My 20v 2.5 stroker track day ur quattro

[DamoM]

Damo. NO! Please stop this thread, must be satisfied with what I've got! Stop putting ideas into my head...!

Another interesting development, hope you get it all sorted Interested to know how well it spools up, presumably you should be able to hit 500bhp at the crank when everything is sorted?

I know i'm sorry!

yes that's the hope. It spools up nicely. It's not MD357 torque monster by any stretch but you have strong boost by 3000 rpm and full boost by 3500 rpm. I would be happy with that IF I was producing the power!

[Audi_CQ]

Do you have a fuel pressure gauge fitted? If not Mount one and watch it under load on the dyno. Should be 3.8 + boost (5,4bar if 1.6bar boost).

To measure backpressure you need to tap into the ex. manifold collector/turbo housing and connect it to a boost/pressure gauge then take a reading when on full power on the dyno.

I think something is lost in translation.
Backpressure refers to the pressure in the exhaust manifold or the exhaust.

What you are talking about is pressure in the fuel rail, same thing as I am

I was maybe a bit unclear, but in the first section I was thinking about the fuel delivery problem.

In the second section(that starts with "To measure backpressure.... ) I describe how to measure pressure in the manifold.

[DamoM]

Well I have a finished (well sort of) article.

The exhaust had 15psi of back pressure in the downpipe. My guy custom made a 3" exhaust and now I have zero back pressure.

Got the largest air filter known to man and got a samco 4" pipe for it to match the turbo inlet.

Turns out the fuel pump was on the way out. Pressure moved all over the place when it was measured. Replaced it with an 044.

Net result was 370 bhp at the wheels (roughly 465 bhp flywheel) at 25 psi. As we went up with the boost above 25psi the timing had to drop as we could hear slight detonation. As a result of this the power at 30psi is pretty much the same as the power at 25psi as so much timing had to be taken out. The fuel injectors are now at 80% duty cycle and the mixture is still fairly rich to aid in cooling which proves the old pump was faulty, it also holds a steady pressure at full boost.

Was hoping to crack 400 bhp at the wheels and get to the magic 500ishbhp flywheel but it seems to be a bridge too far on this engine. I seriously don't see how people get much more power on this turbo or engine.

I have high quality parts all through the engine and have spared no expense to maximise the potential and can't see what else I could have done.

Having said that I have not seen any other plots verifying other claims whereas I am more than happy to post mine up.

Here is the plot.

[Error404]

Still, a real good result and I'm sure its a lot fo fun in a UR
What CR are you running on this setup Damo?

[DamoM]

Still, a real good result and I'm sure its a lot fo fun in a UR
What CR are you running on this setup Damo?

yes, don't get me wrong it will be great fun and it's not always about the numbers!!

Can't remember about the c/r I'll dig out the spec of the pistons and come back!

[jsws3]

It's still a good result mate but not as much as I or you was expecting have you got water meth on yours mate ?

And when turbo company's market these turbos I think we need to take it with a pinch of salt when they say 500+ on a grx3071r.

[diesel des]

it's fuel of compression ratio that's holding up your power. the gtx 3071 will push to 550hp

[DamoM]

Still, a real good result and I'm sure its a lot fo fun in a UR
What CR are you running on this setup Damo?

JE pistons on 7.6:1

[DamoM]

It's still a good result mate but not as much as I or you was expecting have you got water meth on yours mate ?

And when turbo company's market these turbos I think we need to take it with a pinch of salt when they say 500+ on a grx3071r.

I don't run water meth. It's probably the only thing I didn't do. I have aquamist injecting water spray into the inlet at 10psi+

I think that you're right about the claims but I was hoping for that little bit more but we always do!

[DamoM]

it's fuel of compression ratio that's holding up your power. the gtx 3071 will push to 550hp

Fuel pressure is good at the rail, injectors are at 80% duty cycle and the fuel is Shell V-Power.

Do you have any dyno plots of that turbo doing this on these engines? Would be good to see.

[diesel des]

I'm surprised you have had to bring back timing so much with that compression ratio and on good fuel. seems odd. I have saw some dinos of that turbo making more power on different engines, but little on ours.

[A80Avant]

That's possibly the first GTX3071 measurement on the i5 engine even 2.5l

Not bad I have to say for 25psi. Why is the car detonating? What is the compression ratio?

These turbos are able to produce quite a lot with more boost so long as there is no detonation as their map is wide.

The plain 3076R on mine T 1.8bar tapered to 1.7 had done something very similar. The whp was 367 on dyno dynamics and their flywheel derivative was 464hp crank

[Error404]

7.6:1 ? is that your measurement or what JE spec sheet said?
As they seem to have a habit of ****ing up the calcs on CRs for these strokers

[Rocco]

7.6:1 is too low for hat boost true?

[A80Avant]

I'd be very skeptical of detonation from a 7.6:1 comp. ratio.

I have close to 9:1 and don't have detonation with anything near 2bar on overboost which is where usually you get the problems from