32 replies to this topic

[CHILL Gone DUTCH]

Would the injector CC also come into this calculation ?

[CHILL Gone DUTCH]

Double post

Edited by CHILL Gone DUTCH, 17 June 2015 - 01:21 PM.

[siztenboots]

Well the only certainty is you definitely do not want to be using the 450, it's horrendously overpowered for your application, it even has the disadvantage of ticking all the boxes, overheated fuel, noisy, you needed a rewire of the pump harness and it if you try to install it into your current unit you may well damage something, I thought the comments about damage on the above link was scaremongering a little but in the case of the Delphi unit (VX) it is actually possible as the return line is restricted and will not cope with the fuel flow, this means the reg cannot dump correctly so you may see an overpressure at the rail. If you are lucky you will blow one of the safety caps off  of the return line in the unit but then the canister will not charge at all.   U2U me and I will give you some sensible options to think about. we have done about a 100+ pump units for the Elise S2 and VX without issue and with very good sound results considering you are way up on output. We need your power output, future plans on output? rail pressure and boost pressure if applicable. Basically we re-work your unit and install a modern, high efficiency turbine unit matched to your requirements the unit return system is then matched to the pump.   

sounds like the most sensible option

[Spitfire Engineering]

No, the pump calculations are based on the energy available from the fuel and the ratio of efficiency, the BSFC, plus a few margins for losses and in the case of the S2/VX type units a good return flow.

 

 

Calculations with injectors are exactly that, and used to calculate injector size and work ratio (duty cycle) from the total fuel flow required. This is partially a function of the rail pressure.

It doesn't matter to the pump (or the fuel) if it is one big injector, 16 small ones or carburettors, though in the latter case the BSFC would probably change slightly and so would the fuel needed.

 

[siztenboots]

any reason to deviate from 3bar rail regulator

[Spitfire Engineering]

any reason to deviate from 3bar rail regulator

 

That's mostly a function of tuning and ECU setup though anything charged will need a higher fuel pressure to overcome the increased gas pressure in the inlet manifold and a facility to go even higher as the manifold pressure rises with RPM.

Rover NA is 45psi

Honda NA is 58psi

Audi conversions were 60psi +20psi boost, so pump needed to supply 85psi minimum (only a small margin needed for pressure).

 

[Relfy]

I'm running 306 bhp and the std pump couldn't hack it.

[smiley]

I'm running 306 bhp and the std pump couldn't hack it.

 

You mean the original 15 year old one I assume?

[Relfy]

Correct. Obv it's completely up to you, but for me I wish someone had told me to buy it before I went in for a remap. Since I had to limp the car home and pay for a 255 pump anyway and pay for another remap... not fun. Also my pump was clean before I went in to have the map done.

[Spitfire Engineering]

Correct. Obv it's completely up to you, but for me I wish someone had told me to buy it before I went in for a remap. Since I had to limp the car home and pay for a 255 pump anyway and pay for another remap... not fun. Also my pump was clean before I went in to have the map done.

 

The original pumps were fine for what they were designed for.

Lots of possible reasons for the issues seen, it may not be the pump at all, if you have charged the car you can expect the pump to struggle at the higher rail pressure, time will cause a little wear, probably more problems with the motor brushes which are more often than not responsible for the eventual failure.

Add poor wiring or connectors to the harness, lots of possibilities to go wrong.

 

There are not any problems when these units are correctly re-worked for a new pump either, though sticking a Walbro in and doing nothing else is not really definable as correctly.

We had details recently of the second pump in as many months where the unit would not hold the pressure due to a leakage (poor fitting) which causes the engine to fail to start reliably.

 

[vocky]

any reason to deviate from 3bar rail regulator

z22se is 3.8 Bar as standard 

[techieboy]

I'm running 306 bhp and the std pump couldn't hack it.

Mine couldn't cope at 260bhp and had to have a lower rev limit until we could work out the correct replacement.

[kipper]

I'm back up to Courtenay on the 10th July for the full map, after my OEM pump could not deliver the goods (was running lean) at 315 BHP. So had to take the car all the way home and fit the 255 and return...that's the trouble with upgrades, the weak links in the chain are exposed!