Megasquirt on a V8 build

[v8GTmac1]

 

 

Edited March 16, 2021 by v8GTmac1

[cammmy]

Yeah, I'm a broken record when it comes to running multiple ECU's X-D. I have no issue running batch fire, that's what I do on mine. If you ditch the secondaries and size the primaries accordingly, you don't need an MS3/X.

The one thing I will say about the MS. Don't go into it looking to save money unless you have a tuner who will work with them at a decent rate. A lot of tuners won't touch them. I have one that does but they are very high end and charge £120 an hour (and possibly VAT on top of that.) So I likely could have saved money going with a more expensive ECU and a cheaper tuner. Pick your ECU based on your tuner, rather than the other way around.

[alanlambert]

1 hour ago, v8GTmac1 said:

If I was to do it again which I will, while the engine is out I would do all the wiring going everywhere it needs to go like gauges, fuel pump relay. My current state is a wiring nightmare to most but oh boy does she run great! 155mph so far. 

Remember to shop for replacement primary injectors, mine are from a 2000 Mustang Cobra. with MS3x you can run all 10 injectors no problem with the secondaries being LOW impedance. 

But I have to say that I did go away from the OEM ckp sensor and mounted a 36-1 wheel on the harmonic balancer, fabricated a bracket to hold a VR crank sensor and I am still using the CAM sensor for full sequential but thats only because I also got rid of the OEM coilpacks. 

here is my initial success story https://www.msextra.com/forums/viewtopic.php?f=104&t=72257

and btw, if I cant help from overseas, there are 10x better MS gurus in different parts of UK that can be of service. 

I run mine on an Emerald ECU but only use original wasted spark coils and leads.

[v8GTmac1]

6 hours ago, cammmy said:

Yeah, I'm a broken record when it comes to running multiple ECU's X-D. I have no issue running batch fire, that's what I do on mine. If you ditch the secondaries and size the primaries accordingly, you don't need an MS3/X.

The one thing I will say about the MS. Don't go into it looking to save money unless you have a tuner who will work with them at a decent rate. A lot of tuners won't touch them. I have one that does but they are very high end and charge £120 an hour (and possibly VAT on top of that.) So I likely could have saved money going with a more expensive ECU and a cheaper tuner. Pick your ECU based on your tuner, rather than the other way around.

Very valid points. I wonder if the MS people you talked to are the same ones i'm thinking of.

And yes I would also get bigger primary injectors next time around. currently I have 24lb and I dont have a rising rate FPR anymore. I bought a replacement off ebay and didnt know the OEM fpr was rising rate till just recently when someone here mentioned it. Probably why my fuel pressures are different then the rest. 

[cammmy]

A lot of what I know comes from here:

https://books.google.co.uk/books/about/Performance_Fuel_Injection_Systems.html?id=Vxi5NAEACAAJ&redir_esc=y

I would consider this (or a similar but newer one) mandatory reading before undertaking any EFI project for the first time. It's written by the distributors of MS is the states but it covers all makes.

Ah right, your pressure reg isn't boost referenced then? Would it be cheaper and easier to replace it with one that is rather than getting new injectors? Rising rate just accounts for boost/vacuum. If you have 50psi of fuel pressure pushing fuel out of the injector and 10psi of boost resisting it, your effective pressure is 40psi and your flow will reduce. Under vacuum it will increase. The boost referenced regulator adds or subtracts the same amount of pressure from the rail, so your ECU doesn't have to calculate the difference and it will allow your injectors to flow a bit more under boost. This is why you should set them when the engine is off.

Edited March 17, 2021 by cammmy

[v8GTmac1]

17 hours ago, alanlambert said:

I run mine on an Emerald ECU but only use original wasted spark coils and leads.

i have seen this car on the internet long ago.   Now I get to see the details. 😁

I have to ask, how do you like the Emerald,  does it have everything you could ever want? Enough outputs for what you need?

Edited March 17, 2021 by v8GTmac1

[mike_sekinger]

I'm running a Motec M800 with twin wideband enabled if anyone want to follow that route.

[v8GTmac1]

6 hours ago, cammmy said:

A lot of what I know comes from here:

https://books.google.co.uk/books/about/Performance_Fuel_Injection_Systems.html?id=Vxi5NAEACAAJ&redir_esc=y

I would consider this (or a similar but newer one) mandatory reading before undertaking any EFI project for the first time. It's written by the distributors of MS is the states but it covers all makes.

