night

ok, its obvious common sense vtec is gonna make more power, but how much diff are we talking. i need the car to be mobile soon and wanna throw a cheap LS head on the built block.

now looking down the road, im wondering at what point the LS head will really be holding me back. say im at 300whp, what would you expect it to be with a VTEC?

also, just for curiousity's sake , what can be done to the LS head to improve it? valve size? port work? im sure the chamber shape would be a detriment. and what about 'turbo cams' in the LS vs the stock VTEC cams?

yes, a lot of questions, but no reason not to cover everything right?

John

B18bEK

dude 300 on stock ls head is very capable!!

night

guess i worded that wrong. think of those 2 sentences completely seperate :D.

didnt quite mean it like that. say, if i have to run 2lbs more to match the same a VTEC could do without, then that will progresses exponentially until eventually the LS, common sense would say, reaches a ceiling vs the VTEC head.

so these ppl pushing 600+ hp, could probably drop 150 if an LS head were in its place.

im pulling all these numbers out of my *** of course, but i think that gets across what im wondering here.

Joseph Davis

Uh, no. Turbocharged power is compressor dependant, not headflow dependant. So you need a little higher pressure differential to hit your power figure with the LS head than a VTEC head... so what?

Even among the lesser flowing D16 heads, you'll not find one that in stock form isn't capable of more power off of pump gas than you can put to the street.

night

so then it would only be at the extreme levels that a VTEC head would really be beneficial?

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by night &raquo;</TD></TR><TR><TD CLASS="quote">so then it would only be at the extreme levels that a VTEC head would really be beneficial?</TD></TR></TABLE>

Or for the people that like VTEC sound, or think that being able to make "more power off of less boost" than 99% of other cars out there is worth spending money for.

The dynamics of a VTEC engine allow it to hold more whp (partially due to significantly less torque being produced) than the LS in stock form, which in a heavier platform will result in a quicker ride. For a lighter weight hatch, you may find that you get all the power you can put to the ground on the street from an LS, and the only time a VTEC setup can do better than hang by your door is if they ahve their suspension set up better and can get out of the hole better than you can.

Solid logic (not the fools who think 600 whp in a streetcar is going to be anywhere near as fast as 350 whp) Has me spinning all the way through third *with* properly set up suspension on an LS turbo setup in my CRX HF, which weighs in at less than 2000 lbs, from ~225 whp. I need a lower boost setting to launch with, a few more ponies up top for 4th gear and beyond, and someone who doesn't drive like a little girl (I suck) and the car should be untouchable as streetcars go. Not bad for a stock LS... but I'm not trying to build a 2700 lb coupe/sedan.

night

ok, that really does make me feel better.

my car is an old '85 lude. was 2250lbs with me bone stock. should be 1800 with me when im finished cleaning it out.
this will be a B20 block, so i will still be sleeving it and pistons/rods. i never want to touch the block again (/crosses fingers) but the head i'll probably have off several times just trying my own crap.


thanks for the good answers J.

now off to rob a bank...

DaX

iTrader: (1)

I'm interested in how you plan on dropping 450 lbs.

night

math


way back before hp.com went bye-bye, a guy with an 84 lude on the east coast somewhere (dont remember where, NC maybe) did a pretty significant build. full race prepped car. he was running a turbo'd H22.
he had his car at 1905lbs with him.

there's an old post on theoldone i think where they weighed an H22 long block+tranny and it was 80lbs more than the B. also, im 5'7 135lbs. odds are he weighed more than me . so i think 1800 is a fair estimate.

also dont forget these are old school iron blocks. drop a chunk of weight with the swap alone. compared to a regular B/D anyway. the F/H's are probly pretty close with it.

Joseph Davis

Yep, the first hundred lbs is easy, after that you spend hours to drop another ten.