ace32x

Ike the title says. Anyone know the limit of 4 bolts with thick deck heads before pushing water is an issue? After some reading and talking to some people 1200 seems to be the consensus but more imput never hurts.

Anyone in here over 1300 on a 4 bolt?

narfdanarf

Matt Owen is making a little over 1400 on a 4 bolt block but it's oringed.

ace32x

interesting. You know what size headstuds he's running?

1sc334

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turbotuner20v

Curious as well, I'm shooting for 25psi and 1100 with a blower. Ly6 block and lsa heads with ls9 gaskets and the standard arp head studs

narfdanarf

I was a little off, Matt's car made 1162whp. I do think H8RMKR's car makes over 1300 though on 4 bolts.

inspector12

Probably was near that before I pushed the sleeves down, but not sure. No dyno to back it up. I know I've made more than 1200rwhp. Gus and Leathal did like 1265rwhp on 4 bolts as well. Limits meh just depends on the setup IMO. But I'd guess the 1300rwhp mark is probably close. I used L19's TQd to 100ftlbs. And stock LS7 gaskets.

harveyjl

This ^^^^^^ is exactly right, it was a iron block with 4 bolt heads. he used 625 plus custom aged torqued to 115 on an lq9

White_Lightning

I dont think the question should be CAN you make 1300.. but rather.. How long do you plan for it to last.

C6 Curtis

It should last as long as you don't get dogshit basic ARP headstuds.

Go with ARP L19 studs or 625+ and you wont push water.


-Curtis

breecher_7

I know of a few factory aluminum and iron block cars running north of 25psi with the basic ARP head studs and LS9 gaskets. I really think the tune is what kills most peoples cars or causes head lifting issues. Properly machined/cleaned surfaces and a good tune go a long way.

My buddy ran around at 24psi on a lQ9 block with 317 heads for two years with no issues. The engine met its demise because of a dropped valve, aside from that it never had a issue.

5 Liter Eater

I just lifted a head at ~1100/1100. Not sure whether it was due to detonation or if the knock the log showed was actually the flame front exiting the head. LQ block, LS9 gaskets, AllPro cathedral heads, regular 8740 ARP studs. I'm investing in some CA625 studs. They are like the L19's but are corrosion resistant. The L19's aren't actually even in the catalog anymore. Just the 8740, 2000 (pro series) and the cutsom aged 625's.

chriswood

I have a 4 bolt iron block with kurt urban 1/2 head studs with a 317 head. I will be pushing it to the limit.

ace32x

Car already has the good arps in it and ls9 gaskets as it is an ls9. It's already making around 1100 just debating upping the pill on it

0CravenPerformance

To make big power on a 4 bolt block there are quite a few things you can do to make them live.

Thick deck heads are always a good start
1/2" headstuds
Dry Decking the block (not the same as filling, still has water in the motor/heads)
Double Oring

Usually after all this is done youre in it about the same money as an LSX block so unless your class limited to a 4 bolt block its usually more cost effective to to just buy an LSX block.

inspector12

I did the 1/2" head studs and that was worse in my experience. Like snake oil. The bigger fastener distorts the bores pretty good and didn't provide any better clamping force than a nice set of studs such as L19's or the CA625's or even the APR 2000's. The studs were cheaper, but by the time you paid to have the block machined it was with in $100 and The head gasket holes don't work on GM head gaskets so that cost you more to buy the Cometic's which are good, but no better than the GM's for more money.

0CravenPerformance

They only distort the cylinder if the cylinder wasn't bored/honed with them in it. When upgrading to them the block needs to be re-machined in order to keep the cylinders round.

1sc334

How many miles u think u put on that setup? And why are most builders against using stock blocks for say 1000-1100hp if it can be done without a six bolt block.

ace32x

margin for error and failure is a lot smaller and they don't want the liability. And they also make more on upgrading to 6 bolt in most cases I bet.

slow ride

Deck surface is such a huge part of this. Just because your machine shop trued them up doesn't mean the surface is worth a ****. Needs to be uber smooth (low RA) on both sides for MLS gaskets. I hand lap my block/heads with 400 wet/dry and if it's something really nuts I'd keep going to 1000 grit. I love getting the old school guys commenting on it needing the surface to be ruff so the gasket bites, I just roll my eyes. My friends SBC (granted more studs, aftermarket block/heads) does the same surface prep with felpro MLS gaskets on his 1600+ hp 10.5 car and pushed no coolant.

Granted you should finish hone with a torque plate and that should take care of any bore distortion, but if GM went to expense of the larger studs for the ls9 then you know it helps. I'm sure the better stock size studs do the same as the 1/2", but what about doing both.