Mk2 20v Turbo - What fuel pump for 400+bhp

Am I going round in circles here? lol If I fit an in tank I think I may suffer fuel starvation?

 

If you had the mk3 tank mentioned earlier could you run the single in tank pump which would normally provide enough fuel for a vr, to feed a k jet unit with accumulator. Would these then combined fuel the 400 bhp engine safely and reliably?

Also, is the S3 pump you are talking about Bill a all in one in tank pump, or is it a lift only type pump?

 

S3 is all in one pump

 

So the vr pump feeding a k jet one could well work for that sort of power then?

 

mine works fine on >500bhp pumping into 750cc injectors running 4bar fpr

 

Great... Therefore the restriction on a MK2 K jet can may be the lift pump.
But can the in-tank S3 unit fit in a MK2 plastic petrol tank without surge baffles?
What is the flow rate of each those two pumps and at what pressure.

 

I think we may be getting somewhere together!

 

I used to run the S3 tank alone when just IHI'd to mid 300's, but when it was made 1900 and PE1820 the additional pump was added, and has been sufficient ever since..

I will find out shortly if its up to the +100bhp thats headed for it shortly..

 

But did you add the MK1 unit because your started to get lean or run out of fuel flow at high rpm with the standard S3 job and change of hardware or because you thought this component would give extra piece of mind with the new demands placed on the engine?
As a a Mk1 unit is not in a reservoir as a Mk2 I am assuming you run these pumps in series?
I have since found out that Mk2 and Mk1 external kjet pumps are rated 148 l/h @5 bar by Bosch. Very crude conversion to fuel flow HP would suggest 337.9BHP assming correct afrs, steady state rpm and no pumping losses and boost bressure on under 30psi with 3bar FPR. Could be much less if the unit is used.
A 500BHP engine would need at least 223litres/ hr for fuel flow at the standard 3bar fuel flow pressure plus what ever boost that is run to achieve the output, In your case 4bar plus boost pressure.

 

mine are in serie3s. additional pump was added to give more fueling to suit the engine/turbo that was also going in at the same time. It was 390bhp on that initial install, but I changed and dumped my jabba turbo setup for my own which then required more fuelling, so changed the 620cc injectors to run @ 4bar from 3bar previously. Then changed the inlet manifold and t'body for R32 one and then promptly ran out of fueling on the 620's. Fitted 750cc injectors and all was well again... then fitted fo red from previous fp green and then had to fit 4bar reggy to keep fueling.
Despite what you say bosch quote for the kjet pump, its afr has remained 0.78-0.85 on full load 2.2bar to my then 8200rpm limiter.
I do have the accumulator fitted if thats of any note.
regards
bill

 

Thanks Bill for sharing your practical application and clearing that up.
Therefore you have a high flow pump boosting another high flow pump which accounts for the 223litres/hr fuel or greater your engine needs at 6.2bar fuel flow pressure.
The accumulator would be a very small restriction in the system as its on the outlet side. It should hold a minimum pressure between the FPR and itself when the engine is stopped and your pumping system is not working.

This is what has been observed on my own project, the WOLF R, which has a K jet fuel supply system with the main pump immersed in a reservoir supplied by lift pump and returned fuel. When the boost pressure sure is raised to 18 psi and a 20psi overshoot with a 12.1-11.9 AFR target, my fuel pressure is starting to dropping off at 6800rpm. This was done by connecting a fuel testing kit to rail supply and running the car in third to redline.
However at 16 psi its fine all the way to the 7500 rev limit.
5700rpm peak torque fueling is fine though below 19 psi
May have been different if a similar set up for a MK2 involving an in tank Bosch "040" was placed in series with my underfloor 148l/hr 5bar unit. Or if the pump was brand new and delivered close to Bosch advertised targets
Must be the old K jet pump saying its roller vanes have had it for the last 20years!

 

I am a little concerned my new setup will expose my fuel delivery and injectors being undersized.. 750cc in there @ 4bar on the old turbo. New turbo is GT35R, so I may need to upsize pump(s) and injectors... to maybe run 8 injectors now I will be on S60 ecu.

 

Yup will have to.
770cc/cylinder is what you need for from 500bhp and 3 bar net full open.
With 4 bar this works out to 866cc available. Throw in 87% duty and you have 753 cc per cylinder.
>600bhp you need 1095cc (hose pipes) per cylinder and 263 litre/hr fuel flow at FPR pressure plus boost.
Just a rough calculation but you get the picture.

 

Well, not wanting to confuse this, but:

If I'm not sure how my mk2 16v k-jet fuel pumps are (they are loud, so I would guess not very good...) What can I do?
Stock Intank (and what if it's bad) inline walbro/bosch?
Intank walbro/bosch and no fuelpump outside?

Just aiming for 270 now, and maybe 350 in the future...

 

Could the simple solition for me be a Mk3 VR6 tank and Walbro 225 in tank pump. It's been suggested that this alone (without all the Mk2 under car stuff ) will be sufficient?

 

225l/hr will be more than enough. 513bhp worth of fuel.
Will the aftermarket pump fit in the MK3 pump casing though? I seem to recall the pump casing is there to prevent surge

 

Also do I specifically need a Mk3 VR6 tank or are all Mk3 tanks the same?

 

All the tanks except diesel come up as 1H0201075AR ( or AS with 22 lead free restrictor).

 

Toyotec, so, on a mk2, a simple intank walbro is fine to use and to remove the k-jet accumulator, etc?

 

Once you know how it will be mounted in tank to prevent surge, yes you can use this keeping within manufacture recommend flow at pressure, voltage etc. Then you can delete the underfloor and use a fliter in its place.
However if your fuel flow targets are not in breach of engine output/airflow@rpm you may find that the STD 16v unfloor system will be good enough.