Modified Vectra V6 large bore throttle body and modified plenum
2.5 V6 Vectra, Can you mod the throttle body DIY to bring it up to Regal Spec
Vectra V6 large bore throttle body and modified plenum
Throttle body incorporated a larger butterfly which is attached
To a new low profile spindle providing 21.5% increase in throttle
Area at full throttle. The plenum is flowed internally, with
Unrestricted internals, developed on a flow bench to gain max
Air flow, more mid range performance is produced rather than
Top end, with torque increasing by an extra 15%. torque increases of 40 ft/lb torque have been achieved during testing.
I know the low profile spindle thing has been done before but what else is required.
Originally posted by tomstickland The throttle spindle snapped today! I was in the outside lane on the motorway annoying a rep when I had to turn off the engine and cruise onto the hard shoulder.
The spindle had cracked where the screw thread weakened it. So I'd advise people to not cut the spindle in half like I had.
Luckily, no screws went into the engine.
It's all fixed now, courtesy of the scrap yard.
I did have fun on the mway too - I had 100% throttle or nothing, so I drove along by turning the engine on and off.
Surely the throttle body mod can be done for less than that! As for plenum I have been told that modifying this to flow better does give good results, they reckoned +8bhp and up to 40 ft/lb of torque! Dont know how accurate these figures are but the plenum does look restricted.
Anyone else been there and done it yet???
I owuld have thought if you know someone with a milling machine it wouln't be too difficult. Its just knowing how much you need to shave off. Probably only a few mm.
Then you need to find another butterfly flap, or rather cut a new one. Plus the spindle can be cut down or even use flat head screws, anything to reduce air drag I suppose. I have a few engine tuning books and they show this modifcation done DIY on other engines, so its nothing new. £350 is a load of money for what it is.
If the throttle body is simply bored out then it would be a piece of cake. The hardest part would be holding it in the vice! Any competant machining shop should be able to do that in less than an hour.
As for how big to go dont they list the exact surface area in mm2? All you have to do is divide by pye to get your diameter to work to.
Got the V6 throttle body diminsions off Courtenay site
Cross Sectional Areas.
Standard Vectra 2.5 Throttle Body 2613mm2
Modified Vectra 2.5 Throttle Body 3178mm2
Price £252 inc VAT.
Must admit, I don't know if they modify both the butterflies on th C20XE/C20LET throttle body. They might leave the little flap alone. Don't know as they don't list it on their website and the ad in TV is not clear enough.