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The main difference between a 15 and a 19 is the top end is greater with the 19T. The 19T moves more air with less heat at higher RPM than the 15T. Lag time in the lower RPMs increases because the amount of exhaust heat necessary to move the extra mass of the larger compressor wheel and the increased volume of air is greater than the lower mass/less air of the 15T. The lag time is partially reduced by increasing the exhaust downpipe size and, if you are so lucky, sourcing the larger size turbine outlet which is "stock" on the 9000 aero model (#6 housing). There is also a #7 available. A change to the more efficient 9000 aero cams also assists with high RPM performance. I have both a 9000 Aero and a 9-3 Viggen. The Viggen has the 19T with a #7 housing and a billet 19T wheel , the full 3" downpipe, and the 9000 cams, etc. The 9000 Aero is mostly stock as far as hardware. The 9000 is quicker and boost comes on harder (meaning quicker response) than the Viggen when driving in the same RPM ranges. However, the 9000 runs out of steam in the upper RPMs while the Viggen does not. Most people who move up to a 19T know that lag is an issue and therefore modify their driving style to address this issue-since RPMs is the only factor that affects "lag" assuming you have the correct supporting "hardware" one simply takes that fact into consideration and drop down a gear for an increase in RPMs when spirited driving/no lag is wanted. The Viggen is plenty fast, quick, and has so much upper RPM punch that exploring the full throttle travel at those greatly increased levels of power and speed is a very deliberate and focused action. You run out of road and/or safe conditions very fast. I probably have not gone fully into that place but once or twice even though I have owned the car for a year. So to get back to the other part of your original question about fabrication. I see you have most of the "hardware" to support a 19T. However, for the best results, a little modification is required to address the shortcoming of the stock exhaust manifold which, if left unfinished, really keeps the 18T or 19T from performing.The exit of the stock exhaust manifold is sized to match the round intake turbine housing of the stock Mitsu 15T turbo (or the Garrett). It is not a large diameter passage. When compared to the better performing 9000 stock Aero turbine housing, it has about 30% less flow area. The Aero's turbine housing intake is rectangular in shape. So to have a good performing 18T or 19T turbo one needs the #6 9000 Aero turbine housing with the correct "hardware"(3"downpipe/larger innercooler/larger injectors/9000 cam). To have a great performing 18T or 19T turbo one needs the stock exhaust manifold ported to match the #6 or #7 turbine housing. This is easily accomplished with a die grinder and a long tapered abrasive stone both available from Fastenall. This job takes about two hours and simply requires the removal of material so that the opening of the exhaust manifold matches the opening of the larger turbine housing. Fortunately there is enough material to allow porting up to the #6 size. I speak from experience for the #6. Failure to do this means poor exhaust flow through the turbine housing (higher RPM means higher flow) which leads to increased EGTs (exhaust gas temperatures), increased lag, and less than great performance-the top end performance will be hurt-not so much with the low end. Still it makes no sense to skip this step when 18Ts and 19Ts are all about upper RPM performance. So some modification/ fabrication is best practice. One can skip this modification step with a tubular exhaust manifold. That would be built to your turbo's turbine size and would should could "possibly" reduce lag time due to higher exhaust flow less heat loss. For my driving style the 19T is enjoyable when I am in a crushing mood but, as a daily driver, not quite as rewarding as the Aero's 15T-mainly because the quickness of the power delivery better matches my driving style and the roads I am driving on...daily. The Viggen is for fun. It's nice to have a choice.
->Posting last edited on Tue, 29 May 2018 06:14:28.
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