LS1FC

iTrader: (4)

Ok...Im really confused now...

Im going to be purchasing a Greddy FMIC soon and I called Rx7.com to get some info. Well, I just got off the phone with Rocky from Rx7.com and he tells me that I dont need to reroute the aftermarket blow off valve back into the TID. He says that I can have it vent to atmosphere and not suffer any side effects. Is this true? I was always under the impression that I would run rich for a few seconds on deceleration and have major flames occur. When I asked him that he said, "thats just the nature of the beast"

dr0x

Im not familiar with the kit, but if he said that I would imagine the kit includes their bov. In which case yes, you leave it open vented to the atmosphere. Yes youll run rich for a second.. but anyone who says it makes their car any slower is just being retarded.

LS1FC

iTrader: (4)

Thanks for the response drox.

Can anyone else shed some light on this?

rx7_turbo2

Hmm I'm not familiar with the kit either. Find out if it includes a BOV. If it does no worries, but if it doesnt look into buying one. You can do some Home Depot style work with the stock BOV but in my opinion it's not worth it, buy a real one.

SnowmanSteiner

With an open air BOV you will run rich for a second and there is a possibility that you will shoot flames. But it's really nothing to worry about. Flames don't hurt anything. You'll be fine with an open air BOV.

- Steiner

LS1FC

iTrader: (4)

The intercooler kit doesnt come with a blow off, you just have to by one seperately. He said I would have to weld a flange adapter for the blow off and that I should mount it between the turbo and the intercooler. Does that sound right?

SnowmanSteiner

It depends, If you want to protect from compressor surge I believe you need to mount it close to the manifold. Someone please correct me if I'm wrong.

- Steiner

Fingers

Couldn't have said it better myself

Jaared

the one i got was cheap from ebay....

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2430844830

just like that one. It sounds great, install took 2 min.

1) remove stock bov.

2) plug TID hole with cork from wine bottle, glue stick, or a real rubber plug from the auto parts store (please use the real plug).

3) rotate 1/2 inch hose comming off manifold that used to go to the stock bov inlet and insert new one.

4) clamp hose to bov using regular screw clamp

5) plug vaccume line to new bov.


its like it was made for our cars. Now with a fmic i believe you need the bov kit or have to get one welded in if im not mistaken.

rx7freddie

i have the same one off ebay. works damn good when i was running 6psi and now 10psi .

xzyras

He always says that? He told me nothing can get rid of the hicup when the 720's come on, it's just the nature of the beast.

Hey I want one of those BOV. Do you guys think I could use it just for low pressure? I also have an old school bov of the turbo ic flange (hks) But also have the stock one. Low speeds the stock pne goes off (an exhail) then pshhhhhhh. You think I could use both. The vacumm line still going to the stock bov. None to the other, kind of like a dump valve.

Sorry to interupt your thread! Could someone let me know thanx?

SnowmanSteiner

Just make a BOV. Go to Home Depot and buy a one way check valve and your set. It's what I did and it works great.

- Steiner

Evil Aviator

You don't need to reroute the BOV back into the system, but your car will in fact run rich when the BOV activates if you don't re-route it when using the stock ECU. The amount of flames shooting out of the exhaust and the amount of hesitation and/or stumbling between shifts depends on your boost level. If you would like to vent the BOV to the atmosphere correctly then you can install a fuel computer like an S-AFC that can compensate for the BOV. Even better would be a standalone EMS like a Microtech LT8, Haltech E6K or E11, Wolf3D V4, etc., that use a speed-density metering system which is not affected by a BOV at all.

BTW, the GReddy 2-Row V-Spec kit is $153 cheaper at the RX-7 Store.
http://66.216.67.51/subcatmfgprod.asp?0=215&1=301&2=-1

Um, OK.

Yes, and it's best if you can place it close to the throttle body where the low-velocity / high-pressure air can vent better. Placing the BOV closer to the intercooler will also work fine if that is the easiest place for you to put it, but the air there will not vent as fast because it has a higher velocity / lower pressure. See the BOV placement on this GReddy Elbow:
http://66.216.67.51/product.asp?0=216&1=329&3=428

FYI aluminum welding is expen$ve.

amused

i think mitsubishis are the only cars that have problems when not venting the blowoff back into the intake.

i dont get flames when it blows off on my open one unless i immediately get off the gas and then add a little as it's decel. then it's a huge *boom* from the back of the car

Evil Aviator

Any car that uses an AFM or MAF will have fuel metering errors with an atmospheric-vented BOV unless it was specifically designed to function this way. I can go into the long, drawn-out explanation if you like, but you can use the Search function to find it numerous times on this forum, as well as on the internet.

