98hardtopZ

iTrader: (7)

will i lose any power from goin to the 5.3L's? ill up my compression i know, and i can get them ported at a later date, but i have the 98 perimeter heads and i got someone thatll give me his 5.3's for 50 dollars. im going to put a tr 224/224 112 in this christmas and some 918's. i compared the flow chart for the stock ls1's and the 5.3ls and while the stockers barely outflowed the 5.3's will the added compression make up for it?

sdbrown84

iTrader: (22)

While you have the heads off, why not get them ported?

You will get some great flow numbers, and you can replace the valves while you are at it. Really not worth the agravation to just place stock 5.3 heads on there without any modifications.

PREDATOR-Z

5.3s unported will hurt your performance as they flow substantialy less than the poorest of LS1 castings.
Now port them and they are quite a contender , especialy with medium cams.

PM Gunnar At PP, or Zach at TSP and see what they can offer pricewise.

DesertFox

iTrader: (2)

I was looking into this also, b/c just swapping the heads will bump the compression up to 10.9:1. And the only flow restriction is the intake valve, on the 5.3 its 1.89" and the LS1's is 2.00". However I read that you can straight swap the valves without having todo a valve job, but I haven't actually heard of anyone that has done it, or talked to anyone with machining experience.

Both heads flow the same. see here

I think that 5.3's with LS6 valves could be a nice, on a really small budget b/c I'm in college, alternative for heads. and I am wondering if there is an increase in the quench pad since the chamber is smaller.

I am still in the preliminary stages of this research, if you have more/better info let me know.

Josh

slow trap

iTrader: (22)

there was a great deal for ls6 243 castings for around 400 bucks at patriot.those should pick up around 15-20 hp and if you milled them some like .015-.020 with a set of thin cometics you could pick up even more compression/power.i think that is bare but you could swap over your valves and get a set of 918s and be set.

DesertFox

iTrader: (2)

hmmmm.... that is a tempting offer, but I am looking at about 500 assembled with ls6 springs, valves, and a valve job.

What I am having problems finding is info on the quench area of the 5.3's on a 3.9 inch bore, and if I can straight swap a 2.00 in intake valve into the 1.89" intake port (I doubt it, but it would save me some time and money if it did).

Josh

98LS1CORVETTE

Anyone ? I Am Doing The Same Job On My 98 Corvette 5.3 Heads I Had Mine Ported And Polish But They Still Have The 1.89 Intake Valves So I Need To Know If The 2.00 Fits Right In Without Machine Work?

DesertFox

iTrader: (2)

I have talked to a few local people about this, and they advised me against just swapping the valves without a valve job. The stock 3 angle valve job will cause the 2.00 to not seat properly in the 1.89 valve opening. So a valve job at least is necessary. I am surprised that whoever p&ped your heads didn't do this already.

Josh