RS Tuner says BMC causing me 3bhp loss! Any ideas??:(

[sammyhale22]

I fitted my BMC CDA recently with the cold feed pipe and i ran a RS Tuner datalog to 7000rpm in 3rd gear for Henk. According to the log i`ve been told i`m losing 30mbar of manifold pressure between 1500rpm and 7000rpm. Henk says that equates to about 2-3bhp loss.
I`m really confused though because out of interest i fitted my standard renault airbox back on and i noticed straight away the difference in low down power and performance. The BMC makes the throttle feel more responsive and the car feels like it has more low down torque.
I`m starting to wonder now whether it has nothing to do with my BMC, whether it might be a inlet manifold leak possibly? Has anyone got any ideas. Henk says the cars warm idle was slightly higher mb manifold pressure than he expected and at 7000rpm the manifold pressure is 30mbar less than it should be.:S

Cheers all,

Samuel

 

[Jamesstone]

There not the best Ik kit around, ITG MAX would of seen a few bhp increase but at £380 :dapprove:

Standard with the pannel filter just works mate, mine running a few mods made 184.5bhp using the standard airbox! only really gain from the BMC is the induction noise which makes you "think" its faster..

 

[-J-]

Get it on a rolling road, Test with the BMC fitted and with standard box.

When we tested some filters for Performance Tuner Mag quite a few of them lost power over the standard box.

 

[sammyhale22]

To JamesStone.

You think best route would be original box with ITG panel filter then, will it be better than my BMC CDA? I was thinking about the itg panel. Alot of people talk of it! Did you do any mods to your airbox, did you leave both the pipes in same place for example or did you make both feed cold air??

Samuel

 

[Chris n nic]

Where is your caf m8...I have a bmc cda on my Cup and it works great imo

Chris

 

[Fastchip]

Did your car 'feel' different right after your cambelt has been changed ?

 

[Jamesstone]

To be honest mate i have no proof that the ITG pannel filter on the standard airbox is the best for the £££ but most people run it.. The majority of the standard 172's at the Surrey rolling road dyno last week were making 165-170bhp...

With this list of goodies

* Itg pannel filter
* Mathced Inlets, from Angel works
* Acoustic valve removed
* Group N re-map
* Gray's 2.5" bore de-cat
* Powerflow 2.5" bore full stainless sytem

I made 184.5 bhp.. there were guys with similar set-ups running all sorts of airbox's, including those viper things :dead: that were making less power.. so for me, i'm saving the money & keeping the standard airbox



James

 

[sammyhale22]

Hey henk, i guess my car did feel different sort of, although i wasn`t really looking for anything at the time. What are you getting at ??? Is something wrong with my engine timing?

Sam

 

[sammyhale22]

chris n nic, i have my caf pointing down towards bottom of engine bay. It was a tight fit though and i have a sharpish bend straight after the filter before it goes down to the base of the engine bay. Could the sharp bend cause problems at high revs???

 

[Jamesstone]

you want the smoothest route possible mate, bends = more work for the engine to draw fresh/cool air in....

 

[Gaz_]

Always said its a waste of time running a CAF to the lower grille, the bends are just too tight etc

 

[sammyhale22]

Hey people. I removed my CAF pipe and it actually improved my manifold pressure!! So the pipe actually was restricting airflow at higher rpms. I working out im still getting a drop in pressure though, but its only 18mbar now instead of 30. Any other ideas??

Sam

 

[tonykart]

@sammy what where your readings in 3rd ? mine are @7000 rpm = 862.1 Mbar = 142 kmh....

 

[Andyman]

To be honest mate i have no proof that the ITG pannel filter on the standard airbox is the best for the £££ but most people run it.. The majority of the standard 172's at the Surrey rolling road dyno last week were making 165-170bhp...

