109 replies to this topic

[Chris P Duck]

I went from a Walbro to a TRE. The reduction in noise was staggering!

[Spitfire Engineering]

Is there a life span for the oem housing? Looks like a good upgrade I must admit if the old one falling apart.

 

Not as such, but consider.

The pump will wear out, reduce output then fail.

This can be replaced with an aftermarket pump/filter as you know

 

The sender unit resistor surface will wear through and give erratic or no reading.

The electrical harness connector type is poor by design and has been made obsolete.

Both of these issues cannot be solved as the sender is pressed into the housing and cannot be removed and the connector is what it is, period.

 

The eductor design is fine for the Buick it came from but not great for a car with a large width to height ratio fuel tank that corners well (the unit is actually a Lotus special order, it's a 4th generation Delphi unit and it has several mods from the original Buick).

Even now you never see the same issues with the S1 on track as you do with the S2/VX when the fuel quantity lowers.

 

No new units so no warranty, even if there was you are looking at a unit that will have been on the shelf for 15 years.

 

No brainer really, surely?

 

Gaz

[Spitfire Engineering]

I went from a Walbro to a TRE. The reduction in noise was staggering!

 

Indeed it is.

And 5A less!

 

Also a warranty, we always issue a warranty for the work with converted units but TRE also supply us with a 1 year pump warranty, Walbro is 3 month.

 

[Rosssco]

As noted, more expensive than the Walbro (which is an older style, off the self jobbie), but it seems a properly thought out, vehicle specific part that's effectively fit and forget for the vast majority of VX220's, standard to highly modified, without having to resort to an external pump / pot set-up, as personally I like to keep the number of fuel line / pipe connections (i.e. critical failure points!) in the engine bay to a minimum..

[Spitfire Engineering]

To compare, we modify VHP units for about £190+ vat which includes the new pump, fuel pipe, filter, seal, internal harness.

Units are converted correctly, tested and you get a warranty on the work but not the unit of course.

So about £90 more than a home job but it is done correctly both in pump selection and work.

 

But the new unit is just that, new everything, full warranty.

It's the same as buying a new unit from an authorised service dealer only it is a much better pump unit in every way and it's cheaper.

 

Edited by Spitfire Engineering, 26 November 2015 - 07:41 PM.

[Exmantaa]

Gaz,

 

I think we had a discussion about this in the past, but can you elaborate more on the power capacity for the higher HP sc builds here?

 

Lets say a small pulley Harrop SC engine (2.0), running max 1.3 - 1.4 bar boost on top of the std 4 bar fuel pressure. Most run a manifold regulated fuel pressure for the big injectors, so the pump will need to feed 5.4 bar (78psi) fuel at max power.

 

Your pump table here say it will only supply ~100ltr/hr at that pressure and that is only enough for ~320BHP. And that is not calculating the extra power needed to drive the SC...

[CHILL Gone DUTCH]

Lol Only enough for 320 hp 320 is still good power

[smiley]

It wasn't actually that long ago that 300hp was the bomb was it.

 

Nowadays a stage 3 is considered an in-betweener

 

Edited by smiley, 27 November 2015 - 05:18 PM.

[Exmantaa]

Lol Only enough for 320 hp 320 is still good power

nothing wrong with 320hp, but if your aim is around 350 and the sc soups up another 40, this nice new uprated unit will not support it... (I'm aiming here to a few potential buyers that are looking for high Harrop power.)

[Exmantaa]

Just adding to this, my 330hp was done with a standard vx fuelpump. But with a few tricks. ;-) (and yes, I do fuel starvation in left corners)

[The Batman]

You need a nice fuel tank

[Exmantaa]

Well, a good chance you actually don't need one with this new bigger cannister unit.. (I have a new 58l elise tank in the shed)

[Spitfire Engineering]

Gaz,

 

I think we had a discussion about this in the past, but can you elaborate more on the power capacity for the higher HP sc builds here?

 

Lets say a small pulley Harrop SC engine (2.0), running max 1.3 - 1.4 bar boost on top of the std 4 bar fuel pressure. Most run a manifold regulated fuel pressure for the big injectors, so the pump will need to feed 5.4 bar (78psi) fuel at max power.

 

Your pump table here say it will only supply ~100ltr/hr at that pressure and that is only enough for ~320BHP. And that is not calculating the extra power needed to drive the SC...

 

 

Of course ….  

First let's state the obvious, as sometimes it clears the mind.

If you put your thumb over the end of a hose pipe to reduce the flow then the pressure will increase and visa versa.

The available energy from fuel, all things being equal, temp etc, is only dependant upon the amount of fuel.

