Right im just about to make the decision whether to make a short runner intake or not. I love the look of the original manifold and the noise it gives.However im thinking if i went sri it will make my life a lot easier when fitting the f.i. I was having a scoot round a few at UD and took a lot of pics of the engine but forgot to take some of the sri's Basically rather than pay 6-800 for one i was going to fabricate my own. The only queries i have is because i dont have one to hand id really like some dimensions.Ive searched all over but no joy.I know most of the money on these are towards the development but i think i could do an ample job. I will have a forged bottom end and i will be running a turbo.Low teens boost to start with with the scope to go higher. The rest of the engine will have been played with so its not such a case of do i need one,its more a case of why not. My plan is to have the throttle body on the rhs of the bay(looking from the front)using the standard lower manifold with cut off flanges and then onto a nice alloy pipe. The welding and fab side of it isnt a problem but id like to know a few things. Best I.D of the main "log" pipe? Best wall thickness? I know i am better off tapering the plenum towards pots 1 and 2 but to what degree? If anybody has one and could take some dimensions or a few pics id really appreciate it. All input welcomed. Sorry for the long post. Gary
It's not as straightforward as that. 1. Do not attempt to fab an sri unless you have a specific peak torque value in mind so you can tune the resonance accordingly otherwise it is a complete waste of time. 2. What is the application for and what are you final figures? Expected VE of engine so you can determine boost required for that flow etc 3. What is the material you are using? What is the total mani pressure that you expect to see. 4. What size TB and in terms of cfm of air flow and your designated boost will it start to become a restriction? 5. What is the material you are using and will you get full penetration at the duty cycle (i've seen half centimetre thick cast manifolds split at high boost and there are alu ones steel, different alloyed ones). So far i've spent 18 months on VR manifold development and there are still months of work to do. Get all your figures and set them for your FI development, in stages if you want. Here's a few guides to reference first: 2.8 24V AT 93% VE 40 LBS/MIN = 10 psi/ 0.68 bar of boost 45 LBS/MIN = 13 psi/ 0.88 bar 50 LBS/MIN = 16.1 psi/ 1.1 bar 55 LBS/MIN = 19.2 psi/ 1.3 bar 60 LBS/MIN = 22.3 psi/ 1.51 bar 65 LBS/MIN = 25.4 psi/ 1.72 bar 70 LBS/MIN = 28.5 psi/ 1.93 bar 75 LBS/MIN = 31.6 psi/ 2.15 bar 80 LBS/MIN = 34.6 psi/ 2.35 bar 85 LBS/MIN = 37.7 psi/ 2.56 bar 90 LBS/MIN = 40.8 psi/ 2.77 bar 95 LBS/MIN = 43.9 psi/ 2.98 bar 100 LBS/MIN = 46.9 psi/ 3.19 bar 2.8 24v AT 100% VE: 40 LBS/MIN = 8 psi/ 0.55 bar of boost 45 LBS/MIN = 11 psi/ 0.75 bar 50 LBS/MIN = 14 psi/ 0.95 bar 55 LBS/MIN = 16.8 psi/ 1.15 bar 60 LBS/MIN = 19.6 psi/ 1.3 bar 65 LBS/MIN = 22.5 psi/ 1.5 bar 70 LBS/MIN = 25 psi/ 1.7 bar 75 LBS/MIN = 28 psi/ 1.9 bar 80 LBS/MIN = 31 psi/ 2.1 bar 85 LBS/MIN = 33.8 psi/ 2.3 bar 90 LBS/MIN = 36.9 psi/ 2.5 bar 95 LBS/MIN = 39.8 psi/ 2.7 bar 100 LBS/MIN = 42.5 psi/ 2.9 bar These are a rough guide - you can get well over 100% VE from a well prepped head/engine, times by about 9.5 for an inefficient engine and upwards of 11 for a very good one to get HP numbers (I have done a few better ones but these will serve as a guide). As a guide - if your going FI with a VR6 then peak torque will be shifted to about 4000-4500rpms with a fairly standard head and cams and a bar of boost or so. All the variables will change this so you need to stage your levels of tuning and you can take it from there really if you want to do it correctly and in terms of hemholtz resonance frequency tuning your SRI. The first step is determining how you drive (assuming road cars) and seeing as there is both power and torque related values in freq tuning then where you are happy to sacrifice one for the other. In terms of design, although water cooling and a better material would help - the standard VR6 24V inlet manifold is the best design with it's variable frequency modulation. Replicating this in sheet form using a more durable material and additional cooling and angles through testing and re-testing is the best way but takes a lot of time and money! 24v variable resonance pic: Pics pinched from another site for educational purposes as an idea (hope they dont mind), shows the TB taper effect: I'll get the proper figures from the low mach testing I did with some flow dynamics software and what test results when finalised and post them up. As for plenum taper - that's not really the case - most manifolds are generally a box at the plenum so air is drawn equally and turbulence in resonance is not too bad (you have to remember that air is bouncing about off the TB and closed valve and given the speeds reached and the fact that a valve can be opening many times in a second then little changes can make a big difference), throttle body position and incoming air angles, velo stacks in the plenum or not? their position in relation to the TB. These can be seen in the original ABF one when I was first cutting plenum designs before I went to flow dynamics and CADing them. Orig ABF - taper into evenly sized plenum You can always sort the velo stacks in the plenum to account for the VR's variable length ports and you can angle them which helps with air induction into the runner: The fact is that there are a huge number of variables, so much so that after 18 months of testing and variating using CAD progs, flow dynamics software, dyno tests etc that things are still not finalised and ready to be posted up. I think it was INA who posted up some 20vt results and you can see the effect of TB's in relation to HP/TQ values and given the lbs/min a VR can flow under FI then early on the TB will be a restriction. In terms of simple gas dynamics though a larger orifice will slow down the air and the air will not be as dense... it's a balancing act. If you're TIG ing a sheet alu one then you are better off making velo stacks inside the plenum which not only help the bump and swirl as the air is ingested into the pipe but also you can vary the length