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Running a 10% bigger injector for #3

will740turbo

Member
Joined
Jun 15, 2006
Location
Portland, OR
Hey, turbobrickers.

I'm finishing my full rebuild on my L-block b230ft. I'm just using LH2.4.

The #3 cylinder always goes bad, and someone told me that the volvo race team once upon a time ran an injector that was 10% bigger on #3 to keep it cooler. I'd like to copy that, and I've found one candidate that might match, but I want some other people to weigh in.

The only performance mods are a 15g turbo and 3" downpipe (and camaro cat) because my 13c died, and I bought 2 more that were just as dead. I had to get a new flange/pipe, so I went for bigger.

What I've got right now is this:
Stock injector:
bosch ev1 "long" size jetronic connector, pintle nozzle
280150804 2.2ohms - 30lb/hr - 312cc/min

10% higher flow rate:
0280150034 2.6ohms 32.7lb/hr 344cc/min


I'm running into a problem though when I look on websites. It looks like the original part number 0208150804 was reused and the volvo version maybe was 234cc/min... or maybe it was 312cc/min. I've found both listed, even one pdf that lists both and has different version numbers for them. Some are pintle, some are 4-hole, which seems worse.


The goal is to just make #3 slightly richer to keep it cooler, but I could also see it resulting in 1,2,4 running *leaner* which is no bueno. Has anybody tried this? If it's already been done, I don't need to reinvent the wheel. And if it's going to cause problems rather than avoid them, then I'll stick to the stock injectors, possibly doing my own flow-rate testing to put the heaviest one on #3.
 
Before putting in the #80's in mine, I had #65's, still had the issue with #3 plug looking pretty lean. Swapping in a #66 dealt with that, plugs looked really even. Since I did the #80's I haven't noticed #3 plug looking lean like before, but they all are a little dark, tune isn't quite settled.
 
Before putting in the #80's in mine, I had #65's, still had the issue with #3 plug looking pretty lean. Swapping in a #66 dealt with that, plugs looked really even. Since I did the #80's I haven't noticed #3 plug looking lean like before, but they all are a little dark, tune isn't quite settled.

What are the #s you're referencing? 65 66 and 80?

Also, I didn't know all those forum members in your sig died. :(
 
Just remember with a single O2 sensor in closed loop the ECU will see the average AFR.

So if you put a larger injector in #3 and that richens the average mixture, the ECU will pull fuel to get the average back down, this will slightly lean the other 3 cylinders.

Consider installing a MS3 which has a per cylinder fuel trim?
 
Just remember with a single O2 sensor in closed loop the ECU will see the average AFR.

So if you put a larger injector in #3 and that richens the average mixture, the ECU will pull fuel to get the average back down, this will slightly lean the other 3 cylinders.

Consider installing a MS3 which has a per cylinder fuel trim?

I am wondering if +10% on one cylinder will really richen the exhaust enough to lean out the other 3. I don't know what engine the volvo race team did this with - for all I know, it could have been CIS with no O2 sensors.

I don't want to put in the effort to change to a custom ECU. I would never stop fiddling with it.
 
Anyone think of using a GM heater valve bypass for improved cylinder head cooling? This GM bypass valve will bypass the heater core when heater valve is shut off.
 
Anyone think of using a GM heater valve bypass for improved cylinder head cooling? This GM bypass valve will bypass the heater core when heater valve is shut off.

That's a good idea except that you are returning hot coolant. It may work fine but I'd rather have the coolant cooled before I return it to the main system. When we were racing a Bug Eye we used a heater core on the heater circuit mounted up front behind a headlight opening to cool the coolant before it went back to the main cooling system. That helped remove a lot of heat from the system and the head gaskets lasted much longer after that change.
 
I'm very interested in seeing if anyone here has EGT/AFR per cylinder data to confirm cylinder 3 running lean. I have heard this rumor of the larger injector in #3 in the factory race cars as well but of course that was with K-Jet so this may not be relevant to later cars. Personally I think this seems like a bit of a band-aid fix that should stay back in the 80s.

I haven't personally noticed #3 running lean in any of the street or race B230s I have dealt with. Could be a B21FT quirk as well.

Yes, this would make cylinders 1,2, and 4 run leaner in closed loop.
 
Anyone think of using a GM heater valve bypass for improved cylinder head cooling? This GM bypass valve will bypass the heater core when heater valve is shut off.

