ashyk36 Posted January 18, 2012 Share Posted January 18, 2012 I have been searching and i cannot find a definitive answer anywhere. My question is apart from the obvious MOT implications what diferences are there between decats and hfc's on the following: torque bhp (after remap) fuel consumption noise Also which company cats would offer best value for money? thanks in advance Quote Link to comment Share on other sites More sharing options...
leodspider Posted January 18, 2012 Share Posted January 18, 2012 Seats are best value for many just because it's free flowing, especially non silenced ones. But o course it will fail lot or random stop checks. However HFC will pass MOT, and certain trackdays do require them and theyre a lil bit easier to live with. Either way remap is needed for full benefits Quote Link to comment Share on other sites More sharing options...
Tarmac@TarmacSportz Posted January 18, 2012 Share Posted January 18, 2012 Differences between the two - minimal on all i would say torque bhp (after remap) fuel consumption noise You may get a bit better airflow with resonated decats as theres no cat to pass through but one of the tuning companies will more than likely tell you theres not an awful lot between them. HFCs everytime for me, Legal, no hassle and little difference in performance. Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 18, 2012 Author Share Posted January 18, 2012 Seats are best value for many just because it's free flowing, especially non silenced ones. But o course it will fail lot or random stop checks. However HFC will pass MOT, and certain trackdays do require them and theyre a lil bit easier to live with. Either way remap is needed for full benefits Yes to be honest I've never heardbof anyone getting stopped and emissions checked, but now ive said it...... :-P Quote Link to comment Share on other sites More sharing options...
DannyBoy Posted January 18, 2012 Share Posted January 18, 2012 Seats are best value for many just because it's free flowing, especially non silenced ones. But o course it will fail lot or random stop checks. However HFC will pass MOT, and certain trackdays do require them and theyre a lil bit easier to live with. Either way remap is needed for full benefits Yes to be honest I've never heardbof anyone getting stopped and emissions checked, but now ive said it...... :-P It does happen, just not often. VOSA have favourite spots where they periodically pull people over. Thing is with the old rules they couldn't test emissions at the roadside, just tell you to go and get tested within 14 days or whatever (decats off, cats back on, no worries). but now that the decats themselves are illegal, you could actually get a roadside penalty if you get an inspector sharp enough to spot the difference. Just can't see it being worth the massive faf for the sake of 2bhp and a very loud exhaust. DB Quote Link to comment Share on other sites More sharing options...
Chris`I Posted January 18, 2012 Share Posted January 18, 2012 Yup, used to be a "producer", if they suspect your car isnt road worthy, they'd give you a bit of paper telling you to go get it tested and report back to the Police station with evidence otherwise you'd get a fine. Not often they'd do it, just for overly loud cars that obviously had next to no exhaust system. Same was done with loud bikes too. Quote Link to comment Share on other sites More sharing options...
Keyser Posted January 18, 2012 Share Posted January 18, 2012 I'm switching back to HFC's during the rebuild just to save agro but on a back to back dyno run with HFC's v Decats steadyzeddy (previous owner) got 20HP less. But she is SC so that my make some difference!? Quote Link to comment Share on other sites More sharing options...
Chris`I Posted January 18, 2012 Share Posted January 18, 2012 Being SC will make a massive difference as will any FI. Any back pressure on FI is bad, whereas for NA it doesnt make anywhere near as much difference. HFC vs decats on a normal Zed I would bet is only a few HP in it. Certainly not enough to feel it on the road and maybe not even enough to measure on a track. Only the dyno would give it away. Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 18, 2012 Author Share Posted January 18, 2012 thanks guys and what about brands, obviously berks have great reviews, however do the justify spending 400 or will a make half that price be 90% as good as berks? Quote Link to comment Share on other sites More sharing options...