in accordance with the VR unequal length tracts as compensation (which you won't find on lesser manifolds on the market). As for thickness - depends on boost pressures/density of the air, i've seen some cast items rip open at high boost levels half a centimetre or so thick. I assume your welder is able at the required duty? If it's a basic 130-150amp MIG then I'd go the full 3mm or whatever it'll do with correct penetration but even the original plastic mani's can handle 2bar of boost so it's a question of safety margin/weight/material/price etc Sorry for the long answer but there are a huge amount of variables and i've gone through most of them now but still not sorted, the first thing to do is get the figures in your head about peak torque values etc then you can go from there. Here's some reading which'll help. http://www.volkspage.net/technik/ssp/ssp/SSP_212.pdf http://www.phys.unsw.edu.au/jw/Helmholtz.html http://horsepowercalculators.net/intake-manifold-design/intake-manifold-design Sorry for the long reply!
You know.That is possibly the best reply I've had to any question I've had on any forum I'm a member of. As it happens I've already started the Sri. I'm going to have a good read through your post when I finish this 18hour shift. I really appreciate the time you took to thankyou.
Right ive had another good read of your post(thanks again) Ideally i want the PTV around 3500rpm the car will be running a Precision 6262 turbo,Tial 38mm external wastegate and my target hp figures are 350bhp. Forged bottom end 82.5mm pistons,ARP hardware.Polished and ported and blueprinted head which i will gas flow myself.8.5:1 compression plate 268 cams 4"MAF std TB.You get the jist. Now i am extremely fussy and quite a perfectionist and im afraid you have just blown my mind a little bit. I never took all the factors you have listed into account and the main reason i wanted a SRI is because i am smoothing the bay out and it will be easier and neater to route the pipework for the intercooler. Now however you have me worried i am going to hurt performance by making one.I point blank refuse to pay 1000+for a Schimmel one but then i dont want to pay 500 for something i can make myself. I have no measurements and i am just going off the room i have in the bay.These are all templates to see how it will look and will never make it on to the car.I was just interested to see how it goes. Im a mechanical engineer and have access to some of the best welding plant available as im in the aerospace sector,so duty cycle concerns are not a problem. Right ive had another good read of your post(thanks again) Ideally i want the PTV around 3500rpm the car will be running a Precision 6262 turbo,Tial 38mm external wastegate and my target hp figures are 350bhp. Forged bottom end 82.5mm pistons,ARP hardware.Polished and ported and blueprinted head which i will gas flow myself.8.5:1 compression plate 268 cams 4"MAF std TB.You get the jist. Now i am extremely fussy and quite a perfectionist and im afraid you have just blown my mind a little bit. I never took all the factors you have listed into account and the main reason i wanted a SRI is because i am smoothing the bay out and it will be easier and neater to route the pipework for the intercooler. Now however you have me worried i am going to hurt performance by making one.I point blank refuse to pay 1000+for a Schimmel one but then i dont want to pay 500 for something i can make myself. I have no measurements and i am just going off the room i have in the bay.These are all templates to see how it will look and will never make it on to the car.I was just interested to see how it goes. Im a mechanical engineer and have access to some of the best welding plant available as im in the aerospace sector,so duty cycle concerns are not a problem. You will probably look at that and cringe as it will have all wrong values staring at you lol.The flanges will be 8mm and the plenum will be 3mm. Any extra advice you can give would be appreciated. Thanks Gary
Lowlifedubber (Gary) We run this 6262 turbo on a number of Mitsubishi 4G63 'street applications, one being a 10.81secs@131mph miler. Usually on this 2.0 engine (with other supporting modifications) we can achieve ( on Garage Streamline's DD) 600ps@7300 and 470lbft @5400-6000rpm. Manifold pressure is ~1.9bar to get the air through the engine. On your 2.9litre and say 1.1 bar you should be up to target boost on by 4000rpm. The cam (pending other mods) should allow torque to remain high beyond the std 4500rpm and hang flat to 5000rpm, after that you will slowly decay till 6400rpm and then drop off ( but still slower than stock cams). I have seen 400+lbft with a similar combination and near 400ps. Of course you can run a 0.8bar spring, in your external WG and use a boost controller to vary the boost if required. This spec, give or take differences in dyno readings IMO, will still be a force to reckon with, along with the intimidating howl of the big 6. Plenum flow coefficients and distribution aside, the shorter manifold reduces pumping losses from reflective waves leading to pressure drops and increases engine response as the air column from intercooler/turbo compressor has less obstacles to overcome. You may also find the perfect manifold shape may be difficult to construct for the transverse VR6 engines due to packaging constraints. The stuff shown above, on variable lengths manifolds for multivalve VR5 and VR6 engines, are also found on the 10v V5 AGZ and 12v VR6 USDM MK4 engines. The pluse tuning done in such examples, is to encourage the supercharging effect in a NASP motor (that fills from ~101kPa). Most times the manufacturer is attempting to improve midrange torque (to meet their brand feel objectives) . This can be very beneficial on multivalve NASP applications, not just VW. This type for tuning is usually not as applicable to a turbocharger/supercharger config or an application that can force manifold pressure to say above 140 kPa (0.4bar). The suggestions regarding shape and air distribution across cylinders, should be followed within the context of packaging, if making your own. Due to packaging and what RBPE was suggesting on air distribution, also consider a central mounted throttle plate as seem in many OE and aftermarket short runner manifolds/plenums.