Ah right, your pressure reg isn't boost referenced then? Would it be cheaper and easier to replace it with one that is rather than getting new injectors? Rising rate just accounts for boost/vacuum. If you have 50psi of fuel pressure pushing fuel out of the injector and 10psi of boost resisting it, your effective pressure is 40psi and your flow will reduce. Under vacuum it will increase. The boost referenced regulator adds or subtracts the same amount of pressure from the rail, so your ECU doesn't have to calculate the difference and it will allow your injectors to flow a bit more under boost. This is why you should set them when the engine is off.

YOu brought back physics into my world & maybe thats why my F.P. datalogs are so erratic. I have been so tied up with the electronic circuits that I forgot those fundamentals. So being reminded about that I have to make changes again. I would prefer a new FPR over new injectors & Aeromotive to my knowledge is the only company making a rising rate adjustable FPR. I simply dislike having only 1 option and it's my driving force into diy approach. 

I still have my stock FPR just looked to be a little leaky which is why I replaced it, So now i'm gonna put it back on and verify that my pressures changes and is more steady then I will most likely CAD design a rail adapter O-ring to -an and run any adjustable FPR that's rising rate. 

[snowrx]

12 hours ago, v8GTmac1 said:

And yes I would also get bigger primary injectors next time around. currently I have 24lb and I dont have a rising rate FPR anymore. I bought a replacement off ebay and didnt know the OEM fpr was rising rate till just recently when someone here mentioned it. Probably why my fuel pressures are different then the rest. 

My thought is that a rising rate FPR is a hardware crutch for those without the programmability to compensate for boost fuel needs. There's enough variables changing in the engine without the ECU not knowing how much fuel will go in per ms of injector pulse. 

If there's not enough duty cycle headroom with your injectors, perhaps running a higher base fuel pressure?  Going from 3 > 4 bar might get you 15% more flow with the existing injectors.

[alanlambert]

46 minutes ago, snowrx said:

My thought is that a rising rate FPR is a hardware crutch for those without the programmability to compensate for boost fuel needs. There's enough variables changing in the engine without the ECU not knowing how much fuel will go in per ms of injector pulse. 

If there's not enough duty cycle headroom with your injectors, perhaps running a higher base fuel pressure?  Going from 3 > 4 bar might get you 15% more flow with the existing injectors.

My fuel pressure is 58psi (4bar) is this not standard ??

 

[cammmy]

1 hour ago, v8GTmac1 said:

Aeromotive to my knowledge is the only company making a rising rate adjustable FPR. I simply dislike having only 1 option and it's my driving force into diy approach. 

 

There should be plenty of options available. Try searching "manifold referenced", "boost referenced" or "vacuum referenced"

Mine is a Sytec.

[alanlambert]

1 hour ago, v8GTmac1 said:

i have seen this car on the internet long ago.   Now I get to see the details. 😁

I have to ask, how do you like the Emerald,  does it have everything you could ever want? Enough outputs for what you need?

Had no issues with the Emerald but i am a numpty with electronics so have not fiddled with it since i fitted it then Emerald mapped it. At the time i didnt have enough fuel pressure so it was going lean as boost come up and we didnt configure the secondary injectors.

I would like to leave them out of the equation and just run on 8 primary injectors (obviously larger than the rochester originals.

If i was shooting for 400bhp and my fuel pressure is 4 bar, 90% injector cycle and BSFC of .6, what injectors would you reccommend.

Currently looking for 350cc but i might have got my knickers in a twist converting Lbs to cc's and 3 bar to 4 bar ?

any thoughts.

Ta.

alan

[cammmy]

1 hour ago, snowrx said:

My thought is that a rising rate FPR is a hardware crutch for those without the programmability to compensate for boost fuel needs. There's enough variables changing in the engine without the ECU not knowing how much fuel will go in per ms of injector pulse.

I'm not an engine builder but I think it's 6 of one and half a dozen of the other. A boost referenced regulator means the ECU is doing less work, as flow through the injectors should remain the same and it's not making any compensation calculations. There's probably an argument that it may not react quick enough Vs using pulsewidth on the Injectors to compensate but I would need to see logs to be convinced, as it's a well trodden and seemingly reliable path. The ECU doesn't know for certain how much fuel is going in unless a fuel pressure sensor is added into the mix but, that is something seperate.

It really comes down to an individual's situation. If you are building from scratch then speccing the injectors to suit a non-referenced setup is fine, but if you have already spent a considerable sum on 10 injectors, it's a fraction of the price for a good regulator Vs replacing them again. As long as you end up with (ideally) sub 80% duty cycle when all is said and done though (I believe 90% is also common). Both are perfectly valid options to reach the same end goal.

