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LS7 + E85 + Vortech supercharger will make around 650-700whp safely.
Here's the thing about the internet and especially a site like ours....

Many people who are considering doing mods to their Z's keep an eye on threads like this to help them make decisions about future mods. I get pm's weekly from folks asking advice, especially on supercharging their Z.

It's one thing to debate this issue and go back and forth on who's right and who's wrong. It's another thing entirely when someone make decisions based upon reading others experience.

First off, although I am familiar with E85, you have much more faith in it's ability to avoid detonation without causing other engine problems than I do. Racingvette also makes a very good point that it is not always easily accessible. As you know, it's not a situation where a person can go back and forth between E85 and 92 or 93 octane gas because tuning is more or less 'octane specific' and running an engine tuned for race gas on 93 octane can spell disaster in a hurry.

Secondly, I just don't think you have near enough personal experience with the LS7 engine to assure folks they can make 700rwhp with a Vortech (or any other blower) SAFELY.
Your comparison with the heads/cam car that made 600rwhp doesn't piggyback directly into 'add a blower and at 8 or 9 lbs boost you can make 700rwhp'. Totally different setups and the higher compression ratio of the LS7 is an advantage with the h/c car. Just the opposite in a blower car. Also the type of cam that you would use to make 600rwhp would be deadly in a blown application.

700rwhp is not a small gain. The LS7 typically comes out of the factory around 450 to 470rwhp so you're talking about a 250rwhp gain. You won't get that (even with headers, FAST intake, ported TB, etc) with a safe amount of boost and assuring folks they can is just wrong.

You are new to the site but I can tell you that there are a lot of knowledgable folks around here and most all of them are careful with their advice so that they don't steer folks into harms way and/or give unreasonable expectations when it comes to modifying their Z. Too much at risk for the people who may be relying on that advice.

Mike
 

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Problem is your world and real world do not agree and has costly end results
Multi LS7s, go boom :drunken:
The first 2 pictures are pics I took at Autoclub Speedway. The driver stated his car is/was 100% STOCK. Oil starvation siezed a rod thus air conditioning his block, dumping oil all over his cats, which then caught FIRE underneath and since the car was moving forward, it blew the flames all the way to the back and resulted in the torched rear end you see here. This was not a result of any supercharging.

For what it's worth, I wouldn't go past 5PSI with a stock LS7. (In fact, I'd want my tune spot on even @ 4.5PSI.)
 

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Vortech is right down the street from a and a. Also I am running e85 and it is a little bit of a pitta to find from time to time but keep in mind in a pinch you can run reg gas. Our cars will command a 14.7 af on e85 or reg gas on part throttle or cruising, key is you cannot get on it wot or any thing more than light throttle. I tracked my vette na w bolt ons a few years ago on 92 and my water temps were 212-220 w 356 whp. I just did another track day on the same track and 90 deg sunny day w 460 whp on e85 and never broke 205! I will never go back to reg gas unless e85 goes away, too many benefits w the cooler burn.
 

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I too was wondering about the Edelbrock E Force after the seminar by Edelbrock at the Black Hills Corvette Rally a few weeks ago. The blood ran hot for ZR1 horsepower in my Z. The blood has cooled. What I have is already mostly unuseable. I think I'll just keep her the way she is and then I won't need to solve the mysteries of the LS7 on boost, with or without add'l mods or E85. I think I have to drive about 800 miles (Mt to Minnesota) to find any E85. This thread helped me make my decision. Thanks for the discussion.
 

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wether its been stated yet or not a Darton sleeved block can be comparable in cylinder strength as an iron block and even better a ERL prepped aluminum block is damn near indestructable (for its ci sizes). anyways to the OP i wouldnt go anywhere above 5 psi in a stock LS7 if i wanted reliability...anything more its just a ticking time bomb. it can be done but if you want to drive your car hard like everyone who owns a muscle car should 7-9 psi is more a matter of are you ready to replace the motor when it decides it go boom!

edit: gee this was my first post??? where have i been...
 

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this thread is insane..

to the OP- essentially, no
you can run 4-5psi safely provided you have a proper tune. although some would argue it is better to run that $$ amount in N/A form, FI is usually a cheaper route if the proper precautions are taken. do plenty of research before adding any big-boy mods. this thread will open your eyes/ears.


@ euroz06-

so you are stating that a ls7 in "mostly stock form" can gain 250-280whp(60% gain) through a supercharger and some e85?

remember that when someone says "safely" they mean "DD/Track/hard driving/easy driving/powertrain holds/suspension handles it/ etc..

euroz06- You sound like a man with a paper asshole
 

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wether its been stated yet or not a Darton sleeved block can be comparable in cylinder strength as an iron block
Again, not wanting to be argumentative, but can't say I agree with your statement.

I had my C5Z bored (427) and Darton sleeved several years ago and I have an LSX ironblock now. Trust me when I say they are not comparable. Ask me how I know...:doh:

Mike
 

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Hi, guys -

I just acquired an LS7 engine and am using 9.2:1 compression Diamond pistons in the stock bore, and a 4.125 forged crank I had in a 422 Iron block stroker, to create a 441 CID engine to be modestly boosted. (Will see which of my two pullies get me there, but I'm anticipating the ability to run 5-6 PSI or 8-9 PSI .. rough guestimate from what these did on my 422 of 8-9 PSI and 23-13 PSI respectively.)

With a good tune, do you think I'm in safe territory?

I don't have another $3000 to get it re-sleeved and feel I'd be perfectly happy with what a 441 should produice with a modest amount of boost.
 

