Dyno Plots

[Steve Webb]

Following on from my train of thought in the IC thread, who else has got a dyno plot for their car, (doesn't need to be a Q4 either)

Here is mine from (quite) a few years back. As you can see power (bhp) trails off quite early. Personally I think its the IC but anyone else got any other theories?

[SteveNZ]

That looks pretty normal for a standard turbo. For a single dyno run, upgrading the intercooler (assuming the OE one is inadiquate), should see a small improvement everywhere, getting larger at the top end but its only going to be minimal overall. It's not going to make the torque curve flat and the power curve head to the sky.

[SteveNZ]

Here is the dyno plot from my standard Thema

[santino]

one question.

Is it normal power loss on transmission of cca 30%? Is too much?

[Steve Webb]

I'm not sure how accurate the transmission loss figures are, all I know is that on the day the car was at the rolling road there were 2 Lancia Delta Integrales there as well, both of which showed higher losses.
30% is an awful lot to lose though.

[Steve Webb]

Here is the dyno plot from my standard Thema

Any chance you could copy the plots and attach them here. You need to be logged into that forum to see the file.

Cheers

[mindus]

... As you can see power (bhp) trails off quite early. Personally I think its the IC but anyone else got any other theories?

I would say that you overestimate slightly the IC role with regards to dyno readings. In my opinion air flow to the IC with a car on a dyno is very far away from air flow to IC on the real road. (other than abbility to accumulate heat during short bursts on a dyno)

Change a turbo, there will be a different dyno curve. Change cam(s) - again, a vast difference. Increase max boost, a different curve.

Changing IC should have minimum effect on a dyno figures and numbers, unless IC acts a a huge restrictor, which isn't the case with Q4 IC.

No hard data to support those general observations of mine though...

[1NRO]

Personally I think its the IC but anyone else got any other theories?

There's no single reason IMO, the package as supplied from Alfa will of been thought out to be a complete package with each part complimenting the next, a balanced assembly if you like with each part capable enough for the task in hand. To change one part snowballs right through the whole package to do it justice, achieving the balanced package again for a different set of parameters is the hard part

[Steve Webb]

There's no single reason IMO, the package as supplied from Alfa will of been thought out to be a complete package with each part complimenting the next, a balanced assembly if you like with each part capable enough for the task in hand. To change one part snowballs right through the whole package to do it justice, achieving the balanced package again for a different set of parameters is the hard part

Well as you can see from the figures on the power plot, the car made the best part of 250bhp, so not a bog standard Q4.

Various parts of the induction and exhaust system had been changed, but the IC was standard. Hence my thinking that this was causing a restriction at higher rpm.

The car was on the RR to setup the chip correctly, (with the writer of the chip) so we weren't going for outright power.

[1NRO]

I suppose what what I'm trying to say is if you improve the intercooler and the pipe work is already increased in size there will still be a limiting point elsewhere in the system, this would likely be the inlet manifold and followed by the head. A performance gain might appear small if the next weakest area is not a lot better than the part just changed out, like the very poor integrale inlet manifold which gets bolted back onto the freshly reworked head. Fantastic head being strangled by the inlet manifold. Doesn't mean its not worth improving an area but remember it does snowball throughout the engine.

[Suzumushi]

Well as you can see from the figures on the power plot, the car made the best part of 250bhp, so not a bog standard Q4.

Various parts of the induction and exhaust system had been changed, but the IC was standard. Hence my thinking that this was causing a restriction at higher rpm.

The car was on the RR to setup the chip correctly, (with the writer of the chip) so we weren't going for outright power.

i know this thread is little bit old, but have you Steve chaned IC and masured car on the dyno ?

i'm looking for a way to improve performance, as dyno shows only 250bhp and 350nm, but the car on stright shootout is faster than fwd 270bhp 147gta, and gta is almost 100kg lighter..., even nissan 350z watched back of q4.. but that figures on dyno was so dissapointed.

so my next idea was a mainfold, FMIC and injectors... but i'm not so sure if this is the right idea.

regards
w

[corriedw]

Reviving the old thread.
Steve I am of the opinion that the problem you look for is in the boost pressure. The pressure in your torque curve goes up nicely, then the wastegate opens and all pressure is gradually lost. If the pressure stayed intact, the torque would have stayed on the same horisontal level and power would have been climbing steadily.

Possible problems could be wastegate control, turbo not supplying enough air, exhaust manifold limiting turbo, exhaust too restrictive, boost leak.

In the collection of photos is a dyno sheet of a TS with a T3/4B on a hotbox manifold, 7.5:1 compression, std cam. See torque from wastegate opening.
http://s1224.beta.photobucket.com/us...wilde/library/

An intercooler account for a little power, but not that serious. See the IC not as a source of power, but as necessary protection for your engine. Cool air stop detonation by cooling the combustion chamber.

[corriedw]

one question.
Is it normal power loss on transmission of cca 30%? Is too much?

I can not speak for the Alfa/Lancia. The only place I ever saw an engine dyno and a rolling road dyno under the same roof was at Nissan Motorsport SA. I saw engine and rolling road dyno sheets for a 2ltr Nissan group N car and a 3 ltr 4x4 rally prepared truck. (curtsy of Hannes Grobler SA racer/ralley driver) The front wheel drive 2ltr lost 25% through the drive train and the 4x4 lost 40%.

Now those 4x4s have an extra gearbox(transfer box) robust diffs and very heavy wheels, which is all serious extra losses. If I have to wager a figure for the Q4 I would guess between the 25% and 40%. So yes MY opinion is 32% is not far off the mark.