd imagine the same thing with the exhaust. More airflow = more fuel to compensate :dance: going to have to bug the other half now and watch the movie Quote Link to comment Share on other sites More sharing options...
RedKE30 Posted September 17, 2009 Report Share Posted September 17, 2009 sounds interesting... try a book called 4 stroke performance tuning by A.Graham Bell,besides all the other great info, he has a large chapter on carbies, how they work and how they can be modified to suit different applications etc... I've read some of that, that guy is possibly a genuis. Quote Link to comment Share on other sites More sharing options...
RedKE30 Posted September 17, 2009 Report Share Posted September 17, 2009 (edited) Whoops. Edited September 17, 2009 by RedKE30 Quote Link to comment Share on other sites More sharing options...
white_sandshoe Posted September 17, 2009 Author Report Share Posted September 17, 2009 I guess in that regard, the more restricted exhaust would slow airflow, while the restrictor in the inlet would in fact speed it back up? Could be a matter of full exhaust system for on street, but then unbolt half of it and put on a little dumpy pipe for the track. Also, maybe a full box and panel filter would limit the airflow off track which will then be 'loosened up" with a set of trumpets and filter sox for on the track? Quote Link to comment Share on other sites More sharing options...
leWolf Posted January 30, 2012 Report Share Posted January 30, 2012 Ok, wouldn't it be easier to run a 4 barrel carb and just lock the secondaries to kill the fuel and air flow? For the exhuast you could run nice high flow exhuast piping from the engine all the way back to a super quiet and restrictive muffler, just put a cutout before it. Maybe the DCOE's perform way better than a 4 barrel but wouldn't that be because of the awesome flow characteristics? That makes me think that any shutter/valve or modification in the intake could severely hinder flow even when open, right? Seems like an awesome project though. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted January 30, 2012 Report Share Posted January 30, 2012 Carbs I don't know, but we used to do that to the exhaust when rallying. Tune the exhaust & have it exiting in front of the rear wheel, out the side. Then put a plate over it so it goes out through the muffler at the back to drive to the rally and back. Mate had the pipe sliced open on both sides under the passenger's floor with a section of pipe over it. He had a cable going inside that he pulled while waiting for the stage to start, and that pulled the outside pipe down the tube and opened it up. Quote Link to comment Share on other sites More sharing options...
GJM85 Posted January 30, 2012 Report Share Posted January 30, 2012 (edited) Stick a bolt under the accelerator pedal and wind it in when you want to race and out when your on the street. If your not opening sidedrafts up all the time it won't use too much fuel. People don't look at thread dates very often.... '09 Edited January 30, 2012 by GJM85 Quote Link to comment Share on other sites More sharing options...
leWolf Posted January 30, 2012 Report Share Posted January 30, 2012 Stick a bolt under the accelerator pedal and wind it in when you want to race and out when your on the street. If your not opening sidedrafts up all the time it won't use too much fuel. People don't look at thread dates very often.... '09 I know it's kinda old, alright no it's flat zombie status. But I was hoping to dig up an answer and got lost in the info. I am still having issue's learning the site though, sorry about that. Really though, I had a issue with my old carbed civic eventually became a pain in the shorts to drive daily lol. Quote Link to comment Share on other sites More sharing options...
white_sandshoe Posted January 31, 2012 Author Report Share Posted January 31, 2012 I know it's kinda old, alright no it's flat zombie status. But I was hoping to dig up an answer and got lost in the info. I am still having issue's learning the site though, sorry about that. Really though, I had a issue with my old carbed civic eventually became a pain in the shorts to drive daily lol. Wow, Zombified it is! Funny though, as I do have some updates in regards to this car, and the planned exhaust/carb work... I have decided to run EFI, and high compression (14:1) with high lift cams, but not much more in duration. Will be tuning for, and running, Ethanol, and running a Plymouth 'Cuda-esque exhaust, which will go down to a muffler, then double back and exit before the rear wheel... The plan is to have the side pipe a two piece arrangement with a two bolt flange on the exhaust tip, and off the muffler... that 90 degree bend will unbolt, and re-attach directly onto the exhaust once the second two bolt flange prior to the exhaust is removed... Not sure if that makes any sense, but when I start actually building the car, all will become clear. (got my 1MZ T18, my 7KZE KE20 and my 7MGTE MX32 projects to finish before this one gets started...) Anyways, all is well in the world... Quote Link to comment Share on other sites More sharing options...
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