R Tech Remap Results

Seams a lot of effort for how many extra ponies?
 
RichoS 3 said:
Seams a lot of effort for how many extra ponies?
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Hi Rich,
We're in the middle of this great Jetex back box design debate lol. So when are you planning the remap? Would be very interested to see if you have the same issue or maybe mine has a defect in it.
 
R-Tech-Nick said:
Has anyone looked at the Jetex 8l rear box and compared to the oem unit or brands that are proven to flow? The oem rear box is capable off 300hp+ with a decent effective setup. The jetex 8l box is unique and like no other 8l system on the market its going again the grain.
Under load is sounds like the santa pod jet car, a high pitch high velocity air flow sound the type of sound which is related to a collapsed silencer or blocked cat. Its as if the rear box is being filled up with the gasses and forcing the gas out under "pressure" not flowing out clean as if the rear box is a pressure vessel if you know what I mean?
The car did make the delta numbers but during tuning i could tell there was a more effort needed and the timing and egts where higher other setups which I relate to back pressure build up and poor flow. I am seeing this more with the 8p and cupra tfsi on higher power setups on hybrids same effect and same sounds from the rear boxes building up pressure. The fix was to move to a another rear box design which aids a better directional flow exit.
The simple experiment is to kick the rear box off while on the dyno and do back to back runs and logs, a method I have used 100s of times to gain data to resolve issues.

I would love to see the data jetex have in the 8l running stage2 or above power with this design rear box. But we must remember most manufactures will only test and develop on stock untuned engines not setups at the edge of there ve window.

I have ran the inline jetex systems on the Cupra R and they worked prefect and sounded correct not like a jet engine sound.
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Hi Nick, getting very interesting now over this Jetex back box of mine lol. I did phone Jetex & as you rightly said they test there exhausts on stock cars to go with stock downpipes & cats etc. This is the only back box design they do for the 8L which is the same for the Mk 4 Golf v6 4motion & also the TT has the same way pipe goes in but just has two tail pipes either side going out. Must surely have same sort of internal principles from same manufacturer. Would like to see someone else with back box to compare.
 
Sandip said:
Would be interesting to see that kind of layout that Jetex backbox has inside, i can't see it being designed specifically for gases to get in and out quickly tbh

Enjoy the remap bud!

Not posted a picture in ages so heres my set up
P4170524.jpg
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Cheers bud, looks nice. Wished I had made the long journey & got Pipewerx to do the lot now. You live & learn.
 
R-Tech-Nick said:
@paul
How is 1.5bar going to have any effect on the stock intercoolers sub 3500rpm? stage1 stage1.5 stage2 boost in that area is not an issue at all limiting factor is the rods sub stage2 still the boost and torque limiting factor is rods. Stage2 with rods and stock smic can happy go over 340lbft with 1.75bar. (I have seen some come in with the stage1 boost at 1.7bar on stock rods.. cringe factor for me I am happy at 1.5bar peak on stock rods at any stage of tune)

The hold back is when trying to hold boost up the rpm range to a point which egt and ait can rocket the stage of tune is to manage this effect. The addition of a fmic on a k04 at stage2 is for manage the charge temps while trying to hold the boost higher in the rpm range. Stock fmics can be used fine with stage2 if the whole setup is perfect and effective. Rolling roads wont show this effectiveness as most cannot supply both cores with a decent amount of air into the cores. Its the same smic setup as we use on r32 turbo at 500hp.
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Hi Nick, So my peak boost at 1.5 bar is completely safe on my standard rods but any higher is not, is that what you mean? If so is that not a bit close for comfort? I'm a worry guts so humour me if I'm asking a silly question.
Cheers Nick
 
why on earth have jetex designed a backbox for standard downpipe and standard power
yet made the pipework in 2.75 inch and no doubt advertised that fact! the whole point of an aftermarket system is sound and power/flow improvements
what an absolute cope out from them!
terrible response from them
what a joke
poor luck steve
you were trying to be so careful and get it right :(
enjoy it as it is this isnt r techs first attempt so it will be mapped fine
 
SteveSAS said:
Hi Rich,
We're in the middle of this great Jetex back box design debate lol. So when are you planning the remap? Would be very interested to see if you have the same issue or maybe mine has a defect in it.
Click to expand...

