Just wondering what others are seeing as far as the limits of the stock LS head. By that I mean, stock unported runners, stock cams, stock IM etc. I refuse to do anything to my LS head, as I see it as a waste of money, I'd rather just swap a B16 head on it and have the same CFM as a built LS head.

It seems like on the dyno I hit a wall shortly after 350whp on the DynoJet. I installed a less restrictive muffler, made no difference in power, then started retuning and turned the boost up 3-4psi and managed to pick up only 22whp / 22 ft lbs. So I'm looking to see if anyone else sees this barrier. Also, I'm on 92 octane, so tossing timing at it is not really an option

 

I'm not sure of the cost of both options but have you thought about tossing in a set of Crower 404 cams? That has to be cheaper than an LS/VTEC conversion...

 

All said and done, I can do a vtec head conversion for under $800, depending on how cheap i get a head for. buying cams would be 1/2 the price, but probably less than 1/4 of the performance gains, and worse gas mileage. IMO its just not worth it

 

Thats not true. My roomate (sohcd16z6 here) made 503whp on a stock head 404 cam with an SC61 @ ~28 psi with pump gas 93. Cams will make a huge difference vs stock.

 

with 404's though, you need to run springs and retainers right? so i'd actually be in it around $700ish? where as I can rev a B16 head to 8500 all day with stock parts. I get that cams will make a difference, but I feel the LS head is a waste, Rocker arms that pop out, poor flow, etc.

Also I'm a small turbo setup. made 367/343 last night

 

Well the ls head is giving you alot of that torque. The vtec ports are larger and well you can compare dyno graphs all day from a straight ls to ls/vtecs and the ls's have better power bands almost hands down.(i say that as i haven't seen every graph)

If this is a race car or used for drag racing more so then DD i would go the ls/vtec route. simply because it will have a better high rpm powerband. Which works for racing.

But i love the numbers the straight ls's give.

 

The head has nothing to do with this. The reason LSs dyno more torque is because they require more boost to make the same HP as vtec motors.

 

exactly. I will make more power per lb of boost with the vtec head. right now my powerband is 4300-6500, car is 100% a DD, full weight Wagovan. I could care less if the spool drops 500 rpm if i get a longer powerband that doesnt faceplant at 6500. 4800-8500 would be fine with me. As is, on a 23" slick it tops out 4th gear at around 115mph at 7000rpm, which is before the end of the 1/4, and the powerband is already in the ******* by then. The car should trap right around 120-121 is my best estimate based off my last car. last car went 11.54@118. this car weighs 150-200lbs less, makes 37more hp and 59 more ft/lbs and has shorter gearing

 

Really? Because port size and cam specs have nothing to do with it. Come on don't make yourself look dumb.

All i have to say is look at the D15's out of the cx or vx w/e they made 90 ftlb tq at 2000 rpm on a 1.5L 12 valve now the same size engine with a 16 valve head and make more tq but at higher rpm. So how can this be?

It's all in the head and how it is designed to perform, this will determain where the powerband sits.

 

Well no **** cams have to do with it. Im talking about the physical head, not the cams. If your making a reasonable amount of power (300whp), an LS head with stock cams and and Vtec head with stock cams compared, the LS takes more boost because it cant carry the torque out into the revs. I doubt the port size is a limiting factor at that point.

 

Yeah there are many factors that make an engine produce torque early and carry it over the powerband. One he mention STOCK head so me and you should be talkign stock head. that included whats inside.

Now your not understanding why the ls is so different from the vtec's, it is everyway was designed for more low-mid range power. The head, ports, cams, intake manifold(if he's using the stock one) were all designed for this purpose. To make power sooner and make more torque for driving around town.

So it's expected regardless of what pressures it's running that this will carry over into a boosted ls engine. oh it's no coincedence that the non-vtecs tend to make more mid-range and torque then a camparable vtec because the vtec's were not design to make the power there. They were design to make it in the top end.

 

Well if we're talking about making the most horsepower on the stock head (when I think of stock head I think stock valves, stock ports; not including aftermarket cams and the things that go with them) you'd be stupid not to get cams if you want to make more then 350whp.

 

For an LS yes. But there are tons of people making well over 350 on entirely stock vtec top ends (including cams and IMs) Like I said, this is just my DD, I have a hotrod style CRX, so I dont want to dump much money into the Wagon

 

ok ,you seem pretty dead set on vtec then; why are you asking?

 

to run 404s in an ls head do you have to upgrade the valvetrain also?

 

I was asking if people were seeing similar limits with entirely stock top ends. Not for tips on how to make more.

 

be happy with the numbers you got. thats really impressive for a stock dd ls. I wish I made that kinda power.

also do you think the 16g is a big part of your top end falling off... didn't you say that it would drop psi up top?

 

Yes you would need to upgrade the springs. Everything else should be quite fine. LS heads have a less than desirable rocker design for rpms above 8k, just another thought.

There is more expense than just a head to consider. Vtec ECU/Conversion kit/Wiring/Manifold/Possibly New IC piping/Maybe more

Running a stock port B20 w/403's and putting down same numbers as a more expensive vtec engine. (NA 165hp) With modest expectations the Non-Vtec engines work quite well

 

No, it holds psi fine, it spikes 2 psi over then drops and holds to redline. Still running the stock evo internal WG.

 

I had a completely stock LS head, cams, manifold and did 412whp and 397wtq with e85 about 2years ago @ 27psi with a SC34

Switched out the manifold, cams, and intercooler and made 461 and 400 with 111gas @ 27psi with the same turbo.

 

Nope.

 

A bigger turbo will make more power up top. Even with a non-vtec head. If I was in your position I would get a larger turbo and find a set of 402's. As long as you keep your rev limiter under 7500 you shouldn't need valvetrain with those cams.

 

on my bone stock LS, 23psi seemed to be a wall.
Car was 2730lbs and went 12.7@115 when it was bone stock.

These are the upgrades I've done since than that made "MASSIVE" gains in performance.
(on the street or @ the track driving, I did not dyno)

STR Intake manifold
P8R head with Spring/Retainer combo
Crower 404 Cams. (idles great, Drives well also)