X2BOARD

You can just vote, or read and vote.. but please help my sorry butt...

Decisions, decisions, decisions !

Almost ready to reassemble, but I have a dilemma ! I am about to decide to go Turbo LS/Vtec from my prior Turbo LS setup. I already have the LS/Vtec motor ready as far as the oil taps go, etc, I'll list what I have and still need to get, but can't make up my mind as to whether I should stay LS or go LS/VT !

I have been researching the LSVT's newest pros and cons (mostly newer cons) and found the infamous Rod/Stroke ratio problem.

Problem: Perfect R/S is 1.75, the LSVT will have a 1.58 R/S which is less than perfect and has been looked down upon for the possiblity of cylinder wall flex on the upstroke whe n revving in the upper rpms. But if this is so, why do some LS guys rebuild heads and rev them over 8K on better springs ? With some nice cams, wouldn't that be equivalent to an LSVT ?
I am assuming that with the crank girdle in place, that should prevent any unnecessary movement in the crankcase and avoid catastrophic engine failure. .
Or should I just stay turbo LS, since I am eventually going to sleeve (a year or so ?) and just boost the sheat out of it ? (Going to stay right under 12 psi till then) Keep in mind, this would happen to the LSVT anyways as well.

I already have the required Eagle Rod and ARP goodies, but will still need to invest in the GSR girdle, machining, seals, oil pan, pickup and windage tray or I could save that flow with the straight LS and put in towards a standalone ?


[Modified by X2BOARD, 10:13 AM 4/11/2002]


[Modified by X2BOARD, 11:06 AM 4/11/2002]

DIRep972

iTrader: (1)

stay with LS.. LSvtec is just too much complication.. id say just Do pistons/rods/sleeves on the LS motor and get a standalone, run 18psi through that thing and youll haul ***..

X2BOARD

Well, the reason I am even considering the LSVT is that I have access to a B16 head already tapped for it... ok, ok... I already have the Vtec head at home...

I considered just investing the extra to sleeve one of my blocks, but I've already dropped the flow on the R & P and the thought of having a primary cam for daily driving is intriguing as it would allow me to drive out of Vtec and boost so I can save some gas during the weekdays... it is my assumption (am I wrong ?) that staying out of Vtec for weekday driving would consume less fuel than the same drive with a non-vtec cam. Of course the increased HP and Tq of the LSVT would be nice too. Either way, as I mentioned... if I don't sleeve now, I will sleeve on my next rebuild (in 40,000 miles) regardless of what setup I will be running at the time. So, considering, I already have the 'expensive' parts in my possession... what should I do ?

2K_TEG

TURBO LS Why bother with VTEC...it will just cause more problems in the future. If Honda wanted the LS block to have a VTEC head on it they would have done so. They have spent millions on R&D. No one knows more about Honda motors.

X2BOARD

That's not quite so... I've been told that my momma does... heh heh...

I am kinda leaning towards staying non-vtec... but that extra Hp is really appealing, but I've been hearing too many downsides and going LSVT would not be worth it if I have to baby it above 7K.

DSF

Well, if you go by that line of thought, why would you put a turbo on a LS or any N/A Honda motor if Honda didn't design it that way. Yes, by adding VTEC your are introducing the possablility for more problems. You are also introducing the possability for more power. Everyone has there own opinions, so do what you feel suits you

Personally, I'm building a LS/VTEC so I guess I'm biased

2K_TEG

Good point. I am biased too because I am building a straight LS. On the other hand, I think there is a big difference between bolting on a turbo kit and swapping on a vtec head. We are a group of hot rodders though and we get results by trying new things. I personally like to keep it simple. Good luck with your build.

sgT

Actually, R/S ratio for LS is 1.54 and GSR is 1.58
It doesnt really make that much difference as far as reliability being in that range
but i do wonder how it affects the power curve.

X2BOARD

Ok, so the R/S is not even as good as I originally thought One of the articles that I read basically hailed the ratio of an LSVT to be like the anti-christ of Honda motors ! He insinuated that this R/S would eventually cause the motor to be vastly unreliable, even with after market rods and bolts. Now I have seen posts of other with LSVT engines for well over 2 years with no problems, which makes me wonder, are they as unpredicatble as some say ?

As far as the R/S affecting power output... I would assume it does take some power away that should otherwise be there in a configuration of that displacement w/ a Vtec lobe.

InfamousRS

is there anyway to change the R/S ratio to near perfect? probably a different crank and rods, right?

sgT

I hope those articles werent in any magazines......
The problem with LSVTEC is people dont always replace the weak parts or
properly balance the motor which leads to quick breakage. Thats when all
the rumors start.

Regarding poweroutput, ever seen the torque curve of a b16a? I am wondering
how much of that is a function of the 1.74(?) R/S ratio, how much is a function
of the displacement, and how much is a function of ancillary parts. Basically I
would like to see if I could recreate that kind of torque curve on a larger engine.

X2BOARD

Nope, most magazine articles just praise the wonders of LSVT, not it's downsides, and being an avid H-T member, want to know more, no just hear the wonders of anything new. So SgT, are you a proponent of LSVT, or are you indifferent ?

