interesting article on ls/vtec

INFORMATION Articles / Teg Tips
1

http://www.indysol.com/resource/lsvtec.html

good info on r/s ratios, HP and torque and others, but IMO he makes assumptions to base his opinions on that are incorrect

:bow:

2

Re: interesting article on ls/vtec

Originally posted by gen2ls/vtec
[Bbut IMO he makes assumptions to base his opinions on that are incorrect [/B]

Like what?

Regards,

Oz

3

yes the r/s ratio is worse on the b18a compared to the b16a, but compared to the b18c ther’s .04 of a difference :confused: and you can crunch numbers all day long, but the fact is my setup ran for 25k miles with no problems on a stock crank, stock rods, and ITR pistons with a powerband that reaced just under 8k. I think he is making a bigger deal out of r/s ratios than it really is for MOST people’s setups for hybrid motors. Now, if you ARE making power in the 8-10k rpm range due to modifying the head and strengthening the block then r/s ratio makes an exponentially larger difference than a 7-8k rpm peak range would, but MOST people, as i stated before, will not have this setup and if they do, they should be doing something such as a crank girdle or resleeving the block or else something will happen- these are the minory and he’s basing his opinions on the minority of people building hybrid motors

:bow:

4

I think his point was that if you want a REAL monster, you are going to have to rev HIGH, for two reasons:

  1. The best cams out there (Jun, Toda) make their power up high
  2. Since we are talking about 1.6 - 2.0 liter 4 bangers, you don’t have much torque, and since hp=torque*rpm, the way to get max hp is through high rpm
5

Man this was helpful to me :smiley:
I could have used this info awhile back when I made a certain post :confused:

I have a quick question if someone is willing to answer :slight_smile:

How does the VTEC change grinds? If a camshaft has a set grind, how does VTEC change the grind of the camshaft? Does it operate at slower and faster rotations?

6

Originally posted by smokInteg
[B]I think his point was that if you want a REAL monster, you are going to have to rev HIGH, for two reasons:

  1. The best cams out there (Jun, Toda) make their power up high
  2. Since we are talking about 1.6 - 2.0 liter 4 bangers, you don’t have much torque, and since hp=torque*rpm, the way to get max hp is through high rpm [/B]

yes thats correct, but he made this article slated to make the average honda owner want to sway from using a b18a block when 90% of these engine builders are not going to use a cam/head setup where power is made in that high of an RPM. It’s VERY good info, as Psychosix mentioned, just a little too opinionated- he should’ve stuck to facts and strayed from his “ideas”

:bow:

7

Originally posted by gen2ls/vtec
yes the r/s ratio is worse on the b18a compared to the b16a, but compared to the b18c ther’s .04 of a difference :confused: and you can crunch numbers all day long, but the fact is my setup ran for 25k miles with no problems on a stock crank, stock rods, and ITR pistons with a powerband that reaced just under 8k. I think he is making a bigger deal out of r/s ratios than it really is for MOST people’s setups for hybrid motors.

I’d like to see LS/VTEC setups after 150000miles (240000kms). Throughout this lifetime, it would be nice to see:

  • oil trend analysis
  • driver habits
  • maintenance records
  • applicable engine issues

…among other things.

:slight_smile:

Oz

8

Originally posted by psYcoSix
[B]I have a quick question if someone is willing to answer :slight_smile:

How does the VTEC change grinds? If a camshaft has a set grind, how does VTEC change the grind of the camshaft? Does it operate at slower and faster rotations? [/B]

VTEC cams have Three (3) cam lobes per each side per cylinder. Simply, take one cylinder, the intake side has 3 cam lobes, the exhaust side has 3 cam lobes.

Now, these cam lobes are spaced together. The VTEC cam lobe is “sandwiched” between smaller cam lobes (smaller grind) that operate the dual valves (2 intake valves and 2 exhaust valves, remember?). Under “No-VTEC” conditions, the 2 cam lobes operate the valves accordingly (just like a non-VTEC engine would). The Honda VTEC system is RPM dependant, so at a certain RPM, VTEC kicks in. When it does, the VTEC cam lobe operates both valves based on its cam lobe specifications.

Now, in terms of “grinds”. In simple terms, it means the cam lobe’s shape and size (or the cam lobe’s “profile”). VTEC’s cam lobe is bigger compared to the 2 smaller lobes beside it. And no, the camshaft does not operate slower during VTEC. According to Isaac Newton, that would be impossible.

That’s a quick, half-A$$ed run-down for you.

Regards,

Oz

9

[QUOTE]I’d like to see LS/VTEC setups after 150000miles (240000kms). Throughout this lifetime, it would be nice to see:

  • oil trend analysis
  • driver habits
  • maintenance records
  • applicable engine issues[QUOTE]

so would I- and I’m glad you mentioned driver habits- cuz to compare a ls/vtec motor that has been used aggressively its whole life to grandma’s stock LS would be unfair- as I’m sure oyu know. So far I have put a little over 25k miles on mine- only problem being carjackers overrevving the engine(more than likely) and blowing the headgasket.

:bow:

10

Originally posted by gen2ls/vtec
[Bso would I- and I’m glad you mentioned driver habits- cuz to compare a ls/vtec motor that has been used aggressively its whole life to grandma’s stock LS would be unfair- as I’m sure oyu know. So far I have put a little over 25k miles on mine- only problem being carjackers overrevving the engine(more than likely) and blowing the headgasket. [/B]

Hehehehe…it’s funny to see LS/VTEC cars on sale while the owner claims they’ve only done LOW miles on it. Makes you wonder the work that was put in it. 25k miles is not a lot. I don’t know how well you treat that engine, but it would be curious to know WHEN you will start having problems.

Regards,

Oz

11

Originally posted by The_Oz
[B]Hehehehe…it’s funny to see LS/VTEC cars on sale while the owner claims they’ve only done LOW miles on it. Makes you wonder the work that was put in it. 25k miles is not a lot. I don’t know how well you treat that engine, but it would be curious to know WHEN you will start having problems.

Regards,

Oz [/B]

I dont forsee having problems any quicker than if I were to have any other b series motor. I do regular maintenance and the whatnot. I do think my headgasket might not have blown from the carjackers if I were to have installed the ARP head studs previously. The b16a headstuds are a little shorter than the b18c and I’m betting overrevving the motor caused those studs to walk out of the thread- more than likely that was the weakest link between the head and block so that’s where the excesive force went. Those will be going in whent he headgasket goes in.

:bow:

12

yea but if you build a proper Ls/Vtec aftermarket rods, pistons, crank balanced and everything done properly i don’t see how it couldn’t run the same or even better then a b16 vtec.

13

i think it depends on where your powerband is going to be whether a b16 will, not necessarily perform but stay together, be the motor to use. Very high rpm usage i.e. 9200++ or so, which a lot of people “plan” on doing but very few of us do, would be what a b16a would be more geared for- this is where I feel r/s ratio would have something to do with the stability. Other than that, most people are not going to be producing power at that rpm level.

:bow: