C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old May 26, 2015 | 10:05 AM
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dustyjoe57's Avatar
dustyjoe57
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From: Bear Delaware
Default throttlr body

Hello, I've been thinking of replacing the throttle body on my '89. When I go on sites to purchase a new one I see there are two available. A 52mm and a 58mm.
My '89 being a base coupe I'm sure has a 52mm from factory.
I'd like to upgrade to a 58mm throttle body. However there is always a side note listed by seller which reads:

"58mm Throttle Bodies require port matching of plenum to allow maximum flow."

Can someone please tell me what this means and also is the 58mm to much for my car to handle?

Obviously I'm less than novice when it comes to working on the engine.

Expecting quite a bit of poking fun and side wit agitation..... cool... I can handle it ..... as long as answers to problem are thrown into the mix.....

Thanks!
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Old May 26, 2015 | 10:13 AM
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John A. Marker
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On a stock engine going up to a 58mm TB will not increase power. My 85 came with a 48mm TB and that was good to support 400HP. Stick with a 52mm.
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Old May 26, 2015 | 01:22 PM
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dustyjoe57
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From: Bear Delaware
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Originally Posted by John A. Marker
On a stock engine going up to a 58mm TB will not increase power. My 85 came with a 48mm TB and that was good to support 400HP. Stick with a 52mm.
Thanks..... sounds like best advice
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Old May 27, 2015 | 01:22 AM
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The "port matching" means that the holes in the front of the plenum must be made larger for a 58mm.
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Old May 27, 2015 | 07:42 AM
  #5  
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From: Bear Delaware
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Originally Posted by Cliff Harris
The "port matching" means that the holes in the front of the plenum must be made larger for a 58mm.
Thank you info..... definitely not going that route.... leaving well enough alone.
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Old May 28, 2015 | 08:37 AM
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Your stock throttle body is 48mm....................the same one I have on my 383 that runs 11s in the 1/4
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