Bartturbo

Hi guys i have a build ls7 callies rods and crank and arias pistons 4.130 bore , i want it to boost it. i have read many threads, a few guys drive over 1000 hp other guys says its a time bomb before the cylinder walls cracks.

i prefer a procharger f1r .

whats your opinions ?

Undy

You need to sleeve the block or you're heading for some heartache...

Creatre

This. Darton sleeves unless you want to do it all over again soon.

73DBG

I guess I would want to ask this, raise your hand if you’ve boosted and LS7 with heads fixed and forged piston and stayed under 15 psi? Who has done this and personally cracked the block? Lots of people say “it’ll blow” but very few people when asked actually owned one that did.

you don’t need and F1-R to make 1000whp either. A D1X or Ti blower will do it all day long.

Detoxx03

I don’t have any LS7 block experience but I do have blower experience. I wouldn’t bother with the old outdated F1R. Get a D1X or if you must have a F series do a F1A-94.

73DBG

I just see these post all the time, and yes a sleeved block would be “best” but it seems whenever this question comes up the auto response is “LS7 doesn’t like boost” or “better sleeve it or boom” but when you ask those people it’s always well....I heard, or they didn’t fix the heads or use forged pistons. So I’d kinda like to know who’s actually boosted and LS7 with heads fixed, forged piston only and stayed under 15 psi? Did that block crack?

ayeyomoe

I am curious on this as well. I always 'heard' someone say it's bad and it'll 'blow' but never knew or heard of someone actually blowing the walls.

HouseS2k

Just like my post in the FI section. Unless you have first hand experience with a boosted ls7, your opinion is useless and hearsay. @73DBG is making well over 1000 at the crank with forged pistons on stock rods and sleeves. It ain’t no trailer queen either. I’m also doing a similar build. I’m still stock piston for now but have been running 8psi sbe for over 8k driven hard miles.

Unreal

Seen plenty crack a sleeve at way less than 1000. Just takes one bad pull to pop a sleeve. Can stock sleeves hold it? Sure, as long as everything is spot on, and you have good luck, but personally if you are building a 1000rwhp setup, the cost of sleeves is a drop in the bucket for the insurance it offers.

73DBG

Don’t use that crank HP bs on me 😤🤬 lol

73DBG

I know you have, but it’s usually just you and maybe one other guy with the experience or close witnesses of it happening, but there’s two or three threads going on right now and 27 people all saying it’s gonna go boom but you’re the only guy that’s actually seen or done it I know you’ve been in the game a long time, probably not much you haven’t seen.

HouseS2k

944whp

Unreal

Just like people run stock trannys, stock diffs, stock clutches at 700rwhp, etc. Some last, some don't. It will be the weak link, and for what a 1000rwhp fuel system alone cost, you are way more then just getting sleeves done and not worrying about it.

Patriot Six

13 psi, 874rwhp with just a forged piston on e85 and I didn’t crack the block. However, if doing it over, I would sleeve the block.

MRSUPRA

There was a guy on here a while back called EdwardETrailerIII who had 2 stock block twin turbo LS7's making 1150-1200rwhp. And he had a stock block nitrous LS7 that was making over 900rwtq for 8000 miles. He claimed to never have any issues.

Michael_D

The OEM liners are grey iron, which is quite brittle and unforgiving when exposed to detonation. When power adders are used, anytime, any engine - the probability of detonation occurring increases. It's just a simple fact of life that when you add complexity, there are more moving parts involved, so the opportunity of more things not functioning correctly occurs.

So.....when using power adders on this particular engine, you just need to know where the weak links are and plan accordingly. Plan for failures, and exposure to increased risk. If you are the lucky type, follow the lead of others who are also lucky. If you are like me, and more often than not, unlucky - plan for the worst.

Also, remember that no one here offering you free advice has any skin in your game. No one will offer to pay for any damages or back up their claims with their money, that you will be "A-OK" if **** hits the fan and you crack a liner.

Cash1333

Im 8psi sbe on e85 and meth, making 800whp and been doing it for a while, and driving hard. I do rallies and what not. However I am going TSP 427 short block with darton sleeves to make the 1000-1100. I have friends who are just forged pistons making 950-1000whp and doing it fine. The sleeves can handle it, if everything is good. If you want the 800+ you will want to do everything you can to prevent predetonation.

Undy

Yeah, the responses here sort of remind me of a friend that had a 72 Vega that he swore lasted 200K miles without burning a drop of oil on the original engine. He also swore there wasn't a thing wrong with the Vega engines. I would place zip-point-squat weight on most of the responses here...

MikeOC

How many of these boosted LS7s are at 4.130 bore like the OP is?