Clearly for any given pump as you restrict the flow with pressure you also reduce the total energy available, the engine is not interested in pressure, it only converts potential energy to mechanical and heat energy.

 

The effective bottom limit of any pump is when it cannot supply enough fuel for the engine.

There is no upper limit for the engine needs but there are complications with the install and this may be too high a power draw, re-circulating and over heating the unwanted fuel etc.

 

It should be obvious that no one pump can meet the needs of all the possible installs even within the restrictions of a single car, i.e the VX/T

 

To support the above criteria pumps should be capable of supplying the required fuel plus a margin of about 20% minimum, this covers wear, flow restrictors such as filters, NRV orifices etc.

The upper limit is not so simple as an over supply of 100% when a pump is flowing 25gm/sec and using 6A is not the same as an over supply of 100% when flowing 40gm/sec and using 17A

The reason is the amount of fuel which suffers from heating is the fuel in the canister 200ml, fuel lines to the reg 50ml, the rail (if the return is at the other end) 100ml, and the return pipe to the canister 50ml. Basically a fixed amount and not very much.

Hopefully it is obvious the higher end is where the problems start ..

 

What does HP actually mean? No definition for this term as such, so common sense would dictate in reference to a standard, in this case the OE Delphi unit. 

The new HP pump has a much greater output than the original OE pump (hence the HP) but more importantly it has a much greater efficiency due to the turbine pump and does so with about the same power as the OE pump.

This pump is ideal for all OE applications and modded cars up to .8 of the figures shown in the flow table for NA at the relevant rail pressure and about .7 for charged installations.

 

It is not a one size fits all pump unit.

This pump unit is not going to be suitable for your installation that is for sure.

 

So what do you need?

Well enough fuel for 320bhp x 1.25 (margin) = 400bhp at a rail pressure of 80psi.

Using HP x BSFC = lbs/hr we get 

 

400 x .6 (SC) = 240 lbs/hr or 150lt/hr or 30gm/sec

 

This is easily and safely obtained with a converted unit as mentioned.

The pump would draw about 12A and supply about 34gm/sec which is fine.

 

IF you had had a lower rail pressure of about 70psi we could have fitted another, higher capacity pump that also has a dual input and fits into the new unit, this keeps all of the advantages as mentioned in the first post.

Just a little too high.

 

All make sense?

 

Edited by Spitfire Engineering, 27 November 2015 - 11:37 PM.

[Exmantaa]

yes, that all makes sence to me and that's why I have one of your converted high HP units here. (And why I only run with 3 bar rail pressure )

I just wanted to make this clear to people, because I know some "dutch prototype customers" have SC's running stock 4 bar rail pressure and will be aroound the 350 mark at this ~1.3 bar boost scenario...

[Spitfire Engineering]

I need to read up more really as I'm not too sure of the reason why these massive fuel pressures are needed in the first place, of course by raising the presssure you increase the amount of fuel through the injector for any given period but you get exactly the same result by using a larger injector at a lower fuel pressure, and in some cases a more sensible duty cycle.

The atomisation spread pattern does not change much over 3 bar to my limited knowledge so why go that route?

Cost savings on the injectors?

 

Understandable if you trying to gain a few HP from 250-280 cheaply, but when you move from 250-350 which probably already includes a lot of other work then why the high Fuel pressures?

 

I'm not refering to the boost requirement just the base rail pressure.

 

Gaz

[Exmantaa]

4.0 bar is the stock rail pressure of the NA engines. I run with 3 bar and different ecu...

[Spitfire Engineering]

4.0 bar is the stock rail pressure of the NA engines. I run with 3 bar and different ecu...

 

Thanks, that explains it then!

And the VXT?

 

[techieboy]

According to TIS, both Z22SE and Z20LET are 3.8bar, though I thought the Z20LET was a bit less.

[Exmantaa]

Yeah, I've seen different numbers. 3.8 bar, 4 bar, 58psi... :-/

[Spitfire Engineering]

Just received lots of info, thanks for that Rob

Sensibly the new pump will supply as per the sheet for NA, just allow a 10% margin (no eductor feed needed) or for SC cars multiply by 5/6 first to correct the BSFC.

This easily covers all standard spec VX and VXT models. It also covers all the NA options I have seen and certainly up to 400bhp.

 

For the tuned SC cars it is a little more detailed and the output sheet will need to be checked.

There is another pump that fits the unit and raises the numbers about 50bhp, more on that later.

If you are running 3 bar +boost you can use the pump up to 350 with a safe margin.

If you are running 4 bar +boost though you will really need to have the old unit converted as all the dual input pumps loose output due to the canister filling system bleed.

 

Gaz