Cummins Diesel Forum banner

Which turbo will spool faster?

4K views 18 replies 12 participants last post by  TURBOLVR 
#1 ·
Which one of these turbos would spool the fastest if they have the same fueling mods done to the truck? 63-65-14 or a 63-68-12
 
#2 ·
I had a 57/65/14 for a year then a 62/65/12 and they were practically identical in spool. But that map different compressor wheel, not turbine. I'm honestly not sure, but I would think the 63/65/14. Even though the pressure will be slightly less coming through the 14cm exhaust housing, there's still lot of pressure and the 65 has less mass to start moving.
 
#3 ·
Without any real evidence, I'd say it's a toss-up but deserves discussion.

Anyone have any turbine shaft or compressor wheel weights?
I'll see if I can find a 65mm turbine shaft.
 
#4 ·
Also what fueling mods you are wanting to do would help figure things out.
 
#6 ·
I would say the 68/12 would out-spool the 65/14. Although the 68 is a larger turbine, it is in a tighter housing. The smaller housing and more focused nozzle would put more force earlier on the wheel, thus spinning it quicker/faster.
This does not take into account the design of the wheels or housings which can also affect the response speed.
 
#8 ·
63/68/14

I have the SD 63/68/14. I can tell you with my current set-up, I'm seeing 5psi at 1400rpm and 10psi at 1550rpm. Its very quick to spool, only 100rpm slower than my stock HX35 was.
 
#9 ·
every setup will be different...

also what psi you see at what rpm depends on what gear you are in, what kind of engine load, what injectors, what fueling and timing...


hell I can see 40psi at 1400rpm if I really wanted to... on average I see 10-20psi...
 
#11 ·
When I stated what boost I was at for the RPMs stated, I am talking about being in 6th gear.
 
#12 ·
That's crazy... I see much higher boost when I'm all the way in od. But
The auto doesn't loose much spool at all in that locked shift I guess. I can see 20-30psi easy at 1400. 65psi by 1700.

I've always measured rpm vs spool from a stop wot. Never thought too much about when it was in od cause that's when it's the highest.
 
#13 ·
I don't see boost building until about 2100 rpm with the setup I have. Not sure if it's normal.
 
#15 ·
Are you referring to a possible leak on the cold side? What's the best way to check, assuming nothing is visually apparent?
 
#16 ·
cold and hot. cracked manifold, blown gaskets, missing bolts, loose clamps, cut boots, tiny bolt in the boost elbow fell out, ect.
Boost leak tester is a 4" OD PVC pipe plug with a tire valve mounted to the end, clamped to the turbo inlet using a boot, then SLOWLY add regulated air up to say 10psi. sprat the engine/IC down with soapy water and watch for hissing/bubbles.
 
#18 ·
Does it need a constant 10psi air source to test for a leak or should it hold the 10psi once the air is introduced? Thanks in advance, Carl & sorry for hijacking the thread. :banghead:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top