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-   -   AFR check after new turbo (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/994289-afr-check-after-new-turbo.html)

puddy 04-21-2018 04:30 PM

AFR check after new turbo
 
I just installed a new AFR gauge and an upgraded K 27 turbo. Some suggested I may need to adjust my WUR to accommodate. However after going for a drive it seems I'm at about 15 to 14 at idle and between 10 and 11 at higher rpm's. I believe this to be pretty good and hoping I can just leave my WUR as is. What do you think?

Tippy 04-21-2018 05:33 PM

10 is drowning in fuel and leaving a lot of power on the table.

puddy 04-21-2018 05:39 PM

Ok thanks Tippy. Can you recommend a link where I can read about what my AFRs should be?

JFairman 04-21-2018 07:17 PM

Sounds like you could just turn up the boost and dig it since you're getting more than enough fuel the way it is now.

Tippy 04-21-2018 07:56 PM

Quote:

Originally Posted by puddy (Post 10010454)
Ok thanks Tippy. Can you recommend a link where I can read about what my AFRs should be?

Iíll let the CIS pros take care of you, but around 12 is a good median between power and safety.

Not sure how you adjust CIS to get you there!

Alan L 04-22-2018 12:39 AM

Depends a bit where the fuel is arriving in the rpm range. If it is all dumping at boost onset, you are probably below 10s for a fair rpm range. Not good.
The simple fix is to harden the Warm pressure in the WUR - adjust the diaphragm screw in . But before you do that it is really helpful to know what the pressure is now (warm). Normal range 3.6 bar +/- 0.2. If you are on the low side, that is the first fix. Then see where you get to with AFR. Then you can eliminate/delay the boost dump with an rpm switch and solenoid valve on the WUR boost line (Leask switch). Those changes should get you a much more sensible AFR curve. Low-mid 12s should get you close. You WILL feel the difference - much sharper response. You are drowning in fuel - not good for the engine, or performance.
Alan

puddy 04-22-2018 04:47 AM

It's funny I already thought the car had sharp response. So how do I check pressures? Sounds like I have to buy some tools and do some more reading...

patina 04-22-2018 05:05 AM

Quote:

Originally Posted by puddy (Post 10010688)
It's funny I already thought the car had sharp response. So how do I check pressures? Sounds like I have to buy some tools and do some more reading...

https://www.ebay.com/p/CTA-Tools-3420-Fuel-Injection-Tester-Bosch/1455414050

PM me your email address and I'll shoot over Leask's WUR tuning instructions.

1979-930 04-22-2018 06:10 AM

I just ordered this one a few days ago.

https://www.ebay.com/itm/SG-Tool-Aid-33865-CIS-K-Jet-F-I-Tester-w-Case/400930491794?epid=672824579&hash=item5d5951cd92:g: RtgAAOSwstxVbMDB

philip j 04-22-2018 06:35 AM

pm sent
 
I have one , but have since gone EFI... I'm not too far. Philip

Alan L 04-22-2018 11:29 AM

Quote:

Originally Posted by puddy (Post 10010688)
It's funny I already thought the car had sharp response. So how do I check pressures? Sounds like I have to buy some tools and do some more reading...

Trust me. You have plenty more 'sharp' to come. The engine will come alive. The sweet spot is around 12 AFR, but it gets progressively better as you eliminate the 10s and low 11s. You are being robbed of plenty of HP.
Basically you will need to tune the WUR to around the 3.6 bar spec, if not already at that spot. You can push it as high as 3.8 if needed (this leans your fuel out across the range).
The other problem is the diaphragm in the WUR sees the boost pressure at boost onset (3-3500 rpm), and drops this Warm pressure by around 0.5 bar (3.6 down to 3.1). You will need to test this too - make sure not more than this. So on boost you actually run 3.1 bar (richens mixture). The problem is at 3500 rpm you don't need all this fuel - maybe at 6000 rpm but not 3500. But it is a crude system. So you can make it a bit more elegant by delaying this fuel dump til further up the rpm curve. The Leask switch blocks this boost signal til a predetermined rpm point (rpm pills). Then it it drops to 3.1 bar. Ideally you will set it so at boost your rpm and AFR will increase with the AFR going to around 12, Then the boost dump occurs (around 4500 rpm) . The AFR may drop to around 11 briefly then climb in to the low 12s ideally.
So you only have a brief moment (maybe 250 rpm ) in the low 11s. The car comes alive. Hang on tight.
Plenty of guys here to help you thru the tweeks. Look foward to the reports.
Alan

Alan L 04-22-2018 11:40 AM

You will need a CIS check gauge - prob some guys here that can lend one. But it is a good investment for your car (since you now have AFR). And a Mighty Vac for checking boost dump pressure on the CIS gauge. Other than that - basic tools to tweek the WUR - allen keys.
This is the best/cheapest performance upgrade you can do for your car, and help your engine at the same time. Maybe $500 all up - CIS gauge, Leask switch, Mighty Vac?
Alan

puddy 04-22-2018 02:59 PM

Thanks for all the info fellas. It really helps a lot! I realize now that I misunderstood AFR ratios.

Looks like I'll get Philips tool and start playing. ( where's Rawknees when you need him ) I think I can borrow a mighty vac from a neighbor. I'll report back soon!

1979-930 04-22-2018 03:15 PM

^^^ He's fallen into the abyss known as the Political Forum. We need to put together an intervention.

Alan L 04-22-2018 04:06 PM

Running excessively rich fuel (AFRs 9-11) means you have more fuel than needed, sloshing around in your cylinders. Apart from robbing performance, it dilutes the oil which is carefully sprayed on the cylinder walls.
You engine will like you and you will like your engine.
Alan

puddy 04-22-2018 06:10 PM

Quote:

Originally Posted by Alan L (Post 10011359)
Running excessively rich fuel (AFRs 9-11) means you have more fuel than needed, sloshing around in your cylinders. Apart from robbing performance, it dilutes the oil which is carefully sprayed on the cylinder walls.
You engine will like you and you will like your engine.
Alan

Ok interesting! Could this be partly why I'm going thru so much oil? Roughly 1 litre per 750 Km's?

Alan L 04-22-2018 07:51 PM

Nope. Just that what oil is in there for lubrication is compromised with too much fuel mixed with it.
A leak down test would tell you the health of the combustion chambers (re oil consumption). Otherwise, likely valves/guides.
Alan

puddy 04-23-2018 02:03 AM

I think I'll grab a neighbour and go for a ran and get him to video the AFRs as I'm going thru the gears.
Does Leask still sell the switches? Anyone got one they want to sell? Does RarlyL8 have them?

puddy 04-26-2018 03:32 AM

So my AFRs are 14-15 at idle and 10-11 at top end, still to be confirmed soon via video camera, one evening.

But if I understand correctly. I need to enrich my low end and lean out my top end.

So I need to:
1 - set my cold pressure, or confirm its value compared to factory specs.
2 - set my warm pressure, or confirm its value compared to factory specs.
3 - Adjust the enrichment control pressure - lower the pressure to lean my mixture upon boost.

So correct me if i'm wrong, from what i've read, I believe I am able to correct my too lean low end with cold & warm pressures and correct my rich top end by leaning out the enrichment control pressure. However if i'm not able to get close enough I may need to enlist the help of a boost switch?

puddy 04-26-2018 05:02 AM

Also I believe my CIS is an early non lambda version from the 1975 chassis, i'm not sure how that factors into WUR adjustments I need to make.


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