tubular exhaust mani for a gutsy 16v...suggestions?

good stuff
Jon

 

Agree with heat shielding the steering boot but I've had bad results with heat wrapping MK1 headers. Might be the heat down here but it only take a couple of years to turn a new steel manifold into this.











Now I just silver ceramic coat everything, it even works well on cast manifolds.

I made an exhaust heat shield out of this stuff for the race car and it works remarkably well. http://www.aclperformance.com.au/EU/prod_heatshield.htm

I made a second heat shield for the steering boot out of the off cut.







Every body told me I'd melt that washer bottle on the dyno but it's holding up fine, even though it was hot enough under the car that I melted a CV boot on the last run.

 

That's a piece of art Peter you should have submitted that for the calendar

As long as the washer bottle is full you should be ok lol

 

there ya go...I've said for years that exhaust wrap is total crap.....

 

Wrapping manifolds is a pain in the ass too!

 

And the stainless clips cut your hands to bits. Agree with Rob
Jon

 

It certainly is Rob / murph.

I've seen 190hp from a 2ltr 16v with an Ashley 4-1, and Jon (Olds) has recently had a similar result with good torque too...so they work to a point...and the recent ABF we set up also had a 4-1...big diameter primaries but very short...a shiny ebay special. .and that made 190hp too.

There's a lot more to it than just saying a 4-2-1 will give better mid range than a 4-1 etc...if its a pants design with very short pipes then a reasonable 4-1 with long primaries will be better all round...tho again...it depends on what the engine needs based on it's spec...tame engines with tame cams aren't so fussy as high spec engines with wild cams.

As Ed said above...15 ibft isn't uncommon a gain when going from a average manifold to a proper spec one on an engine that needs it.

Generally tho the gain is seen/felt at the lower end unless the manifold is restricting flow alot...flow and tuned lengths are two different things.

I've got a couple of dyno tests coming up early in the new year...one on a 2ltr 8v race engine and one on a 2ltr 16v track day spec engine. .both will have direct comparisons with their old short ish 4-1's and custom long 4-2-1's....I'll pop the results up as soon as they're done.

 

Any more info on this set-up Eddie? Specifically the "custom downpipe". And by "ABF Euro" do you mean the OE LHD ABF exhaust manifold?

 

To be fair though, Jon would ideally need to test his car at Alvin so that a direct comparison could be made. Also because two engines achieved 190bhp, does not mean the same torque trace will be plotted or the response will be the same in the entire engine operating range either.

There is a hell of a lot more regarding the differences and benefits of using a 4-2-1 system vs a 4-1. And it is not limited to aftermarket systems with limited or zero development but in a production environment with hundreds of man hours to validate the differences.
We are indeed speaking about optimising the tail end of exhaust pressure waves, were the pressure is tuned via pipe length, to be lowest during the time of valve overlap to aid the incoming air-charge to fully fill the cylinder. Using a 4-2-1 system with appropriately tuned primary, secondary and collector lengths, allows targeted tuning of this low pressure pulse to the next cylinder that is about to have an exhaust stroke. If your engine is pretty modern with mapped VVT, you can start using your VVT system to make even greater use of this pulse energy without compromising your idle or your top end performance. Unfortunately, 4-2-1 manifold technology is not always implemented due to packaging, cost and applications that a manufacturer produces but, when the product is more 'premium' they certainly favour this type of system.

All JDM NASP performance products, revving to 8000rpm or more use a 4-2-1 system. Whether it is a Honda H22A1 to a K20A, a Toyota 3S-GE iBEAMS to a 4AGE 20v, A Mitsubishi 4G92 MIVEC or a Nissan SR20VE or SR16VE, all use 4-2-1 systems. On a more 'normal' basis the humble 2010 onwards Ford Focus with its 125ps 1.6 Sigma TiVCT motor uses a 4-2-1 system to develop the maximum torque of 160Nm and increased launch torque over the 105ps version with a 4-1 system and only 140Nm and less launch torque. In addition to different VVT mapping, the increased torque of the 125ps version is primarily due to the manifold design and is the only power option used with the Auto. The MK5 Golf GT FSI also uses a similar arrangement. At lower speeds, typically encountered by a road engine 1-4krpm, flow restrictions are not a problem on an OE system. However there is a lot to be gained from tuning the exhaust for maximum scavenging at this engine speed range and beyond.

That would be a good test where the net delta between torque plots can be looked at.

To mr brown and Tristan,
I have recommended the later EU VW ABF (there are two types) system on a chap with MK1 Golf. The manifold arrangement is should below fitted to the engine for my MK2 Golf - JENVEE which is also part of an 200ps experiment, I have been working on in the background.



Club members may be not aware, these manifolds are used in the Golf 3 GrpA engines supporting 220bhp running a plenum as well as other tricks.

After looking around to what was on the market and having a rusty Ashley 4-1 sitting around from a previous engine incarnation, the EU ABF manifold was used on this MK1 Golf ABF which had standard 10.8:1 compression, headwork to some degree, Newman 288 cams and ITBs. With a custom downpipe made and after some concerns to redress cam timing, we achieved the following plots using Garage Streamline's dyno measurements that is shown below.



I can also compare this with my own plot for JENVEE, being a base ABF motor with the OE dress kit and provides correlation to the above as it was tested on the same machine with myself as the operator in both instances.



