oreo

Nice Build!

At one point I attempted to build a 3" exhaust, for a high boost supercharged Miata with a custom header. (similar power to yours)

For the exhaust, I started with the following components:
Magnaflow, 59959 cat, 14419 resonator and a 12589 muffler (all 3").
The car was extremely loud. I couldn't believe how loud it was. It was far to loud for a street car. Too loud for some of the tracks around here.
I tried swapping the 12589 for a couple of chambered mufflers and found that a muffler out of a GM SUV worked well, but for some reason they would break internally (not sure why).
I am not sure how restrictive this was compared to say a flow through muffler on a 2.5" exhaust. I just needed to quite it down.
I tried a active restrictor, using a wastegate controlled valve, however the engine AFR was all over the map. (and it was really loud at full throttle)

In the end, I pulled it all off and went with a 2.5" exhaust. The 2.5" was perfect until I put a turbo on, and then the exhaust was Buick like (super quiet). So I switched back to 3".
Unfortunately when I put the 3" exhaust onto the supercharged car, I also put in a new engine. So I couldn't determine what the 3" exhaust did. The car was so loud with this exhaust, that I was not
comfortable doing a bunch of power runs, as I couldn't hear the engine.

I am not saying that 3" is the wrong decision. I was just unable to find components that would work for me for a 3" system.
I am hoping this info will help you pick components which will work.

Tchaps

Thanks very much for the info Oreo.

The Magnaflow muffler you posted is very similar to what I was thinking of. Straight through design, big oval case, just over 20" long.

Also you had a cat and an additional muffler in your system. An additional muffler like yours was my backup plan if just running a backbox made my ears bleed. I really need to reconsider straight through silencing I think!

There was a link to an industrial muffler manufacturer posted by Warpspeed in my Miata.net thread. It gave info like CFM at 1", 2" and 3" Hg pressure drop and also noise attenuation in dB for their range of mufflers. Basically I crunched the numbers on flow and noise attenuation vs silencer geometry and inlet size. Inlet size had the strongest correlation to flow capacity at a given pressure drop, however there was not a relationship between inlet size and noise attenuation. There were noisy small inlet mufflers and quiet large inlet mufflers and vice versa. Body size of the muffler had a weak positive correlation to noise attenuation (bigger = quieter).

I have found the same, I once fitted a large straight through cylindrical muffler to my current 2.5" system and it was horrendously loud, whereas just swapping back to my current one results in a car that actually is pretty quiet. I didn't do any performance testing or backpressure measurement on the cylindrical muffler because to be honest it was just too embarrassingly loud I wouldn't have cared if it was better (and I think that is a point I need to remember and not get too carried away!!)

I'm going to call up my current exhaust silencer manufacturer and see if they have anything to say. Maybe the same design (I think it is an S flow) but in 3" might be the best balance, possibly with an additional straight through resonator in the system, of reducing restriction while maintaining adequate silencing. I know they generally produce a quieter performance exhaust, it is sort of their company ethos. From what I understand and have read the link between backpressure and power gets a bit hazy anyway once you get down to low backpressure values, particularly on low duration cam 4 valve engines.

Really do appreciate the input there though, and you posting the actual part numbers you used so I could compare. You obviously tried to develop the 3" system with a variety of updates, I need to tread with caution.

Tchaps

Soooo I sort of did what I said I was going to do, kind of

I got in touch with a motorsport exhaust fabricator here in the UK. They build performance and race exhausts, but most interesting have worked on a number of both road and track cars with 300hp NA 4 cylinder engines.

I explained the setup, what I was trying to do and the noise levels I would find acceptable. The advise was unsurprisingly fit the largest silencers you can, namely two of them, a mid and rear.

I measured up under the car and came to a 5" x 24" round mid silencer and a 8" x 24" round rear silencer, both straight through type. This passed the sense check with the exhaust shop, infact they were talking more in terms of how they prefer to over silence to make sure a car gets through noise checks, rather than thinking it would be borderline. This setup still gives me room to add a resonator ahead of the mid silencer if required.

This level of silencing is significantly more than they would use on a Millington equipped rally car (300+hp NA 4 cylinder), and more than they did on a couple of Retropower builds - look them up on youtube - Retropower Chevette and Retropower Alfa Junior GT. Again both 300hp NA 4 cylinder cars. I am hoping this will translate to my car well as I love the sound of both of those builds.

Oreo, the mid silencer in particular is almost twice the length and larger in diameter than the Magnaflow item you used, the back box size is more or less comparable, and as above I have the space to add resonator ahead of the mid silencer. So thanks again for the benchmark there.