88CRXHybrid

The best way to raise the R/S is with a B17A crank. This will give you a 1.68 R/S. An 1.54R/S will be more unreliable than a 1.68R/S if revved high and not properly built. The reason I have chosen to use a B16A head instead of a B18B is simply flow. If you are only running low boost (10-12or so)the B16A head and its flow potental will not help you near as much as if you were pushing 30psi. So if you are keeping the boost/hp figures conservative with a small street turbo then I would probably stick with the easier solution, a B18B head. If you do deside to do a LS/VTEC I would recommend you find a B17A crank. If you cant find one, just remember high piston speed(low R/S)+ 8500RPM or more=bad rings shortly.

dragnGSR

Stephen, hopefully I will be finding out soon the difference b/t a Turbo GSR v. Turbo LS/VTEC as far as dyno numbers. I will be hitting the dyno in a couple of weeks.

X2BOARD

Actually, at one point, I had a PnP head on this motor, it flows better than a stock B16, and BOY did it help at 6psi, at 7, 8 and 9 ! Everytime I increased the boost, I could tell the difference from the stock LS head like night and day. The only problem I would say is that 9.0:1 CR and a wickedly PnP head is just a recipe for no Low end Tq, and my car being a daily driver, in traffic on a daily basis... no low end would suck way too much.
The better flowing stock B16 head would be better in the low end, which is one of the top reasons I am so determined to get the pros and cons of the LSVT and not just listen to hype from LSVT haters. Luckily, none have posted.
Thanks so far for the input fellas. Keep 'em coming if you have any input.

SIK IN DA HED

keep it simple... stick to the LS.

sgT

bad rings shortly? I dont think so.
My B18C with the 1.58 turns 10000rpm and shows 300+ compression and <5%
leak in all 4 cyls. Its also got about 50k on it so far. Just pulled the head on
it recently and all the walls look perfect.

X2BOARD: I am indifferent i spose you could say. From my standpoint there is no
real cost difference since to build an ls block to reliably take what a b18c does
will cost about the same amount. I have built a few LSVTECs and all ran well and
made good power. I am however, firmly against destroking a motor just for the
rod stroke ratio. When we have these small motors we need all the torque we can
get and displacement is the way to do it. All the drawbacks to the supposedly
poor rod stroke ratio arent that apparent from my experience. There are limits,
I will agree, and I probably wont ever build a street motor with an extreme r/s ratio
but i will say that the major cons commonly associated with r/s ratios are somewhat
unfounded in this case.

Rain_man

The way I look at it, it kind of depends what your priority is. If you plan to make the car a street car mainly, then you probably want a smaller turbo to give you better spool up and midrange around town. In this case, LSVT won't do much because the main thing about LSVT is that it allows you to increase your redline. If you are using a smaller turbo, then a higher redline will just cause the engine to outflow the turbo.

Now if you want to run a big turbo and go mainly high end power then you have to LSVT because the only way you can really increase the amount of air your engine flows significantly to spool up a larger turbo is via more rpms. Of course now the street driveability is lower due to lag.

If you just want more power around town, but don't want to move the spool up range around too much, just increase the boost.

sgT

Totally false.
The primary purpose of lsvtec is to give you the benefits of a vtec engine, without
having to go and buy a whole engine. You can increase the redline on an ls motor
without vtec, and you can make power up there with a new set of cams. But
without vtec you lose the ability to have both good idle/low rpm AND high rpm power.

DIRep972

iTrader: (1)

I think it all comes down to your goals, how much power u wanna make, and how reliably/complicated u want your set up..

If all u want is like 350whp or so, i would definitly stick to the LS, with a T04e, 18psi and hondata I dont see any reason u wouldnt make that much power with stock head/cams..

Now if u r shooting for like 400+ u will need to raise the rev limit, larger cams, lots of head work, so I can see why u would want to just put a vtec head on..

but if u only want 350, I dont see the point in wasting all your time/money on LSvtec to just run low boost when all u need is a boost controller to do it with the LS..

Rain_man

Damn, I can't get away with the slightest mistake here can I? I should have qualified my statement by adding what sGt said. I just assumed x2board knew what the benefits of vtec were.

bruthaboost

I completely agree. However since sleeving is in your future, go with the vtec head. You'll will able to meet the 400+ whp mark and you already have the head. As far as all the talk about the vtec head being complicated. Don't believe the hype. It's incredibly easy to do. The most difficult part is hunting down all the bspt to standard fittings and if you need help with that IM me. I really don't understand where all the anti vtec head swapping is coming from. If you already have it, drop that thing on!

The block girdle mod is also easy. Some like machining the girdle. Personally, I machine and dowel the main cap ala factory style though it cost a quite bit more.

Also, since you plan on high pressure, I'd recommend some ss valves. My ls/vtec setup is built except for stock sleeves (damn it all ) and I'll keep everyone posted on its status as it gets boosted-13 psi daily. Hopefully I'll be able to add some concrete data to this argument. I think incognito had a boosted frankenstein. Maybe he'll add something.
HTH

civicguy

i think that mostly of the guys who trash the ls/vtec set up are those who built the engine friday and monday are hittin 9,000 rpm,stock rod bolts,stock oil pump etc.
well, i have spend almost $1,500 in mine and i think im not even started yet
my set up consist:
b18a1 block
eagle rods
je pistons
itr oil pump
ls water pump
ls timing belt
act clutch
and next turbo,what compression should i buy my piston,im looking for 9.2 com. with b16a2 head

VTC_CiViC

Dude, IMO.. stay AWAY from the LS/VTEC....... lessens the chance of you killing me hehe

rondigs

Yep-definitly NOT cheap. Im about two&1/2 grand deep thus far...Still have a ways to go.Not even a single turbo piece has even been bought.

The moral of our story: Do your research and don't throw one together overnight.