Standard G40 exhaust Power limits?

JregGT · August 18, 2010, 09:39:35 PM

Evening everybody, i'm just wondering at what point a full standard G40 exhaust becomes restrictive?
I ask because, i've currently got a Bosal G40 centre pipe and Backbox on my GT, but matched to a 4branch, which i know i can't be used on the G40 engine, due to charger bracket and clearance. With the engine is the manifold, so i would only need to get a G40 decat downpipe to complete the system.
But the car i took the engine from had been rolling road at 150bhp, with an aftermarket exhaust form the manifold back. So i want to know if i'll be strangling the engine if i were to use a standard system when i get it in and running.

Cheers in advance folks.

Rich

cheys03 · August 18, 2010, 09:47:56 PM

Sorry to OT, but where did you source the std. G40 centre section and back box from? Cheers

JregGT · August 18, 2010, 10:00:42 PM

A garage which was recommended to me by a friend of my grandads who always had his vintage cars MOT'd there. Any garage which can get/use Bosal exhausts, should be able to get them for you, it was a reasonable time ago, and it wasn't the quickest turn around to get it, when he got it, he gave me a bit of a speal about how few of these there were. But i wasn't sure whether he was just trying to big it up a little, i can try to did a receipt out if you'd like. It was in the Midlands, Cannock way.

demolover · August 20, 2010, 11:02:15 AM

Bosal no longer do the centre sections. PeteG40 gave me the name of a garage that he got one from and i called them up to see if i could get one. They called bosal and the centre box was discontinued but the rear silencer was still available.

I have a centre section here that was removed from my G40 to make way for the PSD exhaust on there now. Mates up perfectly with the G40 cat in the garage too so i am guessing it is correct. Has no holes or anything grim. Has VW stamps on it?! Will be for sale soon as i won't be using it.

Any idea what the bore of the centre section is? The size of the bore where it joins the cat/downpipe? and the size of the bore where it joins the rear silencer?? I miss etka

must get a copy.

cheys03 · August 20, 2010, 11:11:35 AM

I think the clamps for the front (to cat) and rear (to back box) are listed as 49.5mm on ETKA.
GT is listed as 48.5mm. Might just use a GT centre with G40 back box. Hopefully it'll seal OK with the extra mm gap. Tempted by the one you have though Demolover. Please PM me pics when you have time.

demolover · August 20, 2010, 11:31:07 AM

Loads of time :-)

Ignore the G40 cat and other random odd jobs was just trying to photograph all the little bits and bobs i had.

Been used but was in fine shape when i had a look over it. No corroded skin on the box etc.

JregGT · August 25, 2010, 11:51:45 AM

Nobody got an idea of the limits of a standard exhaust, I'm back from down south at the weekend, so want to start sorting the last few bits out that I need to get the car running. Cheers folks, Rich.

PeteG40 · August 25, 2010, 12:22:01 PM

i've heard about 150bhp - but alan lawrence once got 170+ with a stock exhaust at aldon rollers with a 1341

JregGT · August 25, 2010, 02:23:26 PM

Thanks Pete, so to get the car up and running I should get away with a stock system? What size exhaust is usually used for the first step up on modified G40s? Cheers for your help folks, just need to get my hands on a G decay pipe now.
Ta Rich

demolover · August 25, 2010, 02:50:12 PM

What is the spec of the engine you are going to be running with a standard exhaust?

JregGT · August 25, 2010, 03:04:18 PM

stage4 charger with smaller toothed pulleys, not 100% sure on size, GT inlet, dewedged throttle body, g60 injectors with a map to suit. The car was rolling roaded at 153, still with the G manifold, just a different exhaust from the manifold back.

PeteG40 · August 25, 2010, 03:36:31 PM

tbh, i'd say that the exhaust will make a little bit of difference but not huge. And for me the stock exhaust wins due to the lovely quietness.

I don't think a stock g exhaust will hold it back much.

Next size up is 2", then 2.25" - not many people go bigger on a g40 ladered car

JregGT · August 25, 2010, 07:41:58 PM

Thanks very much Pete, i think i've got my hands on a G40 de-cat now, so things are coming together. Will certainly get the car up and running with the standard system before i look into another one.

Cheers Rich

PeteG40 · August 25, 2010, 07:49:03 PM

ps got some different bonder to try with seals...

also got an idea for a different type of seal to try too

JregGT · August 25, 2010, 08:16:40 PM

Thanks Pete, thats the main thing on my list to get sorted. If you don't mind me asking, what grade, composition sealant do you normally use, or suggest to try, I ask, as i have a family friend who works for Loctite, so really should be able to get me something to do the trick. I'm back from down south as of the weekend, so hopefully, some serious work should start. So i will probably be asking you some questions regarding the charger.

Cheers Pete.
Rich