^ thats some intense complexity to test transient response.


I'd just want both turbos on a load based dyno holding wheel speed steady such that engine RPM stays at 4k. Start with 10% tps and floor it. See which one rises in torque and boost the fastest. And maybe repeat at 3000 and 6000rpm. Its a bit redneck in comparison but whatever. Does the deed.

 

R/T Ernie,
The outermost edge of the gt30's blades is a constant 0.6mm thick all the way from the inducer to the exducer, and the turbine wheel is 31mm high from the backdisk to the root of the exducer. Now if you could be as kind enough as to measure the 7670 correspondingly, perhaps we'll be able to settle this once and for all

 

Be interesting to also weigh both wheels, although I doubt anyone will pull apart an EFR.

Maybe Full race has a turbine laying around they could weigh?

 

Lets not also forget the interaction of the turbine housing with the wheels of which we are also talking two different brands.

 

That's how every single one of our dyno runs are done, every one of them, every time........

 

Except you dont measure time or take multiple starting points. You're not testing transient response Dave.

 

FWIW I wasn't actually talking about a traditional dyno pull. I was actually talking about doing a "pull" while the RPM stays constant. I know dynapacks can do it where it adjusts load to keep the wheel speed (and therefore RPM) the same regardless of engine output. I assumed mustang and dyno dynamics dynos could do it too. Doing this would eliminate the variability of gearing that favours one turbo over another, or changing VE over the rev range, etc. AFAIK any change in torque over time under these conditions should be solely due to the turbo spooling up, fuel and timing (maybe MIVEC advance on IXs). But the latter 2 should really be a product of the turbo spooling up and producing boost. Fastest one wins.


EDIT: btw does leetevo's car have the HKS 4.11 final drive gear? Cause I believe I read somewhere that DB has it in his car. Having a taller final drive would load his turbo up more and make it spool faster. Even when on the same dyno, with same wheels and tires, etc. I've always believed the final drive gear is part of why spool up in tscompusa and CB's evos look more impressive than expected.

EDIT2: Not to say that a good setup and high compression BR stroker motors didn't help in all of the above mentioned cars.

 

dynapacks won't hold an RPM without throttle input, they have a stabilization period where the car is WOT for a few seconds prior to starting the pull. The dyno cannot drive the wheels... so you'll always be altering the turbo speed prior to the start of the pull... and now you'll be loading the engine differently every time you start. Trust me when I say that the deceleration to WOT is the best process.

 

Use the throttle and a boost gauge to start from a given vacuum value and do the pulls. Going from decel to WOT may be the best way but any method of implementing it can have holes poked into it all day long. Besides no body goes from full decel to WOT in normal race conditions.

 

we're not simulating racing conditions we're evaluating transient response. Controlling variables is part of running a legitimate experiment with usable & repeatable data.

 

I think you missed who I quoted and what I said we do. If the car comes into boost faster it is going to recover on a gear change faster, that's a no brainer.

 

Hydra, i measured up the EFR turbine wheel today.

The blades are ~1mm thick

The superback plate is ~1.2mm thick (some areas are smaller from balancing)

the nut at the end of the exhaust wheel is 18mm across (from point to point)
that same nut is 11mm tall

 

I didn't really expect that the blades would be constant thickness. You're saying .... they are?
Same question to Hydra on the GT30 blades.
I thought you'd need a thickness map, or a coordinate measuring machine!

Glad to know this. For myself I wouldn't want a dyno run done like this.

 

Use a Dynapack first... and you'll love it. Don't knock it til you've rocked it!

 

yup because everyone has one of those lying around in the workshop...
i said "~1mm" because ~ means approximate. They are approximately 1mm in thickness.

they have a stabilization period selection which allows the car to hold for a few seconds before starting the pull if thats what the operator wants.
why wouldn't you want a dyno run like this? you dont like repeatable and accurate results for testing?

Measuring transient response on a dynapak is super easy.
Use the hold mode at whatever RPM you want, 4000, 5000 etc.
Then go from 10% throttle to 100%.
Measure the amount of time it takes to reach max boost.
It will hold the RPM at a set configurable amount, no matter what load you put into it (but yes, it must be enough to keep the hubs at the required speed.)

I can happily make a video of this and how our tuner Carl Ruiterman works the machine if you like.