Turbo downpipes before & after stats

[Freddy]

I had my car dyno tuned before and after the fitting the downpipes.
There was no gain to horse power bottom or top end, in fact the numbers stayed the same. Where they did make a difference was mid range. Around the 70 km/h
(road speed, not revs are used on this dyno) the kw output jumped by 12kw. Also lost a little in torque curve.
For the record, my car is running 3" exhaust, boost controller, k&n air filter and mines computer.

[bradc]

That is interesting, your car already had a very strong mid range compared to mine. Any chance you could post the image up here?

By comparison my downpipes did nothing to the midrange at all, but my whole exhaust system gave me 11kw extra at the top end of the rev range.

[Freddy]

Some interesting findings on dyno day.

Turbo down pipes produce around 12kw (on my configuration) @ 70km/h.
3kws more @ 60km/h and 2kws more @ 80km/h. Very small margin.

I ran 15.7 psi boost on the first run, then 12psi on the second run. The difference was 6kw less.

Doing the maths from 4 vr4 dyno sheets and using 205kw @ flywheel as a benchmark, we lose somewhere around 50kw (67 hp) through our drive train.

A Nissan skyline which showed up stock standard at last months dyno day produced 141 kw @ the wheels. He came back with a 3" exhaust, boost controller @ 10psi and K&N air filter in stock box and belted out 175 kw :rolleyes4

A holden commodore 5.0 ltr v8 with computer chip, exhaust and K&N aircleaner produced 158kw @ the wheels, the result being slower than all the Jap cars there except for a Daihatsu Charade. Not to be out done he now is either going to spend 10k on supercharging + camshafts or selling it and is going to buy a Japanese performance car. He was also surprised to learn a Legnum vr4 has twin turbos.

Finally; sent another guy our way who has a stock 96 legnum and hadn't heard of Club VR4 :thumbsup:

[bradc]

Did your run with 12psi mean that you had much less power through the rev range, if I remember correctly your car wasn't running much below 15.7psi at the point you reached max power.

My car was 154kw at the wheels standard, so I'd guess that I lose about 50kw through the drive train as well. Rember there was that guy there last time that only did 140kw at stock, so my car might be something like 210 or 215kw at stock, and we really might be losing 60kw or more through the drivetrain.

That skyline guy was quite lucky. I think I'll go to pitstop next week sometime armed with your dyno results and see if they are willing to try and redo my headers and exhaust. One of them rattles at the back now, and the right one is still a little lower than the left. Or maybe I'll just get Ohlsens to fix the lot, I don't know....

I bet the commodore owner was upset hehe, and he would use tons more fuel than our cars.

Speaking of which, how many km's do you get per tank? I'm curious to see how good your economy is with the Mines.

How much power did the stock Legnum make?

[Freddy]

I did two runs today. One at 15.7, the other at 12.0. Regarding fuel, I need a another week to figure out economy and I will post it on the fuel economy thread that was going around last week. As for Pit stop, my exhaust rattled from day one.
I had such a bad time there, I didn't want to go back, /grr so I'm just putting up with it. Stock Legnum was last, and I couldnt hang around to see.

[bradc]

Hopefully that Legnum owner starts posting on here and we can find out how much power he had. At the moment I've done 460km's and have quite a bit of fuel left, I think I have used about 38-40 litres to go that far.

I need to take it back because they always promised me that they would fix the position of the right exhaust.

I'm just waiting for your graphs now (3, last time, and both of them from this time)

[Freddy]

I dont have a scanner. :bigcry:

[bradc]

sounds like you'll have to come and see me then ;)

meet me at mermaids tonight, from about 11pm onwards, me and uc will be there. Bring your dyno sheets!

just kidding of course, I'll have to get hold of your dyno sheet sometime then.

[bernmc]

I'd be interested to see similar tests with a 2.5 in free flow system. The guys I spoke to here seemed to think that a 3in system is too much for the leggie unless we plan to run BIG horsepower. They did seem to know their stuff...

[i3ooyah]

what you end up hitting freddy?

thats what the downpipes do, lose a lil torque and gain some kw's up high