IS A BOV MORE IMPORTANT ON A HYBRID TURBOCHARGER

advantage101

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VW UP GTI
Hi Folks

I had an exchange or two with members of a different forum about have a Blow off valve fitted to my car.

A chap who seemed to have done extensive research on the matter and even spoken to a manufacturer of BOV's concluded that the UP GTI already has an inbuilt devise which adequately performs this function and that adding an aftermarket BOV is not necessary!

I am swapping the turbocharger to an aftermarket Hybrid using an OEM housing with upgraded internals.

My question now is whether this new turbo would necessitate a BOV for maximum performance??

I look forward to hearing from you.

Cheers
Michael
 
The VW ECU's generally have a big problem with atmospheric dump valves (BOVs) they tend to run rich and are prone to throw error codes or enter limp home mode (Bosh ECU are more fussy than the Siemens ECU's but both complain)

The turbo should come with a bypass controller and it's important to have the right "spring rate" on this for the power of the turbo. The stock N75's are generally quite weak and only suitable for a stock turbo, an N85 was the VW solution for larger turbos but there are better aftermarket units around.

Some members have used partially venting ones, but to be honest the VAG design keeps the turbo spooling up by dumping the pressurised air into the intake so you'll lose throttle response with anything other than a recirculating valve.
 
The VW ECU's generally have a big problem with atmospheric dump valves (BOVs) they tend to run rich and are prone to throw error codes or enter limp home mode (Bosh ECU are more fussy than the Siemens ECU's but both complain)

The turbo should come with a bypass controller and it's important to have the right "spring rate" on this for the power of the turbo. The stock N75's are generally quite weak and only suitable for a stock turbo, an N85 was the VW solution for larger turbos but there are better aftermarket units around.

Some members have used partially venting ones, but to be honest the VAG design keeps the turbo spooling up by dumping the pressurised air into the intake so you'll lose throttle response with anything other than a recirculating valve.

Hi Obi Waynne

Many thanks for taking the time to respond to my question.

TBH this area of tuning is quite new to me and more technical than the other parts of my project, so I am a bit out of my comfort / knowledge zone!

I am planning to use an aftermarket ECU such as a Motec unit so this may have a bearing on some of the points raised in your response. I haven't looked into the Bypass Contoller of the new turbo but will do so now.

Is it possible for you to point me to a suitable recirculating valve please? Or point me in the general direction?

Cheers
Michael
 
What engine and year is your car and which turbo are you looking at and I'll see if I can dig up any more technical information for you. Most of my expertise lies with the early K03 and K04 era engines, but I'm sure I can help point you in the right direction.
 
Hi there

Thanks again.

My engine code is DKRA 10.L TSI engine standard on my 2019 VW UP GTI Reg number NV68 HHR.

The engine part of my project includes upgraded forged internals, engine balancing & modified cylinder head.

The turbo I have purchased is in the link below.


Cheers
Michael
 
That's a good solid engine upgrade plan you have there. I wouldn't fit a BOV to this it is quite likely to run rich and give you rough running.

What is your target power figure, have you considered an upgraded differential on this to get the power down.
 
Hi Waynne

Thanks for your advice, it makes good sense.

Yes I have an ATB differential ready to fit. I worked with Quaife Engineering to design one from scratch as they didn't have one as part of their stock.

I had to order 10 units because of development / set-up costs and managed to sell most of them or swap them for other parts. I sold 2 units to MRD Racing in Germany who created the FIA UP GTI Junior Cup cars to bridge the gap between Kart racing and saloon car racing.

They had a couple of cars with failed standard open diffs and wanted to test my Quaife against a Drexler LSD. They have chosen to go with the Drexler diff and ordered 30+ units which should arrive next month.

MRD have reserved me one in exchange for a number of Quaife diffs which they can easily sell to UP GTI enthusiasts. The Drexler was tested extensively for 2000KM and apparently is far superior than the Quaife when it comes to serious track racing!!

In terms of pistons and rods I have worked with Performance Unlimited in York to design and produce products for the 1.0L TSI engine again, there were no off the shelf items available!

The rods are Carrillo and the pistons are CP brand. I have specified the following:-

185BHP

7000 RPM max

C/R 10.3-1

Ceramic Crown Coating

Skirt Coating

Anti Detonation Grooves

Lateral Gas Ports

The OEM pistons are used on VW's with 250BHP so in theory my pistons set at 185BHP should be a lot lighter and give me a faster revving engine.

The overall project for my UP GTI is to create a road going fast road car that can give me 4 track days per year!!


Thanks again for your advice.

Cheers
Michael
 

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