Well today was pipe replacement time. Noise is much the same at idle, though gets fairly loud as rpm increases, no drone though. Im not sure how restrictive the current resonators and muffler is but things have changed for the better anyway.
Basically I had to pull timing at 2000rpm but now I can put it all back in. This may indicate that the smaller exhaust was optimising things around 2000rpm, whereas now its up at 4000rpm. The car definately seems to rev freer and my logging with the wideband has indicated at high map points that up to 5% more fuel is required. I need to fill in the map to get a good idea, but lower map points look much the same, its just the higher ones which need more fuel.
My timing table is out now, so I have started again with a combination table of a stock hsv gts and my previous table. It will take a good few sessions of logging and adjusting to get an idea of where things are now, however I did a WOT pull to 6300 and am still only making 0.82g/cyl or 300g/sec of air. By way of contrast the stock MAF max's out at 511g/sec intake KPa was 99 from a barometric of 101, so intake looks good.
Other than a full replacement exhaust and a Fast90/90 setup, which will both cost megabucks, Im done with the mods. Did a 0-60 to test today, but zero traction in 1st. So will try again another time. Still not thinking about a 402 stroker!
Monday, July 10, 2006
Saturday, July 01, 2006
The search for the missing millions.
Well Ive been still thinking about where my percieved power loss is. In theory I should have gone from around 240rwkw to around 300rwkw from heads and cam change. Thats like 100bhp increase. However to me it only felt like maybe half that.
I reread this article here and set off to Simpson Race Exhausts in Berkshire. I had previously noted a smaller section of pipe going from the headers into the cats. They were excellent, do great work at a reasonable price and were very helpful.
Well Im booked in there next week for the bypass pipes. Looking at this pic below from popular hotrodding, noted in the link above. I can calculate my current bhp per cfm at 1.44 (500fwhp) Shocking, as its right off the left hand side of the page! Perhaps somewhere around 70% of Max. Stock it would have been around 1.6 (430fwhp) so thats bad enough, but maybe only 10% down 30% is not acceptable.
So without getting too excited I believe I can say Im definately going to pick a good bit of power up with the exhaust upgrade. It should also definately allow a little more timing, or at least reduce the propensity to knock.
On a more serious topic, Ive been starting to have unclean thoughts about 402 and/or 382 strokers, bad and evil thoughts. I think if I get another 50bhp from the exhaust I should be fine keeping these evil ideas away for a while.
I reread this article here and set off to Simpson Race Exhausts in Berkshire. I had previously noted a smaller section of pipe going from the headers into the cats. They were excellent, do great work at a reasonable price and were very helpful.
Well Im booked in there next week for the bypass pipes. Looking at this pic below from popular hotrodding, noted in the link above. I can calculate my current bhp per cfm at 1.44 (500fwhp) Shocking, as its right off the left hand side of the page! Perhaps somewhere around 70% of Max. Stock it would have been around 1.6 (430fwhp) so thats bad enough, but maybe only 10% down 30% is not acceptable.
So without getting too excited I believe I can say Im definately going to pick a good bit of power up with the exhaust upgrade. It should also definately allow a little more timing, or at least reduce the propensity to knock.On a more serious topic, Ive been starting to have unclean thoughts about 402 and/or 382 strokers, bad and evil thoughts. I think if I get another 50bhp from the exhaust I should be fine keeping these evil ideas away for a while.
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