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#121 na8cgee


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Posted 06 May 2020 - 07:57 PM

Hey Dickie,

172bhp is still a good result, it will be interesting to see your torque curve with those cams. The cams are pretty similar to the ones I'll be using, although my lift at TDC is balanced at 2.2mm for each cam whereas yours is more inlet biased, which makes sense because the mx5 heads without doing major porting have an abundance of exhaust flow compared to inlet flow.

I've had a good 48 hours on the build, firstly I finished up mock building the ITB setup:


I'm still using the jenvey DCOE manifold but it heavily reworked to maintain port size in relation to the new inlet port shape. the ITB's are mounted on an Dan ST performance Inverter plate as I need to run the injectors underneath the throttle bodies for improved mixing / increase the fuel to port coverage. I think I'm going to dismantle the inverter plates and remove some excess material now as my next plan for the car this coming winter is weight reduction so I might as well do that now!

The injectors are a fantastic little unit, I believe they come from the BMW motorbike range (potentially s1000rr superbike but I can't completely remember). Main reason for using them was the improved inejctor nozzle design/shape. the old injectors I was using, which were NB mk2.5 purples, had a 2 cone spray design and isn't really ideal when they are mounted on the ITBs. The new injectors are a single cone spray with 75% of the fuel concentrated within a 20 degree cone angle. By utilising this spray cone design, mounting the injectors underneath the port and injecting up to the roof of the port I can improve air/fuel homogenisation per injector pulse. Also, by injecting to the port roof it means 1 injector pulses worth of fuel is exposed to the airflow of the port twice, which should improve high rpm mixing. I put an allen key through the injector port to show the new injection path, its not ideal but much better than spraying it to the port floor where it will potentially start pooling (which is something I saw with the last engine setup).


The main downside to these injectors is that they are not fully plug and play, I need to resolve the injector nozzle protrusion issue first:


To remedy this I'm looking into fitting a double O-Ring seal setup which will push the injector back up into the housing but if that doesn't work I'll order some custom spacers out of a rubber material, something like viton.

In other great news, I had some good parcels delivered today:


Firstly piper came through and got the cams sorted out asap which was great, always get good service from the team. I ordered an 86mm head gasket & 2 slide pulleys from Maruha and once again fantastic service from Ogino-san, they arrived quicker than I expected!

I'm fully committed to the 86mm bore x 85mm stroke engine build, I didn't think I would be able to say I have an oversquare BP engine but here I am! the end capacity for the engine will be 1975cc which is cool.

my supertech valve springs haven't been shipped yet but they are due arrive next week sometime so I can't fully build the head up just yet. I originally modified the combustion chambers for a 84.5mm bore so I might try a bit more inlet valve de-shrouding on my test head to see what gains are available but I'm fairly certain I was at diminishing returns at 84.5mm anyway - Worth checking though as it will be free power if it wants to flow more!
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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

#122 Zed.



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Posted 07 May 2020 - 08:18 AM

Interesting that you are looking to run the injectors from below, I discussed this with my local (tame :whistle: ) dyno operator & he was of the opinion that Jenvey had reserched into positioning with the result being from the top of the port :confused:

I'm using Hayabusa itb's and as with most motorcycle engines these rin the injectors from below, these are easily turned as a bank to inject from above :thumb-up:

I've wondered if this was for space & packaging reasons as much as for oughtright power @ high revs :popcorn:


we had discussed running both positions on the dyno as its easy to swap orientation with the motorcycle 'slip-joint' rubber connections onto the manifold, will it make a diference to a 1.6/1.7L? - fucknose but it's interesting :yes: 

also, the 1.6 differs to the 1.8 as it has its injectors mounted in the inlet manifold, I've a Jenvey dcoe type manifold & cannot use the bosses that are cast in due to proximity to the tb flange :rant:   I've wondered what the diference in length (from injector to valves)  might make?


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50 Shades of Silver. '91 NA6CE, Not a show car :driving: 
Ohlins dampers, COP conversion, 4.778:1 & more ideas than time :yes:
Bodger :ph34r:

#123 dadbif


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Posted 07 May 2020 - 09:15 PM

Better atomisation?
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#124 Dickie


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Posted 08 May 2020 - 07:07 PM

Talking of which, a dual injector system with a rev based switching point will give benefits for high performance.

Really high reving engine have the injectors outside the bellmouth.

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#125 na8cgee


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Posted 08 May 2020 - 09:43 PM

Injector position is dependent on where you want optimal atomisation of the fuel to occur. The higher the rpm the further back you need the injectors, or as Dickie says you can use two sets to get a broader atomisation benefit.

