LS2-240z

I'm starting to landspeed race in the ECTA standing 1-mile. If I set a new record this year with my stock 2006 GTO 6.0L engine, instead of trying to go faster with it, I am considering downgrading to a smaller engine class (the sub 5.0L n/a record looks a little neglected). The engine class break is setup so that 5.3, 5.7 and 6.0 are all in the same class-I have to drop all the way to sub-5.0L to drop engine classes. So, I'm looking into what can be done to a 4.8 lsx engine to make as much n/a power as possible. Any combination of factory or aftermarket parts would be considered, the only limitation is that it not exceed 5.0L. It could be a little time-bomb, and I'm willing to spin it pretty tight, but it has to start with an engine-mounted starter and idle at least enough to get started down the track on it's own power. I'm restricted to gasoline, but high octane race gas is acceptable. As always, cheaper is better and factory parts combinations are appreciated, but I'm willing to throw a little money around. ARP will definitely get some money from me. I haven't found much in the way of n/a discussions on this smaller motor...help me if you can.

MuhThugga

Well, if you are sticking with the factory stuff, one thing I would do is take the 4.8 internals and transfer them over to an aluminum 5.3 block. Unfortunately, GM never made an aluminum 4.8, and since you are staying NA, it doesn't make sense to have the extra iron block weight over the nose of the car.

A.R. Shale Targa

iTrader: (2)

TFS 205 heads which start at 58cc and could be milled even further for additional compression and a call to kip Fabre at Cam Motion for one of his tight lash solid roller cams, FAST92 and small diameter, lengthy primary headers with merge collectors. Lightweight GM hollow LS6 valves fit these heads and they already have powdered metal guides to be stock rocker friendly

LS2-240z

To get a 4.8 using a 5.3 block, I should use a 4.8 crank with which rods?

96capricemgr

iTrader: (1)

The suggestion about using the 5.3l block was 100% about saving weight by finding an aluminum one, which isn't necessarily the right thing to do for a build like this. Some weight may well be needed in the nose to keep the car stable at high speeds.

If you wanted to use a 5.3 block it is just swapping the rotating assembly between them, deck height is the same as is bore etc.

Like I said though you need to put more thought into this and some weight might be GOOD.

LS2-240z

Less weight is good. This will be for standing 1-mile in concrete, not 5-miles of Bonneville salt, so traction is not really an issue. At under 200mph, CG/stability is not a big issue on concrete either. I'm hoping to run up to 175mph as that is all my chassis will be certified for. In a couple months I hope to learn how fast 400hp will do against my current aero package (none). But I think I'm gonna need 400-500hp out of the 4.8. When you say rotating assembly, I need you to be more clear, are the connecting rods the same length on both a 4.8 and a 5.3? Are the main bearing journals the same between both displacement motors? I'm figuring I'm gonna want the flat top pistons out of the 4.8? I read the suggestion on getting ported Trick Flow 205s. Surprised I'm not getting any more replies of folks bragging about how much hp they have achieved, perhaps the 4.8 has been skipped over since the 5.3 and up are so plentiful (and there's no substitute for displacement)!

96capricemgr

iTrader: (1)

The 4.8 rods are longer but you are overthinking it.

You take the crank/rods/pistons from the iron 4.8l and drop them in the aluminum 5.3l block, done.

The reason people are able to use the flat top 4.8l pistons in 5.3l builds is because the pistons are the same compression height. If you use pistons with the same compression height and same rod length but then a shorter stroke the engine wouldn't make much compression, so the rods in the 4.8l are longer, half the stroke difference longer so the piston still roses to the same deck height with the shorter stroke.

MuhThugga

Most people use the 4.8 for turbo builds. I don't think too many people have dropped a 4.8 in something and did a NA build. Those that have are probably under the impression that they have a 5.3. lol

To my earlier suggestion, the crank, rods, and pistons from the 4.8 will transfer into a 5.3 block. If the aluminum 5.3 has flattop pistons, those can also be used with the 4.8 crank and rods.

scout2000

I seem to recall a 4.8 junkyard build on Spike TV last season. They had a few special pieces on it. Reved real good and seemed to dyno at ~500HP if I am recalling correctly.

alowerlevel

iTrader: (1)

http://www.powernation.tv/shows/engine-power#s2014

LS2-240z

Thanks, fellas. I watched the video. I have a starting plan, now thanks to you. I will update this thread as things progress. Now I have to get to work and try to set a new record with my 6.0. If that goes well, the following winter I will buy the L33 and 4.8 and get started.