Audi/Honda pax ride

[Dipper]

NA honda here that you're welcome to have a spin in.

[T8 YEA]

Campbell - I can see why people would opt for the Honda with it's rev happy lesser torque characteristics, but surely there is no lack of 1.8t 20v engines in the world.

Dipper - much appreciated for the offer, where about are you located?

[campbell]

I think the rev happy nature may have a lot to do with it. Lazy torque from the ubiquitous 1.8T doesn't really feel like an Elise. May as well put a TDI in there eh

[robin]

The Audi engine is a little harder to obtain than you would like - the 225 engine that fits was only used up to something like 2000 and then only in a subset of the VAG stable. Later engines don't work (I don't know what the issue there is, perhaps somebody could make it work); non-225 engines have the wrong turbo and genuine turbos are pricey. The other source of them is the Leon Cupra R of a slightly later vintage, but they are sought after, and once you start looking at crashed car engines you often won't get the chance to see the engine run; then you can buy recon engines but your parts bill is going to be very high to fit them out with all the ancillaries required. So buying a runner of the correct type is your best bet.

Honda Civic Type R engines just seem to be much more available.

Cheers,
Robin

[T8 YEA]

I think the rev happy nature may have a lot to do with it. Lazy torque from the ubiquitous 1.8T doesn't really feel like an Elise. May as well put a TDI in there eh

Haha maybe you are on to something there, TDI tuning is very popular these days.

Robin - So there was a change in the 225 lump around 2000, therefore the BAM engine found in the TT, S3 etc just doesn't work. Interesting.

Al

[campbell]

I've long believed the wee VAG 3 cylinder TDI would be great in an Elise. Tuned up to 100bhp with double that in torques. Not rev happy, but v capable, v Eco, and v modern

[T8 YEA]

Don't say that, my daily is a 3 pot polo TDI! haha

[robin]

I think the rev happy nature may have a lot to do with it. Lazy torque from the ubiquitous 1.8T doesn't really feel like an Elise. May as well put a TDI in there eh

Haha maybe you are on to something there, TDI tuning is very popular these days.

Robin - So there was a change in the 225 lump around 2000, therefore the BAM engine found in the TT, S3 etc just doesn't work. Interesting.

Al

No, my dates must be wrong ... the BAM engine is OK and was used up to 2003 in the S3 as you say. Even so, that's 10 years+ now.

Cheers,
Robin

P.S. The other factor is that the BAM engine is sought after by VAG owners wanting to upgrade their vehicles - they put them in the transporter/camper van thing, amongst many other uses!

[Ferg]

The AGU engine is the original with forged internals and no fly by wire that the VAG community love. I think the BAM engine has a better head as standard. Having owned several 20V turbo engines cars the power delivery would suit the Elise. Not sure id want it instead of linear power curve that the Elise has.

[robin]

Not sure what you mean by "linear" power curve on the elise?

On un-tuned K 120 the torque curve tends to be a fairly broad hump centred around 4,000 RPM or so. The power curve tends to rise up linearly to around 5,500 then flatten out before dropping off slowly to the red line. Your mileage may vary - some rev happily to the red line, some really don't want to. Most people give up and change up long before 7,000 RPM though.

On typical tuned K 170-ish the torque curve tends to be shifted up and right - i.e. you get more torque, but at higher RPM; you tend to get a loss in torque below 3,500 RPM or so vs. stock (not always, but typical). The result is a power curve that rises to around 4,000 RPM, then becomes more steep, sometimes rising all the way to the red line. You can most definitely feel this change in power slope as you cross it. It's like you've got two cam profiles, but one of them is sh*t - you most definitely rev the knackers out of them on track

On n/a Honda (and to a lesser extent the n/a VVTLi Toyota elises) you get very much the same shape as the tuned K, but with more everywhere; there is still a change in power slope as you cross the VTEC point. Because of the higher rev limit, power does not increase all the way to the red line, but they do rev all the way and on track you would take it to the red line in each gear, I think, to avoid dropping out of VTEC on up-shift. The difference over a tuned K is that even with VTEC off the engine is no slouch and you can happily pootle about in 6th everywhere most of the time.

On s/c Honda (and again to a lesser extent s/c VVTLi engine) you get an truly linear power curve - torque is more or less flat and so power curve is more or less straight line from 3K to 8.5K.

On turbo audi using the normal turbo fitted to the 225 engines you get a torque curve that is more like a tuned K, but shifted left and up - i.e. at lower revs but much more torque. The result is a power curve the rises steeply at low RPM and keeps climbing to the red line, but the rate of climb tails off dramatically. The whole experience is at lower RPM too ... it's kind of like the original K 120 response but multiplied by 2 everywhere (including the weight, more or less, depending on who you believe ).

Only the s/c honda has totally linear power curve ... IMHO.

The AGU engine is typically 150BHP I believe, so whilst you could fit it I would reckon it's much easier to tune the K you have to achieve more or less the same overall feel from the car.

Cheers,
Robin

[campbell]

The power curve here looks quite linear

http://www.dyno-plot.co.uk/dyno/dynoplo ... -Heads.htm

[tut]

N3's graph. It is on a Dynapack so power is taken at the hubs not the flywheel.

Robin, when you convert by 12-15% to get flywheel hp, does that apply to the torque as well?



tut

[mikeyb13]

The 2nd cam on my n/a Honda's is mapped to kick in around 4300rpm on full throttle. This means there isnt really the same need to redline it as there is for example on a toyota engined 111r in order to catch the cam.

[robin]

The power curve here looks quite linear

http://www.dyno-plot.co.uk/dyno/dynoplo ... -Heads.htm

No, it doesn't.

This is linear power curve (by definition comes from flat torque curve which really can only be done with managed forced induction and/or electric motor "torque fill").

http://www.dyno-plot.co.uk/dyno/dynoplo ... se-TDI.htm

In this context linear means that it appears as a straight line on a normal x/y graph.

EDIT: actually you can get a linear power curve with a non-linear torque curve ... but it still needs to be quite flat.

Cheers,
Robin

[robin]

The 2nd cam on my n/a Honda's is mapped to kick in around 4300rpm on full throttle. This means there isnt really the same need to redline it as there is for example on a toyota engined 111r in order to catch the cam.

Just depends on your gear ratios - the wider the ratios, the higher you'll need to rev it to keep it in VTEC; in any case even if you don't drop out of VTEC, assuming you want to accelerate as fast as possible you need to choose the change up point that maximizes power at all times - i.e. you change up when the power in current gear is lower than power in next gear OR you hit the red line.

Is your VTEC set point also throttle controlled? that's the ideal solution IMHO so that you can cruise at 85-90 tuts on the motorway with VTEC off but still have VTEC available if you're on full throttle.

Cheers,
Robin