My is already remapped although not without it's problems, initially suspected air leak causing it it be down on power( but not torque) and after more investigations turned out to be down to a lamba sensor and knackered spark plugs.

Will be putting it back on the rollers hopefully before Christmas. Will let you know how I get on and importantly if the exhaust is causing any restrictions and impacting power.
 
R-Tech-Nick said:
@paul

Whooooooshhhhhhhhhhh Not a Roooooarrrrrrr lol

and egts wanting to go into oem protection on the 350rpm sec runs which I never see at stage2, so had to use a different fuel and boost strategy counter.

I could add move boost at the top end and power would not climbed just egts went even higher, opening the air box gained around 100mb across the top end but no gain in hp. Normally at this stage by opening the air box I can see 12-15hp delta at the top end from the extra 100mb.
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HI Nick,
Found lots of forums with VW group cars using Jetex & saying how much they like the sound like a jet engine. Here is a link to a Mk3 turbo built golf clip, is this the restrictive sound like mine?
 
<tuffty/> said:
Ah... the 'jet engine' sound was not mentioned... this is a typical noise a restrictive system makes to be fair... this is the noise my Miltek started making when I did the last round of updates on my GT30 setup at 400ish hp...

the Jetex box is not very wide so suspect its chambered at the other end...

EGT's would be a tell... I used an OE back box when I first did my GT30 build and EGT's went through the roof...

<tuffty/>
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Hi Tuffty,

This jet engine sound seems to be quite common with different Jetex style exhausts, is this the bad restrictive sound?
 
vids don't show enough detail.

i had exactly that same 'jet engine' sound when I ran an AUM at st2 with a 3'' DP and a stock back box. you could really hear the gases trying to force their way out with a strange forced ripping kind of sound. Under the car you could visually see the restrictions in the exhaust too where it changed colour dramatically where the diameter reduced!
 
jet noise does'nt mean its a restriction... but the exit of the pipe is causing the noise, but it does'nt exclude a restrictive exit to also make a similar noise.
proof is dyno it with it on, remove the back box and repeat dyno. Facts then confirm reality from perception
 
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badger5 said:
jet noise does'nt mean its a restriction... but the exit of the pipe is causing the noise, but it does'nt exclude a restrictive exit to also make a similar noise.
proof is dyno it with it on, remove the back box and repeat dyno. Facts then confirm reality from perception
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Yes Bill,
Nick at R tech mentioned that is best way of checking the flow of the backbox. Wish he had suggested to have a quick rerun while I was up there to rule it out but I think he was probably short on time & the next booking on the rollers was due. As I said before the same back box design is used on the Golf 4motion & the TT comes in from side but has two exits rather than one. Other forums I've looked at for Seat Leons etc mention the Wooosh Jetex Jet sound at peak revs so obviousely a common sound with this exhaust.
I will email Jetex & see if they can email me pics of the internals of the back box.
 
An exhaust cut out would be cheaper than changing the back box.

You can get electric, cable or ones with their own wastegate that open at set pressures
 
Only developed and tested on a stock software car answers a few questions. Are Jetex willing to develop a system at stage 2 power? I dont mind lending a hand if needed.
 
