Fuel head/turbo query

[Alan L]

In an effort to help Rawknees and the 'dead meat' thread out I am posting a tech query.
If you up grade a turbo, does it change your AFR requirements?
I was running a 7006 until it let go internally - overheated according to my turbo guy. The turbine shaft was blue. Wrecked the internals/housing.
But while I was running that I was dialling fuel back by running high WUR pressures. Trying to keep the AFRs out of the 11s (WUR pressures 4.0 +) - aiming for 12s.
The easiest/cheapest option to replace the 7006 was with a new 7002. I am now struggling to get enough fuel in it. Running into the 13s even with the WUR pressure dialled right down (WP 3.2). Boost dump 1.0. Increasing the boost dump from 0.5 to 1.0 bar makes no difference - so I am guessing there is no more fuel to give.
Would changing the turbo have the ability to push the AFRs from rich to lean? I am guessing it may be breathing a whole lot better in the upper rev range, and asking for more fuel. Boost definitely comes in much earlier - starting at 2500 rpm.
Thanks
Alan

[RarlyL8]

Yes.
Bigger turbo flows more air, more HP requires more fuel at same boost level.

[Alan L]

It is impossible to get a clear pic of the badge on the turbo - had about 20 goes. But I think it is a 7200, not a 7002. I am guessing this has a higher flow at the top end compared to a 7006.
So it seems I have 2 options?
Find another 7006 (my housing was destroyed) to fit with the FD capacity, or
Get the 007 FD modified again to flow more fuel?
I have spent about half a day checking the FD flow numbers and tweeking it to the max.
My pumps are giving 1800cc/30 sec thru the FD.
Maxing the FD adjustment out I went from 994cc/30 sec over 6 injectors, to 1006cc/30 sec.
I don't think there is anything left to get from the FD.
Have some bigger fuel lines on the way, maybe that will help a bit.
Does my analysis sound correct?
Thanks
Alan

[RarlyL8]

Alan, the K27-7200 is the OEM turbo for the 964T. The K27-7006 is special wishes and racing turbo for the 930. 7006 flows more and kicks harder than the 7200. 7200 spools quicker than the 7006.
The 007 FD mod is good for a solid 400whp+ so you should have more left. The 7200 typically cannot support 400whp, 7006 maybe.

[Alan L]

Thanks Brian. I had enough fuel for the 7006. Does it make any sense I am running lean with the 7200 (if that is what it is - and I suspect so. It is an off the shelf current turbo - which is why I could source it down under). Just trying to figure if something else weird is going on, and which way to jump. This current turbo certainly spools early - 2500rpm.
Just confirmed - tracked down some old emails from T supplier. It is a 7200.
Regards
Alan

[gumba]

Where does the k27/29 fit in?

[RarlyL8]

K27/29 has many flavors but generally they flow more than the 7006.
The OEM Euro CIS will support up to 350whp, at that point I add an adjustable WUR. The -037 Euro FD will support about 375whp before extra flow is needed. The aluminum USA -153 FD with Lambda falls short after about 325whp.
Alan if your fuel system was supporting the 7006 it will support the 7200. We have to figure out what changed. First thing suspected is the fuel pumps but you report the volume is in spec. I don't recall which FD you have. What is your system pressure? Do you know what the HP at the wheels was for your previous or current setup?

[Alan L]

Thanks Brian, thats where I was trying to get to - whether the 7200 would be requiring more fuel.
Nothing has changed other than bolting the 7200 on. The 7006 was beyond repair, the 7200 was the only option on the shelf in New Zealand. You can count the number of 930s on one hand here, so parts are NA.
The system pressure is 102 psi. I was running the WUR at around 4.2 bar with the 7006, trying to dial a bit of fuel out of it. (Would probably be better dialling the FD adjusters back - but hadn't got that far with it). Pump flow is same as I measured it with the 7006 - when I uograded them for more flow. I have the Al US FD -which was modded to 007 by Flowtech. (via you I think)
I had the WUR pressure down to 3.2 and the boost dump down to 1 bar, but made no difference to the AFRs. As soon as hit around 5000 rpm, AFRs into the 13s. I have around 380 rwhp at 0.8 bar.
Regards
Alan

[RarlyL8]

If you're using the -007 there should be no issue at all, it can support 400+whp.
The 7200 drops off after 5500rpm typically where the 7006 is still pulling.
You've had fueling issues in the past were they resolved? I don't recall the outcome.
380whp@0.8bar is a big number for CIS but you should be able to hit 1.0bar using the -007.

