7000+ RPM requirements

[Blue89rs]

Long story short.....I spun the crank in my 2.8L 89 Camaro. After seriously contemplating putting in a 350, I've decided to stay V6. So now I'm back on track on building up my little NA 2.8L. (no turbo/nos.....yet)

Goal -> Since GM says everything stock will support 7000RPM, thats what I'm going for. I want to rev it that high AT LEAST!

What I have -> a nice 2.8L block, cleaned, and tested straight. FWD 3.1L alum heads/intake, 2.8L iron heads, 3.1L rotating assy.

I ordered up the GM Power book from my local chevy dealer, so I have tons of idea's and methods, but I need help solidifying on a final goal. 7000 shouldn't be that hard to reach, granted everything is balanced, all oil lines are ported, de-burred, and enlarged where needed. But what should I do with the top end? Should I try to put the aluminum heads on, or should I stay with the irons? I know that the 3.1 heads flow better, but the intakes for the heads are far worse. Headers are a must, and I intend on ordering up the CompuCam. But even then, that cam is sudo-rated between 1500-4500. Will I kill myself if I try to push it that hard? or is it really an approximation?

So my main concern is this:

If the rotating assembly (cam, crank, rods, pistons) will handle the REV's of 7000-10000 RPM's, what would be the best head/intake setup to support onwards of 500cfm of air?

[Doward]

RE: 7000+ RPM requirements

Aluminum heads + the FWD pistons = YES.

[Guest]

RE: 7000+ RPM requirements

Look at the genIII top end, '96+ 3400 and '00+ 3100.

[614streets]

RE: 7000+ RPM requirements

If you want to spin it 7000 plus you need to be able to spin it 7000. What I mean is you need lightweight pistons and cam that operates in that range , use the aluminum heads with the beehive springs with a solid cam. Its not about spinning to 7000+ its about making peak power 7000+ and doing it reliably. Anything less isnt really a respectable target.

[smilinguy99]

About the top end, the valve springs on an aluminum head motor are the limiting factor. The most seat/open pressure springs I found that will work at a reasonable price are from Crower. 1.460" in diameter.

The best springs I've found that will work are from Endura Tech:
P/N,ENV757752
OD,1.460"
ID,0.770"
SEAT,190#@1.960
OPEN,520#@1.210
LIFT,0.750"
BIND,1.163"
I/O,STEP,0.069"
RATE,440#/in.

Only problem with these is that they are $640/set of 16. $40 each.

Still with the way the intake and exhaust lean toward one another the lift limit is somewhere around .550".

The steel heads can support a lot more lift and much heavier valve springs. Curtis runs .615" of lift.

The key to the upper end and RPM is spring pressure. Until someone comes up with a beehive spring with gobs of pressure (not likely) and someone makes taller pedestals and pedestal rockers (also not likely) all to employ longer valves that will support higher lifts, then making power beyond 7000, 8000 or 8500 is going to be a pipe dream for the aluminum head motor.

Still, it could happen. I understand some Winston C...er Nextel Cup motors use beehives, and it is conceivable that you could use titanium valves and retainers to keep the weight down in order to give the springs less mass to control.

What are you going to do with the car? What is the car? How much does it weigh?

sg99

[donk_316]

There are Titanium Beehive retainers available through crane?comp?

Or was it just the locks?! Dammit now i have to look again

[gpse3400]

Mine uses stock replacement parts for the most part and runs up that high to 7000. What you'll want is an agressive cam. Lift around .5. and you might want to use th eiron head pistons to give you that compression edge. But the real deal is that you need to open it up. Bigger TB and a bigger downpipe, and or headers will make the motor wind up. For future referance, don't expect to make decent HP with a 52mm tb and a 2in downpipe. If you have any questions I'd be happy to help. By the way it idles fine with plenty of vaccum.

[geoffinbc]

You are best off with the 2.8L crank. So good start. I algree with going to aluminum heads. Keep hte iron head pistons though because you need compression in the 11's or 12's. Using LS6 springs and the light weight comp or crane titanium retianers and locks is a good idea aswell. I dont think the valves will float with that combo.

Next you need a pretty agressive solid lifter cam. All the major cam makers offer them. So pick your poison. Lift isn't everything duration and overlap will have the most affect on where the cam makes power.

