RPI SCOOP

[Rudd]

hey guys, been pondering this today as im running out of little projects and need to keep busy.

is it true that you cant fit an rpi to a prefacelift zed?

regardless of the fact im thinking, bit of aluminium, some bends with the correct tools, maybe a rivet or two and there you go, could cost a tenner.

i want to give making one a go just out of curiousity more than anything but i need the help of the forum and in return people will get a 'how to' if it works out.


i need:

pictures of it fitted so i can see the fixings
possibly some basic dimensions


what you reckon? this is not a money maker obviously because of patents and copyrights etc etc but no harm making one

 

[Mr Whippy]

Copyright and patent?

Will they really apply for what is essentially a duct for air?

My 2p is that they are snake oil. If you DO do this, then please test it thoroughly so we can put it to bed

Dave

 

[Rudd]

Copyright and patent?

Will they really apply for what is essentially a duct for air?

My 2p is that they are snake oil. If you DO do this, then please test it thoroughly so we can put it to bed

Dave

as you say i doubt there can be protection but you never know. and i was unsure about actually getting anything from them which is why i want to make my own test one. plus if it goes right and looks good its another bit of bling :wink:

plus im thinking its only folded metal and from some pictures that i have seen it looks pretty simple to make



there was this claiming gains http://g35driver.com/forums/v36-engine-exhaust-drivetrain-fi/277190-rpi-intake-scoops-exhaust.html

and another guy with a z4 was claiming about the saim sort of power gains, if anything it may be healthier for the engine to get more air?

 

[Mr Whippy]

There is a dyno showing gains from an exhaust, and it's not independently run, but not the flap.


There are MANY test variables not considered here too.

The RPI scoop may be better at giving good gains at peak power when stationary and having air blown at the car (simulating low speed), but these may well dissolve when the car gets moving and a significant flow of air is passing in to the front of the car air-dam... the RPI gains might just be making up for the lack of any ram air effect of significant size on a dyno with even very good fans. Ie, it's almost designed to give gains for dyno use, but these disappear in actual real life application because the old setup was just as effective by that point (ie, why BMW used it)

I'd want to test wheel power on the road before/after many times, and also run manometer in the nozzle to the scoop, and the dirty side of the airbox before/after as well.


Road/strip testing is the only real indicator for these types of changes because a dyno just doesn't simulate the factors that these types of tuning changes are based upon.


Testing will ALWAYS be key, so good luck to you, just make sure you test it well and prove it with a bit of scientific method

Dave

 

[cj10jeeper]

Personally I think they are as total waste of time and money. You would really need to understand where the high pressure zone is between the radiator and the grill as that's typically where I'd expect the stock intake to be. Surprise - it's right in the upper corner at the edge worth no attempt to face the grille. I'm no expert in this field indeed I aspire to rank amateur, but I can't see why BMW would miss 10hp for nothing...

I also question dyno results where the car is static and then claim xx whp as being a ram air system it surely needs to be on the road, not with as some do a big fan generally blowing at the front of the car.

.....and my final piece of thinking is I have run a DIY one for the last 6 months. Made of CF and cast to scoop air and direct it to where the old intake cover was. End result - zero detectable difference on the butt dyno under any conditions.

 

[PawnSacrifice]

Will be fiddling with a few things over the next couple months - and I will be doing tests! Would like to make it clear from the start, I am going for noise / look ( ), other benefits come are a side affect. But yes, from all that has been said I am interested to try and get some empirical data. It appeals to the nerd in me! I know that whatever method of data collection I use someone will have issue with it, so instead I am going to go for consistency and look at the differentials. Also, if I get dynos they will be independent from anyone working on the car, before and after.

I asked the question whether a car needed mapping if an induction kit was fitted, I was told something like, "due to the airflow meter and DME the ECU is sophisticated enough to handle the additions without mapping."
Understanding was that you need to tell "the car" that the change has been made for any performance gains (live mapping). Am sure I have read elsewhere that an RPI scoop did yield better economy though.

Am looking forward to the experiments almost as much as the mods themselves! (Appeals to my nerd side... mmm, spreadsheets... oh, I have no other side!)

 

[Rudd]

pawnsacrifice im with you. i think performance wise im not too bothered but it would be nice and would satisfy my curiousity. i like the look of them and i think it is worth it from a purely aesthetic point of view (providing my craft skills are up to the job!)


i have a cold feed induction kit on now and next time a dyno is available i want to test with oem airbox and then with induction. i dont think a dyno is a very good place to test the rpi style scoops IMO for the reasons already stated

 

[Mr Whippy]

You will do so much testing on a dyno, if you are doing it right, that you will end up poor

Best to invest in a G-tech Pro RR, and/or a Vbox, and other data logging equipment.

Then you can really do decent comparitive real-world testing

Laptop £400
INPA for logging/diagnostics + cable, £50
Generic OBD for logging ELM327 £50
Generic OBD software, say PCMScan (good) £60
G-tech Pro RR and breakout battery cable for logging rpm £200
Maybe a Vbox £350 iirc...


