Dart owners, got a sec? 6 bolt heads

[eLeSthree]

I just ordered a Dart SHP LS Next 427 from Thompson Motorsports.

After speaking with Dart, it sounds like everything should move right over from my stock ls3 block onto the Dart. However he kept using the word "should"... Please let me know if that is incorrect, or any trouble you ran into.

Since I will be running a good amount of boost, I know I should probably switch up to a 6 bolt head. Since its a 6 bolt block.

However, I just overspent on my shortblock budget, since the deal was too good to pass up. TMS has a nice FED edition of the M311 head for $2400 assembled. So far that is the most reasonable head I've found, and I still cant afford it, hahah.

Has anyone just ported their LS3 head and run them with 4 bolts on the 6 bolt block with boost? Is it essentially the same head clamping surface I have right now with my stock ls3? Or possibly better due to arp studs?

I can probably afford heads later in the year, maybe xmas sale, but not now.

I still need to get a cam spec'd and should have the head details before that.

What would you do?

[RobZL1]

Excellent timing. I was just about to post a question about the M311 heads.

I know they are castings by Liberty that Frank works over. I hear great advertising about them, and they look nice, but I can't find anything about actual results from them.

I'm thinking I'd like to get a set with some softened chambers, but I can't find ANY actual results with these heads.

I certainly don't want to hijack the thread here, and I hope I'm just piling on with a similar question. Let me know if you want me to start my own thread, eLeSthree.

So, simply- has anyone actually used these heads, and how do they perform?

Thanks!

[eLeSthree]

TSP has an LS3 "as cast" 6 bolt for $2000 with springs, but only the combustion chamber is cnc'd. Still flows well. Thats another 6 bolt option.

[racesloth]

Consensus on other boards is ARP head bolts are good to 14lbs give or take. Then studs.

How about drilling everthing for 1/2" head studs that should be a big step up in clamping force.

[graf101]

I have a Thompson Dart SHP 388 w the Thompson/Frankenstein M311's going in as we speak. Thompson told me they recently had a car make over 1700whp with these heads, and I have heard nothing but great things about them.

[eLeSthree]

Originally Posted by racesloth

Consensus on other boards is ARP head bolts are good to 14lbs give or take. Then studs.

How about drilling everthing for 1/2" head studs that should be a big step up in clamping force.

Im sorry i kept saying bolts. I’ll be using the dart specific arp studs to hold the heads down. Im just not sure if ill be using 4, or 6. Lol

[eLeSthree]

Originally Posted by graf101

I have a Thompson Dart SHP 388 w the Thompson/Frankenstein M311's going in as we speak. Thompson told me they recently had a car make over 1700whp with these heads, and I have heard nothing but great things about them.

Pics pics pics!!!

Hey why did you go 388 instead of 427?

[graf101]

Here are a couple.

[fif_gen_powa]

Hey Micah that is a hell of an upgrade, congrats. I've seen ls3 heads with arp bolts made a little over 1100whp on a forged ls3 376ci. You should be fine up to that area he also made over a 1000+ tq as well. If you want 1100+ than just sell your ls3 heads and get 6 bolt also I wouldn't spend any money on porting the stock heads just save it and put it to go toward a set of aftermarket heads

[eLeSthree]

Originally Posted by fif_gen_powa

Hey Micah that is a hell of an upgrade, congrats. I've seen ls3 heads with arp bolts made a little over 1100whp on a forged ls3 376ci. You should be fine up to that area he also made over a 1000+ tq as well. If you want 1100+ than just sell your ls3 heads and get 6 bolt also I wouldn't spend any money on porting the stock heads just save it and put it to go toward a set of aftermarket heads

Thanks John. It wasn't much more than the 408 I was about to buy so...

Thanks for the tip. I don't plan to make much more than 1100 at the moment anyhow. As long as the 4 bolt head will mate to the 6 bolt block same as the stock block, I'll run it like that until funds recover.

I've got to do something about these chopsticks I have for axles...

[Greenhornet2]

I think upgrading to 1/2" studs would serve your purpose but that is not a very educated suggestion, just through I read it somewhere.

[AGP Turbo]

4 bolt heads lift and leak at the farthest point between the bolts where the spark plug hole is. It's the head flexing, not the studs stretching. We learned a lot about this waaay back in the day before 6bolt heads were out. The heads were the much weaker link than the studs. 1600whp on AFR 4 bolt heads, twin 66mm, LQ4 block 408!!

$2400 is a pretty darn fair price for those. Hard to say no to that. But new LSA heads would easily do, they are much stronger than LS3's and are $1200 new.

[RobZL1]

Originally Posted by graf101

I have a Thompson Dart SHP 388 w the Thompson/Frankenstein M311's going in as we speak. Thompson told me they recently had a car make over 1700whp with these heads, and I have heard nothing but great things about them.

Excellent. Thanks for the feedback. I appreciate it. I'm sure I don't need them for my planned power level of 800-850, but I wanted some room for growth just in case. I only want to buy heads for this car once, basically.

[eLeSthree]

Originally Posted by AGP Turbo

4 bolt heads lift and leak at the farthest point between the bolts where the spark plug hole is. It's the head flexing, not the studs stretching. We learned a lot about this waaay back in the day before 6bolt heads were out. The heads were the much weaker link than the studs. 1600whp on AFR 4 bolt heads, twin 66mm, LQ4 block 408!!

$2400 is a pretty darn fair price for those. Hard to say no to that. But new LSA heads would easily do, they are much stronger than LS3's and are $1200 new.

But the LSA is still 4 bolt. I dont plan on making anywhere near that power. Just 1100 +/-.

If someone buys my LS3 long block I'll grab a set. Otherwise, I'll try the ls3 head with 4 studs.