Bit of a punt but hopefully it gets the results I'm after. Fingers crossed!

Zed.

looking good, who are you using for exhaust components?

fi & na are a bit different with their primary lengths, helps to have a 'mockup' engine


I'm adapting a 'Tony Law' manifold made for a Vauxhall 1.6 ecotec in a mk2 escort to fit a the 1.6 in my silver thing, bit more alteration / bending & it'll be good..

Rich.

Tchaps

Hi Zed,

That's a good looking manifold you've got there - pretty meaty! Liking the look of the dry sump pump too, very cool. I started reading through your build thread so far on Mighty 5s, good to see some weird and wonderful hybridding going on so far. I might get to the end of it by the time I'm 70 gives me some good reading so thanks for that!

The bends and piping are from FabCO - been really impressed with the quality, availability (1 7/8 can be a bit of a PITA for angle availability just on the bay) and delivery is quick.

Silencers are being made by Simpson Race Exhausts - not cheap, but they are repackable so should last a very long time.

I'm hoping to attend the 2021 Mighty 5s trackday in Llandow this year, that looks to be your neck of the woods, so hopefully see you there if you are going.

Zed.

Simpson are good, both quality & design - a friend of mine has one of their manifolds on his Focus WRC / Cosworth hybrid & it's a work of art

as to Llandow, it's ~40 miles away so I'll probably come for a looksee even if I've not got my car up&running (too many ideas & I've not bolted anything togther yet) the drysump is one of the stumbling-blocks as I'm designing evrything blind with other parts interaction needing consideration

Rich.

Tchaps

Hopefully I can do them justice with the rest of the exhaust / manifold!

Ha ha ha well the fiddling about wondering if stuff will work is half the fun anyway. Come say hello if you do, I'll take you out on track if we are allowed by then

Supercharger is back from being rebuilt now. It has cleaned up really nice only very very slight scoring in a couple of places in the case.

The correct high speed bearings are now installed with the right grease, new / correct seals, retimed rotors and the rotor bolts done up to the right torque this time, hopefully this resolves the shaving issue.

Hard to tell too much with it just sat on the table but the gear lash on the front end seems to have evened up around the entire rotation of the sc. Way back in this tread I mentioned that there was more lash at one rotational point than at the point 180deg opposite, this seems to have improved with the rebuild.

Zed.

bent shaft or unevenly fitted bearing?

if its sorted then don't worry...

Rich.

Tchaps

When I spoke to Dennis about it originally he said it was pretty normal, so not sure.

Also I don’t know if Pete greased the gears, which would reduce the sound / feel of the lash. The gear cases have to be set up correctly, concentric to the drive boss so I’m not going to take it off and check now that is set correct.

Tchaps

The silencers arrived earlier this week along with the 3" pipe and bends. Got the car in the air this afternoon and had a little look as to how it is all going to work.

The 5x24" mid silencer nestles nicely in the tunnel, leaving the frame rails as the lowest point of the car still. 6" would have made the silencer the lowest point which would have been annoying.

The bend between the collector and the silencer just needs to be a single 45deg which I was dead happy with as I thought it was going to take two bends to wiggle through there.

There is just enough length between the end of the bend leg and the silencer to fit my flexi joint and v band.

Out the other end of the mid silencer looks pretty simple too. Needs about a 10deg bend straight after the silencer to point the pipe just to one side of the diff, then a 30 deg upwards followed by a 60deg into the rear silencer. The rear silencer will be positioned diagonally under the boot floor.

Clearances all look fine, and I will mount it with enough mounts to ensure it doesn't hit things like the rear subframe under cornering.

Just worked it all out today then over the weekend I will start to tack stuff up.

One thing I will have to make a decision about is how to do the exhaust tip. I'm not sure whether to just go straight out the silencer at an angle to the car, or whether to do a bend out of the silencer to bring it back into carline. Either way I would just use a basic outward rolled end tip, I'm not a fan of overly fussy tips. I'm swaying to just straight out the silencer, but not sure if it would look a bit boy racer. Equally I think the end of the silencer is so close to the bumper that there isn't really room for a bend and it would just look a little odd. Any way let me know what you guys think. I might jump on MSpaint again, where I design basically everything.


Not a chance my welds are going to look as good as this!

Rear view

Big rear box across the boot floor

Mid silencer snugged up in the trans tunnel

Tchaps

Spent the afternoon working on the exhaust, happy with how its turning out.

I used pie cuts to get the bend into the rear silencer. They form a 60deg 1D bend, I realised that using a mandrel 1.5D bend would not be tight enough to give me the clearance I need between the subframe, diff and bumper. Using the Mig is easy and economical with the shielding gas and I have all the setting setup so it just penetrates the back of the joint, so they should be nice and strong, while not putting horrible dags into the pipe. The welds aren't as attractive on the outside as the silencer TIG welds, but I can't TIG like that anyway.

I've got the pipework from the back of the mid silencer out to the rear of the car tacked up and I have welded up the V band (I didn't warp it!) and flexi joint, which slip fits into the front of the mid silencer. From that I have eyed up the 45deg to the collector and it looks like it is all going to line up well. Its now just making sure I think about the order I tack / fully weld stuff up in, and making sure I don't snooker myself welding up a joint that I then find provides some needed adjustment for another part. Its for that reason I haven't welded the rear joint or front slip joint on the mid silencer yet so I can make small position alterations if required.

Tchaps

The manifold is pretty much complete, just need to weld on the egt sensor bungs now. I'm pretty happy with the result, I'm happy with the fit, lack of dags in the pipes but the welding in places is a little messier than I would like. The collector was a real pain to weld on nicely. I tried fettling its fit to the pipes but when I cut it it tended to spring into a worse shape. It was also remarkably resistance to assault by large hammer. I ended up buying a fresh one and took my time while welding the larger gaps. No.4 looks like it dumps into the collector at an angle but the collector hides most of the last bend on that primary. There are a few bits of light grinding marks that I will buff out, then I will degrease the whole thing so I can get it to go a nice uniform dark gold colour that stainless goes when heat cycled.





It all links up well with the rest of the exhaust, which is now basically fully welded. Only a couple of the pipe joins are just tacked, the rest are fully welded. After that I just need to do the hangars / mounts. I got hold of some bolt on exhaust mount rubbers, they are meant for an MGF, but I think they will work well for the rear box, bolted to the boot floor.

I put a bit of heat protection on the tunnel as the exhaust is pretty close to it, and I have my ECU quite close to that area.

Then I am going to get the hardware for the water injection in place. It will be easier to do the pipework etc without the supercharger in place. Also going to install a knock sensor and wire the ignition coils sequentially rather than batch fire while I am there. I think we are about 2 weeks from firing it all up again and seeing what a horrible mistake I have made going 3"

Tchaps

Bit the bullet today and ran the hardline for the water injection from the boot to engine bay.

I cut the ?petrol tank vapour breather pipe? (I think that is what it is) that normally runs from the tank to the carbon cannister in about the position of the fuel filter in the rear RH wheelarch, then I added a little mini filter to stop rubbish getting in it. I haven't run the carbon cannister for years and the end hose was just tucked into a hole on my front subframe, so I can't see how what I have done cutting the pipe short and adding a filter is any different to how it was before, except it cleared up a space on the fuel / brake line clips that run under the floor.

I found a grommet just behind the rear roll bar mount in the boot and drilled a little hole through it to pass the 1/4" hardline down through it, down the chassis leg to pick up the fuel and brake pipes. I then clipped it into the spare slot in the clips under the floor and up into the engine bay.

I have been umming and arring where to locate the PWM solenoid for the WI for a while. I wanted it to be pretty close to the nozzles, away from heat and accessible. This only really left two options, on the front chassis leg by the anti roll bar mount - maybe a little close to the radiator, but made the pipework easy, or how I have done it mounting it to the firewall by the brake booster. I thought getting the hardline threaded low enough to avoid any collisions with the supercharger intake would be tricky but it turned out to be alright. I will use a 180deg fitting out the end of the solenoid to bring the hose looping under the throttle body to the WI distribution manifold, that will be mounted from the cam cover bolts. I made a little aluminium bracket to mount the solenoid to the firewall.




The hardline is annodised aluminium and I thought it was going to be anodised both inside and out, but only the outside is. I'm not sure if that is going to be an issue if I went to higher methanol % than I currently intend. I need to research whether methanol only attacks aluminum in the presence of air or not (there shouldn't be any air in the pipes once the system is primed the first time unless I open the pipework for maintenance).

1/4" stainless hardline seems hard to come by in the UK for some reason.

Tchaps

I revisited the stainless tank for the WI this evening. I had stopped work on it because I had cleverly cut the sump for the pickup on the wrong side of the base plate and was having a nightmare drilling the holes for the pick up and low fluid sensor. I walked away rather than bashing it with a big hammer.

