Yesterday I had my car dynoed at the same shop as I always use. Since the last dyno I have had headers fitted. The headers use a 2.5 inch collector and bolt onto a 2 inch full exhaust. I expected to see some change in the dyno figure, better or worse, however it was EXACTLY the same within 0.5kw. VERY VERY disapointed as they cost $600. Why is there no change? my guesses are to follow please suggest any that you can think of. 1. The restriction of going from 2.5 inches to 2 inches. Area reduction of nearly 50%, I think not the restriction. 2. Some other restriction such as blocked cats. 3. Some pipe was disconeccted from headers when installed but don't remember what it was or what it does. 4. Could be the sum of the above. I find it really hard to belive that such a mod would yield 0 results. PLEASE HELP with suggestions.
That is odd.. was your boost, and a/f ratios all the same? Did it make powe r more quickly compared to your other run?
That is very wierd, i would have been expecting a gain as well. I doubt it would be the exhaust size, 2" is still more than enough to flow the power your car is making. As for the pipe disconnected, maybe it was the EGR? It wouldn't have been the oxy sensors, I don't know where they are located exactly on an N/A sorry but I doubt they would just d/c them. The cats wouldn't be doing this, that is unlikely. Did you get a re-tune to go over the a/f ratios? Did you get a chart displaying the a/f as well ?
egr is the diconeccted one the oxy sensors are in the headers no i didn't get a/f, but i dont see why that would change, it still uses the same per tank as it did a year ago.
the a/f would make the biggest different under acceleration what you mean ONE of the o2's is connected? isnt the other connected aswell?
I think he means "egr is the disconnected one" But you should have re-tuned your ECU for that type of mod I would have thought.. Jedi will know more about this as he put headers on a while ago... and I think he got a remap.
it has two O2's To remap don't I need a new ecu, I only have a stock one. I would have thought the ecu would be alright with only mild gains.
the egr will have no effect. At a guess I would say a tune would show the performance gain you should get out of the installation, much like doing a tune when you do some head work to take advantage of the extra flow etc etc.
to get the best result, you need a full 2 1/2 inch exhaust plus high flow cats. what you are doing is trying to cram 2 1/2 inches of exhaust flow from the header into a 2 inch front pipe. not good for flow. and to get the best result, you will need a tune. cheap and effective way is to get a SAFC, or you can go unichip or a whole range of others
Re: to get the best result, you need a full 2 1/2 inch exhaust SGP recommends only upgrading headers if you are going via the nitrous route, else they see very little gains for cost.
was there much difference in tempreture when the dynoes > were done? if the first dyno was done in cooler temps then warmer after the headers were installed might count for a small amount. i didnt do a before and after on mine when i put the headers on but thought they made a difference.
Only 130 kW for NA. How disappointing. I also have NA but have never bothered to do any dyno. With stock air box, mine will be worse than yours. But how come our NAs start and run faster than any other new cars such as Honda Accord Euro in the same range of kW.:thumbsup::thumbsup::thumbsup:
some answers.... the problem is you now have nice flowing headers, but in my opinion a restrictive exhaust.... you should aim for a 2.5 inch exhaust which will complement your headers quite nicely.... at the moment you have a bottle neck, and hence very little gain.... also, not all mods translate well into a dyno figure... I never had a dyno figure straight after I had my headers fitted, but the engine reved easier. In the end, you'll only see a big improvement from your headers if you have the exhaust system to match... Cheers
This taken from ttzed site where headers were bought "Short of Nitrous Oxide, the headers are the biggest single power gain available for the car. Expect an increase power throughout the rpm range with the biggest gains at higher rpm. The car remains driveable and noise level is not increased. TTZ Headers are at their best when combined with a hi-flow intake and 2.5" exhaust system." therefore i would expect good gains not 0.
