Turbo options? - Page 2

TomsSVX · #16 04-07-2007, 03:20 PM

as far as I know we are using a very similar profile to the 300zx twin turbo motors except we are a little bigger

Tom

cdigerlando · #17 04-10-2007, 11:47 AM

I am running an a garrett T4/T3 hybrid with an AR 60 on the intake, and I forget what the exhaust is. It spools at about 3500? I too am doing a built motor. Getting blowby.

longassname · #18 04-29-2007, 11:59 AM

For a street driven SVX run a garrett gt3582r 714568-1

I put some rough #'s on the compressor map and it's obviously an excellent match all around.

longassname · #19 04-29-2007, 12:05 PM

I guess I should warn that those #'s are assuming you have my cams.
and 130 degree intake temps (figuring intercooling)

Quote:

Originally Posted by longassname

For a street driven SVX run a garrett gt3582r 714568-1

I put some rough #'s on the compressor map and it's obviously an excellent match all around.

Jade Dragon · #20 06-13-2007, 10:08 AM

a little late to the thread... But, i am currently in the design stage of my Twin turbo setup. I picked up a pair of old, but still in great shape, IHI VF48s They were on the old loyale turbos. These were a good choice, in my mind, Because they were made for a 1.8, so half of ours being 1.65 it should work damn well. It shold work nicely, putting me in boost very quickly and providing just enough from each turbo to not be over working them, and still have enough left in them to go for higher boost later on. So, thats where i stand on that so far. Im looking for all the flanges and plates ill need to make them mount cleanly. And im still trying to figure out what im going to do for intercooling. Im thinking i will go with two thin sidemounts, or a thin 2-passage.

*ADD-ON*
The only problem with getting the IHI VF series turbos, they are a real PITA if not impossible to rebuild. So we shall see what happens with those

longassname · #21 06-13-2007, 10:31 AM

I don't know anything about those turbos in particular but should warn you that some of the assumptions you are making aren't exactly right. I'm not saying those turbos won't work so don't take it that way or get too scared that they won't before you look into it--just know you need to look into it further.

You need to find the compressor plots for those turbos. The compressor plot will show the pressure ratio (vertical axis) vs the flow rate (horizontal axis). When you go to twins and set them up so that each one is running off of a bank of 3 cyllinders what you are doing is cutting the flow rate you want each one to flow in half. You aren't changing the pressure ratio at all. Let's grab that 9 lb # off of the plot I calculated for the gt35 that's about a pressure ratio of 2 and there we are flowing about 40 lbs/min (that's 400hp) and say that's what you want to run on your set up. You would plot that on your compressor map at a pressure ratio of 2 and flow rate of 20.

What you will find is there are very few turbos that will work well as twins because they aren't efficient at high boost and low flow rates.

Quote:

Originally Posted by Jade Dragon

a little late to the thread... But, i am currently in the design stage of my Twin turbo setup. I picked up a pair of old, but still in great shape, IHI VF48s They were on the old loyale turbos. These were a good choice, in my mind, Because they were made for a 1.8, so half of ours being 1.65 it should work damn well. It shold work nicely, putting me in boost very quickly and providing just enough from each turbo to not be over working them, and still have enough left in them to go for higher boost later on. So, thats where i stand on that so far. Im looking for all the flanges and plates ill need to make them mount cleanly. And im still trying to figure out what im going to do for intercooling. Im thinking i will go with two thin sidemounts, or a thin 2-passage.

Jade Dragon · #22 06-13-2007, 10:40 AM

ahh i see. thanks for the info. With jsut a begining setup, i dont think it will be a problem at all because i wil be running low boost from each turbo. I dont think ill be wanting more than 10# combined to being with.

ohh... and the VF48 is also known as the VJ11

longassname · #23 06-13-2007, 10:46 AM

sounds like you are still not quite getting it...there is no combined versus not combined with twins set up the way you are talking about...

if you are running 10 lbs of boost...that isn't 5lbs from each turbo..that's 10lbs of boost. Whether you have one compressor or two compressors or however many compressors each they are all going to be pressing against 10 lbs of manifold pressure--your pressure ratio doesn't change between twins and singles, only your flow rate changes.