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Hi, guys -

I just acquired an LS7 engine and am using 9.2:1 compression Diamond pistons in the stock bore, and a 4.125 forged crank I had in a 422 Iron block stroker, to create a 441 CID engine to be modestly boosted. (Will see which of my two pullies get me there, but I'm anticipating the ability to run 5-6 PSI or 8-9 PSI .. rough guestimate from what these did on my 422 of 8-9 PSI and 23-13 PSI respectively.)

With a good tune, do you think I'm in safe territory?

I don't have another $3000 to get it re-sleeved and feel I'd be perfectly happy with what a 441 should produice with a modest amount of boost.

This is just my humble opinion so take it for what it's worth....

You're building a 441 stroker engine out of a LS7 block and then want to boost that with FI?

I think you'd be building an engine ready to go boom when you start driving it hard!

Mike
 

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Mike, I appreciate your 'humble' advice. :)

What I'm having trouble with: all the vendors I talk to say if I get dished pistons designed for boost, make the compression ratio fit a boosted configuration and my internals are forged (as they are), it's all in the tune.

Some others who claim success at boosting even a stock LS7:

There is always going to be a limit to any engine with how much boost it can withstand to hold. Increasing the durability of the rotating assembly allows to increase that limit but the engine itself can only withstand so much cylinder pressure before things exit stage left.

The key ingredient to keeping an LS7 happy with higher boost levels is in the tune. You can rattle an LS7 apart at 10psi if you didn't know what you were doing. With that being said we've pushed a stock sleeved stock LS7 block to 23psi without any damage so asking for it to handle 15psi in your set up is just fine.
At 7.0 liters and 7.5 lbs of boost on our stage 2 engine package utilizing our MTI Racing proprietary cylinder heads and valvetrain, we have acheived over 800 horsepower on a STOCK LS7 in our engine dyno test cell.

The final product is quite amazing. Huge power and tons of torque down low in the rev range where you drive the car. (600 rear wheel torque at 3000rpm and above)

We have run 25 psi of turbocharged boost (1500+ hp and 1500+ lb-ft of torque) with the LS7 block in our customer's standing mile Z06. We also have lots of customers running 10 to 15 psi of boost on turbocharged and supercharged LS7 blocks without any block related problems.
What do these guys know that you and I don't? Are they blowing smoke up my rear?
 

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It would be interesting to find out how many of those aforementioned engines are in one piece after a year of driving them.
 

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It would be interesting to find out how many of those aforementioned engines are in one piece after a year of driving them.
Me too. :)

I'd also like experiences by folk who built a forged low compression engine and share how they burst it.

So far, I'm reading mostly theory and the only people who have practical experience are the vendors who say they make it work or people who tried to boost purely stock LS7's.

Theory and opinion is good ... but, I'm hoping I encounter someone with prior experience.
 

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Mike, I appreciate your 'humble' advice. :)

What I'm having trouble with: all the vendors I talk to say if I get dished pistons designed for boost, make the compression ratio fit a boosted configuration and my internals are forged (as they are), it's all in the tune.
While it is true that dished pistons, cc'd heads, even thicker head gaskets will lower the CR of an engine you still have to consider the cylinder walls (even sleeved) on the bl ock itself. The Ls7 engine block is extremely similar to the Ls6 block except the Ls7 is already bored to 427 cubic inch. That means the cylinder walls are already thinned out by GM at the factory. That doesn't make it a brittle engine or unmoddable, but it does make you very leery of how much boost the walls will take.

If the Ls7 block was a strong contender for high boost, GM would have used it in the ZR1 (along with the roots blower) instead of backing off to the LS3 block.

As for vendor claims :lol: :lol: (sorry, couldn't help myself)
You could build your stock engine up to 1000rwhp and never blow the engine....just be sure and never take it out of the garage and for heaven's sake, don't EVER run it hard.

I you really want to build a 441 stroker engine and boost it at 10+ pounds, spend a little more money up front and buy yourself an LSX or Warhawk ironblock to use as a base for your build. Now that would be badass!!!

Mike
 

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Me too. :)

I'd also like experiences by folk who built a forged low compression engine and share how they burst it.

So far, I'm reading mostly theory and the only people who have practical experience are the vendors who say they make it work or people who tried to boost purely stock LS7's.

Theory and opinion is good ... but, I'm hoping I encounter someone with prior experience.
Something to chew on as do shops lie or not when selling high dollar boost installs for stock engine ? :)
 

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Something to chew on as do shops lie or not when selling high dollar boost installs for stock engine ? :)
Ouch! Those pics will give you pause :yeadog:
 

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Boost is bad for ANY engine if it is not properly tuned to avoid detonation and/or you run too much boost. Whoever drove that was doing something terribly wrong, or intentionally over-boosted it, knowing it would die.

The two situations I've had with boosting was knowingly upping the boost on a stock LS1 (while another engine was being built) and lifting a head. The rest of the block was good; only a head gasket blown.

Other than a worn bearing and cam lobe on my 422, the rest of the engine looks pristine. after running it for years.

But, I took it to the dyno when I made changes in boost pressure and had Wideband O2 checked and I NEVER, EVER raced it without monitoring it with my laptop. I feel it would still be together today if I had figured out back then that my tranny settings was the problem I had with it intermittently overevving. It was during an evening of racing with this issue being more persistent that it developed low oil pressure and wore (not quite spun) a bearing.

Since this post I've found a number of people boosting the LS7, from stock to forged, that have no problems and have been doing it a couple years or so. Some are boosting the stock engine as high as 10 PSI with no issues. I found one guy that says he regularly runs 15 PSI on his forged block and has had it as high as 18 PSI(though he did that only temporarily, because he had to run higher than 93 octane to WOT it).

Some people, not necessarily engines, don't need to run boost.
 
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