Anyway, a bit more research on how to drill holes in stainless has helped enormously. I was finding that I was just burning up drill bits trying to get through the stainless. I switched tactic to drilling with an extremely slow drill speed, not even minimum speed adjustment was slow enough. I was pulsing the trigger on the drill, just about keeping the bit moving while applying a lot of downward pressure. This worked excellently. I could see the stainless being removed in clean swirls of swarf and it went through in no time. It was quite counterintuitive but really worked. To get the large 22mm - 7/8" holes required to fit the pick up and low fluid sensor instead of trying to drill out to that size I bought a punch, and it worked great. Nice clean burr free holes.





I tacked up enough of the panels to test fit in the boot and it fits really well. It just about lets you fit it into the space with the sump in the boot area the jack used to sit.





I decided I wanted to TIG the tank together to get some good practise. I only started TIG welding about this time last year, and I am far from brilliant at it. There are parts of my supercharger system that I am really happy with the TIG welds, but they are few and far between. Most of it I would classify as adequate, and that is being nice, and I know this is really just down to a lack of practice with it. Unlike the manifold and exhaust I don't need to worry about upsetting air flow on the backside of joints on the tank so it was an ideal candidate to get some practise. There were a few bits that would need a little bit of gap fill, some holes to repair where I had been an ape tacking some bits of it together a month or so ago. It is 1.5mm thick so is not too fiddly but it would also easily burn through if I didn't get on with it.

Anyway, so far it is coming out great. Not going to win any weld **** awards but I got in a good rhythm, and I think I only dipped the tungsten twice in all the lengths done so far. I felt like I got the machine set up well. I think I am normally too cautious on the heat setting, and this results in the filler rod not going into the weld puddle well and coming up to the tungsten instead. This time I could see the filler rod soaking into the back of the pool under the tungsten as it should. I also managed to pick up my speed with it and did it in know time with very little gas use. One of my gripes with TIG is I always seem to use a ton of gas to make things, even with the flow rate set properly. I think this is due to my weld speed, and having the machine too cold. I just take too long to move along a seam.


Be nice I'm a delicate soul ;-)

Tchaps

Pretty much finished off the tank today, really happy how it turned out. This is the first thing I have ever TIG welded that I am really happy with the weld quality. Just remembered to take my time with it, get the settings right and don't just carry on if it starts to go wrong. Just stop, let it cool down then have another go. The tank features my TIG arch nemesis - fillet welds. These are around the breather fitting, filler neck and front face of the sump. I used a slightly higher amperage and a little more stick out to get right into the corner of the joint. The higher heat meant the filler actually went into the joint, rather than sitting on top and ending up on the tungsten.

The design incorporates a 'sump' that locates the pick up and low level sensor. The main floor of the tank goes most of the way across the top of the sump so I hope that water / meth that lives in here is peaceful and free from bubbles before it meets its noble end getting chucked through the engine.

I decided to put in a service plate on the top, these aren't the final bolts I was just out of suitable M5 fixings. This will allow me to clean it but also insert the anti surge open cell foam I am going to fill it with. This is just to stop 10kg of water sloshing all over the place which I think would be very hard going on the brackets I still need to make to mount it.

Its got a little -4 fitting on the top which is going to be the breather, and I drilled two holes in the side for some compression fixings for a sight tube to check the fluid level.

10 litre capacity not including the sump, so this *should* give me two petrol tanks worth of WI @ 15% WI / fuel ratio (the petrol tanks are about 35 litre I think? its a while since I've driven it now!)

Tchaps

Hi everyone, hopefully someone flowing my build has some answers to this one!

I am going to use my JB perf Tiny iox expander board to run the water injection system. To make this work how I want it needs to be able to run one of the programmable on / off outputs from a custom channel within the Tinyiox, and I am having some problems working this out.

I can create the channel, I go into the tools menu, custom channel editor, select the can device (Tinyiox) and create the channel. It creates a custom ini file in the project folder as expected and I can setup a gauge and datalog profile as you would do normally in Tunerstudio.

What I can't do however is select this new custom channel as a channel to operate the programmable on off outputs within the Tinyiox, it's not visible in the drop down menu. In fact I think all the channels that are driven mathematically from raw inputs are not visible in these drop downs (EGT 1, 2, 3 etc for example that is a calculation from a raw ADC value)

Created the channel within the Tinyiox

Trying to select custom channel to drive on off output in Tinyiox

Am I missing something like a lack of mathematical processing power on the Tinyiox?

Do I need to pass back the raw inputs received on the Tinyiox to my ECU (MS2V3) to handle the data processing to run the output?

The Tinyiox isn't installed in my car yet, just messing around in the software to see what it looks like it can do.

