LS/VTEC anybody here done this??

[shep9ky]

hey guys
as you may no im just researching future mods to my engine and naturally would like the best ahhhhhh...........bang for my buck i guess.

I have heard that the ls/vtec option is great but a little unreliable.

Im just asking if anyone has had any experience with this hybrid engine or the other crvtec?

what were there impressions?
was it reliable?
say i do crack the block cos it's weaker than the b series vtec engines, would my b16 head still be alright to bolt back onto my b16a?

I was planning on using all that i could from my b16a
how much would this setup cost doesnt have to be exact obviously?

any opinions welcome

[Macros]

Their are many reasons why Honda did not put a vtec head on the b18b from factory.

Have a read of this... Taken from http://nzhondas.com/phpBB2/the-truth...-vtu20672.html







The facts, Why Honda didnt make them Vtec in the First Place:

Everyone here will understand what Vtec is and how Vtec works (if you dont, stop reading this and use the search function). The next step is understand WHY honda put the technology into the engines it did.

If Frankenstein Engines are so wonderful, why in the world would Honda put us in such a situation - having to build these incredible motors all by ourselves? Why would they knowingly decrease displacement and torque in a car being manufactured to be faster than our potential Frank engined ve-hicles?

Look at it from a manufacturing standpoint- Honda is already making the higher displacement B18A and B blocks (blocks are identical, only difference was in the head), so why go to the extra time and expense of developing and manufacturing a separate block, especially if it will decrease output? Why the hell did they make the B18C block? why didnt they use the B18A or B for a Vtec engine?

The answer is easy: R/S.

What is R/S?

If you think you know everything in this thread, MAKE SURE you know this. This is bar far the most important part of building a fast and RELIABLE N/A Engine (oh my god i said the 'R' Word!!)

R/S is the abbreviation for rod to stroke ratio. It is the ratio of the length of the connecting rod to the length of the piston stroke, or the distance the piston travels from the top to the bottom of its stroke.

As the ratio gets lower, the amount of stress on engine internals increases exponentially, killing long-term reliability and destroying power output. Conversly, the higher the number is, the slower the piston is traveling, killing power output.

The ideal R/S is 1.75:1 (Big UPs for the B16A, at a near-perfect 1.74:1!).

Why a low R/S is bad for reliability

A low R/S means the rod will be closer to a horizontal angle, rather than being closer to vertical which is ideal, on its upstroke. This means that more of its force will be pushing the piston horizontally, rather than vertically. What does this mean for your engine? Two things.

1. There will be more stress on the sides and in the center of the rod, rather than on its ends, leaving the rod more vulnerable to breaking. Picture a straw. This is no special straw, just an ordinary drinking straw. Is it going to be easier to bend this straw by applying pressure onto its ends, or at its center? Now think of your poor connecting rods..

2. There will be more stress on your cylinder walls. Once again, the rod is pushing the piston at a more horizontal angle- right into your cylinder walls, rather than up and through them. The risk here is double:
A. Putting that piston right through the cylinder wall.
B. The cylinder wall will actually flex under the pressure, causing the shape to turn from a circle to an oval or oblong shape. This causes the loss of the seal created by the piston rings. What happens? A small amount of oil could slip past into the combustion chamber. Bad things happen from here: The oil gets combusted, leaving nasty carbon deposits in your combustion chamber and exhaust ports- not a good thing for flow or valve sealing.

It's also important to note that as the RPMs increase, so does the amount of stress on your engine's internals.

What is Power and How do Hondas Make it

WARNING!! This section could make you think about what you're spending all your money on!!

Most people will have done some (very) basic Physics in School. For our purposes i will use these abbreviations:

P=Power, horsepower in our case.
T=Torque, measure in either Nm (Newton Metres) or lb/ft (some people like Kg/m too)
R=Engine speed, measured in RPM's

The mathematical equation for Horsepower is:

Hpower= (torqueXrpm) / 5252

Heres an Example of it in practice:

hpower= (100x10,000) / 5252
= (100,000)/ 5252
= 190.4..

from this we can conclude that if we increase RPM or Torque, we get more power right? remember this, its important.

Now how do Hondas make power? Our tiny little 1.6-1.8L engines aren't exactly oozing spare displacement and creating gobs of torque.

Hondas make power through revving, and revving high. So why does everyone place so much emphasis on creating torque? It's because all these bolt-ons you see advertised won't raise your redline, but they will increase torque. Bolt ons will NEVER raise your redline.

There's nothing wrong with squeezing every last ounce of torque out of your engine tho. in fact, you should. But trying to get torque from more displacement in a Honda is like trying to fill a swimming pool using a squirt gun. You'll never get enough for it to be useful. comparatively (to other manufacturers 2.2L) even H22a's make **** all torque.

B Series, by the numbers:

As the B-series engines were Hondas pioneer vtec engines, here are some Vital Statistics of the good, and not so good:

B16A:
Rod length: 134 mm
Stroke: 77 mm
R/S: 1.74:1
Displacement: 1587.12 cc
Power Output: 160hp (depending on gen.)

B18A-B; B20B-Z: (Z's have a larger bore)
Rod length: 137mm
Stroke: 89mm
R/S: 1.54:1
Displacement: 1834.47 cc
Power Output: B18A: 130hp
B18B: 140hp
B20B: 126hp
B20Z: 143hp

B18C:
Rod length: 137.9 mm
Stroke: 87.2 mm
R/S: 1.58:1
Displacement: 1797.36 cc
Power Output: 180hp

B20A:
Rod length: 141.7
Stroke: 95 mm
R/S: 1.49-1.50:1
Displacement: 1958.14
power output: 110hp

now you should see at least two things.
1. why the B20A is a piece of shit and should be melted for scrap
2. and why Honda decreased the displacement of the B18c from the B18a/b

you dont see it?? here it is:
Honda decreased the displacement of the B18c (1797cc, compared to the B18a/b 1834cc) which improved the good ol R/S ratio. This allows the B18c to rev higher and (WOW! shock horror!) make more power.

