A discussion on the AudiSRS forum posed a question about experience with a set of K03 Hybrid turbochargers from GP Turbos in the UK. The product is not shown on the page of the GP Turbos website dedicated to the Audi product line, but there was a link to an eBay listing provided in the discussion with the title “Audi S4 RS4 B5 2.7 T GTX Billet hybrid 385+bhp Pair Turbos 5316 970 0016 / 0017”.
Curious to learn more about the product, as nothing had been provided in the forum discussion I sent an inquiry to the email address given on the Contact Us page of the GP Turbos website.
After about a week I had not heard a reply so I used the contact form on the same page to send my question again, but I also noticed the Facebook symbol on this page so I followed that to see if I could send a Message via Facebook to the company. This was a possibility, so I sent a message through the Facebook messenger.
After two days I had not heard a reply back to my question from the contact form but I did get a response back via Facebook. My question to learn some more about the K03 Hybrid for 2.7T engine was responded with, “What information do you require”.
I sent a reply back with a series of questions;
“If I understand the advertisement, these are rebuilt BorgWarner K03’s with the compressor housing machined to accept a larger compressor wheel. Are the wastegate canisters new K03 units or does it use the existing ones from the rebuilt turbo? What size is the compressor wheel? Stock is 36/50. The ad mentions they are high flow compressor wheels, what is the maximum lb/min that they support? The trimming of the turbine shaft, what is the purpose? Load carrying capacity was not reduced with the removal of material? Is the turbine wheel the original K03 design? The ad mentions these have great spool and response, do you have any boost data to illustrate how these compare with an unmodified K03? To what speed are the turbo’s balanced? The ad mentions that No Returns Accepted, does that mean there is no warranty period on the product? Thank you”
My questions were viewed about half a day later but no response came back after more than a day passed.
With idle time I decided to see what I could dig up on GP Turbos. I first looked into the domain name, GP Turbos.com and found that it was created in August of 2017, only 10 months ago, a mark against the business.
I then looked into the business registry data to see what I could find. There was a record of the company incorporating in 2013, a positive sign, but then for two years from 2014 to the end of 2016 there are “Accounts for a dormant company” – that doesn’t seem good. Then in November of 2017 there are a series of changes noted. As a reminder, this is now a couple of months after the internet domain name was registered.
The eBay account selling the K03 Hybrids is for “gti1000bhp” and was established in 2005. It is not listed as being for a business seller.
The Facebook page for GP Turbos first mentions the K03 Hybrid for the 2.7T engine in January of 2018. Aside from the one post the product is never mentioned again.
Based upon what I have found thus far it appears to me that GP Turbos was started several years ago doing something that never panned out or was not done seriously, and then last year a renewed effort began. The website was developed and they appear to be using the owner’s personal eBay account to also sell the products. The company is likely producing the K03 Hybrids for the B5 S4 and never tested them on an S4.
Turning to the product, what do I know about it? Not a whole lot. According to the GP Turbos eBay listing their product has the following features:
- GTX Billet compressor wheels.
- High flow compressor wheel
- Capable of up to 385+bhp
- Great spool and response
- Upgraded bearings
After several days I received a reply back to my series of questions:
Q. Are the wastegate canisters new K03 units or does it use the existing ones from the rebuilt turbo?
A. The Actuators are tested existing ones from the rebuilt turbos, these are optimized and setup 2 psi above standard
Q. What size is the compressor wheel? Stock is 36/50.
A. The compressor wheel is 38/51 billet design
Q. What is the maximum lb/min that they support?
A. They flow approx 26lb/min
Q. The trimming of the turbine shaft, what is the purpose? Load carrying capacity was not reduced with the removal of material?
A. Turbine wheel has had trim to increase maximum flow while maintaining most of low down efficiency
Q. Is the turbine wheel the original K03 design?
These are new slightly thicker blade but original design based wheels
Q. The ad mentions these have great spool and response, do you have any boost data to illustrate how these compare with an unmodified K03?
A. Unanswered
Q. To what speed are the turbo’s balanced?
A. All assemblies are dynamically balanced to Motorsport specifications to within 5mg
Q. The ad mentions that No Returns Accepted, does that mean there is no warranty period on the product?
A. Warranty is 6 months as they are motorsport items
I now feel more strongly that these turbochargers were not tested on a B5 S4. There is an absence of data on the company website, the eBay listing, the company Facebook page announcing the product, and my question about having data was the only question that was not answered.
The question any end user ought to be asking, “what change in performance am I purchasing with a product?” remains a mystery.