v-tec or non vtec that is the question!

[WILD_EYE]

What cylinder head is recommended for forced induction, v-tec or non-v-tec? Some have told me that if I'm going turbo the v-tec really does not matter but a friend of mine has a b18c with turbo in a crx and he says on the dyno the chart jumps up when v-tec kicks in. I have a d16 non -tec but I do have a v-tec head lying around. What would be better: a v-tec head or something else like a sohc zc camshaft or reground camshaft? I really wanted to put a zc dohc head but from what everyone has told me takes a lot of money in mods to do it.

[sqmark]

Go nonVTEC, It's easier to get right. You don't have to play with VTEC fueling aswell as boosting. The only thing I would say is that you can get more tuning out of a VTEC head with valve, springs and retainers.

[jake2001z001]

i whould just say with the head you got whatever that is

[evilfred]

Keep your non-vtec and put your money on something else...

[DraZtiK]

non-vtec

[Dr.Boost]

non-vtec

[kamaleon]

i see a lot of "non-vtec" but no actual facts as of why... i think he asked performance wise..

if in NA vtec offwer better perfomance why would it be less when boosting??

i dont have experience with non-vtec but ut seems common sence to go vtec route, if u allready have a vtec head laying arroudn might as well use it.

[BOOSTEDcivic]

well, who would win in a race, two cars with exactely the same mods (same car) but one has vtec and one doesn't...who would win?

[kamaleon]

if all variables remain constant exept the head.. i woudl think the vtec head

[evilfred]

yes vtec would win....but i just think you could change piston and rod with that money and get a better gain in performance...

[kamaleon]

pss.. he already got the vtec head.. he asked which woudl yield better results, thus vtec is the answer.

[WILD_EYE]

Thanks for the info guys. To kill my curiosity and anyone elses I think I'm going to go turbo with the non v-tec head first and set everything up just at about 5 psi. Then without doing any other changes I'll swap in the v-tec head. I'm going to buy either a g-tech or belltronic dyno thingamagig to measure hp and see how much the gain is, if any. I'll be doing that in the next 2-3 weeks hopefully so I'll post the info when I get it done. Thanks!

[kain]

well the d16a6 head does flow better than a vtec head.

[Dr.Boost]

pss.. he already got the vtec head.. he asked which woudl yield better results, thus vtec is the answer.

He said he has a non-vtec head on it already, but he has a vtec head laying around. The a6 head will outflow the vtec head anyways, so no, the vtec head will not win.

[kamaleon]

uuhmm.. i wanna see dynos on that

[Anonymous]

Hey man this is it. The hard thing about boost with vetec is when vetec kicks in air fuel changes rapidly. How much boost are you trying to run first. If a low amount vetec would not be to bad to work out. But unlike me I have a D16Z6 and getting ready to run 28lbs of boost to it maybe 30 if I get stupid but I doubt it. For me Im going to lock my vetec in full time to start with then start trying diffrent Levels of Rpm to see biggist gains but I will also be doing this using AEM managment so it all depends on how much boost your wanting to run and what kind of managment do you have to back that up with. But either way I would hit it. :bubbrubb:

[Anonymous]

Hey man this is it. The hard thing about boost with vetec is when vetec kicks in air fuel changes rapidly. How much boost are you trying to run first. If a low amount vetec would not be to bad to work out. But unlike me I have a D16Z6 and getting ready to run 28lbs of boost to it maybe 30 if I get stupid but I doubt it. For me Im going to lock my vetec in full time to start with then start trying diffrent Levels of Rpm to see biggist gains but I will also be doing this using AEM managment so it all depends on how much boost your wanting to run and what kind of managment do you have to back that up with. But either way I would hit it. :bubbrubb:

[BOOSTEDcivic]

uuhmm.. i wanna see dynos on that


yea, cause the y8 head i'm pretty sure flows better than the a6.

[kamaleon]

mistabone, in the old site, he tested the y8 and the z6 head.. the y8 was ported/polished..

y8 gave better midrange but lost lots of topend, and with the z6 was the opposite.. a bit less midrange than the y8 but lots more in the top..

both heads are good, depending on where u want ur power to be

[Dr.Boost]

uuhmm.. i wanna see dynos on that

Read up on theoldone.com and you will learn. I'm not making this shit up. I thought this was well known.