Having read a post by stealthfti about cooling higher running temps incurred at sustained high speeds, I plumbed in the heater outlet on the head directly to a fitting near the radiator. It reduced "normal" running temps by about 20 degrees (as per dashboard temp gauge with Dave Barton overlay). I put in an aftermarket heater valve so I could adjust the amount of reduction from inside the car. With the valve closed the car runs as before.
The heater is now supplied from the fitting on the exhaust side of the block - I have not noticed any difference in the performance of the heating system.
I am still running the block in after having it rebored/new pistons so have not yet turned the boost etc back up to take advantage of the extra cooling.
Tim
 
The numbers I referenced are injector size numbers, lbs instead of cc's, that's all.

I do already have a GM heater valve in mine, started that fad a while back. Head temps back by #3 and #4 dropped by a good 20*, putting them on par with the front of the motor, reducing that hot spot. Simply getting that heat from the motor, instead of deadheading the flow from the back of the head makes a big difference, though it's not ideal returning it to the water pump. Returning to post-t-stat would be better, far more work involved at this time though.

Regarding the larger injector, if you look at the exhaust passage or spark plug from #3, they read much leaner than the rest. I've seen a few motors with heads pulled at the yards as well, same thing, seen some detonation on #3 as well, the rest looked fine. Unfortunately when I did the research on mine, I didn't have an IR gun that read high enough to check manifold temps on #3 vs. the rest though.
 
The numbers I referenced are injector size numbers, lbs instead of cc's, that's all.

I do already have a GM heater valve in mine, started that fad a while back. Head temps back by #3 and #4 dropped by a good 20*, putting them on par with the front of the motor, reducing that hot spot. Simply getting that heat from the motor, instead of deadheading the flow from the back of the head makes a big difference, though it's not ideal returning it to the water pump. Returning to post-t-stat would be better, far more work involved at this time though.

Regarding the larger injector, if you look at the exhaust passage or spark plug from #3, they read much leaner than the rest. I've seen a few motors with heads pulled at the yards as well, same thing, seen some detonation on #3 as well, the rest looked fine. Unfortunately when I did the research on mine, I didn't have an IR gun that read high enough to check manifold temps on #3 vs. the rest though.

Wow, you saw a change like that from one end of the engine to the other? I'm impressed. That's with the front maintaining the same temp as before?

Before I bought this engine in 2010, I went around to 3 or 4 junkyards with a compression tester and cranked over about 15 or maybe 20 engines by hand dry. They all had about 80-100psi compression from me turning it by hand on 1,2,4 but they all had 0 compression on #3.

I got an IR temp gun for like 15 bucks off amazon that reads to at least 450F. The compact ones from HFT don't go over 300 or something. Maybe 200F.

What about the idea of opening up the passages in the head and head gasket for coolant to flow through? There are some passages on 1 and 4 (I think) that are full-size. 2 has smaller ports, and 3 has no ports at all.

It's all been machined and is ready to go, so I'm not thrilled with the idea of cutting into it myself - (I would have the shop do it).
 
The numbers I referenced are injector size numbers, lbs instead of cc's, that's all.

I do already have a GM heater valve in mine, started that fad a while back. Head temps back by #3 and #4 dropped by a good 20*, putting them on par with the front of the motor, reducing that hot spot. Simply getting that heat from the motor, instead of deadheading the flow from the back of the head makes a big difference, though it's not ideal returning it to the water pump. Returning to post-t-stat would be better, far more work involved at this time though.

Regarding the larger injector, if you look at the exhaust passage or spark plug from #3, they read much leaner than the rest. I've seen a few motors with heads pulled at the yards as well, same thing, seen some detonation on #3 as well, the rest looked fine. Unfortunately when I did the research on mine, I didn't have an IR gun that read high enough to check manifold temps on #3 vs. the rest though.

I wonder if the air flow was better to 3 than the other cylinders due to whatever. Maybe differences in flow or less turbulence from something like a vacuum nipple. Is that on b230fts? I did notice some sort of different shape inside the head's port for #1.
 
Also, I daily drive an Audi on a decent stand alone (Maxxecu race) and haven't connected a laptop to it for 3-4 months at this point....
 
Probably impossible without a custom one-off chip, but single port aircooled vw's ran the #3 cylinder 3 degrees retarded to help manage heat with the earlier style fan. I don't know the ezk circuit board at all, but it's not as silly of an idea as it sounds, running rich or backing off ignition on a single cylinder to manage heat.
 
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