With this list of goodies

* Itg pannel filter
* Mathced Inlets, from Angel works
* Acoustic valve removed
* Group N re-map
* Gray's 2.5" bore de-cat
* Powerflow 2.5" bore full stainless sytem

I made 184.5 bhp.. there were guys with similar set-ups running all sorts of airbox's, including those viper things :dead: that were making less power.. so for me, i'm saving the money & keeping the standard airbox



James

Its all about set up, not the list of mods thats bolted on..

 

[sammyhale22]

Hi TonyKart,

With my BMC CDA and no cold feed pipe i get 988Mbar at 7000rpm, 141kmh.
Hoping to improve it even further though by reducing the pipe between the filter and TB.

Sam

 

[tonykart]

wow but wot tells me in 120 Mbar diffference according to Bhp ??? Henk ??

kan ik hier het vermogen mee berekenen ?

 

[Dan R]

doesnt surprise me tbh. Standard airbox is fine imo. Renault spent an awful lot developing that airbox!!! I had a bmc on my car and hated it!!

 

[rolly]

Well my standard airbox with standard feeds including acoustic valve drops 30mbar at 7000rpm.

 

[Fred@BTM]

too much info is a dangerous thing LOL

 

[Dan R]

too much info is a dangerous thing LOL

lol.

 

[Little Newms]

The standard CAF pipe withe the BMC is w@nk!!!

I had a BMC and it was fed down to the front grill with minimal bends in the pipework. It worked that well i had to empty the air filter every two weeks becuase it sucked up so many different things...

 

[BenR]

Does this RSTuner thing read true mbar or scale it to read a max mbar value?

Otherwise the readings between days will differ with the peak atmospheric mbar pressure the time the datalog was taken.

I dont see how people can try compare peak manifold pressures when someone at sealevel could have 1013mbar and someone 2000ft higher will have a max of 940mbar available.

Also, does the RSTuner have an accelerometer built in? How does it do these power runs I read about?

 

[BenR]

I've never seen an RSTuner btw, so I'm just asking some ignorant questions....Henk?

 

[Fastchip]

I dont see how people can try compare peak manifold pressures when someone at sealevel could have 1013mbar and someone 2000ft higher will have a max of 940mbar available.

Also, does the RSTuner have an accelerometer built in? How does it do these power runs I read about?

Ben, I ask them to make a run from 2000-7000 rpm and look at the manifold pressure drop. That gives an indication of how effective your air intake is.
Good ones only show a < 10 mBar drop, bad ones up to 30 mBar pressure drop.
Example:
Usually i look at the 3k rpm point, let's say 1003 mBar and at the 7k rpm point, 985 mBar. Resulting in a Pressure drop of 1003-985 = 18 mBar.

Power is calculated through vehicle mass and acceleration rate. Used on a flat road with no wind and the correct entered vehicle mass it's very accurate. Obviously air drag is also calculated and added to the result.

 

[Fastchip]

Does this RSTuner thing read true mbar or scale it to read a max mbar value?

It reads ambient pressure (calculated by ECU) and manifold pressure in mBar.
Both values are automatically scaled between min en max. values.

 

[BenR]

So if runs are taken days apart then the true mbar value isnt represented in the datalog, assuming baro conditions are say 30 mbar different between the days? Only the rescaled mbar readings are given?

 

[partyboy23]

whats all this mbar talk about,can someone explain,i have the rs tuner,can i do mine,whats it all mean,cheers

 

[partyboy23]

anyone?

 

[Fastchip]

So if runs are taken days apart then the true mbar value isnt represented in the datalog, assuming baro conditions are say 30 mbar different between the days? Only the rescaled mbar readings are given?

It doesn't matter. Its the pressure difference between the 3k and 7k rpm points that counts. A lower barometric pressure has almost no impact on this.

 

[Fastchip]

whats all this mbar talk about,can someone explain,i have the rs tuner,can i do mine,whats it all mean,cheers

See this post:
http://www.cliosport.net/forum/showpost.php?p=4494062&postcount=24

 

[franx]

@ Partboy ; i think when you have the Pro-kit this info, with datalogging, can be used by Henk to see if your airintake needs improvement or not