Removing or disabling the air pump will eliminate the anti-afterburn function, causing the huge "boom" or small "popping" noises when letting off the throttle while still in gear. This is also true on NA engines. The amount of flames depend on a lot of things, including your exhaust system.

SPDSTR 7

I'm not really sure what I'm talkin about but what if the AFM was moved after the turbo, then the whole thing about rerouting the BOV is eliminated, isn' it?

amused

hey evil, i understand how it works - i was just saying that i've heard that eclipses and evos have more of a problem with the richening then other cars. every turbo dsm in my area vents his bov back into the intake ducting

and is it even possible to have an afm after the turbo? i've never seen that done before

SnowmanSteiner

Moving the MAF, our cars have Mass Air Flow Sensor not AFM, directly in front of the throttle body can help with response. As far as not having the problem of having a temporary rich mixture, I am fairly certain that it does not solve the problem. If I remember correctly the ECU factors in that once you left off air is going to be returned into the system. Therefor it is still trying to compensate for that extra air, regardless of where the MAF is located. Someone please correct me if I'm wrong.

- Steiner

Jaared

someone on here put the afm after the turbo... dont remember who tho.

Evil Aviator

Yes, but only if the AFM is closer to the throttle body than the BOV so that metered air is not vented. You would also need to adjust the spring tension in the AFM, and re-tune the engine with a fuel computer.

IMO the whole old-school method moving of the AFM has been outdated now that you can get a good standalone EMS for under $1,500. For those of you too young to remember, the AFM relocation trick included thousands of dollars worth of add-on whiz boxes (HKS F-Con, HKS GCC, silly ignition setups that were really made for piston engines, boost controller, FCD, etc.) that are viewed as pathetic band-aids when compared to today's EMS products.

That's entirely possible. Different systems may have more or less of a problem with it.

Our cars do in fact have an AFM (Air Flow Meter) as you can verify by reading the service manual. Technically, I would agree that it is also a Mass Air Flow system, as opposed to a Speed-Density or Alpha-N system. However, recent terminology has dubbed the "hot wire" meter as a "MAF sensor", so I continue to call the 2Gen RX-7's meter an AFM as per the manual's description in order to keep things simple.

No, the ECU doesn't compensate for the let-off air. That is why an atmospheric-vented BOV will upset the air-fuel ratio. Yes, moving the AFM will not solve the problem if the BOV still vents metered air.

SnowmanSteiner

As far as your first response about it being an MAF or AFM over my head, I believe you. And as for the ECU. I may not have explained it right. I thought that once you let off, the ecu automatically factors extra fuel in because it believes that there is more air that is being plumed back in, but it is plumed after the AFM so that's why it goes ahead and adds some extra fuel in. And with open air, it still factors in that extra fuel, you run rich, shoot fire, blah blah. Is this correct or am I just rambling on incoreherently.

- Steiner

ForsakenRX7

Its not factoring in "extra" fuel, its doing the normal factoring. Its just that the metered air has suddenly been dumped. So the ECU adds the fuel accordingly but the air it metered is no longer there hence the rich condition.

Evil Aviator

See the EFI definition at the link below. Next see the "Mass Air Flow (MAF) Sensor (Air Flow Meter or AFM)" definition. It's not very in-depth, so it still may be over your head. Sorry, but I don't know of any link that explains it in better terms.
http://not2fast.wryday.com/turbo/glo...fuel_injection

The previous post explains the "extra fuel" issue.

NZConvertible

There's no "extra" fuel, it's actually a shortage of air. The ECU adds fuel according to the amount of air the AFM measures. When a recirculating BOV opens, the air flows back into the intake after the AFM, so it has no effect. With an open-vented BOV that air is released from the intake system, so the engine inhales less air than the ECU previously measured. Basically, the correct amount of fuel is being injected into an incorrect amount of air, causing a rich condition. This results in unburnt fuel passing through the engine and out via the exhaust. As soon as the hot fuel vapour hits the oxygen in the air it explodes.

SnowmanSteiner

aaaah. Yes yes yes yes yes. Makes perfect sense now. Sorry it took so long for me to see that. I'm usually fairly bright. I totally understand what you guys are talking about now thanks.

- Steiner