"high flow" turbo... always better or???

[TheChad]

Hi,

since my 35r (1.06) has eaten is front wheel (foreign object) i now have to either replace/balance the front wheel or find a replacement.
I have found a turbo for sale over east, it is also a 35r but the front has been "high flowed", in that a t66 wheel has been put in and the housing machined to suit.

now is that always a benefit? to have a larger front wheel?

the rear will be staying exactly the same (eg not even unbolted from the car) and i am looking at just bolting in the guts of the turbo.

so i am wondering how that has an effect in terms of efficiency, max power, and response. given that the rear will be exactly the same...


fyi, the car is a 3L rb30 that has always been close to laggy, perfectly driveable and delivers easily on the street, but i am not really willing to lose any more to lag. normally running 17-20 psi.

[Lump]

the turbine (hot) side is what generally determines how responsive or laggy the turbo is.

did you call up Grant at per4manz turbos in welshpool to get a repair quote from him btw?
that would be my first option.

[TheChad]

the turbine (hot) side is what generally determines how responsive or laggy the turbo is.

did you call up Grant at per4manz turbos in welshpool to get a repair quote from him btw?
that would be my first option.

still in the middle of my working week so i havent got the turbo out of the car yet lol.
not going to bother making appointments untill i see how the rear wheel is, if its clean then yes, otherwise i have bigger problems than a shagged 35.

[-Luke-]

I have the same turbo on my Ford.Very responsive on the 4 litre. Makes full boost (16lb in my case) by 2900 rpm. good for 450rwkw take on the 4l apparently.

[TheChad]

i spose in reality it depends on what t66 front wheel has been used, since the t66 is considered old-tech, so i would expect the front wheel to possibly be less well designed than a 35? then again there are lots of t66 options on the market by different companies...

ive made 400rwhp @ 20psi on the 3L on a 35r.
luke are you saying you have the t66 front on a 35r in your car? where did you get it from? because i'll call them and get their oppinion on a 35r with a t66 front wheel on an rb30 :D

[-Luke-]

Yeah mate t66 front and 35gt rear with 1.06 rear. It's approx 600rpm laggier than a 3582r. MTQ built it for me

[TJ]

You also have an extra litre, and twin cams with vct to play with - Chad wont.

[Madhav]

How much are you looking at spending?

There are decent custom built billet turbos from the USA to be had for about $1300 that are pretty decent.

[TheChad]

well the 35 with t66 front housing is $800, and i believe would bolt onto my rear housing (that will remain in the car)

not really keen on changing turbos since i already have all the pipework and manifold etc made, i just want to know if i am going to be worse off with a bigger front wheel really. if so, i'll just buy a replacement front wheel and have it balanced.

[Oversteer]

I have fitted a couple of the "3566" set-up 35R`s (most people say its a t66 wheel, some say its the same as a t04z wheel whatever its pretty popular and been done by MTQ all over oz and a few other well know turbo shops east).

It does add lag, how much would be a guess as I have not got straight up back to back tests but it also does take the hp rating of the turbo up a bit, makes it more efficient up top.

If a 3582R is rated at 650hp this mod adds about 50hp to that, works pretty well if your pushing for good numbers/drag racing.

If the tubo your looking at has the ported anti surge inlet its a bargin at $800(if its in good condition of course)

[TheChad]

Nice, something to think about!
You say it seems laggier, does it also seem better up top? Even on 20psi?

Why does it make it more laggy though? Just the extra weight of the wheel? I am interested in the science. Looks like MTQ will be the ones to call about it.

I'll sus if it's ported. It is second hand and done by a mob over east. Not really sure if I want to be getting more lag since I was even considering going down to a .8 or even .6 rear just to get more response and sacrifice a few Jo.

I do plan on running race fuel when my testicles grow and defend, so more top end might be nice.

[Oversteer]

I think the lag comes from the pressure ratio change of the bigger comp, more correct may be to say it rasies the boost threshhold....(most people call that lag ! but its not actually what i meant !). To drive the car the lag between gears isn`t any worse that a std 3582.

How much hp are you making @ 20psi ?(if your making 300hp @ 20psi No !, if your making 550hp @20psi Yes !) It should make more hp for the same boost up top... life does begin @25psi tho :p

.63 on a 35R is fucking gay....choose another turbo if you want clip the nuts of a 35 like that !

[Madhav]

Yeah many people use lag to describe what rpm it hits full boost.

I had a 35r on my supra. I think they can be set up to run well, usually there is something that causes the boost to come on late. Like a restriction of some sort or poor manifold design or something is set up wrong (in my case it was also the boost solonoid).

Either way I ended up changing it for a smaller more effecient billet turbo that made more power and was more responsive and it bolted right on to my old setup (manifold, front pipe, oil/water lines etc)

[TheChad]

there is always billlet i spose, and could probably even find one that would just require a bit of machining on my garrett rear.

its making 400 rwhp @ 20psi @ ovaboost. made 425 at the alm dyno day.

cant really reach 25psi without changing fuels :P

thanks for the info guys, i should be finishing work around midday and will get onto mtq, guage their opinion, then pull out my turbo to check the rear (all ready to go, just need to unbolt from the rear housing).



and as for manifold design, my intake manifold is massive! that on its own causes a little bit of waiting for boost. its rated as the best flowing in aus for the rb30 (in terms of its maximum flow rate), and will pay huge dividends when i do eventually go up to a better fuel/higher boost.

[Madhav]

cant really reach 25psi without changing fuels :P.

Water/meth injection kit would solve all your problems. Cheap too :)

[TheChad]

So I got the turbo off last night, rear wheel looks brand new!

Glad it was just that, but still kind of shitty I'm in this situation to begin with. Spoke to a guy, Jamie?, from mtq. He said it will make more power defiantly but with the 1.06 it's more suited to a 4L. My VL does have a pretty aggressive cam anyway, I personally feel that just about any decent turbo would feel laggy up to 3000rpm because of it. Hopefully it's not too much of a sacrifice. If it is I'll just go buy a .82 housing and probably make the same power as I did prior buy with slightly less lag.