jaidedeye

planning to boost my 12A that has 40k miles on it.

im looking for a good externally wastegated turbo to use. anyone have reccomendations?

gentimmy

i'm also pretty curious

Jeezus

iTrader: (4)

S4/5, weld gate closed, remove diaphragm, add wastegate and plumbing.

jaidedeye

although this is a good option i do not want to modify a stock turbo. fit and finish are just as important to me a performance.

not to mention i hate internally gated turbo's to begin with

85rotarypower

I would suggest a T4 for good overall performance. The stock S4/S5 is comparable to a T3/T4 hybrid, so I think that would be a good turbo to go with, though I don't know much about turbos lol. As long as the A/R is above .65 your good. Anything smaller and your wasting your time.

jaidedeye

what about a t04e with an exhaust A/R of .80-.96?

i also have to figure out how much boost i can run and at what efficiency. i mean 12 psi on a t04e may be way too much on s stock 12A where as 12 psi on an s5 turbo is safe

Jeezus

iTrader: (4)

.80 would be better. The higher the AR the more you will need to rev, but more power can be had because you are not choking it at the higher RPMs.

Ex:

Stockport motor:
AR of .70 will spool fast, boost lower in the rev range, and not choke it at higher RPMs
AR of 1.05 will spool super slow (if at all) but will come alive at higher up RPMs.

Bridge port motor:

AR of .70 will provide almost instant boost, but over 5k and you will begin to lose power.
AR of 1.05 will provide some lag but higher boost and not choke the upper RPMs where the larger AR will shine.

jaidedeye

thanks for the info.

Jeezus

iTrader: (4)

No problem. I will look around for a turbo that can work for you.

Jeezus

iTrader: (4)

http://www.turboneticsinc.com/produc...category_id=75

Siraniko

iTrader: (13)

there is no such thing as the "best." what works me may not work for you

85rotarypower

In simple terms, the stock S4 turbo is basically a T3 compressor with a T4 turbine and an A/R of about .60 I believe. I think it would be best for you to size something around this. Like I said, I only have a very basic knowledge of turbos, but it seems the best bet for power levels up to 300hp on a 12A, a stock S4 turbo is excellent.

jaidedeye

i found a T04e A/R .60 compressor and .63 hot side. thinking that would work. only problem is that it has a t3 flange

Jeezus

iTrader: (4)

Get a T3 flange, a 12a Engine gasket and flange, and some 2 1/2 pipe and start welding!

trochoid

iTrader: (6)

Talk to Brian at BNR. Piston turbos are configured quite differently than a rotary one. To properly size one for a rotary application, there are no true off the shelf configurations. It will need to be custom built to spec. I concur that an S4/5 turbo would be an optimal choice and Brian can modify either series in 4-5 different stages. Stage 4/5 has produced around 400 hp on a TII with the appropriate supporting mods.

These turbos are cheap used, rebuild kits are a tad over 100 for the DIYer. In stock form, with a ported wastegate, one can hit 220-240 hp at the wheels on a TII engine. I have 2-3 of them laying around that I may part with. Might even be coerced into building the exhaust mani.

Building a custom exhaust mani is relatively easy, if you or a friend can weld, with the needed engine flanges, a custom cut mating flange to match the turbo, a couple of schedule 80 els/straights and tee/wye for the wastegate mount.

The TO4E maybe a bit big on the cold side, a .84 on the hot side will get you well into redline. The .63 will give you near instant boost, even at cruise, but will begin chokeing before you reach redline. Hotsides generally run .63, ,7?, .83, .96, 1.05 and 1.15. The latter is enerally reserved to 13Bs with a large 1/2-full bridge, hp over 450 and boost won't start coming in until 5k+.

81gsl12a

iTrader: (1)

s4 turbos on a stock port 12a are only good for around 250 hp have to upgrade the turbo to get much more and the stock exhaust ports flow enough to get 300

cheers PaTricK

blackdeath647

iTrader: (2)

this is probably one of the most informative threads about turbo's i've read in a while but there's still a bit of confusion and i'm sorry for "jacking" i suppose....anyways so let's say on a stock port 12a i only want top end boost, starting at about 3800 rpm per say, that means i'd want the hotside A/R to be .83 -.96 being the biggest right?...just for top end boost.

trochoid

iTrader: (6)

Yes, the higher the A/R, the later full boost comes on. Porting and exhaust diameter will affect spool rpms also.

blackdeath647

iTrader: (2)

hell yeah, taking baby steps but i'm getting there lol