Injectors being mounting underneath gives you a little improvement with high rpm mixing as the fuel injection pulse ‘sees’ the airflow stream twice, once injecting through the airflow then second as it its the port roof and falls back down under gravity.

Jenvey has optimised the injector position by injecting straight into the turbulent air caused by the throttle body plates trailing edge, this will certainly aid in fuel/air mixing but it can be improved.

I think injectors being mounted underneath has a bad reputation because people think it will work better at all stages of the RPM range but it doesn’t. My research/conversations seems to show a benefit only higher up in the range and it’s only a slight benefit (we are probably only talking 1-2bhp at 250bhp levels on a 4 cylinder and only any benefit past 6000-7000rpm).

My head/port design compliments this injector position also as when I was velocity mapping the port roof was ever so slightly higher in velocity than the floor, so best to try and get the fuel up there! (I couldn’t 100% balance the velocity gradient within the port as I needed to add material to the floor which I didn’t fancy doing)

Today was a good productive day, now I’ve committed to the 86mm bore I decided to see how much more valve de-shrouding was available:



Yep definitely a good amount of material that could be removed and improve flow throughout the valve lift ranges. Decided to visualise the valve shrouding at max lift:


Definitely can be improved, so marked the head out with gold pen (only sharpie colour I could find!):


There was no need to go any further towards the exhaust valve as the inlet valves were already ‘Geometrically de-shrouded’ according to vizard.

All sealed up with some spare 33mm valves ready for working on:


The results:




Much better, the chambers are very much Apple shaped, once you see it you can’t unsee it!

Decided to remove the inverter plates to remove the excess material. All marked up ready for working on:




Not my prettiest or best job but it saved 400g of weight! I really don’t enjoy doing the gram by gram method but it’s free performance!

Next step is making sure all the bolts are just the right length before lociting them in place;


Mark them up with a sharpie, take them off and trim. Very boring stuff but I will be doing the whole car on a gram by gram method so I thought might as well do this part now to save me taking the engine out later.

Aim tomorrow is to build up the throttle bodies and finish up the injector install. my o-rings that I ordered came in record time so should go quite well tomorrow!

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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

#126 na8cgee


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Posted 10 May 2020 - 06:01 PM

I completely forgot to update this from yesterday!

first up was getting the injectors mounted, using my new viton O-rings I've gone for a dual O-ring setup as the injectors come pre-installed with nice O-ring seat. The first challenge was the new injector height being smaller meant my aluminium stand-off spacers were too big:


Easily solved with a couple of washers


Don't worry, the orange O-ring is not really doing any sealing as the new black viton one before it is well seated. This meant my injector nozzle position could be easily adjusted by using more or less washers and the end result was pretty good:


Finally, the Induction system was build up including fitting the Tomei AFPR onto the opposite side due to the throttle bodies being inverted from their previous position.


I forgot the ev14 injectors have different electrical connectors so I ordered up a conversion harness, not much more expensive to buy them pre-made then to actually buy the connectors which is mad but saves me some time.

Started to un-box the cams and start double checking cam clearances. First up was the camshaft bearing oil clearance, using correctly sized plastigauge:



after following the torque sequence/correct torque settings here we have our results:



thankfully they were slap bang in the middle of the specs on both cams so I was happy with that.

Next step was to confirm lobe to lifter bore clearance, I didn't feel any resistance during hand rotation but always worth checking:



Interestingly, I had 60 thou clearance on the intake and 50 thou on the exhaust, with the exhaust lifter bosses being visually chunkier in material. No idea why, I’d guess mould issues or a bit of core shift but 50 thou is enough so no mods needed thankfully.

the next steps of the engine build for me are:

- Get the block hot washed/stripped to bare metal
- get the cylinder head cleaned again (Still found some porting shavings in from the combustion chamber work)
- get the oil pump housing vapour blasted and rebuilt
- Hope my valve spring kit arrives next week so I can start the custom piston order!
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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

#127 na8cgee


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Posted 28 May 2020 - 12:22 PM

getting back on track with the engine build - Lots of parts have arrived and good progress being made!

First being my supertech valve springs finally arrived, they were on back order and took some time to arrive. Good news is they look great and give good spring rates for the new cams (Whilst permitting 11.5mm lift).


