Okay, here's the deal. I came across two Reman Garrett GT2554R turbos for less than dirt cheap. So I bought them, I've been looking at doing a remote setup on my mild 302, but these things are borderline too small I think. I've been doing some mapping, and they seem to be fine at lower rpms, but quickly become way too small in mid to upper rpms...idk, I would like some opinions from people. There will be pressure loss due to the longer piping, so I'm not sure how that will affect the pressure ratio at the turbos... I've been told about one psi for each foot of piping? I assume the piping will be like 10-15 feet long...so the turbos should see around 17-18 psi if I am running around 7 or 8 at the manifold? Am I correct so far? So calculating that, I'm getting about 70 lb/min at the turbos...which is waaay too big for them(35 each on a twin setup of course). So am I out of luck?

 

You won't lose 1 psi per foot of cold side piping if you size it correctly. Really, you shouldn't see any substantial loss if you keep the pipe as straight as possible and use mandrel bends where necessary. The extra length mostly adds volume to the system and will cause a slight delay in boost rise as the system is pressurized.
Try mapping your compressors disregarding the pressure loss and you should be fine.
Your turbos still look a little on the small side to me but may be OK for a mild low boost setup.

 

Anyone know how to calculate the amount of exhaust flow? Or is it the same as the compressor formulas...I'm not sure how combustion affects the exhaust...But I could understand that it might be identical...but anyways, I'd like to compare that to the turbine map Garrett supplied, it's going on my DD so I can't really have it spooling completely at 1800rpm or somehting....not saying that they will...i just dont know...here's the turbine map

 

Well, going from normal calculations like you'd use for a compressor map, I probably wouldnt see boost til around 2500rpm. Which is fine, but at 6000rpms the intake flow is to the right of the comp map...which means its just less efficient right? I'm thinking about trying this setup, it just worries me that I might go through all this based on some faulty calculations and end up with a non-usable combo....input would be appreciated

 

What are the compressor and turbine dimensions

 

Compressor Inducer: 42mm Exducer: 54.3mm 60 trim
Turbine:53mm(doesnt give exducer dimensions) 62 trim

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT25/GT2554R_471171_3.htm

 

They are a little small but should go 250 hp or so each. I'd think a mild 302 at 8 psi would be about 400-450 hp but then I'm not really a Ford guy They might bo OK for a DD even if they sneak off the map a bit which looks to only read to 65% under 15 psi. I'd give it a try since you got them cheap and upgrade later if you feel the need.

 

Yeah, my only worry is the fact that they are T25 flanged, so going bigger would mean having to redo all the flanges and basically starting over with tubing and all....just want to know if this is going to be a giant waste of money or not

 

I hear ya.
I went through the same thing building my setup years ago. Weird flange turbos and couldn't even get a map for them. Knowing they would be borderline small and not much else to choose from for turbos back then, I went ahead and ended up with more power than I expected. Do I want more? - yes. Is it worth the hassle of rebuilding the whole system to fit standard flange turbos? - Not really. I can't use all the power I have now without blowing the tires off street or track. Would need more safety gear $$$ and a license to go much faster at the track so I figure why bother really for a street car.
If you think you'll be happy with a quick spooling 400 hp street car then you have the right turbos. If you'll end up wanting more (and you will) you need more turbo so may as well sell the little ones and start out with room to grow.

JMO..... good luck

 

My initial build plans were to do a big single, and I found these and jumpe don them with the thought that if I couldn't use them I could sell them. I've actually had them on craigslist a week or so, and I can't post in the classifieds on here. No real interest yet, which is why I was considering trying to get them to work. But I'd much rather start the build with room to grow like you said, I eventually plan on the car being a fun car and not my DD, so then it can get lots of goodies, but I dont want to have to trash everything and start over. Right now I just kinda have to make due and keep it streetable. If you know someone that would want them let me know lol, I'll make them a good deal.