Sorry I'm not on here frequently, but you got the dyno chart. The APR dyno is load based and so I don't think the spool characteristics can be read the same way as dynojet or on the road. I also thought the posted APR whp figures always seem high on the VAG graphs. Although these numbers seem right for the setup.

 

The dyno logs those things partly so it can normalise the data, it uses SAE correction so it should be compensating for that air density difference and making the two results more or less comparable.

 

Peak numbers would be comparable, but colder air will help the turbo spool quicker. Correction factor can't correct that.

 

Absolutely, but I thought the topic was mainly the power difference

 

That's about half of what we're looking at, the other half is where the turbo comes on.

 

The data so far suggests at the very least it hasn't become a lag monster - the temperature change will have an effect, but it's not likely to make something that was going to have a significant impact "all things equal" suddenly look negligable, surely?

 

You are correct. Going off the two charts, and temperature difference I would put money the 2 spool very closely to each other had they been dyno'ed in more similar or cloder to identical conditions. Knowing the source of the graphs also tells me that the way the dyno loads the car hasn't been played with, RTErnie and APR have nothing to gain by pumping the numbers up or making it spool faster with load control.

 

I'm trying to decide between a 8374 and a 8474 currently. I'd like the headroom of the 8474 but not sure id really notice the difference in spool. Initial goal is to break in the motor around 600whp and then shoot for a safe 750 or so. I'm just going to be a fun street car with high horse power. Fuel will be e85.

Thanks

 

If you are on 2.0, the difference will be not much...it will be laggy and that is that.
If you are on 2.3, 8374 will spool nicely, while 8474 we don't know yet...I would not like anything less than 2.3_8374 spool for street car.

 

 

 

You must not know that a 94mm stroker in a 4b11 pulls the piston skirt below the bottom of the cylinder and has a garbage rod ratio and is just a terrible idea.

 

Looks like a quick-spool valved turbine housing is about to be released for the 8374/8474 and 9174/9274: https://turbosource.com/products/tur...urbine-housing
Results will be interesting for sure.

 

There must be a reason why BW abandoned the design/project?

 

They had enough issues with turbine housing suppliers at the time; the reason why there were so many shortages was because they couldn't find a company that could get the "investment cast" turbine housing right, and why the revised version looked like a botch job - adding a quick-spool valve just adds to the complexity that they already couldn't get right. Just my guess, anyway.