Mr.DC2TurBo

Aright, I was searching and debating on what I wanted to do about my LS head. Either to do LS/vtec or port/polish LS head for my LS partly built block (pistons/rods/block guard/stock sleeve).

I saw something interesting. I saw an LS built head making the same hp and better tq than a LS/vtec. Can this be true???

This was from boosted hybrid's site of an LS/vtec with t3/t4e 57trim at 9psi (253hp 175tq @9psi.. stock block with hondata)


Now, here is LS-T's built Ls head and built LS block at 8psi (252hp 228 tq @ 8psi)


His setup includes:
portflow head/ built block
T3/t4B turbo
revhard manifold/ downpipe
fmu/safc/440
high flow cat/ apexi N1


Will building my LS head be better than ls vtec???


Modified by Mr.DC2TurBo at 1:00 AM 3/20/2004

Joseph Davis

For the needs you have stated, you should probably build a Miata head. That would definitely be "better"

PIC Performance

Power is affected by more than just the mods that are listed for those two cars. Tuning, timing, cams, compression, and type of fuel used are just some of those things. Also, different dynos tend to show diff numbers, though I'm not sure how that plays into this situation.
EDIT: The point here is, those two graphs don't tell the whole story. As far as I know, a Vtec head will produce more power than a non-vtec head on two *similarly* built and tuned engines. Thats key here.
As for your question, there have been debates on how helpful vtec is with turbo, though I never understand why. More duration and lift will be just as beneficial in FI as it is in NA *TO A POINT*. Obviously too much duration is not good for boost, but you get the point. You want to be able to use GSR or ITR cams to maximize any gains you would see by building the bottom end and porting the head, and for that you will need a Vtec head. Its simple.

Mr.DC2TurBo

I know tunning has a lot to do with hp/tq but as you can clearly see the ls/vtec was perfectly tuned with a ~12.0 a/f while the built ls head needs more tuning (s-afc running rich) but still made the same pw. So what is up with that? I know vtec head is suppose to make more hp but after looking at these graphs it makes me wonder if I could save some money and just build my ls head.

Danger

build the ls head . im puuting a b20 into my ek and plan on staying nonvtec .

88CRXHybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Noob4life &raquo;</TD></TR><TR><TD CLASS="quote">Power is affected by more than just the mods that are listed for those two cars. Tuning, timing, cams, compression, and type of fuel used are just some of those things. Also, different dynos tend to show diff numbers, though I'm not sure how that plays into this situation.
EDIT: The point here is, those two graphs don't tell the whole story. As far as I know, a Vtec head will produce more power than a non-vtec head on two *similarly* built and tuned engines. Thats key here.
As for your question, there have been debates on how helpful vtec is with turbo, though I never understand why. More duration and lift will be just as beneficial in FI as it is in NA *TO A POINT*. Obviously too much duration is not good for boost, but you get the point. You want to be able to use GSR or ITR cams to maximize any gains you would see by building the bottom end and porting the head, and for that you will need a Vtec head. Its simple. </TD></TR></TABLE>

Diddo...He got it right.

Mr.DC2TurBo

ttt

Griffin@Camtech

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 88CRXHybrid &raquo;</TD></TR><TR><TD CLASS="quote">

Diddo...He got it right. </TD></TR></TABLE>

yeah me too.

all that being equal I like vtec it sounds cool

Teglove2

If you have the money and the time vtec is always better. four cylinders, fi or not, need to rev to make power. like he said different tuning, cams, fuel will make a huge difference. There is a dyno shop by my house and vtec heads ALWAYS make more power.

incogNitto

I think his main concern is torque produced by an LS/VTEC vs. a standard LS engine. There's no mention of compression on both setups and the amount of boost is only listed for one.

Check out quickb18b's setup https://honda-tech.com/zerothread?id=761634 and he's making more torque than a bunch of GS-Rs running higher HP numbers. Looks that way stock for stock at least. Even on a built motor with more displacement: https://honda-tech.com/zerothread?id=729936 there's 161 more HP, but only 23 more ft/lbs of torque. Is that because of the way the HP numbers are calculated? I'm thinking there has to be way more to it than that.

I've always wondered why that happens, anyone care to chime in?

PIC Performance

Good point, thats an interesting comparison to make.
Assuming all factors are relatively equal (and thats a big assumption to make, but we'll make it for the sake of brevity), the only thing I can spot right off is the turbo sizes, and thats stretching it. I'm assuming the SC-34 (t3/t4) that the built LS is running is just able to flow more than the t3 super 60 that the LSVtec is running. Combine that with the extra 4.5lbs of boost they are pushing on the SC-34, and that might give that nice tq boost w/ such modest hp boost on an LS. I'm not sure though...
edit: Dunno why I assumed its a T3 Super 60 they are running I guess it could just as easily be the T3 60 trim.


Modified by Noob4life at 11:41 PM 3/20/2004

Mr.DC2TurBo

You guys are comparing too hard. All I wanted you guys to see was how strangle a built LS head was compared to an vtec head. As you can see the vtec head has a bigger turbo than the LS built head and was pushing 9psi. The LS/Vtec was only able to produce the same hp as the built LS with smaller turbo and 8psi. Clearly one would think, vtec head + bigger turbo would make more HP than a LS built head +t3/t4b but it didn't. Doesn't anyone else find that interesting???? Also by building an LS head it looks like the tq will always be better than ls/vtec combination.

SoulEdge

Thanks for the comparison MrDc2. I think the b18b is a great platform for a boosted daily driver. I love the torque curve on LS-T's dyno slip and is what I'll be shooting for in my LS. If the 2 cars here were both running the same tranny's, I would think LS-T's would faster since it's making more torque from only 4500 rpm all the way to redline.