Here is an example of what you might need to start your adventure to 7000 RPM

http://www.cranecams.com/?show=browseParts&lvl=2&prt=5&Vehicle_Type=Auto&Cylinders=6&Engine_Make=CHEVROLET&Year=1993&Engine_Size=2.8-3.1%20L&partNumber=251241&partType=camshaft

[RacerX11]

The key to the upper end and RPM is spring pressure.

For conventional springs, this is true. The advantage of the beehive springs is their shape, which reduces spring harmonics, and allows more rpm before valve float. For a given rpm, the beehive needs less spring presure than a convential-wound spring. The LS2/6 springs are designed to allow 6500+rpm from a V8 with heavier valvetrain components, and cam lift of 0.550", so they should provide at least that much on the smaller V6. The aftermarket beehives are even stiffer, and should easily support 7000+.

Runner higher spring pressure just for the sake of spring pressure will wear out valvetrain components faster, and create more parasitic losses in the valvetrain. Running almost 200lbs seat pressure is not needed.

Marty

[geoffinbc]

Very true
Overkill is bad in the spring world. Use only the pressure you need. But get the most durable material avalible. Longevity will be key when running the engine to 7000.

[TurboZ24]

I used the Crower 1.46" springs part # 68380-2. The Normal 3.1 iron head install height I believe is 1.7", but I have spring cups and .05" keepers, so I retained the 1.8" install height on those springs.

So, seat pressure is 197 lbs and open is around 450 lbs or so.

This was the suggested spring, with the retainers/keepers/lifters/cam profiles I have.

I really haven't had any wear issues, but I do have bronze valve guides on the exhaust and intake. I did have some wear issues when I didn't have the guides.

[gpse3400]

The LS Springs seem to do the right thing for the V6 as they work well in my app. They are the right pressure for most cam profiles and they fit pretty good. Still retain that beehive thing as well. Oh and they are dirt cheap. Although the cam increases the range of operation.... like I said you won't pull any really good times(esspicially if you are a w-car) unless you at least open up the immiediate intake and exhaust(bigger TB, bigger downpipe or headers). The going trend here is that one can make alot of torque but for some reason fall short of HP. Oh and with alittle bit of tuning you can damn near negate the GEN 3 fall off at 3000-4000 and also boost bottom end.

[Blue89rs]

Wow. You guys rock! This engine is for my 89 camaro, which weights 3240lbs (I weighted it) with a 700r4 tranny, 4-12" subs, and everything else stock (minus suspension mods). I have a T5 that is going in, so minus 100 lbs. So this is where I am so far.

Will a Gen 3 intake fit "okay" in a RWD application? Do all the FWD 60v6's use the same FWD aluminum heads with different intakes? I was going to mod the 3.1 cavalier intake that I grabbed so that I could put those heads on, maybe do a dual intake setup like I have seen on a fiero. If the heads fit, and the intake doesn't, I have no problem fab'ing up my own intake. My motor does run a distributor, so most stock FWD intakes won't work as far as I know.

I have heard of milling down a 2.8 piston .100" and putting it on a 3.1 crank and rod for compression upwards of 10.5. Will this high compression help the motor perform better at higher RPM's, or will it just help all together? I'd like to avoid high compressions, just for the sake of reliability and gas cost *sheesh*. I've also looked at getting a new crank. They have some at Schucks/Checker up here in Washington that claim to be balanced better. Betterthanyou, did you mean good start on the 3.1 crank?

You guys have really helped me out. Keep up the good ideas and suggestions!

[geoffinbc]

No I meant good start with the 2.8L crank. Short stroke means the pistons dont have to move up and down as fast to produce a given RPM when compared to a crank with a long stroke. I didn't thinky ou were using a 3.1L crank, sorry.

You must get the compression up. If not a solid lifter cam that will give you the ability to rev that high will be useless.

Keep the RWD pistons and use the FWD heads. This will get you into your needed compression range.

Dont even bother with the GenII heads. If you are investing in this motor get GenIII stuff. It will help you alot with your goal.

[Kreb]

I'm not as knowledgeable as many of the folks on this board, but can say that I have a friend who put an ARI stage 3 cam in his old - very worn 3.4 iron head and runs it up to 6500 frequently - in autocross he'll peg it against the rev-limiter when there isn't enough time to upshift. Given that, it's hard for me to imagine that it'll take a lot more to spin it to 7k. I haven't had mine up that high yet, but it's very happy at 6K. With my stiffer springs I fullyi ntend to go that high once it's broken in.

My ride: http://usera.imagecave.com/Kreb/