eddierotary

iTrader: (7)

i have a question about the reciculating valve and i see latelly on different newer cars that if you change it to a blow off valve one (greddy, HKS or any aftermarket) you loose power. my question is that i know alot of people have blow off valves on their rx's, have anybody have kept it as reciculating to the intake? i have a blow off one and i wanna know if helps on the spool or even on power by having it reciculating or not. im just looking for quicker spool of my car.

FrankV702

iTrader: (14)

it doesnt give it more power or spool. But if you dont recirculate it and your running the stock ECU, it can seem as if you have a small vac leak and your idle may be lumpy or the car may be proned to dying out once in a while.

gear_grinder

iTrader: (4)

yeah, it doesnt really help any, when its open in the engine bay it just makes a vac leak. if anything the aftermarket is better because you dont lose the power from the vac leak.

Evil Aviator

Peak power and the overall power band (as measured on a dyno) will be the same either way.

The purpose of the recirculating bypass valve is to keep metered air in the system on vehicles that use an airflow meter. If the air is not recirculated, then metered air is blown out of the system, and less air ends up going into the engine than expected by the computer, and therefore the mixture becomes rich. Since this only happens when the air is actually blown out the valve, the engine will only run rich when the BOV operates, and there will be no other effects when it is closed. The result is that the engine will run rich between shifts, slowing acceleration due to rich bogging.

Engines that do not have an airflow meter, such as those using a standalone EMS in speed-density or alpha-n mode, do not see any adverse effects when using a BOV vented to the atmosphere.

That should only happen if there is a flaw in the system, such as an improperly set BOV.

eddierotary

iTrader: (7)

so if i have the stock ecu, wich i have now, will not have that inicial bog down if i have it reciculating?

Evil Aviator

Yes, recirculating the air will stop the engine from bogging when the valve opens.

eddierotary

iTrader: (7)

cool thanks thats all i need to know. im gonna swich it back to reciculating

Poison

You could put the maf sensor after the BOV, that way the engine won't run rich because the metered air is already passed the BOV
I'm not sure if this actually works but I've heard someone talk about that before, if it does then there wouldn't be any problem when the BOV would operate.

djmtsu

iTrader: (3)

Never had a problem with bogging or stumbling with a vented BOV.

Evil Aviator

That would require the AFM to be mounted after the turbo, which would require a piggyback fuel computer to compensate for the different heat and pressure. Back in the 80's before the budget standalone EMS was widely available, moving the AFM was somewhat popular, and everybody had all kinds of archaic a la carte whiz boxes running the fuel, ignition, boost control, etc. Nowadays it is a total waste of time and money to do that since even a cheapie Microtech EMS is far superior to those old 80's setups.

The stock AFM/ECU system has lousy response as it is, so an average person probably wouldn't notice the bogging much unless 1/4 mi track times were actually measured on a recirculating system vs. a venting system. Somebody who races a lot would notice the difference just by driving, but there aren't too many people like that on this forum. Once the stock AFM/ECU system is replaced with a well-tuned standalone EMS, even a novice could notice the difference.