VIPERBLUELX

iTrader: (2)

My car dyno'd at 387rwhp 378rwtq with the mods in my signature. Everyone said that was weak numbers for the MTI X1 cam but the car runs well so that's beside the point.

Anyway I just had a set of 243's fully hand ported with a nice valve job and I'm about to install them and the only other change will be the addition of .040 cometics to replace the stock GM gaskets.

How much power should fully ported 243's add over stock 243's?

Here are a few pics if anyone is interested.

https://ls1tech.com/forums/showthrea...11#post9385111

Ryan L

I am just low-balling, but I would expect 15rwhp. Most say stock 243s are only worth about 15rwhp over 281s, but the gains are multiplied with mods such as a cam. I made the numbers in my sig with stock 243s and wouldn't bother spending the money and time for ported versions.

You should do the swap since you have them already and don't mind spending the time, but don't expect it to solve your previously 'lower' numbers.

The thing about these "what-if" threads is that you set your self up for failure by overestimating. Expect 15rwhp and then celebrate when they make 25 rwhp.

VIPERBLUELX

iTrader: (2)

I hear ya, I just figure I'll have less in this swap(after I sell my stock heads) than I would just doing a FAST 90/90 swap and hopefully gain more throughout the curve than a FAST would have provided. Plus this will get the hard labor out of the way and when/if I find a deal on a FAST it'll be a simple swap

Ryan L

Not to get too off-topic, but did you try getting dynoed somewhere else?

VIPERBLUELX

iTrader: (2)

Nah, I only dyno'd it at Vengeance, but based on the other results I see on here their dynojet should be fairly accurate?

MattIROC

iTrader: (19)

With the x1, it is definitely worth swapping. 15-20 rwhp would be a nice gain.

Jason 98 TA

iTrader: (4)

We typically see 20rwhp with no extra milling on 243 casting cam'd cars.

http://www.texas-speed.com/shop/item...d=649&catid=40

massls1guy

iTrader: (9)

The porting looks great. Are you sure those are 243's - the chambers look bigger than mine around the spark plug area. If you go to a bigger chamber you will lose some static compression and that might offset your porting gains.

allngn_c5

iTrader: (3)

Don't forget that some of your gains may come from upping your compression using the thinner gasket.

At any rate I hope the ported heads make good power for ya.

I'd be curious to know before and after compression to go along with baseline and after numbers.

linegtdt52

iTrader: (12)

The FAST 90/90 is worth every penny I paid for it. I use to have an LS6 intake. definitely showed a difference when I swapped it. I say 405 rwhp on dyno after heads install and good luck finding a fast for a decent price. Definitely not an easy thing

VIPERBLUELX

iTrader: (2)

The head ported sent me the wrong pics, I posted up the new pics in the thread linked up top, sorry.

VIPERBLUELX

iTrader: (2)

I didn't have the heads milled, they just surfaced them enough to assure they were perfectly flat. Any idea what the compression will be with stock CC chamber 243's and .040" gaskets on a stock LS6 shortblock?

massls1guy

iTrader: (9)

The pics look great. Now get them installed and post up some dyno numbers.

VIPERBLUELX

iTrader: (2)

I installed them the same day I took pics, now I just need to dyno it.

algws6

iTrader: (3)

i went from 420 rwhp with 3.42s and 295 tires to 443 rwhp with 3.90s and 305 tires. hope that helps.