redlineit

I really want to go the nostalgia route, but using an all aluminum high rpm LS motor destroked to 283 cid to put in this 'streetfighter' style '55 below.

I was told GM prototype class race cars ran 300 cid using Sonny Bryant cranks. Any suggestions on design features this motor should have are appreciated. While the car will see time on road courses, I need the motor to be completely streetable. The car will be lightened also.

Thanks,

Skip

djsanchez2

iTrader: (14)

I've seen one destroked to 302 before. Lemme see if i can find it for you.....


Here you go
http://www.ttspowersystems.com/articles/7/index.htm

redlineit

DJ, thanks alot .

That should be a great help.

Skip

InchUp

iTrader: (2)

Hmm...simple idea here to put a 4.8L crankshaft into a 6.0L. A stock 4" bore makes a 5.4L 329ci motor and a .030" clean up puts the displacement at 333ci. I'm not sure of any specialty crank for really short throws but that 329/333 would be one helluva motor on your hands. It wouldn't make any power down low and would require quite the camshaft and valvetrain mods, but if you matched the ring and pinion in the rear end right, it could be a fun little motor in that '55.

redlineit

I agree it would be.

But I have thought about this for months and I really want the challenge of using the cubes the old racers were limited to during that time and see what we can squeeze out of a 283 with all the new technology.

It may not make any sense to anyone but me

Skip

hirdlej

iTrader: (31)

Buy a 4.8L then, 295 cubes is as small as you're going to get without putting big bucks into it

Old SStroker

Great looking car, Skip!

What kind of power are you looking for? How much do you have to spend on making a 4.6L (283) LS engine work? If you are looking for much over 400 fwhp, it won't be cheap and you'll need some expensive parts.

The 5.0L (305) Daytona Prototypes use the stock 5.7L bore (~3.90) and a stroke about 3.20. The heads are LS6 based with some killer porting. They are rules limited to about 7100 so I expect power peak is right about 7000. They are making well over 500 fwhp, but they probably rarely get under ~4500 rpm while racing.

Your problem with making power with a bore smaller than 3.90 is the heads.

The least expensive way, as pointed out would be to use a 4.8 (293) which would equate to a .060 over 283. If you want to be PC (Period Correct ), the 283 wasn't available until 1957, so a 283 in a '55 would be a later model swap.

If you wanted to make the 4.8 run, you would need to get the 4.8/5.3 heads ported to work with the 3.78 bore. That is possible, but probably not done as often as 5.7L heads. BTW, are you thinking carbed intake? Done correctly, I think 450 fwhp in a streetable 4.8 (293) LS is doable.

This could be a fun project!


Jon

Kalgorn

iTrader: (6)

What use is there in destroking (in general, not specifically this application). Just curious because I really don't know.

JoeyGC5

iTrader: (24)

Why not do a wellmatched hyd-roller cam and TFS heads on a 4.8 block. Weight balance shouldn't be affected that much and should have good mid/upper rpm range power to go with a well setup drivetrain. IMO

Randy_S

iTrader: (1)

That is a gorgeous car! Good luck on the build up.

LS1Z28_98

When you destroke, you can twist the engine out of the frame. Like someone said, nothing down low, until you get the RPM's up high.

I have a little 283 project now with a 67 Impala.

redlineit

I appreciate the advice, you are right, I will be spending some bigger bucks. I'm getting a great deal on some other parts so it'll work out.

Skip

redlineit

Jon, thanks for the compliments and the specs on those racing motors. I had a generous guy donate his help on that design.

I believe the racers in the mid 50's beat Chevy to the punch and bored out their 265's to get 283's. The 283 was so popular with tri-five racers as we know so I'm period correct enough I think

I'm looking for 500hp.

I also thinking of using a hand fabbed cross ram manifold like the 302 Z's with dual throttle bodies. Plus I really like that air cleaner on the dual quad Z-28's.

I probably will resell this car within the 1st five years so I have to think about how things look more than if I was just going to tinker with it for years and years.

So yes more money spent upfront but I believe I need something unique so when I go to sell it it will stand out.


Kalgorn, great looking '99 Z.

Destroking IMHO is done for several reasons i.e. when the motor is too big for a racing class, like in the late 60's the Trans-Am series Pontiac destroked a 400 to 303 cid. They just didn't spend the money to make it work from what I've read.

Its done when the motor needs to live in a high rpm range. Or when someone just wants it to live in a high rpm range, like me. Sure I could drop a 572 crate motor in the car, but that is not the effect I'm looking for.

As a kid I grew up reading Hot Rod stories about racers and their screaming 283's in Tri-Fives.

So I know know it will be more money and a bigger challenge but that's ok.

fast

iTrader: (24)

remember the rodders of that period bored 283's .100 over making a 301

redlineit

Oh I know.

IMHO if you say to someone 'that's a 301' when they are looking under you're hood at the motor, I think you'll get a blank stare.

If you tell them 'it's a 283' period... I think you get a much more favorable response.

But I do think we may see more 'tribute' LS 302's being built since that is such a respected displacement.

If I was doing a 1st gen Camaro, absolutely I'd do an all aluminum LS 302.

Skip

slt200mph

iTrader: (42)

I had a 55 chevy D/Gas straight axle car ... We bored them 125 over out to 301 cu in (and hoped that we had a straight block with no core shift) and ran the sheeiit out them ... until the 327 block came out and then we used a 283 crank and 327 block for 301 cu in......unless you are limited in engine size by class rules bigger is better...you are making a lot of unnessary work for yourself ... if you really want to go old school use a sbc instead of a LS series engine .. the sbc parts are dirt cheep ...

PS Screw that cross ram intake and carbs..find yourself some Hilborn injection and do it right!!

redlineit

Right, it'll be injected.

In an earlier post I said throttle bodies on the cross ram.

Skip

slt200mph

iTrader: (42)

Going old school means cutting a hole in the hood and letting those Hilborn injector stacks stick out ...

1BadAction

iTrader: (10)

the 4.8 is the one to do it with, you can go with whatever bore your heart desires up to 3.905. the 3.27" stroke is pretty short, too.

Old SStroker

500 fwhp in a 283/292 cube NA engine that is streetable is a BIG challenge. Sure the small stroke allows lots of r's, but you will quickly become valvetrain limited. Even if you use 7500 as a never-to-exceed number, and look for max power @ 6800-7000, you still have to be making 375 lb-ft of torque at 7000 or 1.28 lb-ft/cube at power peak rpm. This is possible, but not cheap, and there aren't a lot of guys who could do it for you and still keep it driveable.

As far as the cross ram shown here, the runner length isn't all that far off the LS series intakes, so one could be fabbed which both looked good and made the power you want.

FWIW, the first 5.7L engine used in the GM Racing Cadillac CTS-R had a 7L LS7 bore (4.125) with a 4.8L stroke(~3.27). It initially ran to 7900 but after one race it was mandated to about 7100 max rpm so the DOHC competition could keep up. The crank in the race engne was NOT a 4.8L production crank.




I'd either call a built 4.8L a ".060 over 283" or just fib a little and call it a 283. It will save you $3-$5K and 3-4 months in the build.

Good luck with you car.

Jon