Brummmm

Dave

 

[PawnSacrifice]

Dave,

I think you're going to be quite disapproving with my testing! Maybe a couple / three dynos and some rudimentary road tests. I only ask that you are gentle when (if) I publish my findings!

The fact that it is Windows based I probably wont look at the OBD bits, also slightly nervous about plugging things I can play with into my car! However the G-Tech kit is interesting - they claim very high accuracy, although again I would settle for +/- 3% with consistency. Not sure I would need the RR... well I don't "need" anything but the SS may do for this. Is G-Tech a manufacturer you know of?

Thanks

 

[AlanJ]

Personally I think they are as total waste of time and money. You would really need to understand where the high pressure zone is between the radiator and the grill as that's typically where I'd expect the stock intake to be. Surprise - it's right in the upper corner at the edge worth no attempt to face the grille. I'm no expert in this field indeed I aspire to rank amateur, but I can't see why BMW would miss 10hp for nothing...

I also question dyno results where the car is static and then claim xx whp as being a ram air system it surely needs to be on the road, not with as some do a big fan generally blowing at the front of the car.

.....and my final piece of thinking is I have run a DIY one for the last 6 months. Made of CF and cast to scoop air and direct it to where the old intake cover was. End result - zero detectable difference on the butt dyno under any conditions.

Cj - you've said it all Now where's the Snake Oil....

 

[Mr Whippy]

Dave,

I think you're going to be quite disapproving with my testing! Maybe a couple / three dynos and some rudimentary road tests. I only ask that you are gentle when (if) I publish my findings!

The fact that it is Windows based I probably wont look at the OBD bits, also slightly nervous about plugging things I can play with into my car! However the G-Tech kit is interesting - they claim very high accuracy, although again I would settle for +/- 3% with consistency. Not sure I would need the RR... well I don't "need" anything but the SS may do for this. Is G-Tech a manufacturer you know of?

Thanks

Any test is good if you control the variables well and make consideration for them

I use the G-tech Pro RR... mainly because the data it records can be sent to CSV > Excel, and then you can do much nicer things with it than the software that comes with the G-tech does.

Then you can use OBD port logging (say vehicle speed, intake air temp, atmos pressure, coolant and oil temps (for fair consistency)) and then correct for atmospherics nicely... so testing on different days may be fair (but I always try do comparitives, so if I test A and B one day, then when I want to test C, I'll re-run A or B, then C, so that I have a benchmark from the earlier testing)


Just use good science and lots of writing down what you have done and conditions of test, and don't go out wanting to see gains. If you want to see gains, you can often fudge things, like guessing the fuel load is actually 5kg lower than it is, and then you get that 1% improvement and lie to yourself that change B has made you power


After doing two dyno runs and paying £90 I soon stumped up £200 for my G-tech Pro RR, and since then have used it literally hundreds of times!

Dave

 

[PawnSacrifice]

Thanks for that - very helpful

I may well go for the Pro RR then - guess I could sell it at an acceptable loss (cost of experimentation) if I don't want to keep it. Will have a think about the OBD side as well.

I did think about the problem of testing on different days; I will keep a close eye on the temperature, make sure the engine is properly warmed up, am going to be making sure I don't change the wheels / tyres (that may be another stage of testing ), will brim the tank each time also... and obviously use the same fuel (although I know that is also a point of contention). Thankfully I do have a local flat straight mile of 60 limit for the drag testing.

With my love for numbers I fear this may be another slippery slope.

 

[Mr Whippy]

I will keep a close eye on the temperature, make sure the engine is properly warmed up

Things like that are important.

You can drive to a dyno and go straight on, warm tyres, warm coolant, warm oil, all as per road, and then get a dyno.

You can turn up, turn off, wait an hour in a group, and then go on with cold diff oil, tyres, engine coolant, and oil perhaps a bit.

You can turn up, sit around with engine running, hot oil and coolant, and mappings might change to reflect that.


So many variables change with these parameters. For instance, cars that I have had a hand in, I have tuned to resume near OEM power parameters as the engine coolant gets too hot, and then OEM takes over and trims it back even more. All it takes is a hot summers day, arriving, and then parking up for 5 mins with engine running, then going on the dyno often in doors, and you may suffer because of that!


So many variables, so keep an eye on them to be fair

Dave

 

[Rudd]

hey guys, just a quick one.

im busy making my template for my DIY RPI and need to know if anyone has done it on a facelift. i know CJ10Jeeper has done it.

what i need to know is do they go behind the brace bar infront of the radiator or behind?

CJ any pics? :wink:

cheers

richard

 

[sammyz]

just bought one of these for the 'M'. Not expecting a great deal really but the filter and air intake might make a bit more noise. I won't be doing any scientific testing at all!

 

[Rudd]

have you fitted it? i doubt they are too similar but would be good to see one fitted.

i like the look more than anything plus it keeps me busy on the weekend

 

[sammyz]

Not fitted yet. Waiting for it to be posted to me. Might fit it next weekend if weather's OK