R-Tech-Nick said:
Only developed and tested on a stock software car answers a few questions. Are Jetex willing to develop a system at stage 2 power? I dont mind lending a hand if needed.
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Well I'd imagine if their back box on the S3 8l & Golf 4motion were the only ones restricting flow then they probably wouldn't want the hassle & expense.
Still confuses me to be honest that they wouldn't have used the same process & testing for all their exhausts, & being a Performance exhaust company for many years it's a bit strange that they could produce a back box that flows worse than the standard box on a mildly (stage 1) tuned car. As you suggested after the horses (pardon the pun lol) had bolted would have confirmed the suspicion by removing back box & running again. If I lived closer I could pop back up but unfortunately I don't :(
 
get to a more local dyno for a couple of power runs. One with, one without.
doesn't matter about what actual figures you might get compared to rtech, just the differences if any at all
 
Can't get hold of any actual pics of the Jetex back box innards just these tech drawings if anyone on here understands them.
This is what the Jetex guy said: " Unfortunately, that's the only information I can get hold of without cutting open a silencer. The technical drawings show exactly how the silencer looks. The perforated tubing inside the rear silencer is 70mm while the outlets are 63.5mm"
 

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I have learn't throughout the years that, just because a company is big and has been doing something for years it does not mean they are getting it right. Advertising overcoming incompetence. Some of the worst tradesmen on the planet have existed and earn t a living doing it wrong all of their working lives.
 
9224a1f1-3b24-4837-93bb-577e395a860f.jpg


That's my interpretation of the engineer drawings. Which appear to be for an Audi TT

It would have been far better, flow wise, if instead of using an empty chamber to join the inlet and outlets together; they had used a 180degree bend. To prevent the exhaust being louder because of this, they could have extended the perforated tubes the full length of the silencer.
 
Last edited:
^thats exactly how I read it, for a TT with twin tips.
So it does look like it's mainly filled with wadding and only a perforated tube for an outlet. Definitely explains things, especially when compared to a miltek, which it's structure is known and it's also known they reach their limit in the upper 300hp range
 
So in the S3 application the whole right side of the back box is an area of high pressure......

I guess it will do a good job quieting down the exhaust at low back pressures
 
It's a shame Jetex haven't designed a backbox specifically for the S3, looks like a bit of a short cut blanking the rightside, they could of quite easily done what Lewis583 said and made a box that would flow far better

Nick hit the nail on the head with his conclusion, exhaust gases will be having a right good scrap in that chamber to get out
 
Hi Guys, this is the response from Jetex:
"The exhaust is designed (and EC approved) for a standard setup. You have added a 3" downpipe and had a remap but the exhaust has not been designed to take this into account. While I understand that a different design may offer more performance gains, you are comparing a non-standard setup with a 'race' setup. The design you have is EC approved with a 25% reduction in back pressure for the standard engine. In order to achieve an approval this is the setup that allows for this. We cannot be held responsible for lack of estimated power gains on a modified engine using our exhaust system."

I still can't grasp how a PERFORMANCE exhaust can give a worse result than a standard system. They say race set up, but its only a stage 1 map so if their system can give give a 25% reduction in back pressure on standard power why the hell would it change with a stage 1 map?
 
what an absolute load of ****
stuff like this puts me off of a manufacturer.
why make it at all?
why would anyone make a performance product that doesnt enhance performance??
and of course they had to put their little "we cannot be held responsible" rubbish in their.
what a joke
sadly steve this is why we tried to sway you toward custom
never known anyone with a jetex on here??
bad luck pal :(
 
its a bit of a cop out really. 25% reduction in back pressure, surely that will allow for a 25% increase in flow from a modified car, whilst being no worse than a stock system comparitively
 
exactly how i would understand it karl.
so if a standard exhaust has seen 300bhp that jetex should be seeing 300 + 25% bhp
:think:
 
daz-20vt said:
exactly how i would understand it karl.
so if a standard exhaust has seen 300bhp that jetex should be seeing 300 + 25% bhp
:think:
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If 25% pressure reduction does equate to 25% flow and 25% power, yes.
It probably doest equate. But it should still be suitable for an increase in power. If they genuinely have tested and recorded that data, and its not just made up marketing waffle
 
yeh i think its entirely made up! but its been proven an oem system can easily do the 266bhp steves hit
id ve very annoyed at that response
like you say karl total cop out
 
Jetex latest reply:
Yes, I appreciate your concern. A tuner is saying one thing, we're saying another etc...

