Blowthrough MAFT installed! Pics inside>

[LucidEclipse]

This is really awesome, I got it finished this morning after 3 trips to the junkyard and 3 weeks of waiting for the translator, intake pipe, and filter. It was well worth it. First off the sound is awesome, turbo is much louder and bov vents, need I say more about sound? The only thing that I found odd, is that I lost some boost. Before I used to get 15-17 (spike) psi. Now I can barely squeeze out more than 13. I have never had a mbc on my car (the WG opens at 14.7 psi.) But it pulls harder (this probably has something to do with my recently installed supra smic as well) I pressure tested the system to 18 psi, no leaks. Any reason why I would lose so much boost? I am getting a MBC soon but I hope that my turbo isn't spooling to 17psi. and I'm somehow loosing the boost. I just don't want to get a boost control and set it to ~15psi but the turbo is actually spoling 20 or more psi. to make 15 on the gauge. I hope this is making sense.

 

[candela]

The more of a restriction the more load then the more boost. Sounds like a good buy, people seem to be having pretty good luck with the translaters eh? Your W/G doesn't open at 14.7psi BTW, and just abotu every turbo pushes more than what the gauge shows...its the inevitable fact of having intercoolers/piping that isnt flawless aka pressure drop...
Good luck on tuning it!

Austin

 

[LucidEclipse]

It's a t28 are you sure that its not 14.7, thats what the previous owner told me. Time for a dual stage MBC! (damn FWD)

 

[Tallen]

get the DSMBC. the translator is a grea tinvestment. mine is still running strong after a few months now

 

[LucidEclipse]

I am gonna go with the dejon tool dual stage controller, since I can trade in my stock smic for 65 bux

 

[RipperXX]

I would think it just becouse it is just a better intake setup and so it has a more controled boost curve ah hell i duno but it's better alright

just get your MBC and set it to what you want, the boost gauge (real one anyway) measures the vacume or pressure in the intake so i dont see anyway the turbo could be pushing 20psi there and somehow lose it in pipeing that dont leak from there to the intake...

 

[LucidEclipse]

I agree with you ripperxx, Just goes to show you though how the stock mas is that much more restrictive than the gm maft!

 

[RipperXX]

well yea, when i first tuck mine out and saw just two small honey combs i was thinkin.. ummm the turbo has to pull a crap load of air though that quickly?? WTF is this big recordian hose/pipe here for and big filter if it just sucks air though that little thing.

for a turbo car it is realy a joke, I can see it on a N/T just fine but not a turbocharged car..

Once i get my little 14B fixed (realy just buying another guys and building a good one from both) and finish geting my clutch in , this is the next upgread im going to do.

then exhaust, then fuel system then turbo then intake etc.

 

[Turbonium]

i thought when you put in bigger uicp you got pressure drop but your flow increased or something like that. i think your pressure drop is from the bigger pipes you put in, and it probably is time for a mbc. well good luck
Ryan

 

[JayHass]

Now I can barely squeeze out more than 13.

I'll bet 50 bucks your BOV is leaking and now that it's dumping to atmosphere you are losing boost instead of recyling it back into the compressor inlet.

 

[tsitalon1]

I'll second that bet and raise the purse to $100

 

[TurBoGs-T]

Originally posted by JayHass


I'll bet 50 bucks your BOV is leaking and now that it's dumping to atmosphere you are losing boost instead of recyling it back into the compressor inlet.

Good call

 

[DCJ98GST]

Originally posted by JayHass


I'll bet 50 bucks your BOV is leaking and now that it's dumping to atmosphere you are losing boost instead of recyling it back into the compressor inlet.

I will take that bet. I think that the loss of psi is not due to a leaking BOV. The explaination is rather complicated so bear w/ me. Jay, I know you know this crap so tell me if it makes sense.

When we calculate the pressure ratio on our turbo it is not just our manifold pressure over atm (14.7 Psi), but the turbo outlet pressure minus turbo inlet pressure over atm. For example say you are originally boosting 15 psi with the stock MAS:

PR = [15 psi manifold + 3 psi intercooler/pipes - (-2 psi for vaccum pressure in the intake pipe after the MAS)] divided by 14.7 = 20 psi equivalent turbo outlet pressure/14.7

so total PR = 1.36

This is the number you put into the turbo maps to calculate efficiency.

For a given turbo there is also a ratio of exaust pressure to turbo PR that drives the compressor side lets call this omega. High exhaust manifold pressure is a drag on the engine so it hurts power and Volumetric efficiency (VE). For larger turbos omega is small and the VE of the engine is high. For small turbos omega is large and the engine VE is low. This is why larger turbos make more power at the same psi and intake temps as smaller turbos!

So anyway by using the MAF (low restriction) you are reducing your PR and therefore your exhaust manifold pressure because omega is constant.

Therefore your engine VE is slightly higer at the same psi.

So why would we see less pressure at the manifold?

Since you dont have a MBC to read the manifold pressure, only the stock BCS which is based on pressure at the compressor housing, it does not know that there is less pressure at the intake manifold and will open the gate at the same compressor housing pressure as before. So your compressor is producing the same psi and your engine is gulping up more air at a faster rate (slightly higher VE) and there fore you wont build up as much psi at the manifold. This is a good thing, it means your are flowing as much air as before but with less boost.

