21 replies to this topic

[dickster]

Did any of you guys have the car rolling-roaded when the exhaust was fitted? This could have found a few bhp from ignition timing, mixture etc already being slightly out with the standard tune, so making the difference seem greater when you have the new exhaust fitted?

I didn't, just fitted the system and got an unexpected noticeable performance increase.

[rick.spi]

i have a twin box maniflow on mine, only from the cat back, but i think its better through the mid rev range than when it had the pea shooter on it!

is the twin box a better for performance than a single as it keeps a better back pressure, as a straight through exhaust isnt good for performance because of the lack of back pressure!

4-stroke engines are not dependent on back pressure like 2-strokes are, it's more to do with gas flow & tuned exhaust length. For instance it's not wise to fit a 2inch system on a 998cc Mini because the exhast gas velocity will be too slow, but on a tuned 1275, it's fine.

5 port engines need back pressure, aint so important on a crossflow engine or something of the likes.

Edited by rick.spi, 10 September 2009 - 10:39 AM.

[rick.spi]

i fitted a maniflow system designed for miglia racing to mine, with cat replacement pipe and stage 2 LCB. i found it made a more noticable feel to the performance compared to the DTM i had prior and a much nicer and slightly quieter exhaust note. here is what mine looks like on my MPI Cooper

wow! looks awesome.

[Mr Joshua]

Designed and built my own system back in 1994 never found another system to match it. Bottom end, mid range and top end. Dont bother ask because I aint telling!

Edited by Mr Joshua, 10 September 2009 - 03:24 PM.

[Bungle]

I'm interested in this

I've heard there is no difference in noise between a single/twin maniflow around town but its noticeable on the motorway?

No idea, we don't have any motorways here!

Well already sounding a little better noise-wise, as mentioned I expect it'll sound a tad throatier once its got some carbon in it.

when i ditched my standard rover exhaust (with cat) for a RC40 single box exhaust (no cat) +matching LCB manifold

i found the car would rev so much freely, it was if something was holding the car back before

i also found a tank of fuel would go a lot further

once things were set up the power went from a standard 62 BHP to 70 on a rolling road

Thats quite an impressive rise from just an exhaust system. Keith Calver suggests in articles that the standard cat is quite efficient but no doubt after 15 years the internals have either broken up or its lost its efficiency-that might explain the vast difference in performance.

there was a K&N filter fitted as well as the exhaust and manifold

[MINI 1]

Designed and built my own system back in 1994 never found another system to match it. Bottom end, mid range and top end. Dont bother ask because I aint telling!

well done !

[1977 Loud_Mini]

I have a standard 1977 mini 998 but never drove it with the standard exhaust all the way through to the back. Instead i cut the rear (last) silencer off and replaced it with a DTM back box which slotted straight on the standard pipe, It drove nicely like this but wasn't loud enough for me so i decided to do some modifications. I cut out the other standard silencer and replaced this with a piece of pipe just big enough to slide over the standard exhaust diameter and clamped it on. I then purchased a piece of pipe the same diameter as the original exhaust pipe which would then slide into the slightly larger piece of pipe and clamped that in place. Finally all was left to do was to re-connect the DTM back box and i was ready to test the newly customised system. It made a bit of difference to performance as it revs past 6000rpm up to 3rd gear (haven't tried it in 4th gear but have had 85mph quite easily at around 5000rpm).

Oh and it sounds fairly high pitched and loud now but not as deep as a 2" system. It's a bit hard to understand but you get the general idea of keeping the standard exhaust system from the original manifold straight through to the DTM back box.