desertchecker

nathan thanks for the info & making things clear !

BTW nathan my MPI twins are still going strong !! so far the setup you helped me to decide on has been great , the next MPI upgrades will be the 64 compressor & add external wastegate on the S480 ..... at the same time step up with a BIGGER set of Don's fluxs

XLR8R

Nathan - all else being equal, would swapping the turbine in an HTB2 62/65/13SS for a 71 accelerate spool-up (in other words, does the mechanical advantage from a larger diameter wheel outweigh the inertia penalty?)?

Also, since the existing exhaust housing would be retained, would maximum exhaust flow through it be higher or lower with the 71 turbine?

TIA

morkable

Just to throw a wrench in,, (or more like to stir the pot) I hit over 1000 hp on a single silver bullet. Also ran a fastest of a 10.84 with it.... That being said, the twins will be going in this winter... just not sure which set yet,, still looking

Kevin

XLR8R

Bump......

cquestad

Mike...no.

It will only "spool" more on the big end...if that makes sense.

Off the bottom...what most people call spool...it will be slower.

soulezoo

And... exhaust flow through the turbine of the same size housing and turbine wheel is roughly the same regardless of which wheel. There is a slight difference due to the increased resistance of the higher airflow of the 71 wheel, but not enough to notice except through careful measurement

XLR8R

OK Christian, you're saying the 71 turbine would produce more drive HP to the compressor, which of course is much more noticeable & effective at higher RPM & airflow.

Therefore Terry, it should follow that the 65 turbine would have lower drive pressure and thus be able to flow more exhaust (I'm viewing the exhaust housing/turbine wheel as a fixed-orifice bleed in terms of drive pressure).

Thoughts?

So what is the advantage of a larger turbine (same exhaust housing) for high-HP twins?

cquestad

The 71 has lower drive pressure...slower spool...but more air on the big end.

The 71 or 65 wheel is also what is "in the way" once the primary is spooled....

So...if it does not move enough air...it kinda blocks the road so to speak. I have a headache/hangover and probably am not making any sense.

I will try again later today...lol.

wap

I may be repeatin what has been said but the 71 will have lower DPs but should be cooler on the top end and a bit slower to lite then the 65.

The 65 should lite slightly quicker but not cool quite as well up top and have higher DPs.

In twins I dont know that the cooling is enough to matter since you should have a hoss up under it but I think the main concern when choosing 65 vs 71 is spoolup vs DPs.

CrashCade

Check out www.dieselpowersource.com I have yet to run on the dyno with this, but I am guessing I should be 650-700. I was 688 on my HTB2 62 with a little spray.

cquestad

You had to have had the world title on the most over worked small turbo...

XLR8R

... maybe it was more than a "little" spray?

CrashCade

It definitely worked that turbo a lot. It only lasted me about a year. I also sprayed it with a -4an line from solenoid to nozzle without a jet. LOL, so yeah it was a little bit more than a lot of spray!

OutOfSight

Well over 700HP with my stocker on top. 11.93 at 116 with bad traction issues. Actually cleans everything up to. At 644HP (old sticks and pump) it ran and towed awesome.

http://www.youtube.com/watch?v=5eMlQ6kTUjU

I'm a beliver in the stock/s400!!

osci

What kind of egts and and drive pressures did you see with the stocker/400?