[Alan L]

Yes, I was short of fuel earlier on. I upgraded pumps, replaced fuel filter etc etc, chasing more fuel. Marginal gains. Then I discovered a small screen on the inlet of the FD. Removed that, and found the extra fuel I was looking for. Have just checked that the screen is not in the FD now. It is not.
I did pull the FD apart a month or two ago and replace the internal O rings. I had one side of the engine running madly rich. That fixed it. Have just checked my notes - in 2017 I had 920cc/30 sec via the injectors. 1500cc /30 sec at the FD.This was before upgrading pumps and removing the screen. I now have 1000cc/30 sec at the injectors and 1800 at the FD.
I am not doubting you Brian - which is why I am glad you are helping out with your CIS/turbo knowledge. But the only thing that seems to make any sense is the 7200 is asking for more fuel than the 7006. I have't altered anything else.
I have a 7006 on the way now (and larger fuel lines) via a Pelicanite.
I guess that will tell us what is going on.
The 7006 is more appropriate in terms of what I should be running anyway - the 930 never ran a 7200 in the day. The 930S ran the 7006. I was quite happy with that turbo - seemed to perform well - quickest lap times. I do run it at 1 bar - when I have the fuel. Had to dial it back to 0.8 and short shift last time - with the 7200, and even then was running into the 13s AFR. Haven't done a leakdown yet. Too scared to.
Regards
Alan

[heliolps2]

Hey Alan
It seems to me that the system pressure is to high . Try bring it down to 6.1 bar and see what happens. That should make it rich across the board

Helio

[Alan L]

Yes, I was wondering about that. Thanks
Alan

[RarlyL8]

Something is screwed up if the 7006 takes less fuel on boost than the 7200 under the same conditions.
I set the -037 FD to 100psi on the 400whp engines. The -007 typically doesn't need to be that high, I set them at 90psi. Higher shouldn't hurt anything as the adjustable WUR compensates.
Have you checked the calibration of your AFR meter? What's going on doesn't add up.

[Alan L]

Just wondering if the 7200 at 5000 rpm is breathing harder than the 7006? The 7200 may peak around there, whereas the 7006 keeps going, but wondering if at 5000 the 7200 is pushing more air?
Sounds like I should drop the system pressure on the 007?
The AFR has a calibration mode each time it turns on, and it says it is in spec. There could be a possibility that it is not - but I do suspect it is right - this time for the first time, I had a light tan colour in the Zork. Normally it is black, from all the boost dump and AFRs in the 11-12s. I am pretty sure it has been running leaner.
Maybe when the 7006 gets here and I bolt it on, things will be clearer. Meantime I will bolt on the Euro fuel lines when they arrive. And I will not be looking to modify the FD until I can check everything against the next 7006. Will take a month or two - heading o/seas to warmer climate for a while. Yes, I agree, if the 7200 is supposed to push less air at 5000 rpm than the 7006, something is weird. Which is why I guess I am here - like a lot of folks. Trying to sort weird s..t out.
Thanks
Regards
Alan

[heliolps2]

Originally Posted by RarlyL8

Something is screwed up if the 7006 takes less fuel on boost than the 7200 under the same conditions.
I set the -037 FD to 100psi on the 400whp engines. The -007 typically doesn't need to be that high, I set them at 90psi. Higher shouldn't hurt anything as the adjustable WUR compensates.
Have you checked the calibration of your AFR meter? What's going on doesn't add up.

Plus 1 on the 90psi, Simple change to make and see where WCP AFR"S falls.

Good luck
Helio

[Alan L]

Reset it y/day. Got 94, may try again today.
Regards
Alan

[Alan L]

OK, reset again and got 90 psi. But we may be getting close to solving the problem. Brian has mentioned the 'weird' factor, and something not adding up. While resetting the SP, I heard a weird noise from the rear pump. Sounds like rattly bearings - intermittent - but frequent. Something not right in that near new pump. Probably done 5 hrs work at a guess.
Regards
Alan

[heliolps2]

Alan

Is the rear pump going out? sometimes the front one is weak causing the rear to act up, causing fuel problems. Make sure all the pumps are working to spec.

[Alan L]

Hmm, a possibility I guess. The rear is an 044 about 5 hrs old. The original rear is on the front. There is no sign of pressure fluctuations etc in all the tests, and everything is in spec. The test would be the pressure differential between the two pumps. From memory spec is 2.5-3 bar approx. Last I checked - after the 044 install, it was correct. But we are looking for something weird. So I should check again. Rear pump cavitating off a weak front pump might explain a bit. Except not showing in any checks so far. Will be a while before I can get back to it - at airport about to depart o/seas.
Thanks for the help guys.
Alan

[heliolps2]

In my option that's part of the problem, never use a 044 pump as rear pump, put the 044 up front and the stock pump in the rear....once you do that you will have to adjust your systems pressure again.