proxlamus© Posted October 24, 2007 Share Posted October 24, 2007 Hey guys... For my welding class project I was going to weld up my own intake manifold using "Ross Machining" DIY aluminum intake parts.. I was going to do something similar to Lonewolf Performance and was curious on what diameter runners I should choose and lengths?! Also which plenum design is more efficient? 4x4 square.. D shape or the half round plenum?! http://www.rossmachineracing.com I am also considering some Suzuki GSXR throttle bodies! mmm ITBs Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted October 24, 2007 Administrators Share Posted October 24, 2007 ...and was curious on what diameter runners I should choose and lengths?! Welcome to the art of intake manifolds The cross-sectional area of the runner is the single biggest influence on where torque peak falls... 1.500" ID puts the natural torque peak (of the runner) around 5540 RPM on an L28. Pretty steep for most folk. 1.450" ID... 5200 RPM 1.400" ID... 4850 RPM 1.350" ID... 4500 RPM I wouldn't run any less than 6" length and I'd like to see more like 7"+. Don't discount taper. General consensus is about 2.5% (in area) per inch. Also which plenum design is more efficient? 4x4 square.. D shape or the half round plenum?! Parallel walls are normally frowned upon... I wouldn't use 4x4 without good reason. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 24, 2007 Author Share Posted October 24, 2007 wow thanks Ron! I was talking to Bryan (1 fast Z) and he was asking about RPM and what I am lookn for The intake manifold will be matching a P90 head with stock porting.. so no port work.. with an upgraded cam and a Holset HY35 turbo. I will be running no more then 6500 RPM. I decided I would like to use the 38mm throttle bodies from a Suzuki GSXR! Quote Link to comment Share on other sites More sharing options...
olie05 Posted October 24, 2007 Share Posted October 24, 2007 gsxr 600? Heres a hint: 2001-2003 gsxr 750 had 42mm TB's, and the same year gsxr 600 had 38mm (which I think you are refering to). Both had 240cc/min injectors. And Both are independently cast. both 600 and 750 (and 1000) are held together by three long rods with nuts at each end with 80mm spacing. Basically you could splice the center two TB's into the other set of four TB's and have 6 itb's with 80mm spacing. The spacing between 1-2 and 5-6 intake ports is something like 50mm or so, so you will have to angle out, because the gsxr TB's can't really be smushed together without any significant amount of machining and redesigning of the linkage. oh no... i've given myself away... Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 24, 2007 Author Share Posted October 24, 2007 I only have a few weeks to finish this guys.. Im thinking.. Intake flange.. 6" runners.. 1.35" diameter (4500rpm kicks in right when the turbo gives fullboost) GSXR throttle bodies.. and this surge tank Whatcha think?! Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted October 24, 2007 Share Posted October 24, 2007 Is that plenum cylindrical? Doesn't look like it, and if you install it like that the opening would be pointed directly at the bonnet? Dave Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted October 25, 2007 Share Posted October 25, 2007 Careful with the ross machine racing velocity stacks as you will have to cut them down to make them work with a l28. The problem is the port spacing of the l28. This will give you trouble unless you angle the ports away from each other. This may be doable and necessary since you are thinking of ITB's as well. Regards, Justin Quote Link to comment Share on other sites More sharing options...
jhaag Posted October 25, 2007 Share Posted October 25, 2007 Prox -I sent you a PM. John Quote Link to comment Share on other sites More sharing options...
olie05 Posted November 1, 2007 Share Posted November 1, 2007 Welcome to the art of intake manifolds The cross-sectional area of the runner is the single biggest influence on where torque peak falls... 1.500" ID puts the natural torque peak (of the runner) around 5540 RPM on an L28. Pretty steep for most folk. 1.450" ID... 5200 RPM 1.400" ID... 4850 RPM 1.350" ID... 4500 RPM I wouldn't run any less than 6" length and I'd like to see more like 7"+. Don't discount taper. General consensus is about 2.5% (in area) per inch. Parallel walls are normally frowned upon... I wouldn't use 4x4 without good reason. Ron I'm just curious as to how you are calculating those diameters/torque peak relations. I would like to know what changes these numbers, and how does it apply to ITB setups vs. plenum setups. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 1, 2007 Administrators Share Posted November 1, 2007 Ron I'm just curious as to how you are calculating those diameters/torque peak relations. I would like to know what changes these numbers, and how does it apply to ITB setups vs. plenum setups. Oliver, The formula comes from a successful engine builder/tuner. I've also taken the time to plug in a few known manifolds and its always been within 2% of actual. So far, the formula confirms that the single largest influence on where the peak falls, is the area of the runner itself. The remaining parameters (TB, plenum size, configuration, etc) will influence the peak to a lesser degree, but can have a substantial impact on either side of the peak (as well as distribution and response)... the formula can't account for 'under the curve'. Unfortunately, I don't feel at liberty to disclose the math. However I'd be more than happy to run a few scenarios for you. Provide the following... Displacement (CID) Number of Cylinder's Intake Dia. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 2, 2007 Author Share Posted November 2, 2007 Alrighty.. Intake flange purchased.... One set of Suzuki GSXR 600 throttle bodies... (ill buy the other set in a few) All I need is some piping for the runners.. some .050 guage aluminum to make my pressure box.. and some flange material for the box. =) should start scooting along quickly. Ron.. what diameter would you recommend for my setup?! Schneider cam with .488 valve lift and a 260 duration The intake manifold will be matching a P90 head with stock porting.. so no port work.. a Holset HY35 turbo. I will be running no more then 6500 RPM. Throttle bodies are 38mm.. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 2, 2007 Administrators Share Posted November 2, 2007 ... some .050 guage aluminum to make my pressure box.. .050" won't cut it. I wouldn't boost a plenum with anything less than .125" unless your plenum shape and size is conducive to it. Ron.. what diameter would you recommend for my setup?! Tapering nicely from 38mm down to 1.375" (at the head) should work well... a fair compromise between response and total power. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 2, 2007 Author Share Posted November 2, 2007 i love this forum. Away I go to depart on a wonderful project. ill keep updating this thread for current progress Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 2, 2007 Author Share Posted November 2, 2007 oh yeh and is 1.375" the ID or OD? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 2, 2007 Administrators Share Posted November 2, 2007 Id Quote Link to comment Share on other sites More sharing options...
Careless Posted November 5, 2007 Share Posted November 5, 2007 Prolax...that plenum kit you show there is the same as the one i posted on the RB forums in regards to making your own plenum. However, if it's going on an L engine... as someone mentioned; it will hit the hood due to it's throttle body position. The better idea would be to go with the 1J or 2JZ intakes that the same fellow on ebay sells, as the intake is on the same side as the L, and it would point either forward or downward, and might give you a better clearance for what you're trying to achieve. go git'm! Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 5, 2007 Author Share Posted November 5, 2007 I am going to take a 5" diameter pipe and cut it in a few sections and weld up some thick aluminum to weld to the pipe for my plenum. Similar to Ron's custom intake manifold. BTW I bought 3 sets of ITB's lol. All for stupid cheap prices. muaha Quote Link to comment Share on other sites More sharing options...
Careless Posted November 5, 2007 Share Posted November 5, 2007 where!? how?! I wanna do an ITB setup on my friend's B20B civic Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 6, 2007 Author Share Posted November 6, 2007 ebay! I found one for $26 on ebay lol. Quote Link to comment Share on other sites More sharing options...
Careless Posted November 6, 2007 Share Posted November 6, 2007 with everything included? Quote Link to comment Share on other sites More sharing options...
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