Quote:

Originally Posted by Jade Dragon

ahh i see. thanks for the info. With jsut a begining setup, i dont think it will be a problem at all because i wil be running low boost from each turbo. I dont think ill be wanting more than 10# combined to being with.

Jade Dragon · #24 06-13-2007, 11:03 AM

ahh, i get it now. Having only 2 hours of sleep makes me a bit slow... I need mroe caffeene.. anyway.. now that i think about it more, yeah. I did find a compressor map, however my airflow is in ft3/min.

*correction*
After doing some more digging, i found that the labels i had previously said are wrong. the turbos i got are IHI VF-7

cdigerlando · #25 06-13-2007, 03:57 PM

I'm not a mechanical engineer, I'm an environmental engineer, but commonly I deal with pumps in parallel or pumps in series. One thing you could try when you are operating two compressors in parallel is to recalculate the graph doubling the flow, and keeping the pressure constant. I don't know how applicable this is, since air is a compressable fluid, and I mainly deal with noncompressable fluids, but you could try it to get in the ballpark range of what you are looking for. That gets back to what Mike was saying, by not doubling the boost but doubling the flow.

Jade Dragon · #26 06-13-2007, 04:01 PM

i did manage to find the map for the turbos i have.

http://www.not2fast.com/turbo/maps/I...ubaru_EA82.jpg

I dont quite know how to translate all of it, but i know someone here can.

XT6Wagon · #27 06-13-2007, 06:22 PM

Very Tiny turbos. Could spool 8psi by 1,800 rpm on a 1.8L with 7.7:1 compression. Max out in the 12-13psi range, and I do mean max out. You will be pushing these turbos hard on a SVX even at 10psi. They truely are too small IMO given that you will be running them hard to get over 300 crank HP, and running a turbo hard is not a wise thing to do on a high compression motor. More over with larger turbos with larger hotsides, you could make MORE power with less stress on the motor. The Loyale turbochargers will be a huge restriction in the exhuast. To the point where external wastegates would make you more power by routing huge ammounts of exhaust past said tiny turbos.

Try a pair of stock WRX turbos first. They suck, but they go for next to free, and the better VF series turbos will bolt in when you get tired of them

Phast SVX · #28 06-13-2007, 06:54 PM

if you want two small turbos that are junkyard units, get two first gen DSM 14B turbochargers.

cdigerlando · #29 06-13-2007, 08:30 PM

Quote:

Originally Posted by XT6Wagon

Try a pair of stock WRX turbos first. They suck, but they go for next to free, and the better VF series turbos will bolt in when you get tired of them

Hey I make 266 HP to the wheels on the WRX turbo

. Probably one would do for his SVX unmodified motor. They are cheap though. Everyone is switching them out and there are a ton of folks rebuilding them for cheap.

I would not do over 8 psi of boost anyway with the stock motor and trans. Even then you are going to need engine management and fuel injectors. Have you thought this through? Modifying an SVX is expensive, and if your engine is old it probably won't last long. You should really do an intercooler or water injection too to reduce detonation.

XT6Wagon · #30 06-13-2007, 11:45 PM

A single WRX turbo is too small for the FXT... you would be amazed at how much money Subaru put into making it work with the 2.5L engine.

The SVX really would need two of them as its flow rates is far from good enough to make it work on a single turbo setup. Though I guess you could do an asymetrical setup and only put one bank of exhaust into it to keep it from corking the exhaust and having severe surge/overspeed issues.

For me, I'm thinking if I end up with a built engine, I'm going to have to start looking at a new class of turbos than I'm used to. T4 flanged turbo will likely be what makes the numbers... Though might go with my old standby favorite... GT35R what?