Heavyweight Bout: RB26dett VS. LS1

[240zdan]

If I were to do it again id probably go LS1. Its cheaper in the long run like everyone says. The rb26 is a more desirable engine however for the datsun since its a straight 6 and nissan.

[stony]

I don't care either way.

 

 

If i were to do it again say if the rb exploded and wasn't savable, i would go turbo v-8. I have said from all the way back in the late 80s. If the US ever gets a hold of turbo tech and applies it to the v-8 it's over. A turbo on a small displacement motor makes up the displacement of a bigger engine but add a turbo to the big engine then where do you go???

[MAG58]

Stony's motor is definitely beast. But, anyone out there care to compare a turbo SBC in the mix?

 

Agreed, many people fail to remember that V8 guys can play with turbo's too. It's not like there is a law that makes it illegal for all cars with more than 6 cylinders to have turbo's. Rumor has it that 4 rotors can have turbo's too. But when this rumor was stated, V8 and I6 guys alike quickly killed him before this could be spread. *hides*

 

Something people fail to take into account is bias. So I'm going to tell everyone now that I love I6's. I love how they sound, how the turbo motors deliver power, and how smooth the are. But at any rate I also think both of these motors have reputations far greater than the engines they actually are. No thermodynamic system is perfect, and both of these are exactly that.

 

Let's look at this from a logical standpoint shall we?

 

1st. Head design. No one is not better than the other. Ported the both flow more or less the same. RB has port floors that are entirely too parallel to the piston/flame front for the kind of RPM's people turn them, IMO. However, a couple of papers toyota and some engineering groups have published have suggested that the pentagonal combustion chamber is a happy medium of flame propogation and detonation resistance. The Pro-stock drag guys have shown that in a GASOLINE engine, the "bathtub" type combustion chamber is quite good at producing efficient engines (why BBC's are still big in pro-stock) while the Hemi design is better suited to alcohol. The LSx heads are nifty things, but to get big numbers required really big numbers porting or aftermarket heads (or ported LS3/L92's?) and still share the head lift problem in very high HP applications that pushed GM to release the Iron LSx block with two extra head studs/cylinder. Also the CC that does so well in efficiency (why LSx's get rediculous mileage for their displacement/power levels) also is not quite as knock resistant as the pentagonal combustion chamber. Because of the cam on bucket design the RB would be better for high RPM's, but the bottom end isn't. We'll get there in a second.

 

Overall: It's a crapshoot really, if anything I'd give a very slight advantage to the LSx heads (yeah, a 2 valve head just beat a 4 valve head, deal with it) due to their efficiency in a street application.

 

The Block: The LSx alloy block is LIGHT. But in high HP applications or very large bore applications, flex can be an issue if pushed enough. If so you'll need to switch to an Iron block which kills the "legendary" LSx weight advantage. The LS does have a deep skirt, 6-bolt main cap design, which is happily shared by it's contemparary Toyota UZ and Nissan VH/VK rivals. (Also the late MB engines, if anyone cares )

 

The RB block is stiff, having a full cradle in the block which sits in a deep skirt. The block is already Iron and is a pretty stout piece, as stock units are used in racing (as if they have a choice?) and have shown few cooling issues or strength issues. The RB block also includes oil squirters for all those happy hair dryers which love to dine on pistons.

 

Verdict: You decide. Both have their advantages.

 

The crank/rotating assembly: Both have cranks missing counterweights. The LSx is missing them in the standard V8 places, and the RB in the normal 2/5 area. The difference here is that the LSx is meant to be a lower revving motor. This means that the harmonic problems that come into play when spinning a partially counterweighted motor at absurd rev's probably wont be an issue, and will never on a street motor.

The RB has a partially counterweighted crank too, though it's known for it's ability to spin crazy numbers on the tach, which means you may get to experience this wonder of partial counterweights. The moral of the story here is that any crankshaft that has a journal and it's corresponding counterweight at least 1 main journal away from it puts stress on that main journal as it has to ballance through it. Not cool.

 

Also, some LS cranks are cast, IIRC all RB's are forged. On a street motor this shouldn't matter but if it does, the RB is covered.

 

Valve Train: This is a double edged sword. From a purley performance standpoint, the cam on bucket direct action of the RB is hard to beat. The belt however needs attention and has fallen out of favor by car companies due to it's propensity to fail (not in RB's particulary, but in all engines).