coldel Posted January 18, 2012 Share Posted January 18, 2012 Are there any brands that do HFCs for the Zed at £200???? Berks are fine, a bit raspy but being metal substrate it comes by default. You could go for Ultimate Racing ceramics which dont have the rasp but also dont flow as well? They are cheaper. Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 18, 2012 Share Posted January 18, 2012 Chris, remember what dan warned you will happen to your hfc's lol Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 18, 2012 Author Share Posted January 18, 2012 Are there any brands that do HFCs for the Zed at £200????Berks are fine, a bit raspy but being metal substrate it comes by default. You could go for Ultimate Racing ceramics which dont have the rasp but also dont flow as well? They are cheaper. Does the ceramic hfc's suffer in performance slightly? Quote Link to comment Share on other sites More sharing options...
coldel Posted January 18, 2012 Share Posted January 18, 2012 Ask Z1 Auto on here? They sell 'em. Quote Link to comment Share on other sites More sharing options...
rtbiscuit Posted January 18, 2012 Share Posted January 18, 2012 Decats do aid higher BHP figures but sacrifices low down torque. Hi flows don't get the highest figures but are a nice compromise between torque and top end BHP. Quote Link to comment Share on other sites More sharing options...
Keyser Posted January 18, 2012 Share Posted January 18, 2012 Chris, remember what dan warned you will happen to your hfc's lol All I can say is Quote Link to comment Share on other sites More sharing options...
agentsmith350 Posted January 18, 2012 Share Posted January 18, 2012 Selling my decats I give you special price Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 19, 2012 Author Share Posted January 19, 2012 Selling my decats I give you special price Why have you decided the decats are not for you? Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 19, 2012 Author Share Posted January 19, 2012 Looking on tarmacs website berk decats are half the price of berk hfc's........................interesting Quote Link to comment Share on other sites More sharing options...
coldel Posted January 19, 2012 Share Posted January 19, 2012 Looking on tarmacs website berk decats are half the price of berk hfc's........................interesting They are half the price for reason though! Quote Link to comment Share on other sites More sharing options...
ashyk36 Posted January 19, 2012 Author Share Posted January 19, 2012 half the price for something that is illegal :| Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 19, 2012 Share Posted January 19, 2012 Decats all the way for track bunnys, road cars/everyday car defo high flow cats. Quote Link to comment Share on other sites More sharing options...
John tarantula Posted January 19, 2012 Share Posted January 19, 2012 Decats do aid higher BHP figures but sacrifices low down torque. is this definite, tested etc as got some decats but won't bother if they eat torque! Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 19, 2012 Share Posted January 19, 2012 I still got a low rev torque increase over standard with decats by quite a bit. Quote Link to comment Share on other sites More sharing options...
rtbiscuit Posted January 19, 2012 Share Posted January 19, 2012 Decats do aid higher BHP figures but sacrifices low down torque. is this definite, tested etc as got some decats but won't bother if they eat torque! on there own they might be alright, but i've seen it on plenty of other cars where the exhaust system is made "free flowing" yes the BHP gain is very good, but its all at the top end, and in order to make any use of it you'd need to be 4th gear doing over 120 mph or more to see its advantage. what you tend to find on most fully free flowing systems is they lose a load of grunt low down, like pulling away at a jun ction/lights etc most don't notice it with the added noise etc makes them feel like they are faster. most people only care about the numbers they can claim down the pub, but real world driving and the fact that on road cars they won't pass an mot and you need standard equipment on i wouldn't bother with them unless you were building a track car. i also don't like them on the zed because they tend to lead to a horrible raspy noise. to me it sounds chavvy and cheap, but to others they think it sounds "racey". but this is my personal opinion, and many disagree with me, so your best bet would be to g oand try someone elses car who has them already fitted. if you like them fit them, if you don't, sell them. Quote Link to comment Share on other sites More sharing options...
Chris`I Posted January 19, 2012 Share Posted January 19, 2012 Think most of the loss in torque can be clawed back with a good map, but we're talking a few HP either way here, maybe 1% of total power output, so its nothing. Far more annoying - agreeing with Rich here - is the raspy noise. I dont like it, so would pay the extra for HFCs with less rasp and keeping it road legal. You may "loose" ~1% power with them over decat, but who cares? As always its horses for courses. Theres no right choice, just the one you feel is the best for you. Quote Link to comment Share on other sites More sharing options...
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