19bonestock88’s first generation L61 build thread
 

Yes, guys, I’m starting a thread specifically for the engine in my car, mostly to note progress on just the next engine but also to ask questions and throw out ideas. I’m embarking on this because the current engine in the car is very tired. It smokes, leaks oil and generally is getting to be pretty inefficient, and I’m starting to get funding to build the replacement.

Branching off into three sub topics engine related in later posts, but in general the next engine will be very much like the existing one, but with work done to the cylinder head/induction system, it’ll retain the same capacity and the transmission won’t change except maybe to add a limited slip differential

So: no off the wall internal mods in an effort to increase efficiency? Just working on breathing? This makes me interested.

The biggest parlor trick will be a ceramic coating on the combustion chamber and ports but that treatment has only usually gotten people 5-7%(in power output) on average. The head will only be shaved a little and the valves currently installed in it have a slightly flatter face, all adding up to a little more compression but probably not much. The shop that’s going to handle the port work and valve grinding has done numerous race winning cylinder heads and is well known in the Ecotec community.

First chapter: cylinder head and induction system
 

So the first step in improving engine efficiency is to improve how it can breathe. In addition to having the head ported by a well reputed shop I also plan to switch to the better flowing intake manifold found on the 2006-07 2.4 (LE5) Ecotec over my ported stock manifold, and the throttle body from a 4.3 Vortec V6 (I think 96-03). In the dirt track community the intake manifold is a bolt on increase of around 20hp and the throttle body is good for between 5 and 10. I also plan to replace the factory airbox (although mine is ported) with a 3.5” fender well intake. The reasoning is that the airflow path through the airbox is almost a 180 degree bend and the fender well intake will reduce that to a 90 degree wide radius bend. All these breathing improvements will likely shift peak power higher in the rev range but that will be discussed more in the second chapter

Less airflow restrictions mean less pumping losses right?

https://duckduckgo.com/?q=extrude+hone?

Any clue on how it will affect the torque curve?

It will undoubtedly shift peak torque upward some. The curve should retain much of its shape given that I’m keeping the stock cams. I should still retain a fair amount of low end torque and if I find after the engine is installed that low end is lacking I can address it then. My thought is that if I’m further into the throttle at low RPM that pumping losses are reduced and efficiency improved, provided the air fuel ratios are the same in both situations

Don't forget you can retard or advance cam timing to shift power back to desred rpm ranges by one tooth.

The thing is, I’m not worried about the shift in power. I fear that shifting the power back down might reduce the output all together and to be honest, I want the additional power. Not that the car feels underpowered, but I kinda wanna make it a little faster with the next engine. I’d be thrilled to see 175whp versus the ~130whp it makes now

Second chapter: engine management
 

So, I’ve determined that to extract the best efficiency from the engine, the original engine management must be abandoned. Thing is, the car runs almost all of its body functions(lights, AC, power steering) through a BCM which needs communication with the engine computer to function. What I need to do to retain full functionality of the car is to have the factory PCM in place and receiving just enough data to show the BCM the car is running but with another engine controller actually running the show. So far what I’ve decided on using is the P11 ECM from the 2003-2005 Chevy Cavalier. That ECM has HPTuners support and can be edited unlike my original E16a PCM that’s not supported. That ECM also natively runs the first generation L61 by default so very little sensor changes would be needed, with the only challenge being how to feed data from my crank sensor and speed sensor to both controllers without their signal being distorted.

The changes to code that I wanna focus on are a leaner AFR under full power (they’re tuned rich from the factory), a “lean burn” mode at light load between 1500 and 2500RPM(45-75mph in fifth), an higher rev limit to take advantage of the better breathing (7200 versus 6450), and more ignition timing. In addition I’d like to modify the fuel and ignition tables for a certain intake temperature only, so I can spoof that temperature intermittently to be able to run E85 on command for more power