TB_205GTI 1 Posted February 8, 2006 (edited) Has anybody here done it? What are the wownsides of using the curved trumptes like the ones GMC make? The good thing is that you can get longer trumpuets without cutting the scuttle. What will the MPG be? What about cold starts? All the cars I have seen with tb's were a total pig to start, especially when it's cold. The engine specs are: 1860ccm Grp. A cams (283 deg, 10.4mm lift) Edited February 8, 2006 by TB_205GTI Share this post Link to post Share on other sites
Sam 4 Posted February 8, 2006 Their setup has yet to make the power over a scuttle cut and nice open inlet. They seem to bang on about theory but results seem to differ. The SF setup, or QEP's new DTH setup would be the best solution, with some 90mm trumpets and maybe a cut scuttle if you need it (you can get away without). The cold starts and MPG is all down to mapping really, but its never going to be amazing on those cams (MPG). Share this post Link to post Share on other sites
christopher 5 1 Cars Posted February 8, 2006 I can't see anything wrong with those trumpets. Trumpets are designed to do one thing. Increase the momentum of air flowing into the carb/TB. Share this post Link to post Share on other sites
Sam 4 Posted February 8, 2006 Its a shame in reality they don't give the results. Also when you start introducing sharp 180 bends you get whats called a back-eddy, where the air starts flowing in the opposite direction. I'm sure Sandy or someone else who's studied fluid dynamics can explain it more. Share this post Link to post Share on other sites
DrSeuss 0 Posted February 8, 2006 making anything change direction through 180 degree's loses momentum. Loss of momentum results in loss of energy. Share this post Link to post Share on other sites
Sam 4 Posted February 8, 2006 There you go, cheers Sam. Share this post Link to post Share on other sites
Rippthrough 98 Posted February 8, 2006 The cross sectional shape of the bend is wrong for a 180* change. Share this post Link to post Share on other sites
christopher 5 1 Cars Posted February 8, 2006 making anything change direction through 180 degree's loses momentum. Loss of momentum results in loss of energy. Well the particles on the outer edge obviously have a longer way to travel then those on the short side radius. But I would have thought that the overall gain in the increase of momentum (due to a longer tract would be beneficial) since the particles are mixed as the diameter of the tract decreases. Its not a sharp curve after all. Have we forgotten that a cylinder head is in essence similar but more extreme a curve Share this post Link to post Share on other sites
Rippthrough 98 Posted February 8, 2006 (edited) Well the particles on the outer edge obviously have a longer way to travel then those on the short side radius. But I would have thought that the overall gain in the increase of momentum (due to a longer tract would be beneficial) since the particles are mixed as the diameter of the tract decreases. Its not a sharp curve after all. Have we forgotten that a cylinder head is in essence similar but more extreme a curve But you'll also notice a cylinder port isn't cylindrical at the apex of the bend. Well, it shouldn't be anyway. EDIT:- do a google image search for "Micron serpent header", it's the easiest way to show what the shape should be more like. Edited February 8, 2006 by Rippthrough Share this post Link to post Share on other sites
Sam 4 Posted February 8, 2006 if it was such a good setup/idea, why didn't peugeot use it ? Share this post Link to post Share on other sites
TB_205GTI 1 Posted February 8, 2006 Sam: Cutting the scuttle is a total no-go for me due to the Danish MOT That gives me two possible solutions: 1) get _really_ short trumpets, 2) get curved ones, but hopefulle better power/torque than with the ultra short ones. With the GMC solution I can still use my Simota enclodes filter, and the engine bay still lokks rather like a std. enginebay. Share this post Link to post Share on other sites
Sam 4 Posted February 8, 2006 Why not just get the jenvey SF setup and use 90mm trumpets, it does fit. Theres a guy running 144@wheels with that setup. Share this post Link to post Share on other sites
TB_205GTI 1 Posted February 8, 2006 Why not just get the jenvey SF setup and use 90mm trumpets, it does fit. Theres a guy running 144@wheels with that setup. Might be an option given it fits with no rubbing and an airfilter.. Do you have any pictures? (I saw the pictures of bic's Maxi engine - what a beast!) Share this post Link to post Share on other sites
christopher 5 1 Cars Posted February 8, 2006 if it was such a good setup/idea, why didn't peugeot use it ? I dunno Sam. Probably beacuse those long straight ones are better:-P But its not uncommon to see 90 degree ones on racing Lancia, Fiats and alfas in the 70's Share this post Link to post Share on other sites
charlie_sav 0 Posted February 9, 2006 Pics of that engine sam is on about, he has just the top edge don't know if he was planning on cutting the whole scuttle out or it helps him get the filter on, pity you can not cut yours it does not really effect the fire wall except fames being drawn into the heating fan, and it's not really a main structual part of the car. Share this post Link to post Share on other sites
d-9 0 Posted February 9, 2006 except fumes being drawn into the heating fan You would be amazed how big a headache you get from petrol condensing on the inside of the windscreen Share this post Link to post Share on other sites
Sandy 189 Posted February 9, 2006 LoL, or badly positioned oil breathers! Share this post Link to post Share on other sites
TB_205GTI 1 Posted February 14, 2006 OK - *maybe* just *maybe* I'm so lucky to get a set of the Original 106 Maxi throttle bodies from a Saxo. It comes with trumpets and a panel filter - but needs cutting the scuttle.. Can the curved trumpets be used with theese tb's? Share this post Link to post Share on other sites
Sam 4 Posted February 15, 2006 I'm not sure if they have clearance but the flange is certainly the same thats for sure. Share this post Link to post Share on other sites
