Suppliers for straight pipe exhaust?

Hi guys,

I'm considering replacing my standard exhaust sytem for a striaght pipe and rear box only. Is this a good move or is it likely to fail track day scrutineering?

Can anyone offer advice where I should get this made?

Thanks for any tips

 

Lack of back pressure on a n/a engine has been known to reduce power, saying that there is an epic thread on a honda forum where they ran either a screamer pipe or no exhaust and saw gains, I say epic as alot of people disagreed with the results and it goes on for ages.

My experience with a 2.5" straight through system on a 1.9 8v with JE pistons, PP head, kent 268 cam and SS manifold, was it was very loud, mid 90's on sound testing and I was 10-15hp down on what the engine should have put out, didnt keep the car long enough to change anything so cant 100% say it was the exhaust but it was suspect number one.

Im sure more knowledgeable people will be along to discuss.

 

It appears that some GUs, GZs and EVs did not have a front silencer. It was part number 191253091G, and seems to have been replaced with 1H0253203E.

 

I have seen silencer replacement pipes on ebay before so they are out there

 

I piece of straight thought pipe 2" should be 12-15 for 2 metres, I've also fitted straight though silencer pipes to cars - best of both worlds?

I've might be worth keeping the pennies until it needs a full sports system

 

Thanks for the feedback..... so there is a chance you could loose power I don't want that

 

not with a std size system, sorry I was thinking along the lines of 2.5" straight through system, infact someone from tsr wrote this the other day about aftermarket exhausts on a more std engine 8v mk1 golf:

Removing you silencer and swapping for a bit of 2" tube is a nice little way of sporting up the std exhaust, and very very cheap!

 

On a tweaked 16v a 2.5" system is the way forward fitted to a 4 branch with 2.5" collector

A Supersprint Gp.A system is straight through with just a backbox. Had one on my ITB'd 16v

Very very marginal with noise tests though...

 

i swear my car lost pace when i went from a single silencer and no cat system to a proper exhaust again.

didnt get a chance to measure any changes though

 

What system is on your car just now?

A single box system on a 16v will be marginal for noise at some track days, but it all depends on the quality and design of the single box.

 

supersprint do a plain pipe to bypass the mid box...so you could just run the backbox

 

i have a supersprint system on there now. before it was just pipe and backbox.

for the sake of a bit of pace, id much much rather have a quieter peaceful car with the number of miles i do

 

the 16v should be a 3 box syetm as stock... front pipe on the straight under the hand brake.. a small silencer that could easily be chopped out.. middle box which is between 2 90deg bends... and then the back box.

if your worried about noise just drop the first box and keep the second two, also get a proper 4 brance manifold on there.

a NA engine can be quite sensitve to flow, but unless you drop the gas speed too much - ie a big bore system thats well over sized - then you will generaly see a power gain but only at higher revs due to the higher gas flows normally being bottle necked by the silenced stystem which have to pass a european drive by noise test.

if you can keep the gas speed up by sensible pipe sizing ie a 2.25" system or so, and heat wrapping a stainless 4 branch manifold then you will improve scavanging too due to the interial of the gas flow (exhaust systems are very complicated bits of kit... theres some general rules but to fine tweak takes alot of knowledge)

 

Thanks for all this advice guys.

I've seen 4 branch manifolds on ebay, are they best avoided? I've heard complications over LHD and RHD models. An ebay business seller has assured me it bolts straight onto a RHD model. Cost is about 175 + p&p.

To bypass the first silencer, do I just need to find a mild steel merchant to order a short section? Without me having to get under the car, can anyone confirm the size required to fit the 16v system?

Thanks again

 

It's 4 boxes if you include the one on the downpipe.

Adam - Jetex are just down the road from you, and will sell you a length of 2" pipe with a swaged end, to remove the front box, and any adaptors you need to fit.

 

Thanks Mike, I ddn't even know that. Looked at their site and the 2" is only a few quid. Peanuts compared to a new exhaust sytem..... that's definately a job to do while the cars up to change the clutch.

Anyone got an answer on the 4-branch? I was looking at this......

http://cgi.ebay.co.uk/VW-GOLF-MK2-16v-GTI-STAINLESS-STEEL-EXHAUST-MANIFOLD-/170357812350?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27aa1dec7e

 

No point on a standard engine, according to Tim Stiles tuning book. Save your 4 branch money for an ABF and megasquirt. Get some real power

 

my 16v had a box on the downpipe then the one under the gear selector one in front of the rear axle and the back box that makes 4.

and any 16v down pipe i'v seen has that box on it.

mines had a hole on the box right at the front near the engine that's the reason i went for a stainless manifold well that and i couldn't get they dam downpipe bolt out without them shearing off

and to the point off straight pipe if you know someone that's a blacksmith/fabricator you could order pipe cheap through them i got 6meters of 2" bore stainless for 105 that was three years ago mild steel should be half that.

 

Cheers. I used Mikes advice and visited Jetex yesterday.

I got a 1m section of 2" mild steel with clamps etc for 15. Bargain.

Also got a 4-branch to connect up.

 

You'll be pleased with the Jetex Adam - I run a full 2.5" Jetex on my 20vT. I replaced the centre section with the Jetex straight-through centre section and it's not loud. Only clocks 92db.