427zm

iTrader: (9)

Ok, so I'm getting more and more interested in a swap to LS3 small bore heads for either a 347 or possibly 383 stroker motor, but with this head flowing so much air what cam would work well for them? I know square ports (LS3's and LS7's) like big splits in duration and more lift, but with the small bores would this be able to be accomplished while maintaining drivability? Can you achieve decent low end torque? I've seen the Ballistic Speed setup on their RX-7 in their blog, but that thing has a Donkey D cam that isn't built for more than track use. Personally, I want a drivable cam with stable lobes, so that I don't hate driving my car other than at the track and have a reliable setup.

I think with these heads 470-480 wheel should be possible NA w/o hating the car. If im out of my mind LMK. Ballistic put out 516 & 530 with their giant cam and small bores.

Give me your thoughts.

garygnu

when picking a cam you have to look at the whole car combo also.pick the cam last after you have the long block together .

427zm

iTrader: (9)

What I'm getting at, is would a wide split large lift square port cam like the larger bore LS3&7's be more ideal for these heads with small cubes or a tighter split cathedral port style cam be better for LS3 small bores? I've heard the cathedral v square port argument stating port velocity will suffer w/ the small bore square ports, but looking at flow numbers in the mid lift areas of the square ports, it sure doesn't look that way. What style cam would optimize the square ports, and would it run as well as a similar cathedral?

Rise of the Phoenix

iTrader: (27)

You would be best suited to contact Martin at Tick Performance and have him design a custom cam. He can tailor the cam around the specifics of your build and how you plan on driving the car. In my opinion, it's the only way to go to get everything you need and are looking for. I'll be interested to see how these small bore LS3 heads work. I know there is a company making them for stock cube LS1's, so I assume that's what you're referring to.

whatsa347

iTrader: (6)

The 230/234 has proven itself time and time again, but then again I'm just a random on the forum. PatG can take care of you or Geoff at eps or Ed Curtis, if you want serious power just get the cam that can take full advantage on those heads and get a cam made just for them.

427zm

iTrader: (9)

So far only 2 companies that I know of Ballistic Speed and Mast Motorsports. From discussions I've had with some major engine shops, they fear the square port will be lazy down low, but then again, when things are new and not tried and true, with engine shops they are reluctant to use them. I think that is part of the reason we haven't seen many of these big headed monsters out there. Proponents of the cathedral port heads don't think the velocity (or lack of) from the square port can work with the 3.9x bore, but then again, they haven't tried a set yet. I know numbers are numbers, but if you compare them side by side, they tell a different story.

Tainted

iTrader: (9)

pat G spec'd me a custom cam for my 408 with the PRC SMALL BORE 260cc ls3 heads. if you really will use the specs, I'll give them to you.

mchicia1

iTrader: (5)

I have the same heads you are buying. I put in a 224/230 .580 .580 114 and it is a bit too small.

Going with an AI 230/238 now. These heads are big heads for a 347 like we have, you need a cam that will shine above 4500 rpms.

I am going to spin mine to 7200 to take full advantage of them.



Listen, they are still ls3 heads that are still using an ls3 intake. Go with variations of what is proven to work with LS3 engines (i.e low overlap in the low 230 duration). Like the SpinMonster 230/234 grind. I only put more exhaust duration on my cam because I am using ls7 exhaust manifolds, not headers.

FYI, mine isn't lazy down low but it does have 4.10s and I am in a light FRC vette. It will be lazier with the 230/238 cam but I don't care. Who cares about power less than 3500 rpms, no one races there. And if you don't race, why mod??

427zm

iTrader: (9)

I know that move air, so some what big is a requirement. I will be real interested to see how your new cam responds with your setup.

Did the 224/230 make decent power? Was there any life down low?

mchicia1

iTrader: (5)

You won't get 470-480 out of these heads with a 347. From what I saw, their 347 car only made like 430. I still say the max effort cathedral options are better for a 347 car. My old AI 799+fast setup made 462.

I mainly bought them for budget reasons. The ls3 top end is basically a fast that comes with bigger injectors already for 1/3 the price. And having new heads for only $1300 is a nice bonus. Plus, they should have more potential if you add boost later or go to a stroker.

But for a 347 build, I'd stick with cathedral. That is my unbiased opinion having run both setups in the same car.

mchicia1

iTrader: (5)

I don't have dyno numbers, all I know is it inched away from a 120 trap car on the highway, so it's probably a 121-122 trap car. Keep in mind, no headers here, just ls7 exhaust.

Oh yeah, it had life down low for sure but I do have 4.10s! It would still snap at 2000 rpms, yeah.

I am gonna try to get the new setup on the dyno, but my car is a heartbreaker on dynos with the new forged 347/4.10s I put in. It only made 345 rwhp with that same cam and 241 heads/ls6 intake! So I would take whatever numbers I make with a grain of salt. I will take it to the track, which should tell a better story because it is much faster than whatever the dyno says.

mchicia1

iTrader: (5)

FYI, I raced the same car before I did heads and he obliterated me, so they will pickup 40-50 rwhp. They are still a good budget head swap (much cheaper than even porting 243s and getting a fast).

427zm

iTrader: (9)

Thanks for the opinion. You're right about below 3500, no one's making pulls from there, and if you are, why? Gear down and rev!

I currently have LS6 2.5's, so I was looking at this setup as an alternative for more power with a bigger cam, and to be a bit different. I know I'd have to spin it high, but I'm not opposed to that at all.

C5Z here with 3.42's, so mine would be near as responsive as your 4.10's.

mchicia1

iTrader: (5)

Oh if you already have heads, I would just get a fast 90/90 setup. That is a solid 20-25 rwhp upgrade every time. I agree, I love spinning high. That is why I put arp everything in my bottom end.

Now, if you're going 383 for sure, I would probably switch to the ported small bore ls3s and spin that to 7400! That would be a ride for sure.

Tainted

iTrader: (9)

id get the 102/90. the 102 will flow better at every rpm

mchicia1

iTrader: (5)

I agree with that, but it doesn't fit a c5 very well. Chances are, it will not clear his cowl. My ls3 intake barely even clears my cowl on my C5.

You have to get special motor mounts to drop the engine a little to get it to clear.

427zm

iTrader: (9)

I have a Fast 90/92 set now, but I truly think I could have spent money more wisely somewhere else. I didn't see near that gain, as a mater of fact, I spent about $100 per HP.

From looking at what Ballistic Speed's 383 LS3 headed build, power can be had w/ these heads on a 383, I just wouldn't want the giant stick they have in it to produce it. I'm a no bucking, smooth riding, lower overlap cam guy. I like driving my away from the track as well.


Yes, and when spinning it, ARP is a must!

whatsa347

iTrader: (6)

I'd say forget it and go 408 to really get the most out of those heads.

mchicia1

iTrader: (5)

What are your #'s/trap speed now????

I think these heads would work great on a 4" bore motor since it will solve the "valve shrouding" issue so many complain about with the standard size ls3 valves on ls2s.

If you didn't see 20-25 with a fast upgrade, then your heads are a restriction for sure. What are LS6 2.5 heads? Is that PRC?

427zm

iTrader: (9)

Yep, PRC. My cam is what needs to be changed to maximize my current setup, but that's why I created this post. I think if I look at a different cam, i mine as well look at a whole new top side setup. As for 408, I don't want the weight of the iron block. One of the benefits of the C5Z and FRC body is the low weight. Staying NA, I'm staying aluminum no doubt.