IPD plenum and larger TB on 3.4 cable throttle

folks has anyone done this on an early car? I know some of the later cars have been done but the throttle cable cars need a different TB do IPD do the 82mm version for the cable cars? Ta.

I have an IPD plenum on my '98 - it's definitely a different specific design for the cable throttle cars - I picked up mine "as new" second hand several years ago.... From all the research I did at the time, I remember coming to the conclusion that I didn't even want to go near changing or enlarging the TB - If you're looking at enlarging the TB, surely you need to be accompanying with larger injectors, exhaust mods and a remap.....? : '

I seem to remember a thread on one of the American forums that exposed IPD plenums as an expensive waste of time, backed up by back to back dyno tests. I simply wouldn't bother. You are guaranteed to get better HP results if you develop the exhaust as this is much more of a compromise than the intake. The primaries on the exhaust, even aftermarket ones are far too short and the they use too tight raduis bends. The remainder of the exhaust is heavy and restrictive. A grand or two spent here with a really well designed exhaust could get you 20hp. A new plenum won't give you a gain you can even measure.

Martin is right the exhaust is the first place to free up more BHP with 200cell cats and a lighter free flowing set up , But after fitting IPD to Both my gen 1 and gen2 997 and remapping them at the same time I have to say the post he refers to is wrong if we are talking fast road cars. Fitting IPD and remaping gave me my second biggest gains after the exhaust. As with all these mods different guys are doing different things with differing expectations. If a guy spends £1k on an IPD then thinks the ECU will relearn the values and doesnt remap or do anything to improve other parts of the induction , YES he is going to be very underwhelmed and think its a waste of money. But combine it with a group of induction and gas exit mods and they work very well. Its all about understanding what each mod will bring to the party and being realistic in what you expect from them. and when you read negatives to a mod you must understand that they either didnt do everything of just had set expectations too high or as I often find when researching were looking for a different win eg max BHP on a track monster which is a whole different set of paramiters to what you want from a fast road car where you want the extra power in the low mid range of the power curve and not at the top in a place you rarely use it on the road. :thumb: :thumb:

thanks all. I would only do the IPD and larger TB change WITH a remap and would take it to Wayne Schofeld as he really is a wizard with this stuff. first up I have done some slight air intake mods, changed the manifolds, I am doing the 200 cell cats and sports boxes. then I will look into the IPD changes and re map. Wayne recommends the remap so that the whole systems can deal with more air coming in as the standard oem ecu won't adapt by itself. it won't happen for a while and just researching some options and what the view is around this.

Perhaps you could approach Wayne for his opinion on the IPD plenum. Presumably he's encountered them and remapped cars that have them. Hopefully he can give you some solid advice either way.

already have and his view is sort the basics of air breathing and exhaust flow before you tackle the plenum and TB. when its all together then do the re map and you get the benefit. he was really straight with me on the GT3 and don't bother and leave the exhausts as they are. more gains to be had in the lower power range cars and the M96 engine.

IPD work - that is a fact. I took two random customers several years ago (there is a thread on here somewhere - think it was a 996 and 997) and did a controlled test which proved they worked. That not only included dyno before and after, but also MAF readings before and after which showed the increased airflow. On NA cars I don't think they give as much of a hp increase that Greg (at IPD) states, but they give a solid 10hp/tq across the whole of the curve, which frankly is better than a peak of 20hp. The problem is this. - your MAF must be 100% - if it is not and operating at 90% which a lot of them do before you get an error message, you will not gain from the IPD as much as you should. - recent plug change should be done and the car should be performing normal before you make the change - I had someone who had 30000 miles on plugs that said it didn't work - no surprise there. - the car needs at least 1 hour of solid driving for it to adapt (if the TB is the same size). - if the TB is different size, it will adapt, but it will create compensation tables - it needs tuning basically. As others have said, you can gain more from better sports cats etc initally at similar price. Ken

As an owner of a 3.4 cable throttle car I'd be very keen to see the final results of your mods! :thumbs:

thanks Ken and all very good points which I did not know and helps owners to think about the mods and effects I am going the exhaust route first as the Dansk boxes are shagged and splits in the flexi joins. 200 cell cats and new back boxes. will see how I feel after this.

I'd be very interested if you locate a cable operated 82mm throttle body.