j200pruf

iTrader: (4)

Hey all, I know that when you use a small a/r hot side turbo you will have great boost response but you will kill the top end do to having the small restrictive turbo in the exhausts path.
My question is could you counteract this by having a lot of wategate area like maybe two 40mm gates, so that the "extra" even though it isn't will have a place to go instead of going through the turbo?

Trexthe3rd

NO, glad to help.

CrackHeadMel

iTrader: (2)

Why will it not? A very large wastegate would be able to keep the exhaust mani pressure in check would it now?

moremazda

iTrader: (4)

Yes a large wastegate will keep the mani pressure in check, but it will not reduce the amount of pressure that is required to spin the turbine at a required speed for your desired boost. The smaller the housing the higher the pressure in the manifold needs to be to get the required volume of air to spin the turbine.

Make sense??

Nihilanthic

I think variable turbos are the way you deal with it.

And um... if you vent out a WG instead of through the turbo, you wont get any more flow, but it will manage to get rid of the back pressure, yes.

Marcel Burkett

If you want to use a smaller A/R turbine then you should get a turbo with a LARGE turbine wheel (larger than a Q trim ) to compensate for it . The large wheel will allow the flow thats reuqired to keep the motor happy at higher rpm's , mind you you still can't go too small on the a/r either , I think you shouldn't go smaller than .82 or .86 .

Carl Byck

Brian Cain will be tuning my .81 ar PT67(TO4R) the beginning of July, we'll know then as I plan on tuning at 20, and hopefully 25psi. If you trust the dyno operator, Kabooski made 520rwhp on a .81 P trim (same as my turbo) If I need a bigger hotside, I will also have a .81Q trim T66 on standby. The car is built for road race, annd the goal is 450rwhp(1/2 hour WOT at a time). LOTS of cooling mods are required for such an endeavor, not limited to reverse cowl hood, and complimentary bodywork, a 33.5x10x3 FMIC, custom CAI, Dual oil coolers,24x22x2.5 dual pass Griffin radiator with custom AST, Aquamist, 11.5 NGK race plugs, dual fans, and 111 octane fuel. We will be watching the EGTs carefully, but I think it will all work as hoped. Carl

RETed

Smaller turbine A/R chokes the engine down versus a larger turbine A/R.
Think of it that way...
The larger turbine A/R has the potential to make more power (i.e. peak).


-Ted

88fc3sw/HX83

Who else is getting their car tuned on that day Carl? Are you guys booked?

Carl Byck

PM sent

ronbros3

WOW! 450 hp for a 1/2 hr. on a 13B , I dont think it can be done , you can not cool it inside the block fast enough, the spark plug area needs serious hi flow coolant modifications ,all the outside mods you do will not cool it quick enough to make that kind of power. RON

jacobcartmill

iTrader: (6)

does anyone even make a .8x turbine housing that will fit a Q trim exhaust wheel? i have a t04s 60-1 with a .96 a/r Qtrim exhaust side and its too laggy for me, making me want to "downgrade" to a .84 housing

frode

turbonetics has .84 a/r Q-trim turbine hosuings

j200pruf

iTrader: (4)

So this idea wouldn't even work with dual wastegates that couldalmost flow as much as teh 2 inch tubes coming from the exhaust?

I was thinking of a BNR stage IV Q trim exhaust and a Super-H compressor with this manifold from rx3mist.com. Aperently this guy makes exhaust manifolds for all kinds of old mazda rx3-FC rx7's repus etc... But with what everyone is telling me I will just go with a T04B P/Q trim and a Super-H compressor on a .96 or 1.00 tang divided housing. Maybe a t04E .57 or .60 trim

Carl Byck

I have a .81 Q trim undivided T'netics T66.

jacobcartmill

iTrader: (6)

sweet. thx for the info

RETed

Uh, I don't know what you're trying to ask?

You're talking first about hybrids, and then you're asking about divided or undivided turbine housings?

If you're going full turbo, go with a 60-1 / TO4E "60" / TS04.
Anything smaller is really a waste of time.


-Ted

jacobcartmill

iTrader: (6)

t04s is where its at

jacobcartmill

iTrader: (6)

these Q trim exhaust housings are expensive...........

j200pruf

iTrader: (4)

I still don't quite understand why the wastegates wouldn't keep the turbo from over spinning, don't they let almost all the exhaust energy bypass teh turbine housing?

Carl Byck

If they are large enough.

Carl Byck

Keep in mind you have two ~2" runners into a ~3" hotside. an HKS 32mm wastegate(1.25") can not keep up with that kind of flow on all but the smallest turbos(~325-350rwhp)

BLUE TII

iTrader: (9)

Small turbo w/ big wastegate is basically what my project evolved into.







It started as a standard 60-1 hi fi S5 hybrid w/ bored stock wastegates and O trim exhaust wheel.

Shown is the latest incarnation as clipped P trim exhaust, 60mm HKS GT wastegate.

Boost control becomes a very delicate balance w/ this type of set-up. It would get into boost off idle and full 17psi by 3,000rpm, but it would creep.

Restricted the exhaust w/ the smaller 3" RB turbo back and it solved the boost creep, but started building boost ~1,500rpm and 17psi ~3,500rpm.

I believe that is about what a decent set-up on a larger frame turbo will do- so is there an advantage? ...

FC3S driver

iTrader: (1)

blue TII....wow, I want that setup. what specs would I need to boost that fast and hold it till redline. you wouldn't wanna sell that one in the picture would you. I don't really wanna go full aftermarket because that involves alot of time & $ and I don't have alot of either.

jacobcartmill

iTrader: (6)

that setup he has right there probably costs just as much as a cheap t04 setup.