BurnOut

iTrader: (1)

Is it even possible?? Let's say that you have a 427" and you want to be able to run it on pump gas, so you set compression to about 11:1.

What heads (not C5R)?? Perhaps a set of hand-worked AFR's??

What cam?? Solid roller is okay; but what needs to be done to convert a motor to solid roller?? Obviously an adjustable valvetrain... but I have heard that the lifter bores need to be bushed... how much labor is usually involved in that??

What about intake?? Could a FAST 90 get the job done, or would it require something else??

strokedls1

iTrader: (1)

You will not be able to get that much power with those requirements. Even the ARE motor that was a max effort didn't put down 600+ rwhp, but it made somewhere around 670 torque. It would take over a year to get something like that built if you had hook ups.

kumar75150

I think there are a couple places in the country that could get you close. Cartek just got 575rwhp out of a 427.

BOWTIE

I do not think it would be that hard with an unlimited cash reserve. I am not familiar with the ARE max effort motor, but 670 ft/lbs of torque and less than 600 hp seems hard to believe. About the only time I have seen LS1's make a higher tq number than hp number has been on the spray. I am not saying it did not, I have just not seen it. In any case, if it was a max effort car and it was being built for drag racing, then it most likely was set up with an automatic (most likely a TH400 which is a hp hogg) with a loose converter. If that was the case, a simple swap to a manual would almost certainly put you well over that number. I would think a well built 427 using a C5R block, a serious set of st 3 ls6 heads or better yet, a set of ported, hand finished AFR 225 when they are available, and a max effort solid cam along with an effecient (read not automatic, not independent, preferably not a 9 inch) drive train would get you there. After all, we have cam only cars hitting the 450 mark. That is almost 1.3 hp per cubic inch, at that rate, a 427 would make 550 rwhp. Didn't the limited edition ZR-1 427 Camaros make over 600 flywheel HP straight from the factory or wherever they came from. I would think a max effort full on build up could better that by 100 hp. You would just have to pay attention to all of the details. Such as ceramic coating the combustion chambers in the heads, the tops of the pistons, using light weight and profiled crank and every other top notch part an unlimited check book could afford. And when you are done, you could give it to me for testing.

kumar75150

I am pretty sure Futal and Cartek can both do it.

LG, Vette Doctors and a few other people should be able to do it as well.

VINCE

iTrader: (1)

Obviously unlimited funds is out of the question. This individual is asking for a mild build, but want wild build horsepower. At this time that is not going to happen with a 427ci. If he steps up to a bigger motor I think it is doable. FMS put down 605rwhp with a 434ci SR setup that could take a bigger stick, but this car was built for the street and to run on pump gas. If a 427ci LS1 with a mild build could get 600rwhp on pump gas with what we know now it would have been done already. Now if you add C5R heads and a custom intake I think Futral can get you your 600rwhp 427ci pump gas car.

BurnOut

iTrader: (1)

What is holding the bigger motors back, then?? I mean, if stock cube motors are over 500 RWHP (remember that I'm also counting solid roller motors) with the same constraints that I mentioned above, then what's the hold up on the bigger motors?? I don't think that an additional 100 RWHP out of an additional 80 inches is too much to ask.

Yeah, I know, the big motors make lots more torque, and as a result, their average power is a lot higher, while their peak power isn't that much higher... but still... just keeping the efficiency the same (as a 500 RWHP 346), a 427 should be able to make nearly 620 RWHP with the same basic setup (read: with the same compression, etc...).

However, for whatever reason, this isn't the case.... so do we know what the hold up is??

Ben R

Remember, it's not all about peak numbers, it's about area under the curve.

You could do a nice Solid-Roller 427 with a custom sheet-metal intake manifold and probably get pretty close to 600RWHP, but you'd sacrafice some power down low. It might not be all that bad if you're turning your car into a race-car, and you don't mind having a raceweight of about 3,200 lbs, but if you're looking for a nice daily driver, gobs of torque is nice to have at your disposal. As far as a daily-driven 427 goes, there is no reason you couldn't be able to reach 540/550 RWHP in a well-manered car.

Fast, Reliable, Cheap. Pick two.

And remember, you get what you pay for.

Scalpel

iTrader: (4)

We're largely intake limited.

CHRISPY

ARE did those numbers with an unlocked TH400 and a 9 inch on 28x10inch slicks with nitrous plugs and tune.

~590RWHP unlocked

That would be close to 640RWHP in a 6speed car with stock rear.