The LSx valve train does not have the ability to adjust exhaust and intake timing individually, and it also has a heavier reciprocating mass with lifters, pushrods, and rockers. However, the LSx recooperates from this with the advantage of being much more compact in head design than the RB.

 

Power Delivery:

Big difference you'll see in these motors is how they deliver power. Due to the size of the turbo that you'll need to achieve the equal power level of an LSx motor, you'll see much less power/torque at the bottom end of the rev range and an exponential growth as the turbo spools to the top of the powerband. An LSx will maintain a much lower powerband with it's greater displacement and should be much more linear. To add power NA though would require a cam that would also move the power up in the band. Running a stock cam and adding a turbo the same size as the RB's will allow a powerband lower in the rev range, with more bottom end torque, as the extra displacement (2x+) will happily spool a turbo much more quickly.

 

For a street motor, the ability to pull from a much lower RPM around town is a fantastic thing to have. Driving a full race motor in a mini with a 4-8k powerband is a blast, but going from stoplight to stoplight or in a traffic jam is a PITA. Good reason why I went to a 256 cam in mine.

 

 

So which is better? Neither. Both engines are good, and both do what they're designed to do. For a site that prides itself on there being not "best", people tend to get rather opinated on the "best" (mightiest, godliest, etc.) engines. So what do you want, a car that has a bunch of bottom end grunt but not as much top end scream in an extended rev range, or that explosive top end with less torque so you have to wind it out to get the power out of it? Odds are that you'll never push each motor to it's fringe limits to really see which design is better.

 

One more thing to remember... You can get LSx parts at autozone. DOUBT you can do that with RB26 parts.

 

Your driving experience.

 

 

...wow that was long

[getoffmyinternet]

I don't care either way.

 

 

If i were to do it again say if the rb exploded and wasn't savable, i would go turbo v-8. I have said from all the way back in the late 80s. If the US ever gets a hold of turbo tech and applies it to the v-8 it's over. A turbo on a small displacement motor makes up the displacement of a bigger engine but add a turbo to the big engine then where do you go???

 

 

Spiro Pappas.

 

[Zeddicus]

why dont you just go with the LS2? i dont know anything about how it fits in the Z32 chassis but i think its just a few inches longer than the LS1. probably a little more expensive too but if you can find a wrecked GTO at a junkyard you could probably get it for cheap. 6.0L and 400bhp out of the box. just seems like more bang for your buck to me.

[getoffmyinternet]

How much more would the ls2 cost? I was under the impression that the ls1 is easier to work with because of all the support for it such as aftermarket parts. Plus you can practically get another 100hp out of the stock setup by staring at it long enough.

[355Z]

why dont you just go with the LS2? i dont know anything about how it fits in the Z32 chassis but i think its just a few inches longer than the LS1. probably a little more expensive too but if you can find a wrecked GTO at a junkyard you could probably get it for cheap. 6.0L and 400bhp out of the box. just seems like more bang for your buck to me.

 

LS1 and the LS2 are externally the same size and weight.

[Zeddicus]

i've seen LS2+T56 combos with all the wiring and belts etc with 75-100K miles go for 3-4K on ebay you could probably get a good engine and tranny for 3- 3.5 k if you are patient. you should also call some junkyards/ pick n pulls in your area to see if there are any pontiac GTOs with undamaged engines with/ without t56 trannys.

[zangiefisgod]

i've seen LS2+T56 combos with all the wiring and belts etc with 75-100K miles go for 3-4K on ebay you could probably get a good engine and tranny for 3- 3.5 k if you are patient. you should also call some junkyards/ pick n pulls in your area to see if there are any pontiac GTOs with undamaged engines with/ without t56 trannys.

 

I've had a hard time finding LS1's in that price range! I guess they go super fast when they are out there...

 

The LQ route may be an option as well. Any LQ9/4 guys wanna chime in with some setups??? I've seen some great deals on longblocks lately...

[355Z]

Agreed, many people fail to remember that V8 guys can play with turbo's too. It's not like there is a law that makes it illegal for all cars with more than 6 cylinders to have turbo's. Rumor has it that 4 rotors can have turbo's too. But when this rumor was stated, V8 and I6 guys alike quickly killed him before this could be spread. *hides*

 

Right on. Since I had a Buick turbo in the 80's and thought of GM's Corvair as the first heavily produced turbo car in the US it's funny how the latest generation thinks of turbos as a purely Import phenominom. If they had ever experienced a v8 with a mild amount of boost it would open up a world that they would think of as impossible. Traditional sbc's with turbos are really the way to go if you want drivability, durabilty, price and usable power in a street driver.

