epion2985

what would it take to get an LS1 to rev to 8k?

DamonB

An LS1 has no need to rev to 8k

projekt

how about 7?

i don't want to let my 7 8 and 9 get lonely with no tach needle to visit them

epion2985

I didnt ask if it needs to I asked what it would take to get it up there.

Why? first of all yes it makes its power in the low rpms but as it stands the power curve grows the hier the engine revs, yes it wont grow between 6 and 7k as much as it would between 2 and 3k but it wont go down so no harm no faul. Second if you turbo it with a nice beefy turbo the curve WILL change significantly just as in low rpms. And finaly there is nothing like nice gear duration on the track.

wingsfan

$$$ is what it will take. You will need to balance and blueprint everything. You'll need to upgrade your springs and likely the rockers. The cranks will probably need to be lightened (though it is hollow already) to do it safely.

As Damon stated though, it's unnecessary. You'd be better off grabbing anouther gear to stay in your powerband. You've got 6 gears, so use them.

Also, boosting a motor not intended for boost is a recipe for disaster, You can safely run about 6 psi on the stock pistons and CR before you need to add in some sort of water, methanol, or propane injection. I'd guess that even with FI you won't need to spin the motor to 8K. It'll do 7K comfortably with just some minor mods.

As for spinning the engine to 7K, mine will do it, although I have a rev limiter and fuel cut set to 6800 RPM. Upgraded springs and titaniumd retainers is pretty much all you need to touch 7K. Again though, peak power is closer to 5K rpm than 7K, so just grab another gear.

epion2985

I just want to say thanks for informative posts wingsfan, aprisiated.

ok first of i would like to know if how you say, only 6psi is ok for the v8 what about all them supercharged v8's out there????

second yes you do have more gears but its the gear duration that is so nice in the fd, I just wanted to retain it. Of coarce you can up or downshift, thats what manual trannys are made for, but the nice thing about ger duration is that say if you are 100ft short of a corner and you have to shift up because you are redlining and then a secnd later you have to shift down again..... if you had longer gear duration you would just stay in the same gear and just let of the throttle when you got to the turn and so on. You see the benifit of long gears duration like FD has right?

cdk 4219

The 13b and the LS1 essentially have about the same useable power band. The LS1 starts at 1800 and ends at 6250 while the modified 13b starts around 3500 and ends around 8000 to 8500. The LS1 has a very flat and useable power curve from very low rpm , while the same cannot be said about the 13b. 6 PSI is a very safe forced limit for the LS1 due to high static compression ratio.

wingsfan

Poke around on the z06 site (http://www.z06vette.com )and see some of the carnage from people running too much boost on their stock motors. It's not pretty. The LSx motor came from the factory with a compression ratio around 10.5-11.0:1 That doesn't lend itself to boosting the motor. The LSx CR and cooling setup doesn't lend itself to safely running large amounts of boost. Smart people who want their engines to last swap out the pistons for a set with a lower CR. Of course, you'd be foolish to crack open your block and just put new pistons in. you have to do new rings too, and most people building a motor for boost will go with forged con rods too. All of that starts to look like serious money after a bit.

Add to that your wanting to spin the engine 2K rpm higher than the factory redline, and you are talking even more $$$ for the upgraded parts and the subsequent porting to allow your engine to breathe in that RPM range. What you're suggesting isn't impossible, just not cost effective. Hell, winston cup motors are routinely run in the 9K RPM range, and they're certainly lower tech than an LS1. Of course, they also rebuild every race, but don;t let the details get in the way.

That's all fine and good, but your scenario exists even with a 20K RPM redline. You'll always be at an advantage if you don't have to shift. Fact of the matter is that sometimes you have to shift. No way around that. And what you're proposing, turning a motor 2K RPM past it's intended redline and running it on high levels of boost, is a really expensive proposition. There are better platforms that are already designed for that (RB26dett comes to mind)

epion2985

I see your point. Thanks.

RB26dett? the skyline engine? I thought about it, actually it hat was my original intention. But it does sit higher than the v8 and I didnt want to loose the handling capabilities of the car. And by handling mainly I mean skid pad I guess, how well it sticks to the ground, raising the center of gravity kinda hurts you there you know...

whats your opinion on the v8 swap vs turboed RB26dett?

Swolbynos

LS1 CR is 10.1:1

projekt

rb26 is super long (not for a 6 tho). the VQ is about as long as the rotary so....

