Ragtop 99

The issue with an automatic is the idle speed. With the stock torque converter, the idle speed can not be raised too high or the motor fights the brakes at a stoplight. As Spin explained, with aftermarket heads over 500 rwhp in streetable form is attainable. The only question is can it be done with a cam that will idle low enough for a stock converter.

Ragtop 99

OP:
Given your goals, why not go with a milder build with a cam selected for road racing and put a 100 shot on the car for lake bed. The nitrous will be far less expensive than good heads and provide far more power.

godzilladude

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If you truly are "cheap and lazy" stay away from actual W2W road racing. It requires a tremendous amount of energy and effort, and a foolish amount of cash.

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Exactly If I could just get rid of these pesky wife and kids, I'd have PLENTY of money for racing . . .

godzilladude

Ah, great minds think alike. I actually looked into this, and all the nitrous builders I chatted with said no way. This isn't 10 or 11 seconds of juice, this is 100-200 seconds of full load. They said it would be very expensive to try to build a motor that could withstand that.

The easy answer really is just a larger motor, a forged 408, 418, 427. There is no replacement for displacement. Then it's EASY to make 500 lolly-gagging horses like the ZO6 guys do. It'd just cost a lot more.

FloydSummerOf68

That's exactly what I was going to say....for high speed events I wouldn't want to open the juice up for that long. Generally 14-15 seconds of consistant use is what is recommended as a max.

JoesC5

I know what the problems will be when going with to much of a cam, especially with an auto transmission. I was questioning the knowledge of the poster who was advocating a wild-*** cam for the OP.

I started hot rodding back in my senior year of high school, 1959-60, with a 53 Ford that I put a 283 chevy in. I bored it 1/8" over to 301 cu in, put 11:1 Jahns pistons, ported the power pack heads myself with 1/8" over valves and then put in the wildest Isky cam I could buy. When I tried to drive the car to school everyday plus take it on dates on Friday and Saturday nights, I soon realized how much of a mistake I had made in my cam selection. I then put in a Duntov cam, that was was still a hot cam, but drivable.

Over the years, on other engine builds, I always went a little on the calm side in cam selection, and it always worked out. During the same time, I saw others repeat my mistake on my first engine build and they always regretted it.

Over cam and over carburetor has always been a problem. People want the big numbers and fail to realize there are always trade offs. With an auto, peak HP numbers mean nothing, the low RPM torque is what matters with a street engine. Normally, to get the peak HP numbers, you give up low end performance.

As far as I can tell from what the OP says he wants, a mild cam that will do around 450 rwhp would be more to his liking. Sure, he can build a 500+ rwhp monster, but will he be happy with it? That's why I pointed him to the LPE engine builds so he could get an idea of what it would take to build a streetable engine to be used with a auto transmission. If he copied the 525BHP engine that LPE offers then he would see around 450rwhp. I sure Spin knows his business, but so does LPE. Not knocking Spin, but I'll go with LPE when it comes to engine building and cam selection.

FloydSummerOf68

What "wild *** cam" was suggested?

JoesC5

I don't recommend going with a LS7 at $15,000 a pop, but I do recommend you look at a larger displacement engine build. Sure, my LS7 ONLY has 465 rwhp but it idles at 600 RPM and I can drive it anywhere without any drama. Yet I can easily light the tires up in first and second gear. I only get traction in third gear and that's with the 325 rear tires. I can also drive my car 570 miles to the Talladega Super Speedway, never see the engine even start to overheat and the A/C never shuts down. Then I can sit in the staging lane, with the air on, waiting to go out on the track so I can run 150+ mph around the 2.66 mile, 33 degree banked turns. All that and I don't have 500+ horses with a big *** cam. Oh, and I get 29-30 MPG while crusing at 75 MPH and I avg 23 MPG on my normal city/highway drives.