Limitations on Frankenstein Engines:

Now the part everyone has been waiting for, why Vtec is no good on engines not built with it.

For this example, we'll use the B18C and the B18A/B.

Everybody knows Vtec Engines are built strong, but why didnt honda make their non-vtec engines just as strong? The answer is simple, They didnt need to. Remember that Manufacturers dont generally cater to the Ethos of the re-engineered Boy Racer. The Racers of the 90's and on dont rely on V8's anymore (at least not in any large percentage), the favoured ride is now pocket rockets, small Japanese cars with 4 cylinder powerplants.

So wht are the differences between the Vtec B18C and the Non Vtec B18A/B??

1. When building a Frankenstein engine, you have to relocate dowel pins for the oil supply. But wait a second, theres a problem here. Non Vtec engines run smaller oil lines than their Vtec counterparts.

Why is this a problem? what do you think happens when you hit Vtec? ever seen a B16a/B18C Dyno Plot? If you have you will have undoubtedly seen a huge jump in the power and torque curves when vtec is engaged. This huge jump has the effect of drastically increasing Oil pressure, one of the factors needed for Vtec to engage in the first place.

So what is the problem with smaller oil lines? smaller oil lines spread oil to thin and too far. When Vtec hits, your oil is going to pump as quick as possible, but because the dowels are smaller, its not going to get where it needs to quick enough, causing major problems.

2. The crank. Everybody talks about the crank of a Vtec engine being so much stronger. But why is it stronger?

All Vtec cranks come Balanced from the factory, unlike their non-vtec counterparts. The B18C cranks are also Tetra-Methyl lead Coated, further increasing strength and reliability. This also gives a low friction coating, aiding in strength at High Vtec operating speeds.

3. B18A/B engines dont use a knock sensor.
This is not so much a problem but more a hassle. because you need a knock sensor to run Vtec youll need to tap one to get it to work. Ever seen the back of a B18A/B block? they dont have the space where the B16A/B18C's have their knock sensor. where are you going to put it? C-speed decided to knock one of their Alternator Legs off and use the bolt tap for the knock sensor...

stupid americans.

4. Rev Limits....the most important part. Can anyone tell me what the redline is on your everyday B18A/B?? 6750rpm. And whats the redline on a B18C? 7600rpm...

This is not rocket science. is plain and simple. As its already been stated, Vtec engines are designed to make power by Revving very very high for a stock standard engine. There is no way a non-vtec engine will survive through that kind of torture. bye bye rods and pistons..

Tis Always Sad to See an Engine Die...

So, in conclusion, i hope you have learnt and taken these main facts on board, if nothing else:

-The LS/VTEC suffers from a bad R/S, due to the fact that it utilizes an LS block with a R/S of 1.54:1.

-A bad R/S is bad for the engine, especially at high RPMs

-Hondas make power through revving, and high power through revving higher, high compression, and aggressive camshafts

As we just discussed, in order to get any considerable power out of an engine, aggressive camshafts are a must. In order to get any benefit from aggressive camshafts, the ability to rev the engine high is a necessity. How valuable is VTEC if you can only use it for the top 1000 RPM of your powerband?

Think about these factors BEFORE pouring ANY $$ into a Frankenstein engine, they could save you a lot of time and money.

any other question or answers to this subject post them here.

Thanks go to Chris, Mark and Shorty for their stupidity, idiotic behaviour and spare engines. Big Big Ups Guys.

[shep9ky]

so what about getting the block resleeved?

[Macros]

why not save you money and buy a b18c block?

[shep9ky]

how much would that set me back?
that seems like the biggest performance boost for the money i agree with you
alot less hassle

[Macros]

Well I don't know in aussie. But in NZ they're dirt cheap

[tinkerbell]

what a load of crap.

read the posts at the end of that thread and you will see that teh "truth" is not as certain as the original post implies.

page 3 in particular...

[Macros]

Please quote. I don't see how the original post is a "load of crap".

[tinkerbell]

Please quote. I don't see how the original post is a "load of crap".

the person asserts that he knows the "truth" and that the Truth is that all Hybrid engines are unreliable.

he uses second and third hand hearsay (r/s ratio gibberish) to 'prove his point'

that is the bunch of crap

and now he has got you quoting it as fact?!?!!?

how naive are you!?!?!?!

[Macros]

He has first hand experience building hybrid motors.

Rod/stroke ratios do have a part to play in engine reliability.

Please give evidence to back up your claim.

[tinkerbell]

He has first hand experience building hybrid motors.

so do i marocs...

read page three, i outline most of my experience there...

page two is where i dispute his "facts"

you are just being a naive sheep for blindly believeing what he is saying.

i know about R/S ratio, and agree that it may affect reliability, but to the extent that he is claiming - rubbish!!!

and his MAIN point that the B20 has a 1.54 R/S ratio and the B18C has 1.58???

hmmm, 0.04 difference WOW!!!!

[LO_N_SXC]

Hey I know this is a old post but I was actually looking at doing this a long time ago when my old engine gave in, I have read simillar things like this thread and other people giving examples of why it is not reliable thing to do, but the ironic thing is that most likely this people have never built one them selves yet alone owned one to say they are a bad Idea, so what I say to people like that is " Go and do it you self before you open your mouth about something you have never experienced " I guess you will never know how reliable this things are unless you build one your self.....

That all from me for now, thankyou! I'm LO_N_SXC and please remeber, same time same place on the same chanell............