View Full Version : Milltek downpipe and sports CAT.
I had this fitted today, to match up to my existing Milltek CAT back system. What a worthwhile upgrade - it's great! Throttle response is greatly improved and the kick in the back is noticeably stronger. Exhaust is only slightly louder, note is deeper but when you floor it ... it takes off!
Peak boost has also increased from 18 to 20PSI too following this mod.
Dormouse
14-02-2004, 14:41
Hmmmm....
Don't understand why the boost would increase. You done a few runs in different conditions? Seems the Leon system is designed well at least.
Enjoy
Dor.
I'm assuming peak boost has increased due to the reduction in back pressure and pipe width increase, the swan neck shape of the pipe between the turbo and CAT has also been removed - the Milltek is much straighter. 2.5" bore from turbo to tailpipes now!
Dormouse
14-02-2004, 15:36
Excellent.
Goes to prove Miltek can design systems correctly. I await a response on the Ibiza issue from them. Hopefully something good.
Dor.
If peak boost changes due to an exhaust swap then you have a actuator problem IMO. Either it was set too high and for some reason the old set-up couldn't reach peak boost (and I don't think that is even possible) or it's been moved or deliberately altered during fitting.
Good dodge for making people happy with your exhaust though; tweak their actuator to give them more boost as part of the fitting!
Cynical, me? Nah, surely not...
My actuator was not touched and it wasn't an exhaust swap - you're WAY too suspicious! Nothing dodgy went on. The downpipe and sports CAT mod is widely known to free up something like 10BHP and reduce backpressure.
Weird response to a great product Fen.
I know that the system should give slightly more power and reduce back pressure, but that should have no effect on boost pressure! You should simply make more power at the same boost pressure.
Perhaps the ECU has adjusted the boost to compensate for the increased airflow and reduced back pressure throught the turbo? Who knows - who cares, bottom line is it's working very well and has made noticeable real-world, on-the-road improvements which is what its all about.
Originally posted by RobDon
Weird response to a great product Fen.
No at all, I just know that reducing back pressure can't increase peak boost pressure, because it's the wastegate or actuator (depending on design) that controls the peak boost. Without an actuator your engine would create so much boost it would destroy itself PDQ, regardless of the exhaust / back pressure.
If what you're saying is it gets to peak boost lower down the rev range then I agree it may very well do, but if I understand correctly that you are now making more boost than before then I can't see how that can be, especially by 2psi, which is a fair old increase.
In a nutshell the exhaust has absolutely nothing to do with peak boost level.
Originally posted by RobDon
Perhaps the ECU has adjusted the boost to compensate for the increased airflow and reduced back pressure throught the turbo? Who knows - who cares, bottom line is it's working very well and has made noticeable real-world, on-the-road improvements which is what its all about.
That's exactly what I was wondering - was it remapped to suit? If so then perhaps the boost was tweaked as well.
If that is the case then that's where the vast majority of any extra power is coming from.
The other claims you made I can fully support - smoother, more grunt lower down, better throttle response etc. are all features of improving the exhaust.
I had a lot of respect for Milltek systems (none through experience, just hearsay) until Dor ordered one for his Ibiza and now I guess I would be less keen to recommend them, but I'm still not knocking the product.
I just think that on a site like this where we have lots of people getting into modding, or modding turbo'd engines for the first time it's only right that what they read is as correct as possible.
Dormouse
14-02-2004, 16:46
Note that there's nothing wrong with a bit of engineering scrutiny.
I guess Fen's like I am Rob. We have an engineering background and simply don't accept 'figures of merit' without actually understanding how they are achieved. For sure, the Miltek is helping to free the flow of air up in the system, and make the car more enjoyable and have a bit more power.
But I for one don't accept products on small sample results 'widely know 10bhp increases' and ZBOYDS's single stealth result (to which I think you are referring - and accept my applogies if you are not) are not rubber stamps by any means.
To be honest, all being equal a wider bore will infact reduce boost pressure! as the flow rate should in theory remain constant.
At the end of the day, your happy, but SCN forums are designed for precisely this. Discussion of product.....
My biggest comliment of Miltek is that I could ring up the bloke in charge and discuss my gripes with him promising to do a decent investigation. That's a magnitude above any product satisfaction IMO.
Basically. Enjoy :p
Dor.
I dunno guys - I just fly by the seat of my pants! :D Maybe I read the boost gauge wrong in all the excitement. All I'm saying that this product gets my approval, it works well, offers noticeable real-world gains, is well made and is a decent price.
The average 10BHP increase was not referring to a single person, rather the multitude of Golf 1.8T owners who have all reported similar findings, I don't know anything about ZBOYD's car.
Mine is an R Chris not fair to compare my Miltek system, too many differances for a true comparison, mine also doesn't include a downpipe.
Mine still uses the standard R downpipe, R Miltek kit is replacement HiFlow CAT, then replacement centre box and backbox.
Restriction is identified to be mostly the standard CAT, standard downpipe works well.
Bit different to the downpipe kit Robdon is refering to, which has been tried and tested on many Golf GTi's as he points out.
My claim based on figures seen, leads me to believe there is an average 8-10bhp increase on figures run in a near to identical situation, as i pointed out at the time, many standard cars showed similiar figures to my map from last year, those with higher figures were using SPS3's with higher boost and timing settings than i originally ran last year, my gains could of been more, but for the interests of uniformity i kept the same SPS3 settings from last year.
