torque curve

[Nerih 0]

Hi, my torque curve peaks near 5k rpm, but my max power is near 6k.

What adjustments (timing/fueling) can you make to move the torque up the the rev range.

would a restrictive exhaust (too much backpressure) contribute to this problem?

[Seademon 0]

Not too sure wether it would help your torque curve but as your running a S/C the less back pressure you have the better I think.

[Nerih 0]

so getting rid of the cat is probably a good idea until MOT time right?

[Seademon 0]

Yeah - will fail the MOT but does make a difference to the performance - not a terrible to do just a bit of a pain in the backside to do it once a year!

[Nerih 0]

does anyone here have a cat bypass? it might not fail the mot , you never know hehe.

[simey 0]

It will fail the mot having a cat bypass, as your car is charged I strongly recommend a cat bypass due increase in hydrocarbons which will damage the cat.

All I tell the mot tester's: The car hasn't a cat on so I've put the cat in the passenger seat to change for the car to pass the mot. They usual say bugger that I'll get my hands dirty and stick the probe up another cars exhaust. 10 quid cash always sorts it!!

[The1andonlygav 0]

i spoke to miltek and they strongly reccomend a cat by-pass along with the cat bat (obviously, they'll make money!). But aparently you'll need it mapping again?!

He put the full system on a charged vr and it ran like poo until the re-map.

Its just money, money, money!

[Ultimatetune 0]

gav, that sounds very OTT, but like you say they are trying to make money etc.....never had to remap any car i have owned after a decat

[Ultimatetune 0]

did not have to remap my car

[binliner 0]

I had mine remapped (dastek) after fitting a decat and straight through 2.5" centre section saw the bhp go from 252 to 265 and torque went up from 232 to 252lb/ft!

[Eat this 2]

does anyone here have a cat bypass? it might not fail the mot ' date=' you never know hehe.

[/quote']

mibe just scrapes through with a decat and i would deffo expect it to flow better at high revs

[Nerih 0]

rob, i hate joo, you know i want that car...give me, i'll trade you my vr, for your skyline, it was so comfortable, on the way home i fell asleep in it too!

-- right justin, thats the kind of factual metric i was looking for, i have one on order, but was wondering if it was worth it, becuase of the MOT issues. i dont mind paying 10 quid more for my MOT hehehe. who knows, i might be like eat this and get thru without any problems (still gotta wait until next year for mot tho!)

[binliner 0]

tbh I picked the car up from the exhaust place, drove the 20 or so miles to the garage and was smiling all the way it sounded and drove like a different car... by the time I got there I didnt care what the figures were because I could feel the improvement

I should point out that this was a custom centre section from downpipe to backbox hand built on my car (nearly £400 worth!)

[mightyvr6 0]

I think the stock exhaust even with a decat is restrictive as you can here the air rushing through the system on acceleration as if the exhaust can't cope with the extra air-flow.

[Ultimatetune 0]

ideally you want a 2.5 inch system from down pipes back, but preferably with a larger port down pipes (manifold etc)

[Nerih 0]

ultimatetune is sorting it for me, so i'm guessing it'll be good. come on rob, when will i see this pipe work .

binliner :- mines not 400 quid lol, its slightly less, probably wont make as much power, but maybe it will open up the top end a bit more, what you think?

[FishWick 21]

Back pressure is not so much of an issue with chargers as they're crank driven (as you know), so you won't get exhaust back pressure trying to stall the turbine blades like you get with restrictive exhausts on turbo engines.

CAT and MOT. Incorrect. You don't need one post 92 to pass the MOT. What you car must pass is the emissions, with or without cat and that's what the lambda is there for, besides, if you get a SupersSprint bypass like what I've got on mine, it looks like a sports cat and that's what you tell the MOT tester, it's a 100 cell sports Cat ;-) The absence of sulphur smells seldom catches their attention and if you're 'friendly' with your tester, they'll over look it..... I mean, they let Allegros and Metros through the test, so......

Mine has the factory exhaust and said SS bypass. If the Corrado VR lientz system is anything like the Golf VR system, then it flows plenty, just don't believe the hype with exhausts...... just remove the biggest restriction, the cat.

[matth76 1]

ideally you want a 2.5 inch system from down pipes back' date=' but preferably with a larger port down pipes (manifold etc)

[/quote']

What is the diameter of a Milltek system (cat back)? Is it 2.5"?

[FishWick 21]

Milltek will do a 2.5" if you ask (at extra cost), otherwise it's the standard 2.25" bore.

2.5s, I've found, will give you gains at the top end, at the slight expense of bottom end torque.

[Nerih 0]

thank kev. i cant wait to get my cat replacement in.

[binliner 0]

If the Corrado VR lientz system is anything like the Golf VR system' date=' then it flows plenty, just don't believe the hype with exhausts...... just remove the biggest restriction, the cat.

[/quote']

trust me the syncro system is completely rubbish... 2 cats, 2 suitcase boxes, pipes the size of pea shooters... it had to go!

[mark@vagworx 0]

lol. Definately decat it.

It pulls much crisper without the cat in place. Get your self a decent single box system nerih, you can't go wrong.

[anorak 0]

Nerih,

5000rpm sounds quite high for peak torque. Mines at about 4k and standard is 4200 I think.

As far as moving the torque peak up the rev range goes that's what everyone after more power wants. 260lbft at 6500rpm would give you 310bhp.

Have you posted your graphs - be interesting to compare.

[FishWick 21]

trust me the syncro system is completely rubbish... 2 cats' date=' 2 suitcase boxes, pipes the size of pea shooters... it had to go!

[/quote']

Yeah that does sound restrictive! The Corrado system is nothing like that thankfully. I really rate it. My Milltek liberated precisely zero hp over the standard one, so the standard went back on and Milltek got their exhaust back.

[Nerih 0]

ive given it to some people as attachments/links if you want a copy, pm me.