86gxl_fc

i know its been discussed before but..
why do i still see many turboed cars with no blow off valve?
i've noticed quite a few volvos don't have one.
couldnt tell on the turbo, but they could've had an internal wastegate?
i was leaning towards simply swapping over the turbo setup onto my NA.
but i ran into this bump. i didnt notice that it didnt use a blow-off valve.
would i be able to run the 7 with the same setup or is it mandatory to have a blowoff valve.
i am aware of what a blow-off valve does, i'm just curious of the severity of it.
what if it were low boost (which i would be running on my high compression NA right?)
if it works it would probably cost me a whole $150.
the turbo setup from the local yard would cost me 80 (intercooler-turbo).
the turbo in question boosted a 4cyl 2.x litre.
and custom manifold would simply depend on where i would get it done.

WadeMCarter

because theyu have bypass valves instead that recirculate the relieved air back into the system. think about it, if you were to release the air to atmosphere after it is 'registered' by the AFM, then it will be rich because the a/r will be leaning towards the fuel more. comprende?

RETed

It's not that they didn't have one - you didn't see it, but it should be there.


Too small.


-Ted

WadeMCarter

hey ted, i read something about the rx-7 turbos being pretty large compared to other 4 cyl, such as the one on the sr20; what turbos are comparable in size??

NZConvertible

Like Ted said, you're just not seeing them but they're there. Manufacturers fit them to prevent undesirable (to the general population) intake noises.

You can see an internal wastegate, because it's internal...

No. The whole turbo protection thing is a myth perpetuated by people selling BOV's...

Ottoman

some cars running low boost and reliable turbo's don't bother with BOV's

some aftermarket ppl don't Run Bov's to improve turbo/throttle response since the pipes don't have to completely "refill" each time the bov goes

new turbo's are implementing Anti-surge technology to help combat this as well..


i bought a Greddy FMIC kit from japan.. and it came with additional injector bungs..

but it never came with a BOV...

many ppl consider the turbo a consumable.. and just replace them when necc..

MHI turbo's last ages and take tons of abuse.. so it's not really a problem for a race car spending most of it's time WOT

Aaron Cake

iTrader: (1)

They likely have a bypass valve that is vented back into the intake. If you have a car running a MAF/AFM, then the airflow into the turbo is being measured directly to calculate how much fuel must be injected into the engine. If you then dump all that air to the atmosphere, the engine runs momentarily very rich. Not good for the engine, emissions, and those driving behind you (exhaust flames). By dumping air back into the intake you keep the MAF/AFM's readings valid.

Very few OEMs use external wastegates.

Way too small. Hell, the stock TII turbo is kind of small for turbo-NA use.

86gxl_fc

muahah.. i took the time to inspect quite a few of them at the local yard.
they seem to have about 3 different versions.
Ted and all you guys were right.. i didnt have a chance to look at them thoroughly.
but they do have blow-off valves.. well they seem to be internal looking anyways.
same goes for the wastegate.

So i take it that it would do me no good to bother swapping it over, even tho my car is NA?? lol
the whole project would probably cost me aboutt $120 (recalculated spendings)

reason i wanted to do it was because i wanted to take on the whole Turbo scenario and learning a bit through it.
and i assumed a stock setup (from a different car) would be a good place to start.
I was planning on running a TO4B previously.
but i spotted the small turboes and i got caught the turbo bug and wanted it ASAP. =D
i'll hold off if its not worth it tho just clarify things up for me a lil bit more please and thanks
do you guys have any recommendations on other car models that i can easily access at a yard that would get me started?
i can afford to invest 150 in a Jyard setup if i learn something from it (plumbing, oil lines, coolant lines.. etc)

Aaron Cake

iTrader: (1)

The smallest turbo you will want to use on the NA engine is the stock TII unit. Even then, you'll have full boost at 2K RPM and have a problem keeping it out of boost on the highway.

NZConvertible

There's no such thing as an "internal" BOV. I think you're getting confused with wastegates. A stock BOV is always a valve plumbed between the compressor discharge and intake pipes.

A stock set-up from an FC would be a far better place to start, a 13BT would be even better. That way everything just bolts together. If you're going to do a custom turbo install, it should be for something bigger than a stock turbo, not smaller.

86gxl_fc

ill take pictures of the small valve.
one of the volvos had it seperate from the turbo (tubing had a T plug and a small plug went to a small valve bolted onto a flange on the side of the block.
and a nother turbo had that same style valve built onto the side, same on the exhaust side.
Dont get me wrong, i mean i'm not trying to argue with you guys or anything.
i was hoping to pick up- at the very least, a better torque curve since im going to be drifting.
and 2k would be GREAT since i'd have a lil more of a kick to get it sideways.
would i even have to adjust the timing since its such a small turbo?

so i take it that its bad for the turbo to start working at 2k??
is that because its causing strain on the engine constantly which would be bad?

MaczPayne

iTrader: (5)

you don't need a turbo to kick it sideways. Ask a_drift.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/blog-91-coupe-drift-time-attack-build-up-546629/

86gxl_fc

i know that you dont need a turbo to kick it sideways but it helps in the long run (makes it easier)

cptpain

iTrader: (1)

i found on a thread around this forum that "ported" turbos are less efficient because of their anti-surge crap and is really should only be used in high power, high boost applications. it also sacrifices response

86gxl_fc

well, just so you guys no i went ahead and bought an s4 turbo/manifold off of ebay.
But thanks for all your inputs.
i'm curious as to how effective the TOP mount intercooler is.



i have the turbo hood so there shouldnt be a problem with the top mount.
the only problem i can think of is if the UIM wont let the top mount fit.
never actually looked at an S4 TII with the top mount taken off.

would i be much better off with a different intercooler?
and what size would you recommend?

(i'm getting a new Pure Blue paint job next month so dont bother making fun of my mix-matched hood, lol.)
its one of the many parts i salvaged from my 86 GXL...