Jump to content
HybridZ

Baby LS motor


mutantZ

Recommended Posts

  • 2 months later...

WHOA WHOA WHOA!!!! If they actually keep the transmission as a separate piece of equipment like it looks like in the pics I'm ordering two!!!

 

Flat plane crank V8 anyone?

 

The main thing that's stopped me from pursuing designing a flat plane crank out of a bike V4 or ever V-Twin is that all of the interesting motors have intergrated transmissions, and would thus be a bit complicated to mate together and to a transmission. The lower rev range of this would be perfect for widely available transmissions.

Link to comment
Share on other sites

  • 2 weeks later...
  • 1 month later...

Can someone tell me why a pushrod valve engine is still in production today? I've been wondering for years...

 

Really? This seems almost temporary ban worthy on this site.

 

Very few production pushrod engines will reach much above 90% volumetric efficiency, and will most likely not hit 100hp liter (NA of course). But that being said their compact design means you can fit more cubes.

 

Before I make my next statements, know that I love OHC V8 engines and I'm not a huge fan of GM in general.

 

Compare the LS1 to the Ford Mod motor. Ford had to really pull out all the stops to get a full 5 liters out of their new Coyote V8, and it makes a bit over 400hp, how much exactly I don't think anyone is full certain, but it's in the low 400s most likely. The new Coyote is the lightest and most powerful NA DOHC V8 ford has ever produced in a production car. It's still quite large though, fairly high weight CG, and is around 500# like most of the other Mod motors. I think I remember reading in somewhere that Ford claims that it only gained like 30-40 pounds over the SOHC Mod motor, which is an impressive feat. Overall, this V8 is probably one of the most advanced V8's any joe shmo can go get their hands on and will be littering the streets everywhere. But then there's the LS1, or even lets say the LS2 (still older than the new coyote). The LS2 makes 400hp stock but is a massive 6 liter design. Amazingly though, longblock to longblock the LS2 is considerably more compact that the Ford Mod motors, and even weighs less! This is the real secret of pushrod designs. GM even has variable valve timing now.

 

The main limitation with pushrod engines has always been, and will always be, high RPM valve train stability. It doesn't mean they can't be made to rev, as NASCAR shows otherwise (and note that I'm not a huge nascar fan either). It just has to be designed right to begin with. I have a feeling that most pushrod designs aren't high-rev designs because it's simply not needed. Why go for the wear inducing revs when you've got the displacement/package advantage working for you?

 

Oh, and because of the increase displacement and the lower VE of the LS2 versus the coyote, the LS2 has more power under the curve and a fatter HP peak that shows up sooner in the RPM range. This is high evidence by the fact a simple playing with intake, exhaust, and cam combos can give you an extra 100hp on the LS2, but forces the numbers upwards in the RPM range, sacrificing some low end. The LS2 has lots to offer, and its hard to beat.

 

So what's wrong with producing that?

Edited by Gollum
Link to comment
Share on other sites

After you mentioned that (VE and such) I searched around the web and came across a pretty good discussion about this in LS1 tech. There was a good point that even though more valves and variable cam timing makes a higher VE more streetable, those aren't the only factors involved. And that there are no rules for displacement on the street–just emissions and mpg.

 

http://www.ls1tech.com/forums/advanced-engineering-tech/724636-100-horsepower-per-liter-naturally-aspirated.html

Edited by mutantZ
Link to comment
Share on other sites

Actually I believe the Coyote is lighter than the old 4.6 because it's aluminum.

 

Either way, it's stilla very wide engine, and there's a reason why almost everyone swaps in LS# motors over Ford engines. It's not because people love pushrods either. I love Ford engines, I think they sound way better then Chevy's (IMO), but unless I'm transplanting one into an already big car, then there's no way I'd consider it.

Link to comment
Share on other sites

Not trying to ruffle any feathers guys, sorry about that. I think golllum laid out all of the advantages and disadvantages, it just seems to me that when designing a compact motorcycle enigne, I would have used a more modern engine as the template, but that's just my opinion. Sorry.

Link to comment
Share on other sites

Sorry, gratuitous post, but I do love me the sound of this engine! V4's always sound awesome. I wish they were more of a standard engine format for cars (or bikes for that matter!).

 

 

Link to comment
Share on other sites

Not trying to ruffle any feathers guys, sorry about that. I think gollum laid out all of the advantages and disadvantages, it just seems to me that when designing a compact motorcycle enigne, I would have used a more modern engine as the template, but that's just my opinion. Sorry.

 

More modern engines have 4 valves per cylinder, dual overhead camshafts, dual camshaft CHAIN drives. The pushrod engines have LESS parts to FAIL! Latest state of the art Corvette cylinder heads are VERY if not more efficient than any other cylinder head on the market by any manufacturer. Displacement for displacement, blown or Un-blown, the pushrod engines makes the same or more power and just as or more efficient than the overhead cam engines with LESS PARTS to fail.

 

Don't understand peoples thinking about modern engines.

Link to comment
Share on other sites

  • 1 month later...

More modern engines have 4 valves per cylinder, dual overhead camshafts, dual camshaft CHAIN drives. The pushrod engines have LESS parts to FAIL! Latest state of the art Corvette cylinder heads are VERY if not more efficient than any other cylinder head on the market by any manufacturer. Displacement for displacement, blown or Un-blown, the pushrod engines makes the same or more power and just as or more efficient than the overhead cam engines with LESS PARTS to fail.

 

Don't understand peoples thinking about modern engines.

 

I would have to disagree, partially. Dohc engines (at least 4 cyls and I6) generally last longer than push rod engines. I've seen honda and nissan motors with well over 200k.

 

Pushrod v8's are still chain driven, and (obviously) have a pushrod that actuates a rocker- more parts to fail. A OHC or DOHC motor that has the cam act directly on the cam bucket would have less parts. Chains in street cars rarely break, so having two of them isn't really much of an issue...

 

That said I do see the merit of the push rod v8. In fact the ls motors are pretty sweet IMO- they get very good gas mileage for their displacement, and are constantly being refined.

Link to comment
Share on other sites

Guest
This topic is now closed to further replies.
×
×
  • Create New...