Hi there

Do you guys find when you wash your car a little bit of water sits in the bottom of the X51 intake where the ducts are, talking very small amount as i see it has drain holes, just wondered if others had noticed this?

This thread makes me want to hurry and install my x51 airbox. Still gotta buy the plenum and TB then I'm good to go.

Hi there

Those of you who have fitted the X51 airbox along with larger throttlebodies, did you find your throttle was a little less responsive at small/moderate throttle in the lower RPM's?

It is marginal but I do feel like I've lost some throttle response going to the larger throttle body. I am heading to the dyno this weekend to see if the mods have improved on my last dyno of 371BHP and if I get time I think I shall re-fit my stock plenum/throttlebody using a hoover belt so the hose fits to see how it also effects power/plot. As I am missing that ulta crisp throttle response I had, but at the same time I love the immense power beyond 5000rpm, question is, does that power come from the throttle body being larger or the dual intakes from the X51 airbox, time to find out. :)

i didn't loose any throttle response. as a matter of fact, it became more clean me linear. what I noticed was a whooshp sound when accelerating from a stop.

Have you thought about adding a sprint booster? I've read threads on both sides of the fence, but am still curious on the results.

My car has Sports Chrono, so in sports mode it does what a sprint booster would do.

Before the plenum, tb and x51 intake throttle was razer sharp, now with changes I'd say its very sharp, minimal difference but I can notice it.

Looking into throttlebodies, it seems that benefits of a larger throttlebody are more towards top-end HP and woosh sensation as rev's build, making everything seem faster and no doubt indeed quicker.

But unfortunately you loose low-down intake velocity which can effect throttle response and low-down torque in a negative way.

Don't get me wrong, not end of world, but I shall try X51 with stock plenum and throttle body to see how it effects things. :)

Please report back with dyno results... I am super curious as to how it will play out.

what plenum did you get?

I agree with you as I never lost the low end. It may be because of the softronic tune.

looks like he got the eurocup 82mm Plenum as apposed to our 84mm

They are all same size, throttle body is 82mm or 84mm depending how you measure it, same for plenum. Major difference is eurocup plenum is same design as stock internally and made from CF.

Maybe what I think is a marginal loss in throttle is maybe just the power band moving slightly, power delivery is certainly smoother and more of a woosh now.

The dyno will hopefully reveal all, booked in for Friday. :)

The Sprintbooster is a wonderful add - hard to beat for the $200 +/- price; I leave it on all the time ("green" setting).

It does effect fuel economy, but a huge difference in throttle response.

Does your plenum has this shape inside?

https://www.6speedonline.com/forums/...ine=1367424783

Nope same as stock inside. That design you posted could maybe help improve air velocity which could help with low-end torque/response. Is that the NHP one?

Hi there

Well went to the dyno today in short with 82mm, tb, plenum and X51 Airbox car made 375BHP, 4BHP more peak than last time, but had lost torque and power sub 3000rpm.

So put stock tb and plenum back on and throttle response improved and the low-down torque/power came back but car made 370BHP peak.

However both runs had a major issue, car was lean, LEAN LEAN!!

This shop does tuning for several makes, but not Porsche unfortunately, however they have got down to the bottom of the cause:

The tube where the maf inserts on the stock and X51 Airbox are different in diameter. The X51 Airbox has a larger diameter tube and the stock or the softronic map can't account for this. Due to the larger diameter the X51 Airbox flows a lot more air pass the maf without it realising this. Because maf calculates airflow based on speed of airflow, problem is with larger diameter tube you chase Venturi effect and as such far more air flows across the maf. As the stock maps are based on air speed and set diameter of the stock Airbox when you increase this diameter the air speed slows down but your getting more air. As such on stock map or even softronic the car air fuel ratio goes out, very badly.

As such anyone who has upgraded their car with X51 Airbox and are running the stock remap or softronic, YOUR CAR IS RUNNING LEAN!!

The only way to fix this will be to either get the X51 map from Porsche or get a custom live map done. I shall speak with Scott at softronic to see if he can help.

The dyno shop feel that with the right map which adds fuel I'd also be able to run 82mm tb and have good throttle response as with stock but also make more power everywhere and no doubt get over 380ish peak.