Well I'am almost done with my twin t3/4 turbos just waiting on the FMIC, new turbos are sitiing on the car down pipes and all finished. I have planned to try to run the factory 89 ecm with MAF just before the intake blowing threw it. I need a blow off valve for 10# or less and not sure how it will effect the MAF when it opens up will the computer go nuts or will it be fine as far as the ECM and MAF are concerned. My goal here is to make 700 flywheel HP on the factory computer. This may be a little ambitious but its worth a try, if all else fails i will get the F.A.S.T and huge injectors.
The intercooler measures 28x16x3.5

 

draw us a picture

 

A 3" pipe coming from the intercooler into the MAF and then a blow off valve and then into the throtle body. I believe the ati D1 has the MAF just before the TB.

 

If you put the BOV before the maf then it should work just fine. I know I'm only running 5lbs, but it works good for me. I'm still using maf with an fmu and the 89 code.

 

the farther away you get the blowoff from the maf the better off you are, and make sure that the blowoff is before the MAF. That way you've got the least chance of seeing some reversion through the maf which would be read as extra airflow. Honestly, I'd probably try running it without a blowoff.

Can you give more details/pictures of your setup? What did you use for manifolds/headers and how did you route your plumbing?

 

I should get some pics this week. I'am running hybrids from majestic turbo in TX. I used headman s-10 headers and modified them to work. I made 3" down pipes and using actuators, Brady over at camaroz28.com is using actuators with his precsion turbos and is pushing around 800hp at low boost so i figure the actuators should work for 15# or less. I'am running a big front mount IC. I'am running the plumbing just like Skulte did y them together into one 3" pipe into the side of the IC and 3" out the other side into the super ram.

 

www.majesticturbo.com is were i got my turbos, they specialize in drag bikes 200mph+ bikes. I talked with them today and they suggested i hook up the water lines tapping into the heater core hoses and he said a oil cooler would be good to. Kevin is the owner of majestic and is very helpfull and friendly to talk to. I will try to get the pics tonight from my brothers digital camera.

 

I am running a MAF system, and my blowoff valve is before the intercooler, and well before the MAF sensor.

Jon

 

The BOV will only open when you close the throttle. When you're on the throttle the pressure is regulated by the waste gate. The BOV is only there to vent in case of throttle closing so there's no pressure wave travelling back (wich slows the impeller and could even damage it). The BOV should be placed as close to the TB as possible.

Marck

 

Man, I'd love to see how the S10 headers postion your turbos... they are fairly cheap. Are you running your down pipe over the top or under the headers (I guess this is sorta decided by which way you've positioned the headers).

I've pretty much decided that I'm going to give up on the stainless shorties that I've been tinkering with because I was spending too much time figuring out how to relocate stuff around them. Right now I'm sorta taking a break and considering 3 possible solutions: building my own, modifying a set of cast manifolds or the S10 swap headers...

 

Unfortunatly, with a maf it's not possible to go anyplace close to the TB, it just about has to be on the other side of the maf...

 

Why can't you use the BOV after the maf? If the BOV opens the maf signal will be incorrect and the engine actually runs too rich. If it happens when you close the throttle there shouldn't be a probblem since before the BOV opens the ECU will already have detected you're off the gas so fuel delivery will be zero (or close to zero). When the BOV opens at throttle you either have the opening pressure set lower than that of the waste gate or you're not using a gate at all. The engine will run richer, I don't see a real problem here. Some builders used to use a BOV on Bosh K-Jettronic (MAF controlled) systems to enrichen it. The BOV vented some of the air so the MAF was registering more air then coming into the engine.

I have never tried this myself but if I was doing this I'd try putting the BOV after the MAF. There's no certain telling what will happen but I'd be willing to bet it works.

If you place the BOV far from the throttle plates the whole thing is useless. The pressure wave will travel through the system possibly damaging the impeller. It will certainly cause it to slow down.

Marck

 

Well, with a stock ECM, the MAF takes priority over all the other sensors, so since it will still be seeing airflow, you'll be dumping fuel, washing down the cylinder walls and flooding the engine, killing it.

I think all the consern over location is misplaced on most of the applications that we're talking about since under about 20psi boost you can easily get away without running a BOV at all. For that matter most OEM setups don't run one, including the GN/TTA, Sy/Ty, Ford 2.3L... and they never have problems.

 

Since the BOV only vents hard when you close the throttle (close it fast!) the fuel delivery won't be a problem there IMO, and on full throttle the waste gate should regulate things, the BOV should open at all (or just maybe a bit if you set the open pressure for that in the same range as that for the waste gate)

But, I agree. If you're running less than 15 psi or so the BOV may be useless.

Marck

 

you dont need a BOV unless you plan to run over 15psi.....and even still ou are an auto right? Not really necessary

 

AI have a manual, I do need that thing (and have no MAF so no concerns). If I were converting to FI, I'd go for a speed density system.

Marck

 

The problems i see in the theory's stated here are... the BOV is in a semi open state when at cruizing speed. It is not just a valve that is fully open, or slammed shut. At no load, or cruizing speed the BOV is discharging air from the system because of the vacuum state of the motor. If this BOV were after the mass air meter, the motor will be running considerably rich.
Just thought i'd throw that info in, it may help you decide where to put the MAF.

 

Man is your avatar distracting (my head is bouncing up and down while I'm trying to read)...

A BOV should only open when there is a large difference between your manifold and intake ducting pressure (assuming that it is properly designed and hooked up correctly). In some cases there is not refrence fitting for the manifold pressure so it opens only when the intake ducting pressure is much greater then it should normally reach under full boost. In other words it should only open when the compressor is spun up and the throttle closes.

Some bypass valves only close at close to WOT (my brother's Eaton blown car actually has a mechanical linkage that only closes the bypass when at WOT, the rest of the time it's open), but that's not what we're describing here.

Either way, if you put it after the maf you WILL have problems with the engine flooding and stalling when you let off the throttle.

 

I see what you are saying... the BOV's I have evperience with (Vortech Mondo and ATI's unit) both have references for manifold boost/vacuum. We have run both units on the car while on the dyno, and while in third gear at cruizing speed, they both release ungodly amounts of air. I am also talking about large, high volume superchargers, not turbo's.
Either way, I think releasing metered air is not a very good idea, and should be avoided if all possible.