Can I just say that there has been no performance reduction. This exhaust is designed to reduce back pressure and improve performance on a standard engine. It was not designed on a car with a Stage One Remap or a non-standard 3" downpipe.

I would also like to point out that you also had the non-resonated system so there should be even less restriction than the resonated EU approved one.

If the exhaust has been approved and obtained a 25% reduction in back pressure, ask your tuner how this can lead to a reduction in performance on a standard engine? Yes, if the engine output is increased by 20% or more (or if the factory had a car in their prototype department with a 3" downpipe and a Stage One Remap), the design may have been different, but this was not the scenario they were presented with around 10 years ago. They designed and had approved a system to suit the requirements at the time.

We have sold a lot of systems, both resonated and non-resonated since 2003, and we have never been presented with this before.

I really don't know what else to suggest.
 
essentially its an ancient design and whilst it should technically be ok-ish with stage 1 power, its not with what you have done to the car, and what Nicki is asking of it.
Lesson learnt and i really feel for you as this is a **** way to learn. Not many people could have warned you as Miltek is the obvious choice for most.
You will no doubt get close to what you paid for it, just pray no one stumbles across this thread lol.

Expect me to contact you early next year as i have a miltek that will unfortunately leave me in a similar situation to yourself, so will need to upgrade at some point.
 
audi upgrades
Thanks Superkarl,

Just emailed this to Jetex:
It seems to me if the advertised 25% reduction in back pressure on a standard car is correct then why wouldn't it give the same 25% reduction in back pressure with a remapped car? I can understand when a car has been seriously modified that a standard exhaust system may no longer cope with expelling gases quick enough, but a simple stage 1 remap of 30bhp should not cause problems to a standard back box, let alone so called performance back box.
It has been proven by two of the most experienced & respected tuners for the VW group cars that the OEM standard exhaust can cope with 300bhp so surely a performance system as Jetex can cope with 260bhp?
It must also be a reasonable assumption that anyone purchasing one of your Jetex exhaust systems has, or is intending to further tune their car & therefore the design of this back box should have been taken in to consideration at time of testing.
The tuner himself suggested he would be happy to test & help develop a back box design for a stage 2 (more than mine) tuned car if Jetex was interested.
Both tuners said that the chambered design of this particular back box is the problem with causing gases to struggle more to get out.
The main competition as in Miltek don't use this chambered design & their perforated pipes inside carry the gases all the way out.
The tuner also commented that he has seen a remapped Seat Leon with a Jetex exhaust that had no similar problem, but this exhaust was in line (no 4WD) & therefore gases flowed straight out.

My conclusion after studying all these facts is that Jetex have fallen short with the design of this particular back box (Audi S3, Golf 4motion) & should have put more effort into designing a better flowing back box for these 4WD cars. Anyone buying a performance exhaust system, whether it be Jetex, Miltek etc their priorities in order would be 1. Performance 2/3. looks & sound (depends on taste).

This Jetex PERFORMANCE exhaust for this particular car does NOT PERFORM.

This has been discussed at length by many owners of this car on a large Audi Forum & unless Jetex can come up with a solution for a better performing back box then many will be avoiding Jetex & looking to the more tested Miltek system.
 
Definitive test... Remove back box and rerun on dyno... If power lifts then you can confirm suspicions

<tuffty/>
 
<tuffty/> said:
Definitive test... Remove back box and rerun on dyno... If power lifts then you can confirm suspicions

<tuffty/>
Click to expand...

what he said
everything else is conjecture @ this point

proof of the pudding and all that

book in here, and I will do the test for you - FOC
intrigued.. I like testing stuff. Fact based data rules
 
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Too bad theres no refund on the cards, there's new clearance on magnex cat backs for the S3 on ebay for £335 incl delivery down from £500. Looks loud but I bet it flows well enough

XSFA1.jpg
 
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