Moving onto the engine building side of things, the first big progress step is the 86mm torque plate. The machine shop did a great job and matched the plate thickness to the same as the cylinder head head stud boss thickness as we are trying to simulate the head being on the block during boring as close as possible:



After de-shrouding the valves previously, I decided to skim the head a further 20 thou meaning that the head has a total of 120 thou taken off. The main reason for doing this was to try and de-shroud the inlet valves as much as possible and by removing this amount of material the back of the valve is completely de-shrouded once its 2mm off its seat (Or in my case at all times as my cams are 2.2mm open at TDC without any adjustment). downside to this means the valve centreline to the piston has changed significantly but this can be remedied with custom pistons.


I also had the crankshaft journals polished just for good measure whilst I had parts in the machine shop:


Custom pistons ordering was the next big challenge for me, I've never done it before so its been a steep learning curve but I'm enjoying it all the same.

First step was to mark the valve centrelines into a stock piston:


as you can see the 120 thou head skim has caused the valve centreline to move away from the OEM piston valve pockets - this turned out to be a big issue as I found out later on!

Second step was to put the piston at TDC and measure the 'valve free drop' which is the distance between the valve being fully seated vs the valve touching the piston when pressed down with the piston at TDC (This was done at zero Lash so you have to account for lash after the fact).

My measurements after lash were 2.57mm intake and 3.46mm Exhaust. This really isn't great as when you account for the valves being 2.2mm off the seat at TDC thats only 0.37mm clearance on the inlet!

The next step was the time up the cams and take some measurements with the valve drop at various points (5, 10. 15 Degrees before and after TDC).

The measurements turned out to be pretty pointless as the valve pockets in the piston were not aligned with the valve centreline (This ended up simulating a piston with no valve pockets at all until AROUND 15 degrees before & after TDC).

for completeness this were the measurements:

Intake at 5 degrees - 3.3mm (No valve pocket assistance here)
Intake at 10 degrees - 3.55mm (No valve pocket assistance here)
Intake at 15 degrees - 8.65mm (Valve pocket did assist but had to push valve down hard due to touching back of valve pocket cut out - I.E not enough radial clearance)

Exhaust at 5 degrees - 6.54mm (Valve pocket did assist but had to push valve down hard due to touching back of valve pocket cut out - I.E not enough radial clearance)
Exhaust at 10 degrees - 7.64mm (Valve pocket did assist but had to push valve down hard due to touching back of valve pocket cut out - I.E not enough radial clearance)
Exhaust at 15 degrees - 8.24mm (100% Valve pocket assist no touching)



The first picture shows the inlet valve pocket rim edge has been cleaned up because of the inlet valve touching it! The second picture shows the valve pocket internal wall being cleaned as the exhaust valve was riding this wall when pressing down (this was the resistance felt)

Basically I didn't learn much from the above measuring exercise other than I definitely need custom pistons with this setup (Stock pistons definitely a no-go, even aftermarket pistons might have an incorrect valve pocket position due to large head shave).

So the next step is to figure out how much valve lift I have per crank degree so I can calculate a safe piston to valve clearance (I.E valve pocket depth). Piper cams have stepped in to help and will be providing this information to me shortly we can make the custom piston suitable to protect against any valves touching pistons!

I am also starting to check valve to valve clearance with different cam gear timing settings to determine a safe adjustment zone but I'll write more about that once I'm finished!
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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

#128 na8cgee


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Posted 18 June 2020 - 02:39 PM

Custom pistons are a very complex thing!

It's taken me quite some time but I have finally placed an order with JE for a set of custom forged pistons.

I have chosen the following piston with some options:

- 86mm piston (2618 alloy)
- 1.0mm top / 1.2mm second / 2.8mm oil ring pack. Slighty less than OEM tension, roughly 20% less.
- FSR style forging
- Race spec pins & locks
- lateral gas ports
- Accumulator grooves
- Tuff skirt coating
- Undercrown milling

The difficult aspect of the custom pistons was achieving the correct valve pocket depth & position which should allow me to swing the cams around on the dyno and maintain a good valve to piston clearance. The Maruha adjustable cam gears have a lot of adjustment and can make drastic changes to the V-P clearance with little movement on the gears. In the end I had to settle for only being the set the cams up on a 105LSA on the cams. anything tighter than 105 LSA reduces my valve to piston clearance too much and starts to require excessive valve pocket depths.


The downside the larger valve pockets in the piston means I have to run the ring pack lower in the piston which means more crevice area (Loose power here) and the piston dome has to become higher to achieve the correct CC I need (Again loose power with bigger domes, ideal piston shape for combustion is completely flat/slightly dished and bigger domes means less effective scavenging during overlap).

With the above adjustments in mind I calculated the valve lift from TDC to 15 BDTC for the exhaust and TDC to 15 ATDC for the intake which was required to set the correct valve pocket depth. Long story short I ended up with 4.6mm intake and 3.5mm exhaust valve pocket depth in the pistons. The intake valve pocket is alot deeper due to the intake valve free drop only being 0.6mm vs the exhaust valve at 2.8mm.