Edited March 17, 2021 by cammmy

[snowrx]

@alanLambert

I was talking in general and mentioned 3 bar as it's kind of the default for a lot of systems, if 4 is normal for your car then bumping up to 5 is might be a bit of a load on most fuel pumps as flow drops off on most of them at higher pressures. But a rising rate regulator is going to increase FP also.

@cammmy

A common boost or manifold referenced regulator is going to adjust  FP at a 1:1 ratio to manifold pressure, keeping differential (and injector flow) the same. A rising rate regulator is a different animal, adding more FP per unit of manifold pressure (e.g. 2:1 or some such). I don't know which type of regulator is/was on v8mac1's car, but he said rising, which would enrichen with increasing boost if the pump keeps up.

[cammmy]

16 hours ago, snowrx said:

@cammmy

A common boost or manifold referenced regulator is going to adjust  FP at a 1:1 ratio to manifold pressure, keeping differential (and injector flow) the same. A rising rate regulator is a different animal, adding more FP per unit of manifold pressure (e.g. 2:1 or some such). I don't know which type of regulator is/was on v8mac1's car, but he said rising, which would enrichen with increasing boost if the pump keeps up.

Ah, fair point. I missed that. I was only talking about manifold referenced. I don't see much point to rising rate unless  maybe you have mahoosive injectors and are struggling with them at low load. You could reduce the fuel pressure to give you higher opening times. I would imagine a fuel pressure sensor is very much required for that though

[v8GTmac1]

23 hours ago, cammmy said:

There should be plenty of options available. Try searching "manifold referenced", "boost referenced" or "vacuum referenced"

 Mine is a Sytec.

cammmy, 

If you look closely where the FPR is on the 918, i'm sorta convinced there is actually No option. THis style Aeromotive is for the GM LT-1 COrvette/Camaro. 

THe other 2 I have seen are way bulkier.   THis style Aeromotive is for the GM LT-1 COrvette/CamaroSo I have to design my own adapter and relocate the FPR 😬

https://www.supermotors.net/getfile/1164433/fullsize/wont-fit.jpg

 

snowrx, 

I dont know if my generic FPR is 1:1 but it's a oem replacment for a '02 Corvette/Camaro. It looks identical to the original so it might be the same exact part. 

Remember the V8 guys have dual fuel pumps and maybe that was to make up for something? 

 

Alanlambert,

the direct drop in replacments I purchased are stock flowing and for someone like you wanting to reach higher HP without the secondaries then I would prolly use one the many online calculators, but maybe more then one and find a consistent answer to what size injector to use. 

58psi base pressure is pretty high !

Edited March 18, 2021 by v8GTmac1

[snowrx]

Yes, the dual pumps are making more sense to me now. Perhaps they were compensating with FP for poor large OEM injector availability at the time.

[v8GTmac1]

On 17/03/2021 at 08:55, mike_sekinger said:

I'm running a Motec M800 with twin wideband enabled if anyone want to follow that route.

i'm sure that Motec has no trouble tuning everything and anything, maybe even does it's only auto tuning/learning on it's on while you drive. On MS you have to have the laptop running for autotune to do it's thing. 

Did you manage to fit an aftermarket FPR ?

 

Snowrx, 

I think the original EFI Tech company who provided the ECU found it easier to tune with smaller injectors and higher PW for a stable idle rather then the other way around. I know that is a known fact. 

[mike_sekinger]

It's running with the stock FPR. 

[alanlambert]

2 hours ago, v8GTmac1 said:

cammmy, 

If you look closely where the FPR is on the 918, i'm sorta convinced there is actually No option. THis style Aeromotive is for the GM LT-1 COrvette/Camaro. 

THe other 2 I have seen are way bulkier.   THis style Aeromotive is for the GM LT-1 COrvette/CamaroSo I have to design my own adapter and relocate the FPR 😬

https://www.supermotors.net/getfile/1164433/fullsize/wont-fit.jpg

 

snowrx, 

I dont know if my generic FPR is 1:1 but it's a oem replacment for a '02 Corvette/Camaro. It looks identical to the original so it might be the same exact part. 

Remember the V8 guys have dual fuel pumps and maybe that was to make up for something? 

 

Alanlambert,

the direct drop in replacments I purchased are stock flowing and for someone like you wanting to reach higher HP without the secondaries then I would prolly use one the many online calculators, but maybe more then one and find a consistent answer to what size injector to use. 

58psi base pressure is pretty high !

Yes ive looked at numerous on line sites, no two give the same answer, but Witchhunter seems logical i just have to keep adjusting their data to compensate for my 58psi fuel pressure as i think their calcs are based on 40psi.

Also higher pressure means the injectors can be smaller so better for low end driving, so no bad thing