T70 turbo

[Unfalconbelievable]

OK just bought a T70 turbo off ebay, I know they're cheap chinese things but for 400 bucks figured I couldnt go wrong Specs are as follows

Wet floating bearings
Oil cooled
Turbine size 64.5mm
Turbine AR .84
Compressor size 60.5mm
Compressor AR .7
T3 flange

I think this will work OK for 15-20 psi in a 250 crossflow, although its a bit on the largish size

What do you guys think?????

 

[Anonymous]

Is the turbine a P trim?

.84 A/R on a P trim turbine, on a 250 won't spool up until over 4,000 RPM....

Also, that 60mm compressor is pretty big.
I would suspect you get some compressor surging if the pressure is high but the flow through the compressor is low. (it's only a 250, that 60mm is good to 500-600 HP)

Find out for sure what size the turbine is (O-trim, P-trim, etc) then get a smaller A/R turbine housing to match.

 

[Anonymous]

yeah..that turbo is for high boost, quick spool up on some motor with some ponies....if you dont have the flow..you wont have the go thoguh...becasue it takes alot of flow to spin up a larger turbine. But if you can..the larger the turbine..the more power you get.

Im suspecting 350 horses with a T04 Garrett with a P Trim .96 A/R housing...and i think its going to be too big...but im going to experiment anyways. Im using a .60 A/R compressor with a V Trim wheel...this is on low compression 300 six...anyways....i havent studied turbos for a bit..so im rusty at the actual pressure ratios and sizes of the wheels anmd housings at the moment...lol

 

[Unfalconbelievable]

Ok well 4000RPM sounds a bit out there, I was hoping for 400hp at the treads so 500-550 at the flywheel although 600 would be nice! Also this is a road-rally based project, 5500-6000RPM limit for a longish life on the engine, but I would like spool by 3000-3500RPM at the most. My plan was to use this turbo to build my manifold and run the motor in with then when I get some funds I was gonna bolt on a slightly smaller turbine housing as my turbo guy said although they are a cheap copy of a garrett they are interchangeable for parts. Linc 200, when you say wont spool till 4000RPM do you mean wont make peak boost till than or wont make any positive pressure till then? Keeping in mind I'm getting the head ported as far as it will go (around 40mm intake and 37mm exhaust dia's), bigger S/S valves, custom equal length exhaust header and custom intake plenum and runners. With this sort of flow I'm hoping I can get some boost by 3000RPM and peak by 4000-4500RPM and then pull strong to 5500RPM


?????????!

 

[Anonymous]

I'm hoping I can get some boost by 3000RPM and peak by 4000-4500RPM and then pull strong to 5500RPM!

That'll be about right. I am curious to see how it goes.

 

[Unfalconbelievable]

Cheers for the info linc's 200, I was hoping it wouldn't take to 4 grand to make any pos pressure at all! That would be way too much lag, but 3 grand isn't so bad if its at full spool by 4 Cant wait although it wont be for a little while cause i havent even got the ute to the paint shop yet, and then I've gotta save the $3000 bucks for the block n chev rods n pistons. I'm figuring on a 12 month build from now unless i get a loan out (which i might yet). Cause theres about 5000 for paint and pannel, 3000 for engine, 300 for intercooler, 1400 for ECU, Spose about 1000 for injectors n fuel pump(s), then I've gotta get race seats n harnesses, guages, plus build my own dash, door trims manifolds and front bumper. Also I'm spending 5000 on RRS rack and pinion and coil over strut front end so i figure on 20,000 for the whole project give or give 5000, yes i know i said it wrong but it'll always go over budget! although you's will hear from me before the end cause i'll be needing advise im sure

 

[Anonymous]

One other thing, those turbos are getting a bad reputation at turbo shops, and since they are often broken during disassembly a LOT of turbo shops won't touch them. Make sure you can get parts for it, even if it is just a different A/R turbine housing (.58 A/R would help a LOT!!!!)

 

[Unfalconbelievable]

Linc's 200, wouldnt a .58 turbine A/R over rev the turbo at these rev's (5500). I was thinking of going to a .65-.70 when I get around to changing it. I'm very cautious of over reving a turbo 'cause thats when the wheels fly to bits and f#*k your whole engine. I know the quick spool would be great but I think it'd spin the hell out of the turbo anything over about 4000RPM trying to keep 15-20psi in this big biatch of an engine! Remembering the wastegate doesnt just open fully when you reach full boost and the turbine wheel and compressor wheel stay at that RPM for the rest of the engines rev's. As engines rev's increase air speed increases and thus the turbo has to spin faster to keep manifold pressure at the wastegate determined psi. Too small of an exhaust A/R would provide better spool but more revs on the turbo, possibly too much!

 

[Anonymous]

on a 250???? No possible way.


Once you reach the boost you need, the wastegate opens and keeps the turbine speed below what is necessary to make the boost you need.

I think it'd spin the hell out of the turbo anything over about 4000RPM trying to keep 15-20psi in this big biatch of an engine!

sigh......I hate to rain on your parade, but 250 cubes is not a "big biatch of an engine". It is tiny, relatively speaking. You should be able to use a 60mm inducer turbo on anything up to around 6 liters.

YOUR BIGGER PROBLEM is compressor surge - from trying to use a turbo too large for a given engine size.

AS you build boost, but have low airflow through the compressor (you are only at ~4.0 literish) the compressor will not like the fact that is has all this pressure built up, but the engine is so small, it isn't using that much flow. Then you get surging problems.

