As far as i can see the turbo wont have any back pressure, all of the boost is getting kicked out not recirc or being held back in a stall.
The SPLIT-R has 2 ports, if the re-circ. is blocked off then it will be released through the small atmospheric port. If it wasn't working properly or wasn't venting enough excess pressure I'm sure RBM would hear lots of flutter and chatter.
The whole subject of blow-off valves is always 'blown' WAY out of proportion on VAG forums by people who know nothing about the subject, if you want one then fit one, it's your car, your money, if it works then fine, you won't blow your car up. Most Imprezas and EVO's all run BOV's and they have MAF meters, if BOV's were SO bad then nobody would run them at all.
The whole subject of blow-off valves is always 'blown' WAY out of proportion on VAG forums by people who know nothing about the subject, if you want one then fit one, it's your car, your money, if it works then fine, you won't blow your car up. Most Imprezas and EVO's all run BOV's and they have MAF meters, if BOV's were SO bad then nobody would run them at all.
Dont get me wrong robdon i agree with you i am planning on experimenting with a few, its just the matter of how ricky has fitted his split R that i just found interesting as just thought that it could cause problems in the long run as not much would be vented like i stated tats all.
But would it really appear as a problem as you can run a turbo with out a DV or BOV its just that it will put adverse strain on it
But would it really appear as a problem as you can run a turbo with out a DV or BOV its just that it will put adverse strain on it
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erick_chumit
Guest
hey! and what about big turbos? What if I decide to install a gt28rs a.k.a disc potato, and use a BOV like HKS SSQV or something?
would that also affect the engine or something?
thanks
Well you’d still be running the same engine management so I guess it wouldn’t be any different! I’m sure someone with that setup will post soon and confirm, MOFF ?
Ruddmeister question
Just read your lengthy post. I have a forge 007p and after reading that it can be used the other way round to make a little noise decided to try it. Mine makes a massive noise, similar to an atmospheric BOV. Could this be having an effect on mine running rich? Or am i just being paranoid???
Just read your lengthy post. I have a forge 007p and after reading that it can be used the other way round to make a little noise decided to try it. Mine makes a massive noise, similar to an atmospheric BOV. Could this be having an effect on mine running rich? Or am i just being paranoid???
Because full BoV works with some cars not others
Some BoV's are better than others (Spilt-R is the best reliability wise but Collins and HKS SSQV also work for some e.g RodDon...then again his car is a long way from standard)
Fact is though your car shouldn't be run with a BoV because you are fooling the ECU.......which is fine but there is a possibility your can could have a variety of issues too including running lean.
Then again it may all work fine for 100,000miles of trouble free motoring..................maybe
The full answer - still yet to see anybody argue against this is as follows - Cut & Pasted from another thread / forum member
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"No rhime or reason"
But:
(and concentrate, here comes the science bit!)
A modern engine management system, ie the Bosch Me unit fitted to 1.8T's has "adaptive" learning on the fuel, ignition and airflow side.
Because Me is a Torque based structure it's calculation of engine torque verses driver demand is critical to the driveability of the car and it's performance / durability.
When you fit a "leak" in the intake system (open circuit valve) the original calibration of the MAF sensor to manifold and cylinder filling modeling will not corespond. However due to the 20% allowance in the long term adaptive values the ECU will relearn you engine and "leak"
At idle the inlet model calculated airflow will exceed the MAF meters measured output, and depending on the state of your particular components - ie MAF ageing / contamination, throttle plate leakage, Fuel tank purge vapour concentration this may, or may not push the adaptive to it's 20% limit. If it hits the limit the ME unit will run in FMEM mode (Failure mode and effects management) causing reduced system efficiency. The Me unit will use the switching signal from the lambda sensor to return fuelling to lambda 1, storing the correction as a map agaisnt airflow. and add this correction to the fueling calc when operating at non closed loop conditions, ie WOT, fuel injector reenstatment (after overrun shut off, traction control intervention etc.) Now depending on how you drive and how sensative you are this may or may not be felt by the driver during certain manovevers. The throttle plate position will also learn the new airflow to maintain control of idle speed, but you may notice poor engine load rejection, ie turn on the aircon and the engine speed varries etc. or engine speed flares on starts or when operating PAS when parking.
However in all cases this will result in "incorrect" fueling. Now by "incorrect" i mean, not as the manufacturer intended. A post MAF leak will cause rich operation initially, but the adaptives will pull fuel out and become negative. This tends to cause a rich to lean spike on tip outs and other throttle transient. Now it is extremely diffucult for an untrained observer to spot these effects as they occur mainly on throttle transients, when the average drive may not notice. Therefore you could say "why do i care?". Well, any AFR excursion from the intended fuelling set by the manufacturer will result in non-standard engine operation. because of the adaptives this is unlikely to cause immediate engine problems, but over the course of time will change things like catalyst ageing, exhaust and turbo charger valve durability etc. Manufactures spend millions accruing miles on development fleets so hopefully the customers don't get landed with big bills as time goes on, and with most modern cars life'd at 150k miles (min design life) this is a big task.
It is unlikely that this will result in any performance loss, as at WOT the system is open loop, but you may see the result of an open circuit valve oas over fueling on gear changes etc. (a tell tail puff of black smoke is what you can see, a 1200 degC Catalyst is what you can't see, as excess fuel when injection reenstates and excess air from overrun shut off period combine in cat)
Now as you can see this is a seriously complicated subject and i haven't even mentioned the dreaded EOBD or OBDII words yet. Typically Bosch Me units have approximately 9000 calibratable parameters (constants, maps etc) and an engine calibration program will take a team of 8 calibration engineers 18 months to do the basic mapping and OBD validation. These days it's no problem to do the basic fuel and spark mapping, maybe 4 weeks on a midlimit engine on a dyno, but the diagnostics and emmisions devs takes years.
Moral or the story, before you start playing with something you don't understand, find someone who does!(And not just thinks they do!)
(for anyone thinking, "hey what makes me such an "expert" on this subject?" then i'd better mention the last 10 years i've spent as a senior calibration engineer at Cosworth and Prodrive!)
(sorry , another monster post!)
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Feel free to draft any counter arguments
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