20 replies to this topic

[P11 COV]

I think i've caught the bug. I'v got a piper induction and de-pre-catted so the engines breathing a little easier...so what next. ECU remap or proper sports exhaust. Do you think the exhaust should be done before a re map or is the air flow free enough now with the pre cat gone.? Views opinions please? PS money is in relativly short supply!

[speedyK]

so what next.

PS money is in relativly short supply!

A cheap way to improve power-to-weight ratio is to do a Ricky (and I don't mean wreck your car at the Nürburgring every year ).

Follow Colin Chapmans's credo: More power makes you faster in a straight line, less weight makes you faster everywhere.

Chuck out the bits that serve no useful purpose – what they are only you can say.

[P11 COV]

As my car is an every day commuting/shopping car I can't see there's much to chuck out!!!

[paulb]

I'd be tempted with exhaust first and then a remap to take advantage of improved flow later. A proper remap that is mapped to your car without the exhaust will be substandard if you fit an exhaust later.

[Bengie]

I think you've got rid of the most restrictive part of the exhaust in killing the pre-cat off. I'd go for a re-map, or at least talk to the guys at AMD/Regal/Wherever, and see if they'll re-remap for a smaller fee if you change your back box.

[NickB787]

do you feel you notice the difference with the pre cat gone? I was thinking of doing it myself I already have a regal exhaust and K7N filter but I was wondering this and a remap (amd or regal?)

[BogBrush]

Why stop at the pre-cat? I really haven't investigated it yet but i might try and see if I can buy a second cat pipe and gut it totally. Should make a difference. Anyone know where I might be able to get one cheaply? (breakers?) Also that air intake pipe could do with replacing. I'm sure something better could be made. Again I really haven't looked into it yet but I will do soon. How about a flexible metal tube from somewhere like b&q? Something that doesn't restrict the air going round that bend to the engine. One day i'll have thorney's and minimes spending power on mods but not just yet Anyone know saturdays winning lottery numbers? Just some cheap suggestions. Colin

[Jase_MK]

Also that air intake pipe could do with replacing. I'm sure something better could be made. Again I really haven't looked into it yet but I will do soon.
How about a flexible metal tube from somewhere like b&q? Something that doesn't restrict the air going round that bend to the engine.

Saw something in Hombase the other day. It was a peice of guttering - the joint that takes water from the horizontal gutter down into the vertical pipe. I'm not suggesting anyone use guttering on their car but the shape looked the right size rectangle to fit behind the side vent and graduaally flowed from a rectangle into a circular pipe. Got me thinking about how much more efficient this would be at ramming cold air into the filter box than the pathetic pipe that sticks about 2 inches out of the box at the moment.

Anyone know anything about laying custom shapes in fibreglass? Steve Crisp, you seem to be our resident engineer...?

[BogBrush]

There was this...

http://www.vx220.org...ct=ST&f=2&t=903

and then it all went quiet

[Jase_MK]

Oh yeah. I assume no-one knows what happened to M17D VX or his silicone pipes? This is what I was talking about (below). Like I said, not suggesting you stick this in your car but you get the idea right?

Attached Files

•  gutter.jpg   2.16KB   0 downloads

[BogBrush]

Well it'll keep the leaves out! I just sent M17D VX an email. Colin

Edited by BogBrush, 05 November 2003 - 10:23 PM.

[P11 COV]

I noticed when I put the piperx on that it was along way from the side air vents and quite near the many body of the engine and therefore was going to suck in lots of nice warm air. So I used the air tube from the standard air box and placed it between the new piperx filter and the engine mounted air intake so that the piper is right down near the side air intake.

[P11 COV]

I think you've got rid of the most restrictive part of the exhaust in killing the pre-cat off.

I'd go for a re-map, or at least talk to the guys at AMD/Regal/Wherever, and see if they'll re-remap for a smaller fee if you change your back box.

So we have a differing opinion from Bengie and Paulb.

This was what i was unsure about. Is there any point in having a back box replacement now I've done the pre-cat. Surely it won't make much difference and getting the remap done now would be just as good?

Bog brush - considering the effort needed to remove the precat I think you'd be a glutton for punishment trying to clear out the full cat

Surely you could get a straight thru pipe. - maybe a bit of drainage pipe from B & Q would do the trick

[Jase_MK]

It can't be that hard to get someone to make up a straight through cat replacement pipe - loads of people make them for the Elise for about 40 quid. Paul - be aware that the length of piping between the filter and the throttle body has an effect on the performance characeteristics. varying that length makes for more performance higher up or lower down the rev range and the supplied length of pipe for you filter will have been chosen accordingly. I don't claim to be an expert on this but I read a long article on it once on some Elise related site - will try to dig it out. cheers Jase

[Jim_Cross]

BogBrush - when I took mine into Sinclaire's (the Lotus Gods) in Romford they said they could do a de-cat pipe for it no problem. Probably worth giving them a call. Don't expect to escape from a conversation with them without being well out of pocket though!

[Jim_Cross]

P11 COV, it depends how far you take it. The Vauxhall Sports exhaust won't really give you much, if anything. However, something like the Milltek or Courtney exhausts replace the cat with a race cat, which again should have a noticeable effect.

[Thorney]

In order of highest restriction (for NA this is) Cat Pre-cat backbox pipe routing/size For VXT it's: Cat Pre-cat Turbo downpipe backbox pipe routing/size In terms of getting more power but on a budget the order should be: Precat removal (basically free if DIY) racecat backbox You've already done a small part but next pick would remainder of exhaust and then do a chip. Get the engine to breath right first and then make its heart pump harder.

[P11 COV]

Paul - be aware that the length of piping between the filter and the throttle body has an effect on the performance characeteristics. varying that length makes for more performance higher up or lower down the rev range and the supplied length of pipe for you filter will have been chosen accordingly. I don't claim to be an expert on this but I read a long article on it once on some Elise related site - will try to dig it out.

cheers

Jase

Did wonder about that. Sounds like time for a little testing with differing lengths then. Although of course the shorter the distance between the filter and the throttle body the further away the filter is from good air.

[PaulCP]

Paul - be aware that the length of piping between the filter and the throttle body has an effect on the performance characeteristics. varying that length makes for more performance higher up or lower down the rev range and the supplied length of pipe for you filter will have been chosen accordingly. I don't claim to be an expert on this but I read a long article on it once on some Elise related site - will try to dig it out.

cheers

Jase

Did wonder about that. Sounds like time for a little testing with differing lengths then. Although of course the shorter the distance between the filter and the throttle body the further away the filter is from good air.

Jase

i know what you mean but I used to have 2 cold feed pipes between the air intake and the K&N filter head but after the short pipe between the Filter and intake manifold split i replaced it with a 30cm lemgth of Samco piping to get the head further down by the air intakes.

There is no noticeable difference in performance

Paul

[Jase_MK]

Jase

i know what you mean but I used to have 2 cold feed pipes between the air intake and the K&N filter head but after the short pipe between the Filter and intake manifold split i replaced it with a 30cm lemgth of Samco piping to get the head further down by the air intakes.

There is no noticeable difference in performance

Paul

I thought that might be the case to be honest. It's probably the sort of thing where you might see a slight different shape on a RR graph but being able to feel that when sat in the drivers seat is another matter...