I have been contemplating converting over to a sbc head since a lot of the aftermarket ones have so much more potential than standard lt1 heads. However I'm looking for a head were I won't have to use offset lifters if possible, and I can buy an off the shelf intake for. Basically I'm not looking to run a radical 400+cfm head just something in the 300 range that will require minimal modifications. Also who can convert them to reverse flow cooling and what kind of price would i be looking at to convert them? I would also convert over to a regular style distibutor, what kind of issues would I run into with the pcm? Would i basically just be ditching it for the most part? I would like to keep the monitoring capaibilites of it to add in tuning it with the carb and distibutor, ie knock sensor, o2s.... Thanks

P.S. Mods if you don't feel this belongs here please move it, i figure i have a better shot of it getting answered here.

 

http://store.summitracing.com/partde...artSearchFlag=

 

I second MrDudes post. The 18x heads are some of the best flowing heads that are still able to run a 23degree valvetrain setup. The heads flow like crazy all throughout the lift range, and you can even get them in a standard SBC exhaust port layout. They can easily be converted to LT1 cooling, and with a LT4 intake was told you could have them port mached up, no need for a carb'd intake if you wanted to stay EFI. Thats the kind of setup Im looking at.

Kyle

 

For the money, the 18X is tough to beat. If you're set on it, I'd get them bare and match the valvetrain components up with the camshaft.

Good head for a stroker, don't know if I'd be too crazy about running on a 350 build turning less than 7500rpm.

-Mindgame

 

How much power do you want too get? I've seen some pretty big numbers out of LT1 specific castings with a carb, distributor and single plane intake. I'm not sure if you have to go the expense of converting over heads to get where you want to go.

Bret

 

Elky thanks for the input, that's what i was hoping to hear. If i could keep fuel injection it would be a lot less problems. Is there anyone that can confirm that the lt4 intake can be matched properly? SSstroker I'd like to see at least 420 through an m6 with close to stock compression and a hydaulic cam, hopefully a little more. That would also be stock bottom end. I might check my funds and go to a 355/383 solid roller with a little higher compression over the winter. In which case i'd shoot for 480 or so with a more agressive cam.

 

If you're looking for power like that, why not run something like a ported LT1/4 head or at the most an AFR 210/220? I just can't see using an 18X head @ low RPMs on a stock bottom end to only make 420hp. That's like running a Little Chief head to make 350hp on a stock 350.

 

no the LT1 or LT4 intake wont come close to matching the 18* heads.

your choices would be a fabricated FI intake or a cast single plane carb intake.

keep in mind, this is the stuff made for 650+hp N/A engines... not the thing to be doing on a sub 500hp street car.

 

420 rwhp is achievable with ported stock heads and enough camshaft. Doesn't necessarily need to be solid roller either.

The "race head" conversions, IMO are for those guys wanting to make 550+ at the rear wheels NA. Using them for a 420rwhp build is like using a nuclear warhead to kill a chickadee. Way to the other side of "overkill"....

-Mindgame

 

I have to say these two put that best.

420rwhp just means very good heads and a good valvetrain setup. You could spend a little extra money to get these things done top notch and you would be well on your way to 420rwhp+

Bret

 

Back when Ellis was doing his 18x setup, I chatted with him a bit via PMs and he mentioned that the LT4 intake could work, maybe with some spacers if I remember right. Thats been a long time ago tho.

Kyle

 

In the original post, stik6shift93 did not mention what he plans to use the motor for. But if he's aiming for ~500hp I assume it's a street car. In that case, the compromises of a carb really come into play. You can pretty easily get a carb to make top end power that's as good as EFI or you can get the same low end torque and throttle response. But it's VERY hard to do both. The components must be chosen carefully and a carb expert needs to set it up. Carbs have a lot of compromises that EFI does not. The BBC I am building will initially use a carb, but that's based on budgetary considerations and I will go to EFI eventually. Since stik6shift93 already has an EFI setup, I would strongly advise him to keep it.

Rich

 

Nice analogy...gotta remember that one.