VINCE

iTrader: (1)

You have to remember that the majority of the 500rwhp 346ci cars are not ACTUALLY what you call a street car. I tend to question the ACTUAL FACTS of compression, cam size, and other reasons for getting those #'s. Dont always believe what you read.

BurnOut

iTrader: (1)

Okay, to continue this discussion, let's say that I have in my greedy little hands and C5R-block 427 (well, on its way to me, anyhow). This motor (supposedly) made 587 hp at the crank with a mild cam (230/236 on a 115, not sure of the lift) and some heads that flow in the low 300 cfm range on the intake side. Compression is supposed to be right around 11:1, maybe a bit less (like 10.8:1). I'm not sure what intake was used... probably LS6.

The target weight for the car that the motor would find its way into is 2900 pounds, and the tallest rear gear I can run would be 3.90:1 w/ a ~26" tall (tire), so it isn't like I'll miss any low-speed torque... torque could be the same as a stock LS1 and I would still have PLENTY of it. I'd just really like to be able to have the pull up top.

Now, my options are to either get the current heads touched up (maybe the super-duper TEA 340 cfm port??) or sell the heads for use on a stroker or something, and go with a set of hand-worked AFR's or similar. Intake options are somewhat limited due to the low hood line on the car, but I know for certain that a FAST piece would fit. Convert the thing to SR (how much machine work would it take to bush the lifter bores??) and maybe bring the compression up a notch (thinner head gasket or decked heads), and what do you guys think??

kumar75150

on a 427, I would wait for the AFR 225s and run about a 244/250 cam on them with the FAST 90mm intake and 90mm TB and 1 7/8 headers with 3" exhaust.

Money no object, I think Cartek has some great heads right now with the Inconel valves.

strokedls1

iTrader: (1)

The thing is that the 346 cars still have a 10 bolt with m6 that put out big power. The m6 won't readily handle 750 fly wheel horsepower. ARE had a th350 in there car with a dry sleeve block, ported c5r heads, and a belt drive. It is the craziest ls1 I have seen. The big displacements require stronger parts, like 12 bolt, built tranny, upgraded drive shaft. These thing cost power but are a necessity if you plan to drive the car for any period of time. Why not just spray a hundred shot on a typical 427.

11 Bravo

iTrader: (3)

I was thinking along those lines. What these motors are putting down right now isn't too shabby since they are still running factory cast heads. The 90mm intake and tb is already proven to give @ 25rwhp gain on 427's. A set of ported AFR 225's looks promising.

BOWTIE

[QUOTE Convert the thing to SR (how much machine work would it take to bush the lifter bores??) ?[/QUOTE]
I could be wrong, and I am sure someone on here will let me know if I am, but I do not think you would have to bush a C5R block to run a solid lifter. I know we use to bush factory blocks, but that was because from the factory the lifter bore were not always straight.

mudz5.3

What about the block that MTI used in there project GTO. It was 455 cubes and built for street manners. Couldn't this be used with a little more race inspiration and put out good numbers. Although since he has a 427 coming I guess that would be out of the question, huh.

VINCE

iTrader: (1)

Since you are in the supposed world right now. The motor you have on the way makes just under 500rwhp currently. You supposedly have a 2900lb car to put that motor in. You could have the heads that are currently on the supposed longblock touched up to get better #'s and you could increase the size of the cam. Depending on the new combo with a LSX intake my best guess on this supposed setup would be 530rwhp to 560rwhp. It could be higher, but who knows. With a supposed 2900lb car.... Why would you need more horsepower? Your up top is going to pull like crazy. You could also spray this motor and not worry about ANY sleeve issues, but that all depends on the supposed C5R block.

BurnOut

iTrader: (1)

That's a really good point, and it is also why I am looking into using a Tremec TKO 600 5 speed and a Ford 8.8" rear end (which would open up my gearing choices considerably).

VINCE- Those are some good points... as for the 600 RWHP goal, I just like the idea of having a 5:1 weight to power ratio... Out of curiosity, regarding the intake, does anyone know of any results using the GM carb style intake?? Thinking that one of those could probably be converted to EFI for about the same cost as a FAST 90 manifold.

VINCE

iTrader: (1)

Contact Allan Futral about modifying a GM Carb intake. He will have some information for you..---------------------------->

I think your car is going to be NASTY with what you have planned. 2900lb raceweight is just sick. Are you putting the motor in a 93-96 RX7???