[AK_CRX]

in his case I would go non-vtec, simply because putting a vtec head on an a6 motor would put the c/r a little to high for my comfort.

[AK_CRX]

i see a lot of "non-vtec" but no actual facts as of why... i think he asked performance wise..

if in NA vtec offwer better perfomance why would it be less when boosting??

i dont have experience with non-vtec but ut seems common sence to go vtec route, if u allready have a vtec head laying arroudn might as well use it.

As far as sohc motor are concerned, I say BS on the na vtec offering better performance than non-vtec... There are much nastier cams for a non-vtec sohc than there are for a vtec sohc engine. <PERIOD If we were talking about B series dohc engines it would be a totally different story

[unsivil_audio]

I would have to agree, engine tuning is going to be a lot easier with a non-vtec. I'm staying non-vtec for that very reason, if I want the lope of Vtec engines I'll get it with switching out camshafts and have that power throughout the power band. Now, as for wether the a6 head will flow better than a z6 vtec head, I think its quite possible that the a6 head will outlflow a z6 head. A6 head is the SOHC ZC, correct? after all have you ever listened to one of those compared to a vtec motor? They sound way more pissed, plus they have a lot better torque curve than any d-series vtec motor.

[kamaleon]

so, any new update on this?

[dnasty18]

yea, where is there alot of cams for a non vtec head? i have been searching for like 5 months and just now switched to a vtec head and i am about to boost.. i couldnt find a cam that want reground for a non vtec to save my life

[kommon_sense]

www.exospeed.com and www.deltacam.com both do regrinds for non-vtecs.

[S Q A D]

why would non vtec be better for boosting?? when boosting, is it VTEC or non VTEC that determins( sp? ) where the power would be distributed along the powerband ? like does non vtec gain more power at lower rpms ? and vtec more power at higher rpms??or what ?? i know that air/fuel does change cause obviously with VTEC the valves open and change .. but why wouldnt that be good for turbo ? ive never even seen a non vtec boosted civic ( not in person, anyway ) ?? im just confused?? :?

[dnasty18]

i am too, if a vtec give maximum power gains along a broader rpm range... wouldnt that be the same with a turbo vtec?

[91civicDXdude]

a VTEC head, with the design of variable valve timing, is designed to make great power gains NATURALLY ASPIRATED. Although im sure that great power numbers can be found with a turbo VTEC, It really isnt needed with a turbo. As the rpms rise, the turbo spools, and begins to make power.

IMO, a non VTEC engine with the same lift specs of a VTEC engine, but with lower duration (for better spooling and less compression loss through open valves) would make more power.

Isnt it true that the top honda turbo racers all have "VTEC eliminator" setups?

[dnasty18]

why dont they just have non vtec heads? what if on race day you set ur vtec controller to kick vtec in at like 8,000 rpms (somthing that ont be reached)... is that the sme thing.. then u would have vtec on the street when u need it right?

[S Q A D]

hmm good point dnasty .. that seems like it would work ... and im sure VTEC doesnt ONLY work good N/A ... if VTEC is bad for turbo applications , whats the deal with everyone with turbo'd GSR's ... your saying they dont know what they are doing because they have TURBO on their VTEC motor ? that doesnt make sense to me ... because our engines are smaller .. that automaticaly makes it better for N/A with vtec or turbo with no vtec ... i havent really seen any facts that make non vtec better for turbo .. and civicdude .. why would a non vtec motor with the same life specs as a VTEC work just as good .. ?? u dont really explain anything ... aND I Only know of a handful of NON VTEC racecars out there ... mostly everyone runs a GSR motor or LS/Vtec or B20Vtec ... and none of those are NON-VTEC ?? like i said im confused , but regardless of what yall say .. im still going for y8 vtec ... i guess its just personal opinion and time and money issues , why people would choose non vtec over vtec

[dnasty18]

i agree... i mean if non vetec was better for racing.. why is vtec so coveted? and those of you who say non vtec turbo is better bc its simpler to tune... im new at the tuning thing but since when is simpler better? i know why dont we all go get big block v8s and throw them in our civics.. those are really simple engines.. ooooh we can go carborated too thats really simple..... i bet its easy to tune too. how about a diesle? all u need is a hypertech programer to get 90 more horses out of those.. im gonna put a big cummings diesle in my civic...

[specialED]

well the d16a6 head does flow better than a vtec head.

