I need your help! I'm planning on building my own cat back exhaust system for the simple reason that uni holidays are coming up soon, and I need something interesting to do.... like build my own exhast system! Even if ya think i'm crazy!
I have access to all the tools necessary from arc welders to mandrel bending machines, so what i'm in need for is info on upgraded fto exhausts. Anything from photos of underneath your car to most chosen pipe diameter, number of resonators etc. I'm deciding whether to put dual exhausts on coming from the rear or buying polished mufflers or even having the exhausts coming out from the side for the car!
Any opinions or ideas are very welcome
Also, being 5th year engineering students, we will be fabricating intercoolers of all shapes and sizes and a small on the side business, Anyone interested should keep us posted if interested in one, as over the next couple of months i will be turboing my fto to around 3psi
believe me, there's no point in running 3psi on your fto coz the noticeable difference in performance is only very marginal... plus all that trouble and messing around with the manifolds is not worth 3psi only (unless you wind it up) there's a whole lot more than just getting the plumbing sorted for the turbo kit, coz onviously you'd have to tune it as well to accomodate the extra fueling required etc etc...
i actually thought 3psi would in some way improve some needed torque down below, I'm guessing i should be looking at 6psi or around that. I've had enough of people simply talking about turboing there car, i too talk about it a lot with no actions after it! I'm just trying to gather information on what is neded to turbo these tricky gpx's... From what i've read it's difficult but always possible.
o2NV, do u have any pics of your exhaust? or ideas?
The old muffler pic gives the best view of the piping involved... still hard to see but u notice the hard bend from the left to the right - not good for turbos...
my suggestion is to run it the piping as straight as possible for the least back-pressure - hence you'd have to mount the exhaust exit piping on the left hand side of the car...
assuming you're running with std internals, you should at least run 6-7psi for some real low-down torque and decent midrange mumbo...
personally i'm quite happy with the torque on my NA motor atm... but then again it can never be enough forever!
yup, apparently a resonator will make a lot of difference to the sound without much compromise on performance, so get a hotdog resonator if you can get a hold of one... the muffler is still up for sale, so let me know if you're interested.
if i upgrade my exhaust to say, 2.5 inch and fit a hotdog, doesn't it 'decrease' HP? or is it not noticible?
Also hehe, sorry for the questions at 2 o'clock in the morning but, what realistic HP figures should i expect from the exhaust upgrade?
i can't say exactly how much HP increase an cat-back will give you (because there are several designs and they have various effectiveness) but i'd estimate somehwere between 5-10% gain. if you get a hot-dog resonator, i been told there should be no noticeable compromise to HP.
to give u an idea, i run a 2.5" cat back with a silencer fitted... nice muffled note and quiet, good response from low-mid rpm, but quite restrictive in high rpms (which is ideal for day to day driving only). However, out of curiousity i removed the silencer and the overall response is just beautiful (albeit slightly boomier and louder). it pulls cleanly and smoothly even at 4th and 5th gear.
i really oughtta get my act together and have a dyno run some time to give myself a clear picture of what my HP readings are with my current mods, but until i can find the time (and money) to do it all i have for the moment is my sense of 'conservative estimation'...
of course, since you're planning for a turbo conversion all these info is irrelevant...
Yeah from what I hear running 6-7psi on standard internals is OK, but fit an intercooler to keep the intake air temp low to avoid detonation.
The size and model of turbo (eg when it spools up) will determine where you get your torque increase. For example a big turbo won't spool up until high revs and therefore won't provide low-end torque.
I've scanned in and posted an article from ZOOM magazine about turbo'ing the FTO...its on the Yahoo members webpage.
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that's right, so if you want plenty of low-down torque, either a ball bearing GT25 or T28 should give you plenty of mumbo... (i think they start to run out of puff from 5500 rpm onwards) Ensure they are ball bearing turbos because they spool up faster (less lag & more response)
if you want to run high boost, you probably should invest in a de-compression gasket to lower the C/R and when you do - make sure you run nothing less than 98-RON fuel. also remember, the higher the boost, the more lag you will start to get so if you have a balanced setup, the power delivery will be smoother (more responsive).
blk jet,
Sounds like you really need to sort out what you want and can afford first.
Buy the way, what size engine is it - 2.0 litre??
Exhausts on n/a engines can make or break the power and torque.
the nakaya tune exhaust has to resonators in it and is still quite loud
if you want to turbo the fto and do a proper job think 15000 plus you want it to get some serious hp and quarter mile times think 25000 plus.
you can save some money doing things yourself but its the price of the parts that really add up
you turbo the mivec engine with out doing the internals dont expect it to last to long unless you run very low boost
hey then i say why bother turboing it unless you are going to run decent boost
there are so many things you need to do besides just putting a turbo and manifolds and intercooler on there are
bigger injectors
blow off valve
after market computer
modifications to make it all fit ( and they add up )
fuel pump
external waste gate on bigger turbos
new exhaust
ceramic coating
plenum chamber
bigger throttle body
heat shields
rewiring
new leads and plugs
fuel pressure regulator
boost control
extra guages
better brakes
better clutch
strengthening the gearbox or auto transmission
limited slip diff
engine internals ( big bucks )
dyno tune
strut braces
now there is a lot of these things you could say ok i will get away with out doing but if you want it to really get up and boogie with out going bang you will need to do most of them
then after you spend all this money you want it to look nice so you also put on
silicone hoses
fuel linesand fittings
polish a few bits
possibly paint or powder coat some bits
guys and girls please be aware that there is a lot more to turboing a non turbo car, then there is to adding a bigger turbo to a turbo car.
but if any one wants some advice from someone who knows what is involved i am always willing to share what i have learned
