ZEXY

Im looking at T3/T4 twin turbo set up and 15lbs of boost will this work with my setup

.57 compressor wheel trim
wet float bearings & properly balanced
3" inlet diameter with a 2" outlet
.50 A/R compressor housing
.63 A/R turbine housing
T3/T4 hybrid

SBC 406
9.0:1 - 9.3:1 compression
was told 700HP

My uncle told me that 14lbs should double my horsepower levels is he right??? if not what horsepower levels am i looking at???

Street Lethal

iTrader: (16)

No, 14-15 psi would be more like doubling your cubic inch displacement ratio. Horsepower can vary at 15-psi depending on your modifications....

ZEXY

OK so quick question with the mods that are in my sig how much boost could i run with a 9.0:1 CR ... i guess that matters on the tune right??

Street Lethal

iTrader: (16)

If your tune is dialed in, and if your forged, you can run a great deal so long as you air temps are kept in check. Even cast parts will survive so long as detonation is kept in check, but for only so long of course. If your not running an intercooler, then alky injection (meth) is a must. Believe me though, 15-pounds + 406 cubic inches is more than you'll ever need....

ZEXY

haha im sure it will be. The bottem end is forged and i am intercooled aswell Now one more question with the turbos be to small for my build, there not going to choke out on the top end only planning on going to about 6,000 RPM

ZZ3Astro

Assuming 100% efficiency, 14.7 psi would double your power. Of course no engine combination is going to be 100%.

FWIW I figured up the efficiency on my stock TPI with 10.5 psi of boost and the crank hp increase was 62%, which worked out to something around 87% efficiency. If it had been 100% efficient I would have seen a 71% power increase at 10.5 psi.

ZEXY

Ok that makes sence. So what about the turbos Ive been reading on Garretts website there turbo tech 101 and so forth and still cant figure out how to read a turbo map lol tough stuff. So the last question ill have for a little bit is if there going to work with the engine ive got just a tho maybe you cant tell me if thell work?? just got to try it like i will with the cam to lol thanks for the help

Street Lethal

iTrader: (16)

No, it doesn't quite work that way. When you compare two identical engine sizes at 15-psi of boost, static compression and effective compression come into play. If you target an effective compression ratio of 12.0:1, using a lower static compression, for example lets use 7.0:1, this will allow you to run more boost to equal that targeted effective compression ratio of 12.0:1 over an engine using a 8.0:1 static compression ratio. Meaning, same cubic inches, but the one running lower static compression came make more power at that targeted effective compression ratio because it is running a greater percentage of air. However, pull the turbo's off, and the lower static compression ratio engine suddenly makes less power than the higher one, again, with same cubic inch displacement, so it doesn't double, per se....

daverr

iTrader: (1)

yes it works that way. when you double the density of air using forced induction you double engine power output.
in your example the two engine running 15 psi of boost will nearly double the engine output. the engine with more compression will make more power than the other . IMO effective compression is meaningless.

Street Lethal

iTrader: (16)

No, it doesn't work that way, too many variables for that to be the case. Not to mention, a substantial increase or decrease in turbo size alone at 15-psi will have a tremendous effect in horsepower with no other changes to the engine, so it is never really the same. Normal atmospheric pressure, divided by one pound of boost, times 15-psi, gives us an approximation to work with in terms of how much we can see, not that we will, but that we can if all things are perfect. That figure does not stay constant as boost rises though, obviously, as octane, air temps and timing come into play, which is why a targeted effective compression ratio in relation to lower static compression will make a world of difference in how much power you can make. Power never really doubles at 15-psi, only on paper through the formula used; .01 divided by 14.7% (6.802%) times 15% equaling a 102.03% increase in power, however turbo size and dynamic/static compression levels tell the real story at 15-psi....

83 Crossfire TA

iTrader: (2)

To answer your question, "will it work?"

Sure

Well?

it's hard to tell, you don't have enough info. First, you post AR and trim numbers on the turbo, but you don't post sizes. AR and trim are just ratios, and can have both and still not know the size of the turbo. Knowing that they're T3/T04 hybrids I can guess that the .63 exhaust is probably the original t3 exhaust side which tells me that it will spool well on that engine but restrict flow up top.

Similarly, you have almost no info for the engine, we have no idea what powerband it will want to operate in, anything restrictive in the combination... just it's size.

That all said, lucky guess, it looks like you're going to have a combination that is going to have gobs of low end and die up top, and most likely have a hard time reaching 700hp. Whether the rest of your combination will tolerate that or blow up/let go when you try it... well, again, not enough info, but a lot of that will depend on tuning also.

Orr89RocZ

iTrader: (20)

I dont think it will work well. I have a 401 with .68 a/r T4 turbines and it will choke the motor alittle up top. A T3/T4 will certainly hurt things on a 406. You dont have actual wheel sizes but going by those dimensions alone its probably a small 50mm type compressor and a small turbine wheel. That setup would spool up instantly but backpressure would become an issue. I could only see trying a setup like that with a TPI based intake and small cam where rpm range is limited to 4800 rpm. Basically a diesel truck with an insane torque figure.

T4 is definately needed for a 406 IMO. My .68's spool instantly and my 401 isnt very radical. 15psi will push my 3550-3600 estimated weight to 141mph in the 1/4 mile and its not even 100% tuned....10psi on a well built 406 is capable of a 9 second pass at 134-136mph, but the compressor and turbine need sized right to pass that airflow efficiently

Need more motor info and rpm range/head/cam information to really tell