The second reason is because you have more restriction in your ic pipe that your BCS does not see as well. This will also reduce your manifold pressure.

I think a combonation of these two reasons makes more sense. After all it is the same BOV right. The BOV actually sees less of a pressure differential than before due to not as much sucking from the intake side. And he tested for leaks.

 

[tsitalon1]

I think my head is spinning

 

[FourG63 97GST]

got more pix? like a close up?

 

[candela]

DC you are right about the efficiency part and it makes perfect sense. As anytime hard pipes/more efficient intercooler is used this will happen period but....

I think that he said he was getting like 17psi before and I dont know of many BCS's that will allow that. Second he said he pressure tested it to 18psi and didnt have one leak. The load thing that I said earlier I had proven abotu a year ago for myself. Im not sure if you guys knwo what Im talking about but it doesnt matter.

 

[RipperXX]

Originally posted by DCJ98GST


I will take that bet. I think that the loss of psi is not due to a leaking BOV. The explaination is rather complicated so bear w/ me. Jay, I know you know this crap so tell me if it makes sense.

When we calculate the pressure ratio on our turbo it is not just our manifold pressure over atm (14.7 Psi), but the turbo outlet pressure minus turbo inlet pressure over atm. For example say you are originally boosting 15 psi with the stock MAS:

PR = [15 psi manifold + 3 psi intercooler/pipes - (-2 psi for vaccum pressure in the intake pipe after the MAS)] divided by 14.7 = 20 psi equivalent turbo outlet pressure/14.7

so total PR = 1.36

This is the number you put into the turbo maps to calculate efficiency.

For a given turbo there is also a ratio of exaust pressure to turbo PR that drives the compressor side lets call this omega. High exhaust manifold pressure is a drag on the engine so it hurts power and Volumetric efficiency (VE). For larger turbos omega is small and the VE of the engine is high. For small turbos omega is large and the engine VE is low. This is why larger turbos make more power at the same psi and intake temps as smaller turbos!

So anyway by using the MAF (low restriction) you are reducing your PR and therefore your exhaust manifold pressure because omega is constant.

Therefore your engine VE is slightly higer at the same psi.

So why would we see less pressure at the manifold?

Since you dont have a MBC to read the manifold pressure, only the stock BCS which is based on pressure at the compressor housing, it does not know that there is less pressure at the intake manifold and will open the gate at the same compressor housing pressure as before. So your compressor is producing the same psi and your engine is gulping up more air at a faster rate (slightly higher VE) and there fore you wont build up as much psi at the manifold. This is a good thing, it means your are flowing as much air as before but with less boost.

The second reason is because you have more restriction in your ic pipe that your BCS does not see as well. This will also reduce your manifold pressure.

I think a combonation of these two reasons makes more sense. After all it is the same BOV right. The BOV actually sees less of a pressure differential than before due to not as much sucking from the intake side. And he tested for leaks.

That is exactly what i was think, but i didn't have a clue how to explane it..

 

[LucidEclipse]

Holy crap DC, that makes perfect sense (after i read it like 5 times ) Yea my bov isnt leaking, The whole system held ~18-19 psi without any problem until it shot the PVC end cap I was sealing the system off with out of the compressor side. I was gonna run it up higher but I didn't feel like putting the end cap back in (19 psi. is enough anyway) JayHass and Tsitalon1 wheres my 150 bucks? (j/k)

 

[LucidEclipse]

Can anyone give me some detailed instructions (pics perhaps) of how tho connect the white rpm sensor cable to the CAS? When I start the car cold the rpm's keep going from ~400-~900 (frequently) until it warms up and I'm pretty sure this is because the translator itsn't hooked up to the CAS. Thanks

 

[boost_junky2000]

Lucid hows the tunning been with the blow through. Are you tunning with the translator?

 

[LucidEclipse]

since my fuel system is stock I don't have much to tune yet, I am also waiting on pocketlogger software. I am planning on boosting to about 14-15 psi, then when i get my 660's and 190 lph pump im gonna go to ~19-20 psi depending on how the car (and turbo) like it. I'll keep you posted on how tuning works though

 

[ChicagoGSX]

Did you need to tune it at all or did you just set it to blowthrough? I plan on running the same setup w/ stock injectors and then eventually 550s which I will be tuning with my S-AFC. Correct me if I'm wrong, but I can just leave the Translator alone and do all my tuning with the S-AFC?

 

[LucidEclipse]

the maf works wether you put it in drawthrough or blowthrough setup, you dont need to do anything special. I would tune with the maft first, then fine tune with the safc, Maft tunes in 5% incriments and the safc tunes in 1% incriments. I just set all the switches to 0 since I am running stock fuel

 

[tsitalon1]

Not yet... If you get your boost back without replacing bov then we owe ya

 

[LucidEclipse]

ha, ok, but I don't see how the bov is gonna leak even when I get the mbc because I pressure tested to 19 psi. and it didn't leak, see where I'm going with this? Can anyone help me with that CAS thing though?