But for me the biggest improvement is the way the car now pulls longer and harder than before, and the turbo lags less and spool up is much improved, that can be seen in my graphs as the power and torque start to climb earlier and for longer.
Having driven my car i trust my butt dyno more, as whatever you think are fair figures someone else will always think that they are not. Rock and a Hard Place scenario, so i dont try, im happy with what ive proven, if others are not then thats their problem.
Dormouse
14-02-2004, 22:02
Sure no issue with that.
However, butt dyno's are interesting things. Guess it depends on moods, time of day etc :p. Also there's always the case of putting yer foot down more (slightly more, unknowingly) cos your testing new kit.....
Tis obviously a good bit of kit, I'm just one of those people that likes to understand what's making things work better :p.
I'll go put on my greasy cap and check out a few steam engines with Fred Dibnah now :)
Dor.
My only interest in this was that I can't see how an exhaust / downpipe / cat change can increase boost, purely in the interests of accuracy. As if to prove that I didn't know what model of car we were talking about, nor what bits of plumbing under the floor have been replaced.
Interesting about the butt dyno. I sometimes feel like my car (any of them) is going pretty well, and sometimes not very well. Since this has happened with every car I can remember since I started trying to get more than the manufacturer intended out of them then it can't be because my car is dodgy and sometimes goes better than others. So it must be the dodgy butt dyno. Either that or ALL cars have good and bad days (or strings fo them seems more like it). I favour the bad arse theory :D
Originally posted by RobDon
I had this fitted today, to match up to my existing Milltek CAT back system. What a worthwhile upgrade - it's great! Throttle response is greatly improved and the kick in the back is noticeably stronger. Exhaust is only slightly louder, note is deeper but when you floor it ... it takes off!
Peak boost has also increased from 18 to 20PSI too following this mod.
Out of interest how much did all that set you back - I note from your profile you have a std Cupra as do I and I thought Milltek don't do a system for the Cupra?
Supplied and fitted, with a new turbo/downpipe gasket it cost £490 including VAT, labour etc. Yes, Milltek do indeed do an exhaust for the Leon, probably the Golf MkIV one, same chassis.
chriskaven
15-02-2004, 13:36
By adding the exhaust you have decreased backpressure. This means that the turbo will spool up quicker.
Look at it this way:-
(Before adding the exhaust)
You floor the throttle and the ECU requests a target boost of say 17psi. At this point the wastegate is probably completely closed or almost closed.
Once the 17psi target is reached, the ECU changes the N75 duty cycle which opens the wastegate to maintain the 17psi target. However because the system is vacuum controlled, there is a slight time delay in this process so what you actually see on the gauge is probably an overshoot to maybe 19psi before it settles at 17psi.
By adding the new exhaust the backpressure has gone down and the turbo therfore spools up quicker. This means that although the target boost is still the same (17si), the initial overshoot is slightly higher giving you a higher peak reading on your gauge.
You should find that the boost figure that the gauge settles at should be the same before and after fitting of the exhaust, but the peak overshoot figure may have increased slightly.
Hope this helps.
Dormouse
15-02-2004, 13:43
A good explanation Chris. The spool-up issue is true, the mechanical overboost could well be so. It makes sense.
Don't suppose you have the ibiza Miltek downpipe / CAT on yours?
Dor.
Sound right to me - cheers!
chriskaven
15-02-2004, 13:48
No I don't have the miltek exhaust.
Originally posted by RobDon
Supplied and fitted, with a new turbo/downpipe gasket it cost £490 including VAT, labour etc. Yes, Milltek do indeed do an exhaust for the Leon, probably the Golf MkIV one, same chassis.
Sorry been offline for a while - where did you get yours done?
cupra-neil
06-03-2004, 20:23
would a miltech down pipe and cat fit onto a Scorpion cat system are they the same bore???
Dormouse
06-03-2004, 20:27
Originally posted by cupra-neil
would a miltech down pipe and cat fit onto a Scorpion cat system are they the same bore???
1. What's the scorpions internal dia?
2. Check miltek's site for the downpipe and cat internal dia.
3. See which one has the reduction for sliding over the other.
4. Hope.
Like most things here it's a case of experimenting. If the scorpion fits the oem CAT joint point and the miltek is a pattern fit, Then why shouldn't the two match?
Dor.
this happens on the majority of turbo cars. reduction in back pressure causes increase in boost. not so noticable in ECU controlled cars but if you have an older turbo car runnign a bleed tehn it is noticable. happens a lot on jap cars. it;s known as boost creep. can cause serious problems because it can lead to the car running lean.
Shock_Xe
06-03-2004, 22:41
Originally posted by Dormouse
Excellent.
Goes to prove Miltek can design systems correctly. I await a response on the Ibiza issue from them. Hopefully something good.
Dor.
do as i did and cut the miltek downpipe up and replace for 3" :D
As for increased boost, when i added my dp/cat with Revo i too saw 1/2psi increase. I assumed that the ECU was requesting this ammount all the time but due to a bottleneck and pressure build up it could not be achieved but due to the miltek and freeier flowing it allowed the turbo to meet the requested boost as it was able to dispose of required pressure quicker/efficiently
[blantant plug]Take note on specail price of LCR Milltek and sports cat in group buy and discount forum :)[/blantant plug]
Dormouse
07-03-2004, 00:09
Originally posted by techie
[blantant plug]Take note on specail price of LCR Milltek and sports cat in group buy and discount forum :)[/blantant plug]
Any news on the 'Ibiza Investigation' Downpipe?
Dor.