You can see the net sum of work done to the that MK1 meant very little maximum torque was lost (or axle acceleration in the real world), compared to that of the optimised stock plenum engine, though the cam does give a healthy bump near 5500-6000rpm rpm . Usually with typical DTH ITBs fitted to an ABF motor alone, 150-155lbft is seen as a maximum of 5000-6000rpm shifting torque to the right.

Thankfully as I am not a business but have been blessed with unlimited time to use the dyno on evenings. So there has been the time where experiments were done on a different OE Plenum ABF motor, stepping from a OE cast manifold, to an OE 4-2-1 to a Golf 3 kit car 4-2-1.
There was very negligible differences at full chat between the cast 4-2-1 and the OEM tubular system. There where differences at launch engine speeds and up to the first torque dip.
The kit car manifold allowed a small improvement in filling post 5k to our cutout but alas, there was not enough 'engine' to really use the properties of this part properly. I suspect ITBs, cams, CR increase, a 9000rpm limit and extra capacity would be needed to make use of this part properly. Else the LHD 4-2-1 would suffice for most.

For the aftermarket shelf solutions, usually packaging and cost to make extra collectors also play a part in a 4-2-1 (aka tri-y) vs a 4-1. Until someone takes the time to set up an A-B-A experiment with the 4-1 vs a 4-2-1 optimising the calibration to suit the change in cylinder charge motion for each step and back, I would always recommend a TRI-Y system, especially on a road engine fettled a bit for track use.

That is my 2p

 

That OEM-looking ABF manifold looks very nice - the ones I looked at in the past were not as nice as that and had a squash in the lower part of the manifold below the flexi. That one though looks good.

One experiment I intended to do and never got round to was linking the cylinders in different orders - I've seen some unexpected results with 1600 Duratecs in this regard - so my 4-2-1 was made so that the 2-1 pipes could be fitted in both orientations.

Anyone ever done this with a VAG valver?

 

Thanks Eddie, it looks like it's the same manifold I have



Is that particular mk1 on this forum? It would be nice to have the downpipe measurements

 

That is the one! You are not far from a very good exhaust place that can make the down pipe with mandrel bends etc for you. Send me a pm and I can hook you up!

 

Not such an issue on anything I've ever wrapped? Was that mild steel I take it?

Was the car used daily? Rain etc? I'd imagine getting the wrap wet isn't ideal..

 

That would be the ver 1 4-2-1. This one.



This version 1 is prone to cracking around the header to d/p flange branches and VW later updated to the mandrel bent one as shown above. These were also used by VWM. Down pipe on the production car was different to the VWM, which is where I believe there can be further improvements with a custom part.

I have been running my car with this for 2 years and knew about and had parts imported from Germany for about 3 years before! This is the first time I have shared this.

The exhaust pulse is grouped based on engine firing order to alternate pulses at the final collector.
So 1-4 and 2-3 would mean the pluse at 1 would leave low pressure in the tract to cylinder # 3 and this will carry on sequentially, with the pressure drop increasing on the next cylinder as the frequency of the engine firing increases to a point.

Never seen the grouping different 4 cylinder not even on a turbo car but you never know.

 

This was on a track only car. stock 2.0 8V bottom end running an enormous cam, lots of head work and twin Dellortos.

However I also have the same manifold on a street driven 1800 8v MK1, also wrapped and I've had to repair that several times. They last longer on the street but need maintenance.

They're the only domestically manufactured MK1 header available here and no businesses import MK1 headers so we're sort of stuck for choice.

The ones in the photo were replaced with the same, but ceramic coated this time and they're lasting really well.

They're a very basic 4-2-1 mild steel design. Stainless steel exhausts aren't common here, mostly custom work is done with aluminiumised steel.

Here's the cracked one beside it's coated replacement.

 

I would imagine 4-2-1 would be more suitable for OEM as the extra pulses from the extra changes in diameter probably allow for a greater spread of torque.

From what I have read "full race" tend to use 4-1 but id imagine this means makes getting your lengths correct more critical..... although if your intake lengths are not correct then it could be fighting against it.

Unless your tuning your engine on a dyno for what its worth id go for off the shelf if possible..

 

I know I'm a year late to this party, but, I've had a a stainless manifold sitting in my shed for a while now. I've not installed it because I really don't want to heat wrap it, but looking at this thread the coating in the post above looks like the the option over the wrap?

Can anyone recommend a place to get this done locally? I'm based in Bedfordshire but don't mind a fair drive if it means going to the right place. I don't have a lot of money for such things either and I've even conteplated running it 'plain/standard' as I my standard ABF should'n't get hot enough anyway, right?

It's a daily driver with a blown exhaust and a pile of parts in the shed I need to install. I have a decat, some spare flexi pipe and a whole cat back system waiting to replace the blown system that is currently on the car. I've been waiting to fit it because the 'heatwrap or not to heat wrap' arguement confuses me. I'm looking for advice from people that have actually treid both and can give me genuine advice.

Needless to say, any advice on this is welcome as I'm totally clueless!

Cheers,
Milton

 

Cheer up Milton we've all got to start somewhere

It's all a bit beyond me to be honest but I'm ok with understanding the pulse stuff on a 4-2-1 system but I've got a 4-1 Chinese S/S one to put on my track car

 

Aluminium duct tape is remarkably effective at reflecting heat - split to suit the concertina and provided the boot is clean it sticks like the proverbial and offers decent protection for little cost when replacing it now and again.