Throttle body length

[Tony Martyr]

I have to decide on the final built up length of my intake tubes made up of direct to head QED TBs plus a 19mm spacer to take the filter back-plate clear of the injectors plus the trumpets. The trumpets can be 40mm or 90mm long, both would fit but require differing filter housing (not yet decided upon)

My inclination is is go for the shorter system but I'm not sure of the secondary effect such as noise attenuation etc.

Any advice or comment greatfully received.

Now I notice that Demon Tweaks is selling a K series lit. I'm going to see if they will sell just the throttle quadrant which looks as if it will be better than may lash-up that currently relies on a wire crimp to hold the cable from pulling through the swivel pin supplied with the TBs. Theirs looks as if if uses the orginal cable end.

[Rob Walker]

I fitted QED DTH TB`s, 19mm spacers and 90mm trumpets. I mounted the air filter on the end of the trumpets, this was an ITG domed sausage type 100mm deep JC50 backplate. All worked well and fits under the bonnet. 186 bhp 132lbft out of 1600K. If you worried about the induction noise I found lagging the inside of the bonnet directly in front of the trumpets/airfilter to be effective. I used thick felt carpet underlay suck on with carpet adhesive. The car was used at four track days at C Combe with no problem.

[Sid Spalding]

I'm looking to do exactly the same in the new year. I have been talking to QED and Jenvey and the best spec seemed to be the Sausage filter with 90mm trumpets. BTW I have 1600 SS - you reckon you get 186 bhp out of yours - what would you expect me to get out of mine - I was hoping for around 150-155 bhp !

[Mike Bees]

The longer the better Tony (as far as mid-range torque is concerned).

 

Mike

[Peter Carmichael]

I have the ubiquitous 19mm spacers and 90mm trumpets. I did some fag packet calculations which suggested a useful inlet resonance somewhere between 7500 rpm and 8600 rpm. Longer would be lower rpm. My power peak is at 8400 rpm, so maybe I got it right.

[Geoff Dixon]

Car & Car Conversions March 2000 published an article headed "K Series Tweating". In that article they with expert help and guidance from QED investigated the tuning options for the K series. Much of this article was concerning the fitting of throttle bodies. Their advise on trumpet length was to use 90mm intake trumpets. I have done this myself using carbon fibre trumpets with an ITG filter (all ex QED). The filter back plate is fitted between the trumpets and the throttle bodies (no spacer is reqd),the filter then covers the whole length of the trumpets. This has necessitated using a new fuel rail, smaller QED injectors and a new fuel pressure regulator as the filter backplate is very close to the injectors etc. Have only just finished - sounds absolutely fabulous, as yet not been on a rolling road so can't say how much bhp etc as I am now alos fitting a VVC (Dave Andrews ) head. The whole lot fits easily under the bonnet. Fitting the throttle linkage is fiddly to say the least. I have found QED very helpful. If you push them you can also get discount. I was party to a block order and we got reductions averaging 15%.

[Tony Martyr]

Thanks Guys. This has been very helpful. The 90mm trumpets plus spacer will be fitted this weekend.