SpeedyWankel

Some numbers:

LS1 compression ratio: 10.1:1
LS1 factory redline: 6200
LS1 combustion chamber volume: ~66.7 cc
LS6 compression ratio: 10.5:1
LS6 factory redline: 6500
LS6 combustion chamber volume: ~64.4 cc

Want lower compression so you can run some boost with an LS1? Trade your heads in for some LQ9 6.0L heads. I'd be willing to bet a shop would give you an even trade. Even if you had to buy some cores, they're around 300 bucks for the pair. LQ9 heads have ~71.5 cc combustion chambers, which, when used with a stock 5.7L bottom end and stock GM head gasket, will bring your CR to around 9.3:1. Beef up the head gasket, and you could be looking at 9-9.1:1 ratio. Sounds boostworthy to me! The LQ9 heads also have exhaust ports shaped like the LS6 heads, which is beneficial.

As far as redline is concerned, an LS6 cam with LS6 springs and retainers should get you near the 7k mark, although you'll want to shift before that to stay in optimal power. 5000 RPM in 3rd pulls harder than 7000 RPM in 2nd, etc...

SpeedyWankel

Some numbers:

LS1 compression ratio: 10.1:1
LS1 factory redline: 6200
LS1 combustion chamber volume: ~66.7 cc
LS6 compression ratio: 10.5:1
LS6 factory redline: 6500
LS6 combustion chamber volume: ~64.4 cc

Want lower compression so you can run some boost with an LS1? Trade your heads in for some LQ9 6.0L heads. I'd be willing to bet a shop would give you an even trade. Even if you had to buy some cores, they're around 300 bucks for the pair. LQ9 heads have ~71.5 cc combustion chambers, which, when used with a stock 5.7L bottom end and stock GM head gasket, will bring your CR to around 9.3:1. Beef up the head gasket, and you could be looking at 9-9.1:1 ratio. Sounds boostworthy to me! The LQ9 heads also have exhaust ports shaped like the LS6 heads, which is beneficial.

As far as redline is concerned, an LS6 cam with LS6 springs and retainers should get you near the 7k mark, although you'll want to shift before that to stay in optimal power. 5000 RPM in 3rd pulls harder than 7000 RPM in 2nd, etc...

383Mazda

"Why? first of all yes it makes its power in the low rpms but as it stands the power curve grows the hier the engine revs, yes it wont grow between 6 and 7k as much as it would between 2 and 3k but it wont go down so no harm no faul."

Wrong, HP and torque will eventually start to drop off the higher the revs. Too many people don't understand that... if you take two new SS camaro's and race them side by side, the one who shifts at 6 grand is going to beat the one who shifts at 8. While the second guy is waisting time and power reving up to 8k, the first guy is already in second gear, picking up more speed and using more power.
To get a small block to rev high you'll need a cam / head combo that are ment to "live" up there, along with very strong parts. Although a small block wound up to 8 / 9 granb does sound very neat, it's expencive, and it's a lot more wear and tear on a motor. Also... on the street you want torque... you don't want to have to down shift 3 gears, wait and wait for the rpm's to clime to 8k to start going fast, you want to hit the gas and snap your head back in any gear
And to put SpeedWankel's info into laman's terms, high CR's don't like boost, or even nitrous very much, you'll detonate easier and cause more damage to the engine that what it's worth... 6psi isn't that much.
7.5 ~ 9.0 are pretty much where you want to be inbetween for a "boosted" street motor. I have a GN with around 9:1 I think. I run 18~19psi on the street which is pusing it a bit. Top fuel dragsters run around 5:1 I heard.

But anyways, the guys are right, it would take $$$ to get you to 8000 rpm's.... but you don't need to. Pick up the latest HOTROD mag and check out how fast guy's with LSx motors are running with just a few mods, i.e. cam, heads and so on...
Just start saying this every morning when you get up, "high rpm's are my street car's enemy, low end torque is my friend"
brandon

WaachBack

iTrader: (21)

Thats some good info.

projekt

that's why 4 cams are better than one

383Mazda

what you really mean is 4 vaulves per cylinder are better than 2...
4 cams are a lot more money than 1, along with twice the valuves, and twice the springs, and twice the parts to worry about brakeing.
Besides, 500hp out of an "old fashion" LS1 pushrod motor isn't too hard.

But I admit, it would be cool to see GM make a DOHC head for small blocks / big blocks!

cdk 4219

A dual OHC LS1 would put you out of the running for install in an FD, it would be too wide and tall. The new version will have 3 valves per and still a pushrod engine.

383Mazda

The new LS2 engines? I thought I read something about a 3 vaule head on some new GM motor. But are they all going to have that displacment on demand feature? It's a neat idea, but can you imagine the cost when that thing starts going bad!?! I can see the reason for putting them in big trucks or SUV's, but how many people but fast sports cars and then worry about how many MPG they can squeez out of their motor?
25+ MPG out of an LS1 making 400+ hp is enough for me to be very happy!

rynberg

The LS2 engine in the new Vette will NOT use the cylinder-on-demand "feature" as the vibration from it resonated with the Vette chassis. Oops.

3isacharm

you could always just change your gearing a bit.

projekt

i mean the 4 cams too. having 1 cam for both exhaust and intake is bitch to tune.