123 replies to this topic

[vocky]

Is the corvette the LS1 and is it electronic? Difficult to explain how I ported the throttle body, I previously worked in flow control systems for ten years so restrictions stand out to me, anyway basically the intake shape is not the best for flow - it should more look like a cone or funnel and the outlet shape is the same, but not quite as bad. Also I ported the inlet and outlet to the maximum size possible (beware of the outlet side as the walls are quite thin at the front). Then I polished the butterfly valve, modified the spindle to countersunk screws and thined out the lower portion of the spindle to allow more flow in the centre of the throttle body.

[vocky]

Here is a pic of a similiar TB, but the screws are not countersunk and the shaft is not flat

Edited by vocky, 26 November 2004 - 10:03 AM.

[clipping_point]

What methode did u use in order to get the funnel shape? Lathe, boring/honing conical?? Thinning the center part by filing it down? Counterunking the screws by using different screws and boring under them.

[vocky]

Nothing so technical, my diegrinder then many hours of polishing . I achieved a result as good as the photo, the shaft I filed down by hand to prevent any damage to the freshly polished bore. The new screws required a simple countersink bit and a bit of careful engineering, I was unable to locate countersunk screws with the same thread so rethreaded the shaft to suit the new screws.

Edited by vocky, 26 November 2004 - 10:20 AM.

[clipping_point]

Sorry, being swedish, what is a die-grinder? Dremel? Or something u put on your drilling machine?

[vocky]

Sorry, it is a pneumatic powered high speed drill @20,000 rpm, a Dremel is an electric version.

[clipping_point]

Is the corvette the LS1 and is it electronic?

Yes, it fully electric and plugs into the Ecotec system without modification, according to some sources

[vocky]

First, very important for anyone considering porting their throttle body themselves, do not touch the surfaces where the butterfly is sitting - as this would increase air flow at tickover (unless you want 2000rpm or more tickover ). Leave at least 5mm before modifying where the butterfly starts to open to prevent any problems. Anyway, do you have the part number for the 75mm throttle body and where is the best place to get one, it sounds ideal for my engine. Thinking about 268 cams rather than 256 cams so the extra area of the 75mm TB would be nice

Edited by vocky, 26 November 2004 - 12:53 PM.

[clipping_point]

You should wait for my evaluation first.............I bought mine off ebay for a mere $90-100 including shipping

[vocky]

Yes I will wait, that is the best bit about joining - sharing infomation and helping when you can. Still wondering if it will plug straight in But if it works I'm getting one E-mailed 'venom' yesterday still waiting for reply

[clipping_point]

Care to comment at this thread, Vocky (tho it is in Swedish, please use your own language)

TB modded

[clipping_point]

Another engine that looks good

[clipping_point]

Here´s the old one together with the new. My god, what a difference. Thats good cos I plan to pump out 230 horsepower thru the new one!!!

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[clipping_point]

And the new one fits snuggly! No problems with the sub-frame either as I suspected!!!

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Edited by clipping_point, 29 November 2004 - 11:05 PM.

[clipping_point]

The gap, could be a factory option!!!

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[Robski]

That really does look great CP! I'd love to see the boot mods once the clam is refitted... Rob

[clipping_point]

I guess they will be pretty marginal, a box cutout 50 x 200 x 300 mm or something. Next thing on the schedule to investigate!

[vocky]

That is looking good , the standard manifold would look better on a 1.4 engine I am only aiming for 190-200 bhp, are you going to get throttle bodies to get 230 bhp

[clipping_point]

190 HP can be reached with a good inlet, porting and a 256° cam. An exhaust mani and a 275° cam together with your +1 mm valves has to deliver way over 200 HP!

[vocky]

Over 200 bhp, that would be nice My new valves arrived yesterday, saved @33% on uk prices Going to really port the head, will weld up the cutout below exhaust ports 2 + 3 to allow a perfect port matching with the wR, cannot understand why gm put them there or the holes either side of the exhaust ports, maybe the holes were for a secondary air fan system but they do not do anything