LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Porting stock Throttle Body

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Old 06-02-2009, 10:17 PM
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Default Porting stock Throttle Body

Is there a writeup on this anywhere?

Thanks
Old 06-02-2009, 11:08 PM
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there is very little if not anything to gain with such work... thats an Ls1 mod
Old 06-02-2009, 11:13 PM
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Duane always preaches that porting the stock one is superior to an aftermarket unit.

Cant you get like 52mm out of the stocker before upgrading?
Old 06-02-2009, 11:25 PM
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Yes you can. There is some horsepower to be gained, and it smooths the intake flow, since the manifold is already 52mm. I have run a ported 52mm stocker for about 8 years now. If I can find a writeup, I will post the link.
Old 06-02-2009, 11:26 PM
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Please do. They sell them on ebay for like 160 but I dont want to pay that when I can do it myself or have it done in town.

thanx
Old 06-03-2009, 01:09 AM
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You can actually get a 54mm out of the stocker before you have to switch. As for a write-up, it's not really going to be easy. You have to get it just perfect. You'll also have to find the butterflies that are the right size, for the increased bore size also. I couldn't find anything when I was looking into it. So, I'm just going to get one off eBay. After, a core refund, you can get them for around $130-$140. That's still a lot better than an aftermarket 52mm.
Old 06-03-2009, 01:10 AM
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Originally Posted by gregrob
Duane always preaches that porting the stock one is superior to an aftermarket unit.

Cant you get like 52mm out of the stocker before upgrading?
yes you can. if youve gotten the intake worked then the max for a stock throttle body would be 54mm also have that on ebay with core buyback.
Old 06-03-2009, 05:04 AM
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You'll only see gains if your car needs it.
Old 06-03-2009, 07:26 AM
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Unless you know how to manufacture new butterflies there really isn't a lot of a point to do it.
Old 06-03-2009, 09:11 AM
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Originally Posted by gregrob
Is there a writeup on this anywhere?

Thanks
I've got a spare OEM one you can have if you mess yours up in the process
Old 06-03-2009, 09:19 AM
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It's not something that you can just up and do yourself. Most likely you'll end up ruining your stocker and buying an aftermarket one anyway.
Old 06-03-2009, 09:20 AM
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You will need at least a milling machine to do the job properly with basic machining knowledge and skills. You need to keep the bores straight and round all the way through the throttle body. You will also have to have the proper sized throttle blades with the proper angle. I do port throttle bodies and I machine new blades from sheet .063 6061-T6 aluminum for the proper blade size. The main advantage with using a bored stock unit is you keep the stock IAC passages.

Old 06-03-2009, 01:37 PM
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I was going to have my buddy at a machine shop do it. Certainly wasn't going to attack it with a dremel lol.

I dont see boring it being too hard, but one off butterflies make it not really worth the time I would spend. If you could buy bigger butterflies somewhere it would be a different story.

Guess I'll just get one off ebay "when my car needs it".
Old 06-03-2009, 01:37 PM
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Originally Posted by 97pontta
You will need at least a milling machine to do the job properly with basic machining knowledge and skills. You need to keep the bores straight and round all the way through the throttle body. You will also have to have the proper sized throttle blades with the proper angle. I do port throttle bodies and I machine new blades from sheet .063 6061-T6 aluminum for the proper blade size. The main advantage with using a bored stock unit is you keep the stock IAC passages.


Well what do you charge?
Old 06-03-2009, 03:55 PM
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i am sorry but the topic started out as "porting" and the conversation has now shifted to "boring" there are a few ways to go about boring the factory TB one is 52mm and the other is 54mm. there is a company that goes through ebay that does this mod
http://cgi.ebay.com/ebaymotors/52mm-...Q5fAccessories
Old 06-03-2009, 04:01 PM
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Originally Posted by 97pontta
You will need at least a milling machine to do the job properly with basic machining knowledge and skills. You need to keep the bores straight and round all the way through the throttle body. You will also have to have the proper sized throttle blades with the proper angle. I do port throttle bodies and I machine new blades from sheet .063 6061-T6 aluminum for the proper blade size. The main advantage with using a bored stock unit is you keep the stock IAC passages.

You keep those with aftermarket throttle bodies too.
Old 06-03-2009, 04:15 PM
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Originally Posted by speed_demon24
You keep those with aftermarket throttle bodies too.
Most aftermarket throttle bodies that I have seen have the passage where it enters the intake manifold split and opened into the bores behind the throttle body blades. The stock units have the IAC passage completely sealed from the bores. I don't believe all brands of aftermarket units are like this though.

Boring the throttle body is porting it. 54mm is possible from certin year TB/casting numbers but the housing becomes very thin in cretin spots when bored this large. Most stockers you see are bored to 52mm.
Old 06-03-2009, 04:17 PM
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Ny 58mm edelbrock.

Old 06-03-2009, 04:20 PM
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I agree that is correct. But a lot of the older BBK units were not like that. Here is a BBK 58mm with the IAC opened into the throttle bores.

Old 06-03-2009, 04:31 PM
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Agreed this is something best left to the shops that offer the service. The bores need to be nice and round and the blades need to be cut right and are OVAL not truely round.

For a 52mm I would do a bored stocker, I think only one place on ebay commonly offers 54mm and needs certain castings to do it, bet he ruined a few finding that last 2mm and I would not assume that is dead centered on the existing holes.


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