A LSx454 crate engine at $9,300 will give you~500 rwhp, without any drama and you get a GM warranty plus you still have your original engine to put back in the car if you decide to sell the car later on, or sell it up front to help pay for the crate engine.

tomlink

Car Craft magazine has a great series going on a LS3 crate motor mod. They started stock and then dynoed in stages after adding cam, intake, heads, and then a 417 stroker kit. I think next month they are going to throw a blower on it.

Check it out at www.carcraft.com

JoesC5

Just remember, while reading the article, the numbers Car Craft recorded were on an engine dyno without any HP robbing restrictions. That is the way the car companies rated their engines years ago. Today's readings are done with all accessories(water pump, power steering pump, A/C compressor, alternator) on the engine, full exhaust, air breather, etc. For example a 1965 327 rated at 250 HP GROSS was rated at 210 HP NET. A 1959 fuelie 290 HP GROSS was 245 HP NET. GM's NET HP was about 15-16% lower then their GROSS HP readings.

Today's horsepower readings are NET HP. The way Car Craft is testing their build is GROSS HP. So their numbers are way over stated if you are comparing to GM's HP.

Then you factor in the driveline losses to get a rwhp reading.

Ragtop 99

I was think more a long the lines of spraying the last 15 - 20 seconds once you have reached your max NA speed, but I don't know how much room you have to hit 200 mph.

More cubes would be great. I'd be very happy with a stock Z06 and 3.90 gears if only the roof came off.

PRE-Z06

what tires/gears are you planning on running 200mph with? With stock you will only be turning 5500rpm in 5th at 200mph...

godzilladude

That is pretty close to peak HP, so I think that the current set of gears should do just fine.

FloydSummerOf68

5500rpm isn't going to be close to peak hp with a big enough cam and set of heads to make 500rwhp.

JoesC5

I agree. With his 2.56 gears he will be at 5400 RPM at 200 MPH. With 2.73 gears, he will be at 5950 RPM at 200 MPH and with 3.15 gears he will be at 6860 RPM at 200 MPH. He really needs around a 3.00 gear(6385 RPM at 200 MPH) but that's not a std off the shelf gear ratio. His best gear choice would be the 2.73:1.

Or he could go with a off the shelf 3.90 and at 6540 RPM he will be at 200 MPH in 6th gear. Only problem, he would be way over geared in first and second gear and his gas mileage would be horrible.

louiecvt

There are plenty of good places to get information and work done in your area (LG, Extreme, etc). I have an 08 A6 that I had modded by ADM in Lewisville. Callaway cai, Kooks LTH, hi-flo cats, cam, 3200 stall, 3.42 rear end and tune. This combination made 453 rwhp. Still streetable. Does "Shake, rattle, & roll" a bit but I personally like it. The only downside is I should've beefed up the transission cuz now it's sitting in my garage waiting for a built tranny. I've been very happy with my car. If your going to do any racing or hard driving I would recommend a built transmission. However there are some people who's stock transmission held up fine so maybe It's just me.

FloydSummerOf68

His best bet is probably playing with tire height if he wants to really fine tune the RPM at the big end.

FloydSummerOf68

The transmission giving out at only 450 rwhp doesn't sound normal

Did you find out what happened with it?

louiecvt

Yea. Obviously, because of modifications there's no more warranty (not that I would trust them anyways). I haven't had anyone look at it yet. Regardless of wether it's something minor I was planning on upgrading it anyways so I'm saving up the money to get it all done. Right now it won't go past 2nd gear. I'm thinking I just had a bad transmission from the start.

ls3gotcha

I drove my 501rwhp stock headed cammed ls3 to Texas from Florida getting 30 mpG with the ac on jamming out to xm. Then I went to lonestar motorsports park with my buddy and ran 10.80's all motor sprayed a 100 shot ran low 10's. Drove it to the strip club went fishing and a week later drove back home with rubber on my rear quarters and white track numbers on the window still getting 30mpg and listening to xm