The overview of the setup I am trying to produce is like this:

Programmable on / off output to drive the pump relay, PWM out to drive the fast acting valve to progressively meter the water flow at a constant pump pressure (best atomisation at low flow rates).

Flow sensor for a failsafe. This produces a 5v square wave signal that I can feed into a PWM input - frequency determines the flow rate.

Create a channel to turn the flow sensor frequency into something more useful, ccmin or water/ fuel% etc.

Create a second channel that compares the PWM valve duty to the water flow rate and turns this into a numerical value.

Run a second programmable output on the tinyiox to activate when this second custom channel (PWM vs flow) is within acceptable limits to switch the ECU to the aggressive WI map.

Kdog47

Nice fabrication! I plan on picking up a TIG welder soon and explanations like this really helpful.

Tchaps

Thanks mate. Good luck with the TIG when you get it - don't get frustrated and keep at it! I'm fairly obviously no pro at it but I'll glad you found it useful.

After I posted the tank on the Miata DIY facebook group it did turn out that I overlooked a key point in fabricating the tank out of stainless. I didn't back purge it when welding and as a result I will need to give it a very good clean on the inside before I use it. I didn't mind if the weld went all the way through because it didn't need to be smooth like an exhaust manifold inside. However the 'sugar' that forms on the unprotected weld is quite gritty, and the loose stuff will need removing or it will block the WI nozzles.

Its also a bit hot - I think I took it a little too far the other way from my normal too cold. I also think the reason the welds are grey rather than gold, apart from the excess heart is the lack of backpurge. I think oxidised stainless from the unprotected rear of the weld is flowing through to the top of the weld. When I tacked on the nuts under the maintenance hatch I used a low heat and the weld pool did not go all the way through the material, and the welds were the classic stainless pretty golds and purple colours.

But live and learn. If I can't get the grit out of it I will make an aluminium version - I hope it doesn't come to that but I'd rather spend the £50-70 it would cost to remake the tank than run the risk of the grit getting into the WI nozzles.

On the Tinyiox output question above I have realised that even in my MS2V3 I can't drive a programmable on off output by a custom channel. Bit of a PITA but I think I still run the failsafe from the tinyiox just slightly simplified - just a min and max flow rather than comparing it to the valve duty. Still think this is superior to just running a pressure sensor which on a system with a fixed pressure self regulating pump would only flag if there was a failure of the pump or the electronics driving the pump, or an empty tank. It wouldn't show a PWM valve fault, burst or loose pipe or blocked nozzle.

Tchaps

Finished off adding the WI nozzles to the manifold. The nozzles are canted back to allow the feed tubes to avoid the fuel rail and injectors but also to aim more down towards the valves, like the fuel injectors. I have shaped the ports so the bottom of the nozzles sit exactly at the top of the port without sticking into the airflow, with the area downstream of the nozzle hogged out a bit and shaped to make sure there are no quick angle changes or flow obstructions. I also spent a bit of time honing the radiuses at the entry to the port runners, smoothing the welds and increasing the radius of the corners to try to optimise flow as much as possible.




I have also added the pre sc nozzle to the inlet. This turned out to be a total nobber to weld. I knew it would be because the inlet is not something I want to have to remake because I have melted a big hole in it. Anyway third time lucky I managed to weld a boss to it that angled the nozzle how I wanted at the right depth. Still need to do the final finishing but its basically there.

Tchaps

Steady progress made.

I've installed a K type thermocouple in the chargecooler to measure air temps after the supercharger but before it is cooled in the chargecooler. I'm using a thermocouple because it is just about compact enough to fit (1/8npt vs a normal M12 or 3/8npt temp sensor). Downside is I will have to amplify the signal using an AD595 chip in my MS2. These chips put out a 0-12.5V for temps between 0-1250degC. I am going to feed this signal into an ADC input. I will clip the signal at 5v with a zener diode so I get a temp range 0-500degC for 0-5V input. Hopefully that will be good enough resolution to see temp differences at different pulley ratios, ambient temps and water injection. If its not I may try to amplify the signal with a direct coupled amplifier with a gain of 2, 0-2.5v from the AD595 would give me all the range I need temp wise, and I could amplify that to be 0-5v to double the resolution.




I am also going to put two temperature sensors in my charge cooler pre radiator, one in the inlet one in the outlet so I can gather that data too. All this should mean I will have a very accurate picture as to what is going on temperature and efficiency wise in the supercharger / chargecooler system.

I also made the little bracket to support the WI injection distribution block for the WI. Looks pretty smart IMHO but I am biased