Raceco exhaust + decat = 15bhp?

[edb49]

Does that figure sound right? I've just had a decat pipe and Raceco "quiet" exhaust fitted to my Duratec R500. I wasn't expecting any difference in performance, as that's not why I bought it, but it suddenly felt a bit more "manic". I don't have any traditional way of measuring power, but I had a camera on the car and I did two straight line acceleration runs in 2nd gear. From 20mph to the red line. I did two runs with the Caterham track day exhaust and catalytic converter, then another two runs with the Raceco exhaust and cat bypass pipe. Same bit of road both times.

So I did a video of these runs, and then loaded the video up and went through it frame by frame to see when the acceleration started and when the shift lights came on. The results were interesting:

	Caterham exhaust+cat			Raceco exhaust+bypass
	Run 1	Run 2	Average	Run 1	Run 2	Average
20mph to Shift 1	4.583	4.571	4.577	4.439	4.339	4.389
Shift 1 to Shift 2	0.434	0.334	0.384	0.384	0.35	0.367
Shift 2 to Shift 3	0.333	0.434	0.3835	0.4	0.418	0.409
Shift 3 to Shift 4	0.534	0.433	0.4835	0.334	0.367	0.3505
Shift 1 to Shift 4	1.301	1.201	1.251	1.118	1.135	1.1265
Improvements
20mph to Shift 1	4.1%
Shift 1 to Shift 4	6.2%

I ignored Caterham exhaust Run 1 in all Shift 1-4 calculations, because it seemed to be miles different.

Any opinions, do you think 6% more power has been liberated by the new exhaust set up?

[Ammo 7]

Hi edb49

You've probably picked up more bottom end and mid-range, possibly some top end too. A lot of people have commented in the past that their cars feel a lot more willing and accelerate better after fitting Raceco silencers.

Whether you have picked up 15 bhp is hard to say. 4bhp for the cat and 6bhp for the silencer? I'm only guessing and could be completely wrong.

The only way to find out for sure would be to do a back to back test on a rolling road. I have been using Emerald in Watton, Norfolk for the past few years and I have a large amount of dyno sheets from there.

Here is a graph of a 250bhp 2.3 Duratec I built. Before and after fitting a complete big bore exhaust with 2" headers.

http://www.dyno-plot.co.uk/dyno/dynoplot/id%3D492_...

As you can see there is a large increase in torque at the bottom end. That is for a complete exhaust. I doubt you would see anything as dramatic by fitting just a silencer.

I'm very interested to see what happens on a rolling road. I would be willing to fund the testing of your car with both exhausts if you are willing to go over to Watton.

Please let me know.

[edb49]

Ammo 7 said:

As you can see there is a large increase in torque at the bottom end. That is for a complete exhaust. I doubt you would see anything as dramatic by fitting just a silencer.

I'm very interested to see what happens on a rolling road. I would be willing to fund the testing of your car with both exhausts if you are willing to go over to Watton.

This is the combined result of the silencer and decat pipe, so maybe the decat made a significant contribution? It feels quicker to me, and the evidence points to it be quicker too. I can't help but be happy with that.

Thanks for the offer of a rolling road session, I can't really spare the time to make a trip specifically for that, but if I'm in Norfolk for whatever reason I'll get in touch.

[Ammo 7]

edb49

It would have been good to test a stock R500 Duratec and what effect a Raceco silencer has . If you ever are within reasonable distance of Emerald in Watton please let me know. I'm sure Dave Walker would book me in at short notice for a quick power run or two.

Thanks

[theoneandonly944]

to ebd49 , in a selfless act for another human being i will , ( for expenses) come and drive your car over to ammo7 so it can be dyno'd , and then return it to you. ( unwashed , no petrol. ) pm me to arrange .

[edb49]

Thanks for the offer, and what a strange first post!

[sam919]

My duratec lost 13 bhp with the cat fitted for MSA regs, this was done on an engine dyno, so gaining 15 without cat seems pretty accurate.