For reference I aimed for V-P clearance of 1.5mm intake and 2.5mm exhaust (exhaust valve needs more due to valve expansion and piston chasing the valve). Radial clearance of 1.5mm for both valves as well. These figures are based on a design criteria of 9000rpm rev limit although it is unlikely to be revving that high unless the exhaust manifold is revised (Which is a possibility!)

The take away from this is shaving the head 0.120" means the intake valves are very close the deck height/top of the piston especially when you start to optimise the squish/quench distance.

anyway enough blabbing, here's some cool CAD pictures of the pistons:




Downside to custom pistons is the long lead time, currently looking at 5 weeks roughly although this could change due to COVID 19 and the current situation we all face.

Moving on to the bottom end of the engine, I double checked my main bearing clearance with a dry mock up build using the king main bearings and ARP main studs. The clearances were exactly where I wanted them and very consistent across the board. The rod bearing clearances will be the next to be checked but that will be done soon.



The oil pump casing has been thoroughly cleaned and is ready for rebuilding with the billet gears and 72psi shim, just another job I need to finish off (Originally I was going to wait until I was building the actual engine but the assembly lube I am going to use throughout can last upto 3 months when applied so no reason why I can't build the pump up now and get it on the shelf ready).

I have ordered a full set of OEM gaskets from BOFI and mx5parts (depending on who had stock of what) so once the Intake & exhaust valve stem seals arrive I will be building the head up ready to measure and purchase valve caps to set the lash on the valvetrain.

Its been slightly slow progress recently but I'm starting to see the light at the end of the tunnel now the pistons are on order!

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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

#129 1outof5


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Posted 19 June 2020 - 04:13 PM

always amazed how thorough this is going    :thumb-up2:

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#130 na8cgee


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Posted 24 June 2020 - 03:44 PM

thanks 1outof5, our conversation over oil pumps got me thinking about updating this thread about the oil side of things!

The engine's expected usage is 10-15 lap sessions on a trackday then cool off and street miles so oil temperature/pressure control needs to be addressed. The last engine just utilised the OEM oil cooler which although I never had any castastrophic failures I did feel I was on borrowed time hustling the car on track without any idea of my oil temps/pressures. With this engine I wanted to take all variables out of the equation so it meant a means of controlling oil temperature and ensuring I had enough oil pressure/flow upto 9000rpm.

Here's the oil side specs:

- VVT oil pump with boundary gears & 72 psi shim
- Mishimoto thermostatic oil sandwich plate (using 92 degree stat)
- Laminova oil cooler using AN10 lines/fittings.
- Oil Temp & pressure gauge (Combined gauge, probably a SPA unit as I've used these before with great success)

The oil to water cooler was a really good solution for my car, mainly for packaging reasons and the car has always had an abundance of cooling capacity on the front end (I ordered a very thick polo radiator at the start of the build).i could never get my coolant temperatures to rise above 100 degrees, usually hovering around 95 after 15 laps on a 2minute per lap track. I also haven't ducted my radiator yet so I have even more capacity to improve cooling should I need it.

The laminova is slighty larger than I need to be honest, being the 180mm version, I'm fairly confident I could have used the 90mm but this one came up at a great price. Due to it being a used item, I decided to strip the unit down, clean it up and replace all the 0-rings and gaskets. Here's what this looked like:





and after a quick clean up:


The laminova helps me keep the oil lines as short as possible, which means less pressure drop and I can position the oil cooler away from the nose of the car (Unlike your standard oil to air) so if I come off the track and hit something front end on the oil system integrity is maintained.

The thermostatic oil plate is crucial to achieving the correct oil temperature during street drives. The car being so light/no requiring much power to get it moving at a 'normal' driving pace the car can sometimes struggle to warm up, the last thing I need is the engine & the oil to be colder than optimal. My ideal oil temperature will be around 95-100 degrees for street work, with a maximum oil temperature limit of 125 degrees, I'm fairly certain the modern synthetic oils can survive above 125 degrees but I can imagine the oil quality degrading very fast at higher temperatures.

On the coolant system side of things, I will be running a 82 degree stat (previously used a 72 degree but again struggled to warm the engine up sufficiently). It may prove with testing that the 72 degree is the better option with the laminova equipped but we'll see (I'd rather get the engine & oil temperatures higher/in the right region and work backwards than the other way around!).
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Trying to achieve 220+bhp and 180+ftlb naturally aspirated

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