I understand that the mid-range and top-end power of a head has a lot to do with port size, port shape, and the design of the divider, but how does the A6 head flow better than the Y8 head with 1mm smaller valves?

Or are those who are running A6 heads and getting better top-end HP with it than Y8 setups also upgrading the valves to oversize units to eliminate that bottleneck?

[unsivil_audio]

You guys gotta remember that VTEC was created for FUEL ECONOMY (<-emphasis), with out sacrificing performance. Thats why a non vtec head with a high lift cam would do better for turboing, NA, or any other type of performance. Its gonna give you a lot better low end torque, and honda road cars dont really eliminate vtec, they just eliminate the x-over point and are running on the vtec cam lobe all the time. So, basically if you have a vtec head keep it and get a VAFC (you'll need one anyways if your turboed) and set the crossover point lower, if you dont have a vtec head, dont worry about it just get a cam (and get a SAFC, you'll need it for fuel tuning anways), there are several companies that make them such as Skunk2, Zex, and even other D-series donors such as the cam the d16a6 came with is completely interchangable with the other non-vtec heads.

[HumanResource]

why dont they just have non vtec heads? what if on race day you set ur vtec controller to kick vtec in at like 8,000 rpms (somthing that ont be reached)... is that the sme thing.. then u would have vtec on the street when u need it right?


They use VTEC heads simply because they flow better. They eliminate the VTEC mechanism and run VTEC eliminator cams because it simplifies the valvetrain-less drag

[91civicDXdude]

^^ thank you for clarifying to them.

If you thikn about it, the only reason people boost VTEC is because it is a good platform to start from. When you are using a turbo, you dont need the more mild non-vtec lobes as the turbo takes care of the powerband.

[hotrex]

im backing up dr boost on this one, the a6 is a nice piece.

[7thGear]

hey what about the y7 heads.... they any good ? :D

maybe i should just get a properly matched turbo and forget about NA....

[S Q A D]

y7 head sucks ... take it from me ... the y7 man ...

[Honda4VW]

y7 head sucks ... take it from me ... the y7 man ...

WHAT!!!???!!! Why do you say that?

[S Q A D]

cause i hate my y7 .. non vtec slow ass dx ... its not THAT slow ... i just want y7/y8 combo ... hehehe i was only HALF joking

[7thGear]

do u have any flowbench tests to show that a y7 flows worse than a y8?? assuming no vtec and idential cam

cuz i have a sneaky suspision that the intake and exhaust inlets along with the valve guides are identical on a y7 and y8 head....

[FC_Drifter]

if i would go with anything it would be vtec......sure its more diffcult to tune with a turbo cuz of a/f ratio.........vtec parts are more money and all but sohc vtec turbo kickin in at 4500 it will allow more power cuz the valves are opening more means more air fuel and more everything :hijacked:

[oscarmayer]

well lets start off with a/f ratios and vtec cross over point. vtec kills the turbo just like shifting when it kicks in so it causes a slight delay in power for the moment when boosting. (yes tehre are a lot more details but that is a very fast and basic run down so no flaming please) Now while vetec is great, my project will use it, but that's becuse my car is already vtec if yours si not, there's no point to useing it then. it's really much easier to tune a car right and have it work jsut as good if you stay no v-tec. heck the racers lock the vtec lobs so the car runs the vtec cam all the time or the remove the vtec all together. the vtec setup is really designed to give us a good smooth idel and then allow for a more agressive cam setup than not havnig it. it's like 2 cams in 1. hope this helps on the idea.

as for zc, a 92+ vtec head (maybe non as well but that was not tested) out flows that zc head hands down. ported or not. the technology that went into designing them is much better than the Zc heads. so stick sohc. zc s ok but you'll get more out of the sohc than the zc

[984drcivic]

i am sorry but this topic rocked. The most I have learned off this site in a long time. Just my two cents.

[ZC-CRX49]

Great run down guys Ill take a lot away from this as well.

[Honda4VW]

cuz i have a sneaky suspision that the intake and exhaust inlets along with the valve guides are identical on a y7 and y8 head....

My y7 head I have sitting in my room HAS the mounts for a vtec selenoid, just no passages for the oil to actually come through. I am very confident that I could bolt a y8 cam and rocker arm assembly to it. Also very confident that it is the same casting apart from the combusion chambers. Wish I had a y8 head at home to compare to!