So I got my new Porsche 911 fuel pump installed tonight and the car is still leaning out around 6000 rpm. The pump is good for 450 hp, so I know that the bottle neck is elsewhere.
System pressure is at 80 psi, warm control pressure at 50 psi.. Next I'll try bumping system pressure up to 85 psi and see what happens.
Attila, I may be in need of some Benz gold injectors soon so I can crank pressure up to 90-95 psi. Or maybe I'll end up wiring a pressure sensor up to my cold start injector to activate it above 6000 rpm.
Josh any pics of it installed? Does it look just like a factory one from outside?
"..Horsepower is a measure of work done over time, or the rate at which work is done."
http://www.cardomain.com/ride/579694/1
Isn't the 911 Fuel pump the same as what was used on the old CIS VW Rabbits, 924's, etc etc
'82 320i M10 Turbo with VEMS
'95 525i with VEMS M50 PnP
'99 528 Wagon
It is a CIS fuel pump, it looks identical to the stock 76-79 e21 pump. The only visible difference is the stamped part number which ends in 984 rather than 982.
The real difference is that it flows 180 L/hr and will flow over 450hp worth of fuel. I bought the pump from Jayracing.com for about $190 which is less than what Bavauto sells the stock E21 pump for.
Last edited by jrcook320; 07-31-2008 at 12:08 PM.
I will try and see which injectors they and give you the info and we can work something out.
If you are leaning out, with the fuel system maxed out, i would def. recommend rigging a system up to the cold start injector starts spraying. What i did is have 2 injectors go off, one at 3-4 PSI and the other at 12psi.
Try and mess with the system once its up and running, but its your running smooth throughout the power band till 6k, try and see what happens when you set injector to go off at 10 psi.
I think this will solve your leaning issue.
Well the MB gold injectors are part # 0 437 502 047. I have found them for as little as $37 each. Here's a link to a thread on turbobricks:
CIS fuel injectors
I will see what the fuel system does in warmer weather when the air isn't so dense, it was around 50 degrees last night when I tested things out. I also still have the ability to add additional system pressure using shim on the pressure regulator, so I'll see what happens when I bring things up to 85 psi.
I just remembered to ask you something. How much boost are you running? I heard the dsm bov is good up to 12 psi and then after than it needs to be crushed to retain more boost. I don't know if it will affect your car by any means, but maybe you've gone beyond the limitations of the dsm bov?
So you have purchased the gold injectors? Dont you have to have custom injector mounts made to fit them in the manifold? I take it they are not the same size as the stock injectors and wont fit in the head....
Keep the updates commin!!
Ok, so here is an update on my fuel system. I now have a wide band O2 meter installed so I know exactly what's going on. With my current tune I run at 12.9 afr from 3500 to 5000 rpm, but by 5500 rpm I lean out to about 13.9 to 14 afr so I have to short shift it.
My system pressure is currently set at 90 psi which caused no issues with the stock injectors. My next step was to buy the Mercedes Benz "gold" injectors. They are the same size as the 2.0L m10 injectors, which is exactly 12mm longer than the stock 1.8L injector. This means it protrudes into the intake port an additional 12mm. I installed the injector in a spare motor I have lying around to see how bad it would be:
To correct this problem, I cut an old injector open to see how much meat was there, and it was obvious there was plenty. The pic shows the stock 1.8 injector, a VW rabbit injector cut in half (same length as the 2.0L injector), and of course my new MB injector.:
I took measurements, drew up a print and had a new groove cut in at the machine shop, so now the new injectors will fit the same as the shorter 1.8L injector:
I'm not ready to start any tuning yet, my car is torn down right now for a rear brake job, subframe modification, control arms w/ poly bushings, tie rods, and oil pan & timing cover gasket replacement, so it will be awhile.
The plan will be to crank system pressure up to 95 psi, retune the car to get it running properly with the new injectors, then adjust the maximum enrichment stop on my WUR to get my WOT AFR down to ~12.1. From there I'll see how many R's I can pull till it starts to lean out again.
Wow, that's pretty clever regrooving the injectors. I didn't realize the gold ones were actually brass, I wonder if thats just for more corrosion resistance or what?
Pretty innovative man, great thinking!
I love how Josh doesn't settle.
Last edited by TheNeek; 05-21-2008 at 06:46 PM.
that's pretty interesting! I will have to replace my injectors soon (they aren't vaporizing so much as just squirting) - maybe i'll look into that.
Hmmm....May need to see if you can't do a set of injectors like that for me too, depending on what I find in the near future. I won't thread-jack this to talk about my issues though, need to start a new one...
Metal Bumpers Are For BEEETCHES!!!!! "King of Lean" - Retired
"If that bikini isn't made of Micro-Fiber and has Quick Detailer on it then GTFO!" -BabyM
so, does the 2.0 head and the 1.8 head have the same flow rates and chamber volume? why do the 2.0 injectors protrude so much more into the flow path then the 1.8s
No e30s again.
IIRC, one of the engines has the injectors mounted directly into the heads, whereas the other has them mounted in the manifold.
IIRC the injectors on the 1.8L motor are mounted on head but the 2.0L injectors are mounted in the intake runners on the manifold. The extra length is to get them where they need to be.
Edit: Greg beat me to the punch by a few seconds.
Metal Bumpers Are For BEEETCHES!!!!! "King of Lean" - Retired
"If that bikini isn't made of Micro-Fiber and has Quick Detailer on it then GTFO!" -BabyM
BTW Josh, what would be so bad about hanging down into the port more? Just the impedance of airflow?
Yes. What's the point of a nice ported and polished intake port with a big wang hanging out in the middle of it all? It stuck out further than the valve guide.
IMO injector placement is important, I would be willing to bet that BMW spent some time determining optimal placement to minimize port obstruction and maximize flow.
hmmm, my 2.0 in the shed on the stand has the injectors in the head, just like my 1.8 in the car
No e30s again.
i'm thinking it sounds like it has a 1.8 head on it. i wish it had the in manifold set up on it as i want to convert to carbs here very quickly and i didn't want to have to use some dumb plug in the 1.8 head. dammit, i wonder why a person would swap their block and keep their head. if something over heats thenthe head gets messed up more then the block, usually. at the least they are both trashed.
so, is the 1.8 on 2.0 block going to work as well as the 2.0 on 2.0? should i just make another thread to stop messing this one up?
No e30s again.
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