Arif Posted February 20, 2002 Share Posted February 20, 2002 Anyone know what year and model Mercedes the 65mm TB came from? I have a line on one and want to make sure it is the right one before I have them ship it. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted February 20, 2002 Share Posted February 20, 2002 Actually, it is a 66.7mm TB and it came on an earlier V8 mercedes. I am not sure about the year, but most likely in the early-mid 80's. Quote Link to comment Share on other sites More sharing options...
Arif Posted February 20, 2002 Author Share Posted February 20, 2002 I heard it was off a 75 SEL. Just need someone to verify it for me. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 20, 2002 Share Posted February 20, 2002 I received an education when I watched my L6 on the dyno. Velocity is more important than flow. My L6 3.0L is currently making over 300hp using a 60mm TWM TB. I also saw an LMP 675 3.0L VQ motor making 450+ horsepower through a 40mm restrictor. Careful about going too big on the throttle body. Quote Link to comment Share on other sites More sharing options...
stony Posted February 20, 2002 Share Posted February 20, 2002 i may be wrong but i believe volume of air either forced in or sucked in (NA) is what will makes power. so even though its the same displacement... bigger valves or more valves, big cams, bigger turbo (more volume not PSI) is what makes the difference. the hard part is matching all this stuff up so it works good. if its running a restrictor they are trying to limit the HP. If they had a bigger throttle body on it it would allow a larger volume of air to move thru the manifold making more power. .. DO i have my terminolgy right guys? Quote Link to comment Share on other sites More sharing options...
johnc Posted February 20, 2002 Share Posted February 20, 2002 True to some degree but sometimes we forget about inertia. If we can keep the mass of air going into (and out of) the combustion chamber moving at a high rate of speed then we don't have the delays associated with accelerating that mass of air. That mass moving at speed also dampens reversion which tends to slow down or stop the mass of moving air. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted February 20, 2002 Share Posted February 20, 2002 Great post. John made a good point about velocity and the velocity created by a forced induction engine makes the need for a huge TB less critical. I personally think a modded L28ET is just fine with a 60mmTB. A stock GN uses a 57mm and I am using a 62mm. Many high HP GNs are still using the stock TB. I went for the modded TB not for the extra size alone but because it also has mods to help maintain the velocity such as cleaning up the bore, knife-edging the throttle blade, moving the screws out of the airflow, etc. Those mods sound minor but they are effective. When upgrading the L28ET to a larger TB, if the intake is not properly port matched, it will defeat the purpose of going to a larger TB. The bigger the TB, the more porting has to be done to make the increased bore effective. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted February 20, 2002 Share Posted February 20, 2002 At the same time, the RB26DETT guys are using 90mmTB's and making 1000++++hp Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted February 20, 2002 Share Posted February 20, 2002 That is true, Jimbo. The Buick boys in the 800-1000hp range use between a 70-90mm TB. However, they are moving a tad more air than a 350+hp L28ET . Hey, don't be wasting your time on this forum, you have important work to take care of . Quote Link to comment Share on other sites More sharing options...
DAW Posted February 20, 2002 Share Posted February 20, 2002 While on throttle bodies, does anyone know why the L28 Turbo is excluded from the Weber "big bore" T.B. applications in MSA catalog? DAW Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted February 20, 2002 Share Posted February 20, 2002 DAW - the only plausible reason I can come up with is the way the air bypass is routed differently on the turbo setup. Also, the turbo has an automatic idle control, and the Weber allows a manual idle setting. I'm not letting MSA's recommendation keep me from installing it!!! Quote Link to comment Share on other sites More sharing options...
Arif Posted February 21, 2002 Author Share Posted February 21, 2002 Ok I knew I should of gottten an engineering degree instead of accounting dagree So then let me back up and ask wether I will see a noticeable gain going from a 300ZX (55mm) TB and upgrading to the Mercedes (66.7mm)unit? I know I will have to bore out the intake to get the benefits of greater flow. Also, what would be the downside of a TB that is too big for an application? loss of HP, TQ?? Educate a poor accountant!! Quote Link to comment Share on other sites More sharing options...
johnc Posted February 21, 2002 Share Posted February 21, 2002 I can't say whether you will see a noticable gain or not. Some folks have done this conversion so I guess they would be the best ones to reply. Going out on a limb with an uneducated opinion - If that's the only change you make to the motor I think you'll be disappointed. If that change is made in conjunction with other modifications then you might be happy. Quote Link to comment Share on other sites More sharing options...
Guest Aaron Posted February 21, 2002 Share Posted February 21, 2002 In the late 80's Hot Rod did an article testing several bolt on parts for a 5.7L FI Camaro. They went to a larger TB, and made several other changes. They did not replace the computer or anything in the engine. They tested each combination on the dragstrip, and everything they did actually slowed the car down. They theorized that the TB was optimized to the engine as it was and without porting the mainifold and heads, the larger TB, etc. did not make any difference. Quote Link to comment Share on other sites More sharing options...
Kennysgreen280zt Posted February 26, 2002 Share Posted February 26, 2002 just an FYI, the benz TB doesnt "bolt up" to the L28 manifold. also the TB came on the benz V8's. laterz ~Kenny Quote Link to comment Share on other sites More sharing options...
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