 

[Anonymous]

In other words, for simplicity, the engine cant keep up with the turbo. To flow air, you must use air. If you dont use it fast enough, theres only one other place for it to go, back out the turbo the way it came, or attempt to anyways. Turbos dont like spinning backwards.

 

[Anonymous]

In other words, for simplicity, the engine can't keep up with the turbo. To flow air, you must use air. If you dont use it fast enough, theres only one other place for it to go, back out the turbo the way it came, or attempt to anyways. Turbos dont like spinning backwards.

EXACTLY!! 100% correct. :tu:

The air doesn't have to flow backwards, it just has to stall (or not be used up fast enough) like Emerald says.

That is why it is so important to use a Compressor Map - You don't have a "True" T70 so you can't use a T70 map, but if you measure the inducer and exducer of the compressor wheel you may find a nmap that is close....

Anyways, as you go up (vertically) along the map for the amount of boost in Bar, if you are not flowing enough air (along the map, left to right) you may run into compressor surge line. Basicly says the pressure is there, but the turbo just can't take it unless some pressure is relieved in the form of bulk airflow.

 

[Unfalconbelievable]

Ok, all this time i thought the turbo was a cheap chineese version of a garrett because thats what is flooding ebay at the moment. Got the turbo today and it appears its made by a company called XS POWER. It's based on a T3 for the flange but I'm not entirely sure other than that. Any one heard of this company before????? any negative or positive comments welcome. With enough work on the flow of the engine I was hoping to avoid surge. And the turbo does keep spinning faster and faster even once the wastegate is open because the engine requires more air the more it revs, say your wastegate opens up at 2800RPM and your turbo is pulling 30,000RPM, to keep boost at the same level when the engine is doing 5500RPM the turbo is probably doing 55,000RPM. The wastegate hovers between open and closed to keep the boost level at the desired PSI.

Also can someone help me read a compressor map? Assuming this turbo is similar to a garrett T70 then i have a compressor map, but what figures do I need to read it? I dont get it at all HELP!!

 

[Anonymous]

Ok, all this time i thought the turbo was a cheap chineese version of a garrett ..... its made by a company called XS POWER

It is still a cheap Chineese version of a Garrett.

They are sold by ssautochrome and a few others.

You can go to turbomustangs.com and do a search:

http://www.turbomustangs.com/forums/sea ... ?s=&action
=showresults&searchid=148745&sortby=lastpost&sortorder=descending

http://www.turbomustangs.com/forums/showthread.php?s=
&threadid=47825&highlight=ssautochrome

http://www.turbomustangs.com/forums/showthread.php?s=
&threadid=42757&highlight=ssautochrome

http://www.honda-tech.com/zerothread?id=1097918

Any one heard of this company before?????

A lot of people have - I have not heard good things. They come from ssuatochrome

And the turbo does keep spinning faster and faster even once the wastegate is open because the engine requires more air the more it revs, say your wastegate opens up at 2800RPM and your turbo is pulling 30,000RPM, to keep boost at the same level when the engine is doing 5500RPM the turbo is probably doing 55,000RPM. The wastegate hovers between open and closed to keep the boost level at the desired PSI.

yes, that is true but don't get dramatic about it. If your wastegate is set at 2.0 (14.7 psi boost), then go up the map on the left to 2.0. then move to the right to where the amount of air (in lbs) is flowing. The sweeping lines with big numbers are turbine speed.



Here is an S-3, which is what I use to push 20 psi into my engine:

Alright, If I make full boost at 3000 (about where I am) then my engine flows 19 pounds of air per minute. go to the bottom, and look at where 20 pounds is, and go straight up to where 20psi should be (about 2.4 bar)

http://www.turbofast.com.au/tfcalc.html

Notice I a right up against the surge line, and turbo is spinning about 102,000 at that point.

As revs increase to 4700, I'm moving 30 lbs of air.
Go to the bottom, find 30 and go up to where 2.4 bar is.

See how the line for the turbine speed is curved down? At 30 lbs and at 2.4 bar, my turbine speed is now 106,000

Big whoopee deal. Shaft speed went up a whole total of 4,000 rpms.

SEE, that is why a map is so important. you can't just be pulling numbers out of your arse. You have to have the facts.

Even if I go to 5500 (34 pounds of air) the shaft speed is now only 116,000 so it doesn't go up THAT much.

And why on earth are you so worried about turbine shaft speed?


bye for now, I leave for Siberia in three hours..............

 

[Unfalconbelievable]

Thats great and helps a little but you didn't tell me how you came up with the fact that at 3000RPM your engine is flowing 19lbs/min and at 4700 its flowing 30lbs/min. How do I work out what my 250 is flowing, taking into account all the work I'm getting done. I can move redline to 6000RPM if its gonna help in the flow department, also are these turbos still interchangeable with the T series garrett turbo's because I can get smaller A/R housings. Also does anyone know what I need to do to the chevy 305 rods to make them fit the ford crank? bigger bearings or mill the rod big end out? And will they foul on the block with a good set of ARP rod bolts? And I know the crossflow alloy heads can only be taken to about 40mm on the intakes because of the pushrods but what can the exhaust be taken to? I was thinking around 38mm but if they can go slightly larger it would help with the 80-85% exhaust flow I need. And with unshrouding and chamber work what size valves can I fit in this head?