LOL they were so cheap ($575) I couldnt help it....and since my current turbos are from Ebay and have a little shaft play....I felt this was a good idea. But I really didnt realize how big these things are , and they will probably find their way onto my 331 stroked 66 down the line.
But for now, what do you think about them going on my 04 GT? Currently it has 2 of the ebay (NOT ssautochrome) t3/t04E hybrid turbos. .50 Ar compressor 2.07 in 2.36 ex, .63 A/R turbine housing with 2 1/4 outlet.

Vs the new T-70s
Turbine Wheel Compressor Wheel
Exducer diameter Mayor diameter Exducer diameter Mayor diameter
2.53" 2.91" 2.72" 3.58"


Turbine Housing Compressor Housing

A/R . 70 Divided T3 A/R .70 4.00" Inlet


I was SOOO close to buying those Ebay "T-70" turbos....but those are a joke. Their inlet looks to be around 58MM or less....nowhere close to a real T-70. So im glad I went with something good....but like I said they are probably too big for now. Im worried about compressor surge, and plotting on the Garrett map puts me close to the line with twins. But oh well guess we will find out (will be running 8-9PSI BTW...stock shortblock)

Anyone know what sortof power these bad boys will support? And I wonder if ill pick up some powa in the mean time at the same boost lv. Thanks for your input!

 

My buddy's 355 SBC just went 6.3@112 in the 1/8th on 10psi, non intercooled, twin MP T70s.

 

Yikes! Thats fast....looks like I have plenty of room to grow! And looks like ill shoot for 1000+ RWHP when I build the bottom end. I talked to proturbo kits and they said that each should support around 600-650 HP give or take on my application.

Any pics of your friends setup? Sounds wicked!

 

Look in the builds section for no2chevelle...

His are T4 flanged though. I suppose making lots of power the t3 may limit you.

 

Let me ask you something then about T3 vs T4 hotsides.

Given the same AR, how can the T4s flow more than a T3? A/R is an area ratio correct, so wouldnt it be the same "area" inside the housing???

 

Compare a t-3 flange and a t-4flange the inlet to the turbine housing is much bigger.

Paul

 

Ah so its the actual inlet itself....square vs the rectangle. So more volume of air is allowed in...but velocity would be down I suppose. Another reason why a T3 would spool quick right? My little 281 is going to need all the help it can get LOL.
Thanks for the input

 

I think twin mp t-70s wiht t-4 flanges and .68 a/r on your 281 would be ok. t-3's will lead to a faster spool time.

Paul

 

It's not so much the size of the housing in this case, as it is actual wheel size. There is a difference between a stage 3 T3 wheel and a P trim wheel ( same with the 57mm small shaft setup, vs big shaft 70mm comp wheel). It's all about rotational mass here. That coupled along with the larger housings (.63 vs .68) will def yield a slower spool. Just make sure you have the valve train ( springs, cams, retainers and heads that will flow) to handle some higher RPM's, because you may possibly need to rev it a bit, lol.
Should make some numbers, to say the least!

 

Thanks Magic! And thanks everyone else too!
Yea I hope it works out well...and the main thing I was worried about was compressor surge. But it looks like I should be ok.

Since I already know how much power I make @ 9PSI at every RPM, I dont have to do any of those VE calculations or RPM calculations or the such. I can just do lb/min calcs at whatever HP I make at X RPM as soon as I get full boost. (I have a dyno grapgh ) For example my car makes 475HP (flywheel) @ 4200RPMs and thus consumes 57.5 lbs/minute of air. Split that in half (twins) and we have 28.75 Lb/min @ a 1.61 pressure ratio. So on the T-70 map I am still just inside the surge limit when I first will hit full boost and by 5500 when I make 560HP I am well within the limit.
And being that there is accessory drive loss, the engine is actually putting out more power at the flywheel, (more air than is being calculated) which further drives me away from the surge line.

Sound right to you guys?

 

Well decided to play it safe and went with twin T-61s. Should still support over 1000HP if I ever want to, but now I dont have to worry about compressor surge . And the turbine housing are .96 so it should make even more than the T-70s with my current configuration, not to mention I will be further into the compressors effeciency range with these. See if I can break 500 WHP @ 9PSI this time around

 

Its always better to grow into something than to outgrow it....