Cologne 2.9L V6. How far can I safely advance the ignition?

[NTEL]

Hi Chaps,

I'm trying to squeeze a few more BHP's and Torques from the engine in my TVR Tasmin race car. The ignition timing is currently advanced to 32 degrees at 5200rpm and runs fine on ordinary 98 octane V-Power.

With the addition of Millers CVL Turbo (or similar) Octane booster what do you think I could safely advance the ignition to?

At the moment the output at the fly is 230bhp @6250 rpm and 190 ftlbs at about 5200 rpm. Compression is between 160 and 165psi on all all cylinders.

[Daveuk9xx]

What on earth makes you think that more ignition advance is a good thing in its own right? At any given rpm/throttle position the advance needs to be a certain figure and either more than this or less than it will reduce power. Go to a rolling road and get it checked out properly. Guessing at it will get you nowhere.

Your cranking compression figures are pretty dire for a race engine. 200 psi minimum if the CR and cam are properly matched. There's probably 20 bhp to come just from sorting that out properly.

Dave Baker

[NTEL]

Daveuk9xx said:

What on earth makes you think that more ignition advance is a good thing in its own right? At any given rpm/throttle position the advance needs to be a certain figure and either more than this or less than it will reduce power. Go to a rolling road and get it checked out properly. Guessing at it will get you nowhere.

Your cranking compression figures are pretty dire for a race engine. 200 psi minimum if the CR and cam are properly matched. There's probably 20 bhp to come just from sorting that out properly.

Dave Baker

Thanks for your reply Dave, but hey, cut me a bit of slack I know bugger all about tuning, hence the question. The car is booked in at the rolling road on Friday so I am looking for some basic figures I can work with to improve things a bit. The engine was built about 21/2 years ago and has had some stick in its life. Its never been freshened up since. I'll be removing it at the end of the season and sending it back to the original builder in November for a rebuild.

In the mean time I'm just looking for a bit more power where ever it can be found

Edited by NTEL on Tuesday 2nd September 12:44

[Chassis 33]

Dave, the only real way is to get on a rolling road and try it. For example with the Chim, Joo gave the car a run, once the baseline was set we tried increasing advance by rotating the dizzy 2deg, and while we gained 2hp, we lost about 5lbft on average across the board, retarding it we lost both torque and power, after a bit more testing ended up putting it back where we started.

Regards
Iain
ETA. Are you sure about those figures, is 190lbft max torque? My sums show (230*5252/6250=)193lbft @ 6250rpm. Granted its a minor error, but it does show you've a lovely flat torque curve.

Edited by Chassis 33 on Tuesday 2nd September 13:22

[Daveuk9xx]

The following articles on my website explain most of the basics of engine calibration.

http://www.pumaracing.co.uk/chip.htm

http://www.pumaracing.co.uk/combust.htm

Dave Baker