https://www.youtube.com/watch?v=VsmbbuSq9m0
With an interview with Tom Nelson of Nelson Racing Engines. Just go look up nelsonracingengines on youtube or go here: http://www.nelsonracingengines.com/
This guy is legit. Been watching his videos for years, as he builds insane cars for clients.
/DRIVE asks why the LS engine is so good
Re: /DRIVE asks why the LS engine is so good
I watched this last night. It was ok. There were a few minutes where it was an NRE advertisement, but you have to expect that. Also NRE builds good stuff so it's not totally invalid.
But I did learn a few things:
1) Problems with stroker kits and the piston skirts coming way out from the bottom of the cylinders (seems obvious to me but who knows)
2) I guess I could have predicted but I had no data on the aluminum block builds cooling better at higher power levels
3) The intake section was interesting since it also confirmed something I have thought to be true (stock stuff or the FAST intake is probably what you want unless you are revving to over 7000 rpm)
4) I also knew this but he put it in very understandable terms: mid-lift head port flow numbers are extremely important and that's where consumers can get fooled. Aftermarket porters can sell very high flow numbers at specific high lift values, but often these heads suck at low to mid valve lift, which means the car will drive like a pig, especially on the street.
He also reiterated the importance of tuning, but that's also common knowledge.
One thing that I know is nice about the Gen III+ PCMs is the way spark advance is set up in the tables. In older stuff, you basically had an electronic version of the old mechanical dist with vacuum advance. Except you could control it with FAR more precision. It was vacuum (MAP) based, and RPM based.
The LS stuff is based on grams/sec of air per cylinder. The old way, you tuned from a high vacuum (overrun conditions, closed throttle) to atmospheric or about 100kPa (wide open throttle). And that's as far as the table went, if you were naturally aspirated. The new way lets the table cover conditions that the engine may or may not actually experience.
For example, the stock engine may peak at 0.84 grams/sec/cylinder. But the table goes all the way to 1.36. And the table will be preprogrammed to somewhat cover these conditions, even though they never happen on the stock engine. What this means to the enthusiast is the tuning required after, say, a cam swap, is actually EASIER.
Spark requirements for a cam swap are generally these:
- Bring spark advance in sooner at lower rpms, due to the inefficiency at lower rpms with the more aggressive cam (more overlap).
- Add more cruise and idle (low MAP) spark for drivability and to help clean up the idle
- Possibly increase the maximum spark advance from stock, especially if you make the switch to 93 octane
This was done in the old days, and also how spark was tuned in the 80s and 90s cars.
In the LS world, that profile is already sort of built into the stock timing table. For example, the new cam is probably flowing less air at lower rpm (lower volumetric efficiency) than the stock. The stock timing table would provide more spark advance under those conditions. I would suggest that the LS engine with a cam swap and NO tuning would be far more drivable than a cam swap and no tuning on an 80s or 90s V8. But tuning is still highly beneficial.
I thought that was interesting.
But I did learn a few things:
1) Problems with stroker kits and the piston skirts coming way out from the bottom of the cylinders (seems obvious to me but who knows)
2) I guess I could have predicted but I had no data on the aluminum block builds cooling better at higher power levels
3) The intake section was interesting since it also confirmed something I have thought to be true (stock stuff or the FAST intake is probably what you want unless you are revving to over 7000 rpm)
4) I also knew this but he put it in very understandable terms: mid-lift head port flow numbers are extremely important and that's where consumers can get fooled. Aftermarket porters can sell very high flow numbers at specific high lift values, but often these heads suck at low to mid valve lift, which means the car will drive like a pig, especially on the street.
He also reiterated the importance of tuning, but that's also common knowledge.
One thing that I know is nice about the Gen III+ PCMs is the way spark advance is set up in the tables. In older stuff, you basically had an electronic version of the old mechanical dist with vacuum advance. Except you could control it with FAR more precision. It was vacuum (MAP) based, and RPM based.
The LS stuff is based on grams/sec of air per cylinder. The old way, you tuned from a high vacuum (overrun conditions, closed throttle) to atmospheric or about 100kPa (wide open throttle). And that's as far as the table went, if you were naturally aspirated. The new way lets the table cover conditions that the engine may or may not actually experience.
For example, the stock engine may peak at 0.84 grams/sec/cylinder. But the table goes all the way to 1.36. And the table will be preprogrammed to somewhat cover these conditions, even though they never happen on the stock engine. What this means to the enthusiast is the tuning required after, say, a cam swap, is actually EASIER.
Spark requirements for a cam swap are generally these:
- Bring spark advance in sooner at lower rpms, due to the inefficiency at lower rpms with the more aggressive cam (more overlap).
- Add more cruise and idle (low MAP) spark for drivability and to help clean up the idle
- Possibly increase the maximum spark advance from stock, especially if you make the switch to 93 octane
This was done in the old days, and also how spark was tuned in the 80s and 90s cars.
In the LS world, that profile is already sort of built into the stock timing table. For example, the new cam is probably flowing less air at lower rpm (lower volumetric efficiency) than the stock. The stock timing table would provide more spark advance under those conditions. I would suggest that the LS engine with a cam swap and NO tuning would be far more drivable than a cam swap and no tuning on an 80s or 90s V8. But tuning is still highly beneficial.
I thought that was interesting.
Re: /DRIVE asks why the LS engine is so good
Funny comment:
This response to the above comment rates a close 2nd:
I think this is fairly true. This demographic (and many others) just haven't experienced the power level (N/A or FI), and the torque, in vehicles that the LS can fit into. Just totally foreign (ironically)."LS swaps are stupid" - 17 year old JDM fanboy who has never had a car faster than 15s 1/4 mile
This response to the above comment rates a close 2nd:
and his car sounds like a dying vacuum with a kazoo attached
Re: /DRIVE asks why the LS engine is so good
The rest of the comments are probably worth a looksee...