Thread: compound turbo set up

4" seems like a minimum requirement for those 'big' Cummins 4 and 6 BT engines. I'd say you will be approaching this requirement judging by what Dougal says regarding the pump mods and required airflow....

Air in, Air out....

Good Stuff J, looking impressive.

The other J (C)

Ok
Pretty much certain my pump needs attention. The scenario is

Fuel screw basically all the way out
Minimal smoke from midrange up

In top gear say 100 to 110 which is near the limit with our tyres and gearing. The engine is very erratic on throttle response. If you accelerate or decelerate slowly it's erratic like you are crimping a fuel line.

Now this motor has always had this problem, only to a much smaller degree, the compound set up has magnified it.

Open to all pump suggestions before it comes off for a trip to the test bench.

Justin

No smoke is the way it should be. So that's not a problem you should be fixing. That just means you have enough air to burn all the fuel cleanly.

The erratic behaviour, certainly look into that.

How is the power and torque feeling?

Originally Posted by DRanged

Ok
Pretty much certain my pump needs attention. The scenario is

Fuel screw basically all the way out
Minimal smoke from midrange up

In top gear say 100 to 110 which is near the limit with our tyres and gearing. The engine is very erratic on throttle response. If you accelerate or decelerate slowly it's erratic like you are crimping a fuel line.

Now this motor has always had this problem, only to a much smaller degree, the compound set up has magnified it.

Open to all pump suggestions before it comes off for a trip to the test bench.

Justin

Justin, I have a similar fault with mine (NA pump) and it is now sort of fixed itself, hasn't done it for ages. The diesel pump tech I explained the symptoms to THINKS it is indicative of a sticking fuel governor, but obviously his advice was "Maaaaate, bring 'er in we'll take a look on the bench...'" which I read as "you'll need a pump overhaul..."

JC

Originally Posted by Dougal

No smoke is the way it should be. So that's not a problem you should be fixing. That just means you have enough air to burn all the fuel cleanly.

The erratic behaviour, certainly look into that.

How is the power and torque feeling?

Power and torque is very smooth and linear to say 3/4 throttle . From then on say 18-24 psi it struggles and will only respond properly if you put the pedal to the floor. I am leaning towards a pump check I think. Over the weekend I will **** off my neighbors in the valley and run it just with the dump pipe for comparison.

Justin

Originally Posted by justinc

Justin, I have a similar fault with mine (NA pump) and it is now sort of fixed itself, hasn't done it for ages. The diesel pump tech I explained the symptoms to THINKS it is indicative of a sticking fuel governor, but obviously his advice was "Maaaaate, bring 'er in we'll take a look on the bench...'" which I read as "you'll need a pump overhaul..."

JC

Jc
Mine is also an NA pump. I think it could be the Govenor now you mention it. Might pay just to get it on the bench to see. The local pump guy is a genuine bloke so all should be good.

JL

Exhaust should be pretty quiet with two turbines in it.

Was idle effected ? Maybe this irrational behavior is due to all the different air fuel ratios as there is now 2 of everything at play and getting the 2 working/crossing over in the optimal efficiency range may feel like a irregular power delivery...I'd get them to look at the torque cam profile however as Justin said "most" injection specialists do actually mean rebuild when they say test... If the fuel screw is all the way as in cam sitting on its rest try winding it in just a tad see if anything changes..