131 replies to this topic

[Curley]

This really is an exceptional build.

Ball park figure, what kind of money would it take to acquire a similar engine?

 

Do we include the gearbox and diff? Truth is the short block + head were very reasonable. I'm using a stock crank, rods, pistons  - all be it balanced - with a heavily worked MPI casting. Assuming you had the engine already & the gearbox serviceable, (no reason to go SC anything on a road car), maybe £1500 'up North to £2500 'down South.

 

It's the EFI conversion that adds additional cost & there are way to many individual choices that need to be made that affect the price for me to say X = Y. I recon you could get as good results with a set of SU or Webers without any of the hassle of going EFI! Just look at the Miglia engine spec.

Edited by Curley, 13 September 2020 - 06:46 PM.

[Curley]

Thanks Nic! I have bungs for the three round holes. Was planning to #racecar the fill lines with a goop of intumescent corking.

[nicklouse]

Thanks Nic! I have bungs for the three round holes. Was planning to #racecar the fill lines with a goop of intumescent corking.

Gold stuff but so much easier later if you don’t goop the hoses etc in place.

[no66]

When you set the corner weights and hight, how did you meaure ride hight? Sill to ground? 

Thanks

[Curley]

The way I do it is to measure from the seam at the sills to the floor. As Nick says, you need to add weight for the driver & fuel before doing this. BMW recommend using 80Kg per passenger and a full tank of fuel. However, I've done it with nothing added and it's worked just fine. What I like to do is get everything but height as close to factory with nothing no driver and fuel, this gives me an idea were the ballast (if any) needs to go. Corner weighting will only get you so far, at some point you'll need to physically move stuff round to get it dead on. At 560kg without driver, fuel or electrics we should be there or thereabouts on race weight of 670kg (690kg when I go 8 port).

[paulrockliffe]

Not sure how I've missed this build before, but it's awesome and some useful bits for my own project.

 

It looks like you're running the fuel pressure regulator on the return - is that normal?  I've not got as far as working out the detail for mine, but was expecting the pressure to be set on the feed side.  How have you got the fuel filter and pump plumbed together - it looks like you have a neat something or other letting them sit side by side.

 

I really like the CANBUS PDM setup, I looked at similar, but way out of my budget at the moment.  I got as far as wondering whether there was anything on production cars I could lift from a scrapyard, but nowhere near wiring yet.

[nicklouse]

carbs you control the pressure to it so it does not flood. injection you control the pressure so it is never less than you want. that is to say very high pressure to the rail. regulator return the fuel to the tank at the required rate that is required by the injectors. some are adjustable to allow the pressure seen by the injectors to be increased during acceleration (like an accelerator pump  in a carb).

 

I had also missed this thread.

[Curley]

Welcome Paul! I'm pleased someone has found the thread useful. The fuel pump and post filer are plumbed via a billet manifold like this:

 

The way I like to think about the Fuel Pressure Regulator is to think of it as a fancy bleed value. With the tap closed the fuel pump is building a head of pressure between it and the pump. By placing the FPR after the fuel rail we're able to guarantee a specific known pressure of fuel in the rail. Any additional pressure in the rail is bleed off by the FPR to be returned to the tank. As Nick says this is complete opposite to a carb were the FPR needs to only provide (bleed off) the correct amount of fuel so as not to flood it. 

 

When tuning for EFI we need to know the fuel rail pressure (hence the fuel pressure sensor) and the injector flow rate. This is where you hear people talk about the cc size of their injectors; the injector flows said nominal amount of fuel when fully open. The ECU uses these two variable to calculate the exact amount of fuel to be delivered for a given engine load.

 

The thing I had not fully understood was that the pressure at the face of the injector changes with manifold pressure, MAP. Thus changing the effective pressure across the injector, which left un-controlled would change the amount of fuel bing delivered. This is why, as Nick says, one needs to add a 'vacuum/boost' reference to the equation so as to maintain a constant pressure. You can add this reference to the FPR and have it scale automatically or you can use the ECU MAP reading and scale injector times, both approaches aim to provide a known amount of fuel for a give engine load.

 

Simples, right?

 

 

[paulrockliffe]

That manifold looks ace, though I'm not sure it's the best option for me at £250.  You can sink some proper money into these things if you're not careful!

 

Maybe I'll just run them end on end, I mean £250 seems a lot of money for something that adds a restriction to the flow rate......

[mitch19]

Happy 2022! Any update on this pretty epic build?

[Curley]

Life happened and not in a good way but updates will follow later this year.

[evoderby]

Sorry to hear about ‘life getting in the way’ . Your project is one of the favorite builds I’ve been following on here, I very much look forward to seeing new updates as soon as you’re well and ready.