JimmyZ wrote:Actually, it's not junk. SPS and other companies have been selling tapered throttle body bores for years with excellent results on Saturn 1.9 engines and more recently for Ecotecs.
The original design was an improvement on the 50mm stock 1.9 throttle body. They started with a 52mm bore tapering back to the stock 50mm and back out to 52mm. Later on several companies released 56-52-56 tapered bores as later throttle bodies came with more machinable material around the throttle bore.
The taper to 50mm acted to raise inlet velocity without causing the same restriction as seen on the throttle body with the smaller diamer for it's entire length. The 52-50-52 throttle body posted flow bench numbers less than 1% off from a straight through 52mm TB, but behaved much differently on the engine because of differing flow velocities. This is a common practice going all the way back to the days or carburetors. While I can't say I've ever never seen a taper quite that extreme, the reasoning behind it is still sound. Just because SCC doesn't endorse it doesn't mean it doesn't work.
Turbo Tech Racing wrote:JimmyZ wrote:Actually, it's not junk. SPS and other companies have been selling tapered throttle body bores for years with excellent results on Saturn 1.9 engines and more recently for Ecotecs.
The original design was an improvement on the 50mm stock 1.9 throttle body. They started with a 52mm bore tapering back to the stock 50mm and back out to 52mm. Later on several companies released 56-52-56 tapered bores as later throttle bodies came with more machinable material around the throttle bore.
The taper to 50mm acted to raise inlet velocity without causing the same restriction as seen on the throttle body with the smaller diamer for it's entire length. The 52-50-52 throttle body posted flow bench numbers less than 1% off from a straight through 52mm TB, but behaved much differently on the engine because of differing flow velocities. This is a common practice going all the way back to the days or carburetors. While I can't say I've ever never seen a taper quite that extreme, the reasoning behind it is still sound. Just because SCC doesn't endorse it doesn't mean it doesn't work.
^Very good info, I was thinking the exact same thing on increasing the air velocity. This is exactly how a carborator works having the fuel brought into the air flow.
D Hall wrote:There is no Performance Gain there! I actually got one done from him awhile back and had it dynoed! I lost o.8 hp and the only thing i did was changed to his tb. This is nothing you can't do by buyinh a dremel and doing some grinding and polishing! SAVE YOUR MONEY!I'd be VERY interested in seeing those dyno sheets. SPS, saturnperformance.com and several other sites have been making, testing and selling tapered throttle bodies for years and loss of power has never been an issue. I had a SPS 52-50-52 throttle body on my Saturn and, while I never dyno tested it, it provided a noticable difference...especially at the low end.
Turbo Tech Racing wrote:JimmyZ wrote:Actually, it's not junk. SPS and other companies have been selling tapered throttle body bores for years with excellent results on Saturn 1.9 engines and more recently for Ecotecs.
The original design was an improvement on the 50mm stock 1.9 throttle body. They started with a 52mm bore tapering back to the stock 50mm and back out to 52mm. Later on several companies released 56-52-56 tapered bores as later throttle bodies came with more machinable material around the throttle bore.
The taper to 50mm acted to raise inlet velocity without causing the same restriction as seen on the throttle body with the smaller diamer for it's entire length. The 52-50-52 throttle body posted flow bench numbers less than 1% off from a straight through 52mm TB, but behaved much differently on the engine because of differing flow velocities. This is a common practice going all the way back to the days or carburetors. While I can't say I've ever never seen a taper quite that extreme, the reasoning behind it is still sound. Just because SCC doesn't endorse it doesn't mean it doesn't work.
^Very good info, I was thinking the exact same thing on increasing the air velocity. This is exactly how a carborator works having the fuel brought into the air flow.