Ad: SteamSpeed STX 78R BB N55 Turbo (aka stage 2.5) - specs & details

[sam@steamspeed]

It isn't anywhere near done, but here is the 3rd revision at only 16 psi and 50% WGD. Here some quick and dirty analysis, but on Virtual Dyno with default settings, it looks like it hitting 466 whp 508 ft*lbs with just 16 psi! There was a 19 psi revision, but I wasn't seeing the logs. Stay tuned, I think the owner will get it tuned to at least 25 psi. I would guess the turbo probably has another 100 ft*lbs it wants to give, but it will be interesting to see where and when the housings will start to bottleneck it.

https://datazap.me/u/vthorpe

Anyway, this is a quick and dirty chart, so take it for what it is. We have some logs from the car on the dyno with the stage 1 turbo that will be a good baseline for comparison.

 

[pabloN55]

What fuel?

 

[sam@steamspeed]

What fuel?

This is with 92 octane .

 

[N55uk]

This looks promising!!! I might havr to hold out

 

[Jacques.delange]

When can we see the 25psi gains and logs

 

[luchocamp]

I saw your turbine wheel comparison but the picture of your turbo is taken with a close up against other two pictures.
Is not a fair comparison. Just look the size of the wastegate on three pictures.
I do not want to add water into yout soup but the big problem with N55 is
bad design and size of turbofold not the size or design on compressor and turbine wheels.

 

[sam@steamspeed]

Here are the 3rd, 4th & 5th revision on one chart. This is 92 octane with single port meth. They haven't finished dialing in the boost, and haven't really started working on the timing.
v3 - 16 psi - 476 whp / 512 ft*lbs
v4 - 18 psi - 517 whp / 534 ft*lbs
v5 - 19.5 psi - 509 whp / 574 ft*lbs

So, still working on the tune. I think the CHRA should have the capacity to make over 600 ft*lbs to the wheels, and also 600+ whp. I think the exhaust manifold will be the main limiting factor though. I think over 600 ft*lbs can still happen, but maybe 550 whp will be the flow limitation of the turbine housing/manifold. Stay tuned. We'll see how far we can take it.

 

[sam@steamspeed]

Not a lot has changed, but here is rev5 and rev6. Still at 19.6 psi boost target.

 

[ShocknAwe]

What if the AR was increased on the turbo? N55 is a torque monster, looks great.

 

[sam@steamspeed]

What if the AR was increased on the turbo? N55 is a torque monster, looks great.

The basic idea of A/R is that smaller A/R responds faster, and larger A/R flow more, so it can make more peak power sacrificing response. This is assuming that the housing is appropriate for the engine. Having a housing that is too small or too big will make the turbo operate inefficiently, so sometimes going bigger will make the turbo respond better, or going smaller will make more power.

 

[cookiesowns]

Do you have any interest in a M2 development car? 6MT so no DCT woes.

 

[terryd5150]

Do you have any interest in a M2 development car? 6MT so no DCT woes.

I'd be interested to see that.

 

[sam@steamspeed]

Do you have any interest in a M2 development car? 6MT so no DCT woes.

For sure. PM us if you have a M2 that would be a good candidate.

 

[Jacques.delange]

Any feedback? When can they test 25psi

 

[sam@steamspeed]

Any feedback? When can they test 25psi

It is currently on the schedule for a tune on the dyno in about two weeks. We'll see how far the customer wants to push it. He is already feeling like it is a lot of torque. I think the ultimate tune will limit torque, but hopefully we can get a max power tune first.

 

[Jacques.delange]

Lools like its gone quiet on this thread. Any update with higher boost

 

[terryd5150]

Hard to sell turbos without data....

 

[doublespaces]

Hard to sell turbos without data....

I've been contemplating a minimum data requirement of some sort before things can go on sale. Not sure what that would mean but its something I've mulled.

 

[Jacques.delange]

Any higher boost feedback and real dyno figires

 

[sam@steamspeed]

Hey guys, sorry for the long delay.

The car is on the 9th revision. You can grab the logs here if you like to do the analysis yourself: https://datazap.me/u/vthorpe

I will try to get the data visualized in some virtual dyno charts so you can see the progression. The car is fighting with some ignition issues at the current power levels, so we'll be trying some other spark plugs, and eventually coil packs if the plugs don't resolve the issue.

Once we resolve the ignition issue, we should be ready to strap it up to the dyno for final numbers.