Ligit LS/Vtec Question

[bov300zx]

All I've seen are question about hp gains and how to do the ls/vtec right. I have yet to see any questions about the ls/vtec at lower rpms. I read in other posts that with the higher compression of the ls/vtec the reliability goes way down and the engine wants to throw a rod around 8 thousand rpm. What about the automatics? My 91 redlines at 6.5 so would the ls/vtec be a more practical mod? Would a new vtec ecu be benificial with that? I guess what I'm trying to get at is would a basic head swap cover the conversion for me?

[Beyond Imagination]

r/s ration will still be 1.54:1 even with a vtec head. yes you can rev the ls/vtec higher than your ls motor because of the head but keep in mind that even with a vtec head the r/s ratio is still the same. you would need a new ecu for the ls/vtec.

[bov300zx]

I've heard that different internals are needed for a reliable conversion. But if I can't rev as high would I need them? Would the redline change if a vtec ecu was installed and if it would; would my tranny be capable of the higher rpms?

[Beyond Imagination]

if the motor is built right it'll be as reliable as any other motor. if you're looking for a better r/s ratio and a higher reving motor you could always put in a b16a or b18c crank which help to achieve a better r/s ratio but by doing so you'll lose displacement. i personally don't think that a 1.54:1 ratio is that unreliable if you're not trying to rev to 8500+ all the time. to achieve a high reving motor you could always work on internals ... custom rods, sleeving etc. redline on a vtec ecu will be higher than a non-vtec. i would say use a gsr tranny for an lsvtec because of the shorter gearing which is easier to keep your car in the powerband.

[civickiller]

why does everyone mention rod ratio ? its a theory without any fact.

best to get new rod bolts and a vtec oil pump. that should set it up pretty good

[scallywag]

You don't need to rebuild your block if you want to do ls/vtec. But it is always a nice thing to do, but not essential. You well be able to rev to 8k no problem, you will just need a new ecu. Just make sure you do your oil tap right on the head when you do the ls/vtec. If it is done right, it will be very reliable, and you wont have any problems, even with the stock internals in the block. If you ever have plans to boost then I would say go ahead and put in some forged rods and pistons, since you will already have the head torn off (save you money in the long run). Make sure and get good head bolts to. Some cheap ones can streatch and can cause your headgasket to crack, which is never fun! Good luck, and let us know if you do the swap!

[Beyond Imagination]

Originally Posted by civickiller

why does everyone mention rod ratio ? its a theory without any fact.

if there was no fact then 1.75:1 would not be quoted as the ideal r/s ratio. how many near stock lsvtec's have you seen be able to rev over 10,000? probably none. stress on the side of your cylinder walls may not be seen but compare that to a b16 say 10 years down the road. i'm not against the lsvtec because i'm building one myself at the moment. but i also have a 88 b16a1 which is ALOT stronger than my 94 b18b and would say would outlast it by a margain.

[bov300zx]

Everyone has mentioned high reving when I'm not trying to increase my rpm range. I was just curious how the setup would perform and how reliable it would be with a redline of 6500. How much would my redline increase if I got a vtec ecu out of an automatic integra? It would be nice extend my rpm range but i'm not going to replace my stock tranny. If I did all that I would still have an auto (which I don't want), I might as well just look for a gsr or vtec integra.

[civickiller]

what do you mean your b16a is alot stronger then your ls motor. i dont think so. turbo both and see which one blows first with boost. both would be about the same hp.

so what, there cant be no numbers in a theory ? first i heard of that.

i dont konw of any near stock b16s that can rev over 10,000 alot and not break. my friend blew his motor cuz he use to rev it to 9500 alot.

again do you have any real evidence of the damage that can happen to you cylinder walls ?

again im not saying that your wrong but i just wanna see evidence of this then ill believe it, everything is just rumors until it is actually proven.

if your ls vtec is built right it would ahve no problems handling the rev limit of a b16 ecu, if not higher.

well if you only revving your ls vtec to 6500 then it would be realiable and it would perform better because you would be hitting vtec at whatever vtec is 5200 or whatevers. if you got a vtec ecu then your redline would be set to whatever the ecu is set at, which might not neccesarily be the motors redline.