Another great reply thanks Toyotec. Ive never thought about a central mounted throttle plate.I have no room at the front of the plenum so it would have to be on top,this is something i will certainly look at.Like i say the above design is just a mock up with no real flow measurements taken into account. Instead of running the pipework from the intercooler down the n/s of the car to the throttle body i think it would look much better coming up and straight into the tb at the end(or top)of the plenum. I was looking at going with adjustable boost as the engine is currently in this state So with it having new shells,bearings,rings etc i will want to run it in very gently for the 1st 500 miles or so. Another thing that concerned me was getting a generic base map,a "running in" map if you like,just to loosen the motor up before giving it grief and going for a live map. Is this something you know someone could do?It will be running stock ecu but undecided what chip to go with. Another problem is the fitting of the piston rings.Apparently you need a special tool for these.Struggling to find one anywhere!Any tips? Sorry for the topic diversifying questions but i know your pretty clued up on this sort of this sort of thing after reading your posts for the past year or so lol. Thanks again Gary
This is what I mean. Another picture from the internet for the Ford 2.0 Ecoboost engine, as fitted to Mondeo, S-MAX, Galaxy and Focus ST And VWs TSI EA888 unit All these vehicles have packaging constraints for the best airpath, partly solved with a bit clever repositioning of components. Send me a pm on this. You need vw3278
Hmmm im starting to like the idea of the plate on the bottom of the mani.I will have another look at that tomorrow thanks for that. Ive seen the vw tool for doing the rings but apparently its still not very good and people still snap rings!As they are only low tension i may even have a go with my fingers. I will sling you a pm now re: the map help. Thanks again.
For the 12v mk3 then the SPA mani is probably best for keeping short piping as you can then run a standard intercooler and standard inlet to the TB and the compressor air intake is at the other side of the bay. With the 24v the TB orifice is on the opposite side so a twin-pass is better to keep piping short if using a similar cast underslung exhaust mani. With this exhaust mani: http://www.ebay.co.uk/itm/SPA-Turbo...r_Truck_Parts_Accessories&hash=item4a8acccbe2 compressor outlet is on the passenger, so as it is also underslung you can use the shield and standard inlet mani and piping is relatively short. Also saw this on the bay? http://www.ebay.co.uk/itm/VR6-SPA-I...arts_Vehicles_CarParts_SM&hash=item416a451604 The inlet mani you've fabbed looks fine, is that about 75% the engine volume in the plenum.... it's a bit of a funny one really. The smaller plenum can keep air speed and bump up well but there is a limit to the volume, remember you're running a 68lbs/min turbo and 50lbs/min is easy enough on a VRT so it'll be ingesting a lot of air. I'm testing some basic box shapes at mo. With such short runners your peak torque value is about 5000-5500rpms so higher boost and plenty up top but a bit lost lower down, just due to the short runners and where the ram effect takes place. You could always change to the standard one if you are using something like an SPA underslung exhaust mani though. Hvae you got the exhaust mani or are you fabbing that too? TB placement may make a difference then and whether to use a twin-pass or standard intercooler. Is it 65mm or 70mm TB with the 12V, can't remember. Those diameters you're looking at about 600-650cfm max air flow before it becomes a restriction so above 450-500hp you're much better off using a bigger one.
P.S. With how you're doing it, PT6262 - 1.5bar - 600hp and peak torque around the 5000rpm mark would be about right, otherwise, std inlet mani or fabbed one with long runners, PT5858, bar of boost and ultra quick spool with well over 400hp, you'd prob see positive mani pressure about the 2000rpm mark! No need for a 68lbs/min turbo for just 35! Also - if you haven't got your turbo yet - specify the new ones with the CEA Turbine wheels, the older ones just had CEA compressors.