 

The attached dyno sheet below is my traditional sbc with a peak of 12 lbs of boost. The turbos are capable of twice that much boost when it's time too turn it up. It also makes more than 500 rwhp at 3500 rpm so it has a little low end grunt too. This run is on methanol, but it also has an E85 and a gasoline tune too. Dip in graph at 90 mph is when the tires started spinning on the rollers.

 

 

 

I've had a hard time finding LS1's in that price range! I guess they go super fast when they are out there...

 

The LQ route may be an option as well. Any LQ9/4 guys wanna chime in with some setups??? I've seen some great deals on longblocks lately...

 

 

 

I built an stroker LQ4 (402ci) combination last year with a set of bone stock L92 heads other than Manley valves. It is now in the 9's in a 3750 lb street driven 2000 Camaro. The heads are what does it for the combination. The L92/LS3 heads flow 330 cfm at 0.600 lift out of the box which surpassed a set of prepped SELF racing 23 degree heads that I have on my 427 sbc.

 

Sorry i got off topic! I also believe there is a certain desirability in sticking with the same brand engine as body and the RB26 sure looks right at home in an older Z car!

[zangiefisgod]

The attached dyno sheet below is my traditional sbc with a peak of 12 lbs of boost. The turbos are capable of twice that much boost when it's time too turn it up. It also makes more than 500 rwhp at 3500 rpm so it has a little low end grunt too. This run is on methanol, but it also has an E85 and a gasoline tune too. Dip in graph at 90 mph is when the tires started spinning on the rollers.

 

 

 

 

 

 

 

I built an stroker LQ4 (402ci) combination last year with a set of bone stock L92 heads other than Manley valves. It is now in the 9's in a 3750 lb street driven 2000 Camaro. The heads are what does it for the combination. The L92/LS3 heads flow 330 cfm at 0.600 lift out of the box which surpassed a set of prepped SELF racing 23 degree heads that I have on my 427 sbc.

 

Sorry i got off topic! I also believe there is a certain desirability in sticking with the same brand engine as body and the RB26 sure looks right at home in an older Z car!

 

WOW. Great power numbers! Any feedback on a cost effective 500whp LQ setup? I would plan for a heads/cam/nitrous combo to get there intially; with future plans of a turbo configuration.

[drive185mph]

I've been researching this exact topic and both engines are beautiful but i find the LSX wins the day as far as power-weight, power-price, power-drivability and power-serviceability. besides that some guy on here said he was getting almost 30mpg from his LS1 s30, if he's half telling the truth i'd say that's not bad. the LSX, is unique perhaps not as unique as a RB but you don't see alot of engine swaps driving around anyway.

As for your power goals: the LS2 has 400 hp with all it's emissions crap and cats, and a mild enough cam so your grandmother likes it. It seems to me that 500hp can be coaxed out of it with very little capital

 

there is no best but for your application i think there is a better

[MassMayhem]

Agreed, many people fail to remember that V8 guys can play with turbo's too. It's not like there is a law that makes it illegal for all cars with more than 6 cylinders to have turbo's. Rumor has it that 4 rotors can have turbo's too. But when this rumor was stated, V8 and I6 guys alike quickly killed him before this could be spread. *hides*

 

Something people fail to take into account is bias. So I'm going to tell everyone now that I love I6's. I love how they sound, how the turbo motors deliver power, and how smooth the are. But at any rate I also think both of these motors have reputations far greater than the engines they actually are. No thermodynamic system is perfect, and both of these are exactly that.

 

Let's look at this from a logical standpoint shall we?

