rabies

before you get heated. flame suits are free but are to your immediate left to the dressing room.

i am putting a 4.8 into a little truck. i would like rpms.
i am also not a guru on the gas V configuration engines.
what head parts should i use to have a safe rev happy 4.8?

1. forged rod/piston combo with ARP rod bolts
2. behive springs?
3. type cam?
4. what about any fancy trunion or rollers?

i also have a spare set of 853 heads. from 99 ls1. i could get them shaved to increase CR. but they are bare. so not sure what parts to buy to fill in the spaces. type of valve seals and what valves i could sue.

thanx.

Bob570

Might want to define rev happy. 7000 rpm isn't that hard, 8000 rpm is going to cost a fair bit more.

G Atsma

How are you going to use it?
As said, the difference between 7k and 8k RPM cost-wise is huge, and it mostly goes into the valvetrain. 6k can be done mostly stock.

Haggar

IMO, don't limit yourself to a 4.8, unless you want it. Revs/usable range are going to a function of your cam and intake. As noted above, valvetrain parts and rods/bolts will be what keeps it alive.

AwesomeAuto

I take it you're from the import community?
They almost always come here posting about an RPM goal.

blsnelling

iTrader: (4)

4.8 won't rev any more than a 5.3 or 6.0.

rabies

being the 4.8 is more square the theory was that is what to start with.
this will be a sideways truck if one must know. so having power up top and keeping it there is ideal.
i am not opposed to spending the $.

AwesomeAuto

The LS engine isn't RPM limited by stroke, its RPM limited by the valvetrain and oiling.
You can rev a stock gen 4 5.3 shortblock to 8600 RPM with the right valvetrain and oiling upgrades.
I have a gen 3 4.8 in my car that I rev to 7600 and am currently looking for an aluminum 5.3 so that I can actually rev it higher.

There are guys out there doing just fine drifting on N/A 4-cylinders. A mild LS will make more power/torque than that 4 cylinder at 2500 RPM.

Summitracing

Piston speed uses up air. The bottom end isn’t more taxed, but the valvetrain is. We have the top end covered to 7500 with fairly inexpensive parts. There are options though. What are you wishes?

rabies

awesome. i L33 motors go cheap around here. what parts do you recommend valve train wise? lighter rockers? arp bolts etc?

Summitracing

L33's are a good start. ARP bolts are a good idea and we recommend honing the big end of the rod afterwards to make them round again. The factory rockers with a trunnion kit are as light as it gets and our .625 lift targets fit the scroll diameter. HDR Thickwall 11/32 .120 wall Pushrods. The TFS-2500286P (Steel retainer) or TFS-2500287P (Ti) is a good option, but higher rate TFS-2500295 and TFS-2500300 would be better is 7500+ is the goal. As for lifters, the LS7's we use in our SUM-HTLSKIT-1 are good if you push preload toward the .070 number, but if you don't mind the extra work and set up time, Short Travel lifters are a plus. Attention to detail is a must. HDR Pushrods are available in .025 increments to help you remain in the window.

ddnspider

iTrader: (26)

This is the first time I've heard that on here. Isn't more RPM more piston speed more stress on the rod bolts?

Summitracing

Piston speed is tougher on rod bolts, but that can occur at higher or lower rpm depending on the stroke. We can add stroke to lower rpm and keep the valvetrain happier (as it's more likely to fail than a rod dollar for dollar). An example of this is a 5.3L turning 7k and a 4.8L turning 7750 have the same piston speed and have the same load on the rod, but the hydraulic valvetrain on a 4.8 is going to be less stable and would lose power for that reason. Both engines could make about the same peak hp at two different rpms (assuming good valvetrain), but the 4.8 would always be down on torque. Runner lengths will have an effect too since most factory style intakes are designed for lower rpm...once again helping out the 5.3L and hindering a 4.8L.

Torque is tied to displacement, but HP is independent of displacement. Of course people can spend money on valvetrain and turn 11K if they like. Jud Massengill's 1100+ HP 433 CID engine is turning 10,100 through the traps with the available flow from his C5R heads and the expensive PSI valvesprings that are replaced after X amount of runs.

ddnspider

iTrader: (26)

Thanks for clarifying.