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This article was originally published in the June 1988 issue of VW & Porsche. It has some good technical information about 8v head tuning, but at the same time it is somewhat of a commercial for Techtonics...not that they didn't deserve it. Enjoy! |
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BY JAMES SLY The Techtonics tests that we feature in this issue show the results of the Techtonics StreetPort cylinder head, a modification applicable to any 1800 VW motor. The results closely paralleled those of the exhaust testing in a very important way. The quick-and-dirty gains that a ported and well-developed head or exhaust offered on the pre-GTI motors just aren't there any more. The Techtonic's StreetPort Head alone provided up to a 4 percent gain in torque and horse power over our previous best, with an extra 3.5 horsepower at 5000 rpm, 4.2 ft-lb of torque at 4500 rpm and a uniform increase in low- and mid-range torque. An engine equipped with a Neuspeed/Techtonics cam, Supersprint header, Gillet exhaust and that has ignition timing advanced to 12 degrees BTDC can expect 124 horsepower (more than a 16-valve). But if you bolt on just any cylinder head, don't expect a miracle. BACKGROUND In the last two issues of VW & Porsche we covered the extensive Techtonics dyno test program for Volkswagen's 8-valve high-performance HT and RD engines in the '85-87 GTI and GLI models. The tests evaluated an array of exhaust systems and camshafts, with the sturdy German-made Gillet performing best in the former category, and the Schrick 268-degree cam and the new Neuspeed/Techtonics 268-degree cam superior against other cams tested. Techtonics was able to boost the stock motor's 102 hp to 120.6 hp, using simple bolt-ons. In the process, we discovered a good many performance do's and don'ts, not all of them obvious. |
 HEAD DlFFERENCES The 38mm valves found on pre-1983 GTI Volkswagens were small compared to these on American-built cars. Porting the "big-valve" head that resulted from enlarging these valves used to afford a dependable increase in high-rpm horsepower, and was an essential modification for any serious high performance motor. In 1983, the GTI came out with an all-new cylinder head featuring 40mm intake valves. While a good porting job and fitting bigger valves still gave results, the added horsepower gained from the mods on the GTI heads has never equaled the dramatic leaps in horsepower afforded by the earlier big-valve conversions. In 1985, VW announced that the performance engines in its lineup would be getting a new hydraulic-lifter cylinder head that would make valve adjustments obsolete. The GTI was the first recipient of the new technology. As of the 1988 model year, all Golf, Jetta, Scirocco, GTI and Cabriolet models will be fitted with a version of this new head. As we have outlined in the last two issues of VWP: a number of changes make this engine different from previous ones. |
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