 

1st. Head design. No one is not better than the other. Ported the both flow more or less the same. RB has port floors that are entirely too parallel to the piston/flame front for the kind of RPM's people turn them, IMO. However, a couple of papers toyota and some engineering groups have published have suggested that the pentagonal combustion chamber is a happy medium of flame propogation and detonation resistance. The Pro-stock drag guys have shown that in a GASOLINE engine, the "bathtub" type combustion chamber is quite good at producing efficient engines (why BBC's are still big in pro-stock) while the Hemi design is better suited to alcohol. The LSx heads are nifty things, but to get big numbers required really big numbers porting or aftermarket heads (or ported LS3/L92's?) and still share the head lift problem in very high HP applications that pushed GM to release the Iron LSx block with two extra head studs/cylinder. Also the CC that does so well in efficiency (why LSx's get rediculous mileage for their displacement/power levels) also is not quite as knock resistant as the pentagonal combustion chamber. Because of the cam on bucket design the RB would be better for high RPM's, but the bottom end isn't. We'll get there in a second.

 

Overall: It's a crapshoot really, if anything I'd give a very slight advantage to the LSx heads (yeah, a 2 valve head just beat a 4 valve head, deal with it) due to their efficiency in a street application.

 

The Block: The LSx alloy block is LIGHT. But in high HP applications or very large bore applications, flex can be an issue if pushed enough. If so you'll need to switch to an Iron block which kills the "legendary" LSx weight advantage. The LS does have a deep skirt, 6-bolt main cap design, which is happily shared by it's contemparary Toyota UZ and Nissan VH/VK rivals. (Also the late MB engines, if anyone cares )

 

The RB block is stiff, having a full cradle in the block which sits in a deep skirt. The block is already Iron and is a pretty stout piece, as stock units are used in racing (as if they have a choice?) and have shown few cooling issues or strength issues. The RB block also includes oil squirters for all those happy hair dryers which love to dine on pistons.

 

Verdict: You decide. Both have their advantages.

 

The crank/rotating assembly: Both have cranks missing counterweights. The LSx is missing them in the standard V8 places, and the RB in the normal 2/5 area. The difference here is that the LSx is meant to be a lower revving motor. This means that the harmonic problems that come into play when spinning a partially counterweighted motor at absurd rev's probably wont be an issue, and will never on a street motor.

The RB has a partially counterweighted crank too, though it's known for it's ability to spin crazy numbers on the tach, which means you may get to experience this wonder of partial counterweights. The moral of the story here is that any crankshaft that has a journal and it's corresponding counterweight at least 1 main journal away from it puts stress on that main journal as it has to ballance through it. Not cool.

 

Also, some LS cranks are cast, IIRC all RB's are forged. On a street motor this shouldn't matter but if it does, the RB is covered.

 

Valve Train: This is a double edged sword. From a purley performance standpoint, the cam on bucket direct action of the RB is hard to beat. The belt however needs attention and has fallen out of favor by car companies due to it's propensity to fail (not in RB's particulary, but in all engines).

The LSx valve train does not have the ability to adjust exhaust and intake timing individually, and it also has a heavier reciprocating mass with lifters, pushrods, and rockers. However, the LSx recooperates from this with the advantage of being much more compact in head design than the RB.

 

Power Delivery:

Big difference you'll see in these motors is how they deliver power. Due to the size of the turbo that you'll need to achieve the equal power level of an LSx motor, you'll see much less power/torque at the bottom end of the rev range and an exponential growth as the turbo spools to the top of the powerband. An LSx will maintain a much lower powerband with it's greater displacement and should be much more linear. To add power NA though would require a cam that would also move the power up in the band. Running a stock cam and adding a turbo the same size as the RB's will allow a powerband lower in the rev range, with more bottom end torque, as the extra displacement (2x+) will happily spool a turbo much more quickly.

 

For a street motor, the ability to pull from a much lower RPM around town is a fantastic thing to have. Driving a full race motor in a mini with a 4-8k powerband is a blast, but going from stoplight to stoplight or in a traffic jam is a PITA. Good reason why I went to a 256 cam in mine.

 

 

So which is better? Neither. Both engines are good, and both do what they're designed to do. For a site that prides itself on there being not "best", people tend to get rather opinated on the "best" (mightiest, godliest, etc.) engines. So what do you want, a car that has a bunch of bottom end grunt but not as much top end scream in an extended rev range, or that explosive top end with less torque so you have to wind it out to get the power out of it? Odds are that you'll never push each motor to it's fringe limits to really see which design is better.

 

One more thing to remember... You can get LSx parts at autozone. DOUBT you can do that with RB26 parts.

 

Your driving experience.

 

 

...wow that was long

 

Best post I have ever read with detail on each engine. Really just answers the topic perfectly