Bad day on the dyno... - Page 5 - Lateral-g Forums

**GregWeld** · #41 01-18-2015, 07:45 PM

Quote:

Originally Posted by Sieg

AEM recommended my sensor be mounted at a minimum 10* downward angle.

Correct?

I've had 'em at 9 O'clock (looking from the rear) and 12 O'clock..

I think it's mostly that you don't put 'em in the bottom half where stuff could hit 'em etc. better to keep them up and protected. And not to far back from the collector. I think it needs to stay within the first 18" IIRC. But why not put it in the collector.... is my thinking.

carbuff · #42 01-18-2015, 07:48 PM

Here's a picture of the bottom of the car. The recommendations I have seen are that the sensor should be about 8" downstream of the collector for this sensor and system. As I understand it, the narrowband sensors need to be as close to the engine as possible, as they rely on the engine heat to heat the sensor element. The wideband for the Holley is self-heating, and it actually needs to be far enough downstream that it doesn't overheat from the engine's heat.

**GregWeld** · #43 01-18-2015, 08:02 PM

I'm not an expert on them at all Bryan -- I've installed a few -- and haven't had any issues with this sensor where I've placed them. I think the heated version heat themselves to about 900*..... I've even seen them where they're probably only reading two of the four cylinders and they read just fine. They need to be burned clean - so "hot" is a good thing.

Some guys run "dumps" with basically a muffler not far back from the collector and a very short downturn pipe on the end. In that case I'd want it far enough from that "opening" that it wouldn't see any reversion - but your system has full pipes so that's not an issue worth mentioning.

My basic understanding is that you want them hot - and in full stream of the exhaust....

I've had faulty MAP sensor -- that was a PITA! And I've had TWO faulty TPS.... one that would just "break down" after driving for awhile. Had to do data logging several times to find that one.

Solid LT1 · #44 01-18-2015, 08:55 PM

Before dumping a bunch of money re-sleeving the block I hope your aware that the LS2 block is probably the best bang for the $$$$ in LS performance. Pricing a new block at Summit.....they are $1120.00. I would reuse your existing parts and buy a set of shaft rockers before spending the $$$ for an LS3 upgrade.....I take it the motor is pretty low mileage and all other 7 cylinders are in good shape. Sleeves are great if you plan on dumping a big load of N2O or blower/turbo upgrade, if your staying normally aspirated there isn't any big advantage in installing a set of sleeves. You might want to check over on the Corvette Forum, LS1 Tech or other sites for a quality LS builder if you don't already know of one. Good luck on the rebuild, I really like your Bird!

71RS/SS396 · #45 01-19-2015, 03:28 AM

Quote:

Originally Posted by Solid LT1

Before dumping a bunch of money re-sleeving the block I hope your aware that the LS2 block is probably the best bang for the $$$$ in LS performance. Pricing a new block at Summit.....they are $1120.00. I would reuse your existing parts and buy a set of shaft rockers before spending the $$$ for an LS3 upgrade.....I take it the motor is pretty low mileage and all other 7 cylinders are in good shape. Sleeves are great if you plan on dumping a big load of N2O or blower/turbo upgrade, if your staying normally aspirated there isn't any big advantage in installing a set of sleeves. You might want to check over on the Corvette Forum, LS1 Tech or other sites for a quality LS builder if you don't already know of one. Good luck on the rebuild, I really like your Bird!

Shaft rockers are unnecessary in his application and you're just adding weight to the valvetrain which will require more spring to control it. I'm still using upgraded stock rockers on mine with a stud girdle and spinning it to 8,000 rpm with no issues.

71RS/SS396 · #46 01-19-2015, 03:53 AM

The 02 should be 6-8" back from the last tube in the header, if you put it in the collector it will read the cylinder it's closest to.
I'm not sure that it is rich, after looking at the pics I suspect the oil it's ingesting from the pcv is what you're seeing on the pistons. You need to address your venting as this can cause a whole host of problems. What pcv vent are you using? Most, if not all of these do not work properly. I put a restricter in the vacuum line to slow the velocity. I would also vent both valve covers to a catch can. The LS engines have horrible windage problems and need a lot of topend ventilation to deal with it. The path you're headed down with a larger stroke is going to make it worse since you're basically installing a bigger fan in the crankcase.

Che70velle · #47 01-19-2015, 06:11 AM

Quote:

Originally Posted by 71RS/SS396

The 02 should be 6-8" back from the last tube in the header, if you put it in the collector it will read the cylinder it's closest to.
I'm not sure that it is rich, after looking at the pics I suspect the oil it's ingesting from the pcv is what you're seeing on the pistons. You need to address your venting as this can cause a whole host of problems. What pcv vent are you using? Most, if not all of these do not work properly. I put a restricter in the vacuum line to slow the velocity. I would also vent both valve covers to a catch can. The LS engines have horrible windage problems and need a lot of topend ventilation to deal with it. The path you're headed down with a larger stroke is going to make it worse since you're basically installing a bigger fan in the crankcase.

Agreed, all that most systems do on these LS engines is fill the intake with an oil like gel. Bryan, have you looked at the plugs? Spark plugs are tattletales, and reading them has become a lost art. This engine shut off at 5500 I think you said, so it would be ideal to take a close looksey at the plugs.

Payton King · #48 01-19-2015, 09:25 AM

Agreed on the oil windage. I ened up using 2 catch cans on my car to solve the problem. Just like Tim stated, you will need to pull from both valve covers and from the valley tray. Kurt Urban ( http://kurturbanperformance.net/home/ )is the man on the LS stuff, let Tim guide you to the promosed land.

**GregWeld** · #49 01-19-2015, 11:27 AM

WHAT HE SAID.....

"to do items" on your list...

Talk to Urban

Talk to Tim

Go to Salt Lick for lunch... or Franklins...

See ya at the Lonestar Roundup... 18 or us are driving down for it.

**Sieg** · #50 01-19-2015, 12:50 PM

Quote:

Originally Posted by GregWeld

I've had 'em at 9 O'clock (looking from the rear) and 12 O'clock..

I think it's mostly that you don't put 'em in the bottom half where stuff could hit 'em etc. better to keep them up and protected. And not to far back from the collector. I think it needs to stay within the first 18" IIRC. But why not put it in the collector.... is my thinking.

AEM referenced condensation effecting the sensor long-term, so the downward angle allows it to drain off vs in.

Downstream from the collector gets a better mixture blend from the individual primaries......as my brain perceived it when I cut the hole in my system.