[Beyond Imagination]

stronger in terms of reliability. my 88 b16a1 is outlasting my 94 b18b. there is a 6 year difference between these motors and i run the b16 ALOT harder than my b18b. the b18b has less km's and is burning oil already. i wasn't talking about turboing these motors.

my friend has a jun stage 3 cams along with spring and retainer. running on hondata with rev limiter removed. even though it's not daily driven to 10,000 i've seen it plenty of times around that region. he's had his motor for about 6 months and its running as strong as he first got it.

i'm just speaking from personal experiences with my motors and not with what i hear and i can still say that my 1.74 to 1.54 r/s ration has been the better of the two. to me r/s isn't THAT important or else i wouldn't be building an ls/vtec for myself. but in terms of reliability i think differently from my experience.

[civickiller]

you cant say that the b18b is bad from that example. because a motor burning oil has alot to do with the care the motor was given its whole life. i mean if you got a b16a that had oil changes all the time and never ran low on oil, then you got a b18b that did run low a few times and the oil wasnt cahnged at the required intervals, then yeah the b18b will start to smoke and leak oil faster then the b18b.

i got 1 car and my friend has 1 truck. my car with 200k burns about 1 quart per oil change, this car never ran low on oil and always had it scheduled oil changes, and i would like to note, ive been racing this car since 120k and it only burns 1 quart. friends truck 80k never seen redline once eats 1 quart of oil a week, trucks been run low on oil and hardly changed. if you want the motor to last just gotta give it the care it needs. point is, since you dont know hte exact maintance done to the motor before you owned it, its hard to say the condition of the motor. you can only say that unless you owned that motor the day it went to the car lot of whereever you could of got it

and since your friends b16 has cams, springs and retainers, it is built to handle 10k revs, if you do the same thing with the ls it will handle higher revs too. if rod ratio was such an important number they wouldnt make stroker kits, top racers wouldnt be using stroker kits in there race motor going up to 10k every race.

r/s isnt that important, building a motor should never come down to hmm i wonder what the rod ratio is, maybe i shouldnt build it because of the rod ratio.

[bov300zx]

What would be a mell matching ECU to go with an ls/vtec conversion? I don't know much about codes so if someone could list a couple that would work I'd appreciate it. Would the ecu need to come out of an Integra with and obd0 sensor in it to match my wiring harness and sensors or would any ecu out of an integra with vtec work? If anyone happens to have an ecu from an auto integra with vtec that will work in a 91 RS fell free to pm and let me know. Thanks again.

[blacksi_r]

actually i think rod to stroke ratio has a lot to do with a motors longevity while taking high revs. a shitty r/s will ovalize your cylnderwalls over time. and yes pro racers do stroke their motors to very large displacement but they also use deck plates so they are able to bring up their r/s ratio, most pros motors with stroked motors have almost the same r/s ratio as a b/16 also they have sleeves and rods that can take the stress of high revs

[almxdupintegra]

Originally Posted by bov300zx

All I've seen are question about hp gains and how to do the ls/vtec right. I have yet to see any questions about the ls/vtec at lower rpms. I read in other posts that with the higher compression of the ls/vtec the reliability goes way down and the engine wants to throw a rod around 8 thousand rpm. What about the automatics? My 91 redlines at 6.5 so would the ls/vtec be a more practical mod? Would a new vtec ecu be benificial with that? I guess what I'm trying to get at is would a basic head swap cover the conversion for me?

I am just going to reply about the "Automatic question". As for me I have been running LS/VTEC on my auto for about 6 months now. I haven't had any problems with it and the power is great. I have raced against many standard cars and I have spanked many cars. Don't feel bad about the auto. On another note I don't think you can change the ECU if you have an auto. Your car wouldn't shift using another ECU unless VTEC comes with an automatic ECU. I am clueless on this part.

[bov300zx]

Originally Posted by almxdupintegra

I am just going to reply about the "Automatic question". As for me I have been running LS/VTEC on my auto for about 6 months now. I haven't had any problems with it and the power is great. I have raced against many standard cars and I have spanked many cars. Don't feel bad about the auto. On another note I don't think you can change the ECU if you have an auto. Your car wouldn't shift using another ECU unless VTEC comes with an automatic ECU. I am clueless on this part.

Did you replce your ecu? I don't know if the vtec would kick in with an ecu not designed for it. I also don't know if Acura made an auto Intgegra with vtec. Anyone got any ideas?