8000 rpm or bust!

[dskopek]

If you can not find solids for your build one option is to use the hyd lifter but shim up the internal motion of the lifter to a max of about .050. This is not as good as a solid but it will be much better then a hyd at high engine speed (7500+) I have done this in both Fords and Chevys in classes that require hyd lifters and have had very good luck with it. You MUST have your push rod length right when you do this. I have not done this with a 60 degree v6 to find the preload that it likes but it will depend on the valve spring package you run. The Ford 302 that we run right now has 345 Lbs spring load at .565 lift and we set the preload at .010 cold. With this setup it will run 7500-7800 RPM all night and not miss a beat.
I would think that some one would have a solid that would work with the 60 degree but have not heard of anybody running any yet.

[Superdave]

Curtis ran a solid roller in the old TurboZ24, iirc he was revving it to around 8K with iron heads and lots of boost.



You can rev to 8K all day if the mechanical parts will take it but you need to figure out where you want your peak power and design everything off of that. Keep in mind most transmissions will crap themselves around 7K, some even lower than that.

[95SleeperAcheiva]

Your talking about spinning 8k, but you also stated peak power to be below that. Your shift point is not a matter of getting out max RPM.
Most chevy motors are HP based. Meaning they have more HP vs torque or are equal to (hp=tq). (I know I'm running a chevy motor myself right now.)
I ran an Olds 350. W-31. On a stock forged lower end, outside of balancing, polishing, etc.. I spooled 8600 for a gear change and could free rev to 10500 on a stand. Why not shift at 9500? Why bother I say. My torque curve fell off at 8650. I could feel her nose start to drop over 8600, which means I am just wasting acceleration by trying to put out more rpm.

I run a hydraulic valve train. In ANY high rpm application you MUST have an adjustable valve train. Actually, with the High rpm's your talking you need to take into account possible float, which means higher spring rates, which means your going to have valve train deflection, etc.....
Also take into account your air flow "speed" never changes, just the volume. Being boosted, will help a ton.
Where does this turbo fall into for it's efficiency? Will it be able to still deliver in the power band you've selected? Wanting power at 8k means your low end power will be crap. Granted crap can still be 300 hp but the motor won't start into her curve till 4k+. If she's an automatic, do you have a converter already to get you launched in your peak? and/or If she's a stick are your prepared for the suspension cost, wheels, tires, etc, to make sure she bites when you dump the clutch at 5k? My W-machine runs a 5k stall converter, 5:1 gear, and 32" slicks, she hits HARD. My achieva (3.4) runs a 4800 stall converter, 3.73:1, and 28.5" tire. Point being, launch RPM's come up in order for you to get into your power curve quicker otherwise your costing yourself time. Is this a track or street car? if street now your talking a whole set of practicality issues which can bring us back to the transmission again.

Cams, going to depend on your efficiency of the turbo and select to that. High RPM your going to want much duration, much overlap, prob a 108-110 centerline.

Over all, I don't mean to rain on the idea, hell go for it! Just be prepared for plenty of variables to make you stumble. Just because the motor runs on paper, maybe runs great on the running stand, once she has weight to pull and a transmission to go through.... all kinds of thing happen. Good luck. Seriously good luck, not a knock.

[ALLTRBO]

Thanks for the reply, I appreciate the help. I do understand the hurdles to overcome and the trade-offs.

For background again... (some is subject to change depending on the test results and 'feel' I get from my current TGP shortblock w/Gen III top end and Getrag 282... once I get it running right):

3000lbs wet if not a tad lighter
Primarily street w/track days and occasional 1/4 runs (so it can't be hard-tuned to one purpose)
5-speed (F23) with, and here's the big thing, a 4.41 final drive
Quarter Master 7.25" twin-disk
~26" street radials (ultimately going to go for 295/35/18's rear), drag radials for the strip (specs depend on final performance characteristics)
BW S258 turbo w/ Garrett T3 .82 a/r exhaust housing (turbo will support ~650hp, gimme a bit and I'll post up the compressor map), 25+psi to get where I want
8.5-9.0 CR
Ported heads/intake, don't know how ported at this time, ~65mm TB

Obviously the valvetrain specs were the reason I started this thread, but after doing a lot more research and with all of your help I'm getting a slightly sharper picture. I thought it was clear from above that the rockers would be adjustable no matter what I go with now, sorry if it was as clear as mud. I am planning on the best compromise between strength and weight, with strength taking precedence. I understand that I'm going to need some comparatively beefy hardware to durably and reliably handle the RPMs.

First and foremost, I want 8000rpm because screamers excite me to no end (that is, as long as the gearing is right), and this car is all about exciting me to no end. Going higher than that starts to quickly take a toll on the intended purpose of this car and its budget (which isn't too light, but isn't unlimited either).
I built an 11 second 2 liter DSM pulling to 7500 and I built a twin-turbo IROC-Z with a 5.7 TPI falling flat at 5000 so I have extensively driven both ends of the 'street car' spectrum, this one I'm going for somewhere in between. It's lighter than both and will have a bit more low end than the Talon but less peak torque to shred the tires like the Camaro, all the while revving higher and making a lot more power than both.

My desired power curve and max rpm depends on the gearing I will have, 'slightly' tapering it off by 8000 will give me more area under the curve for the average shift points, it's not an extremely closely geared tranny. I don't have plots of the gearing vs. rpm online but I've done all the calcs. That's as much as anyone has to go by until it's built.
You're right as far as I can tell, it won't start coming on hard until 4k or so, that's where the low final drive and reasonably small tires help. I don't care about highway cruising RPM or gas mileage, though I do plan on a few long trips. This isn't a daily driver, I have a new 6-speed 30mpg 320hp V6 Camaro for that.

HP vs. torque in a stock Chevy doesn't mean anything, I mod these things because the stock engines aren't good enough for me.

Can you list your specific valvetrain specs to turn 8600 with a hydraulic setup? It's not directly comparable to a 60*, but getting all possible info paints a clearer picture.

Thanks again for the input.

[ALLTRBO]

...gimme a bit and I'll post up the compressor map

[95SleeperAcheiva]

YOU sir, have been holding back! I'll see if I can dig up my cam specs and post.

...and this is why I stopped running Olds. Well, my cam is discontinued. I'll give you what i remember.
int. dur @ .050" 302 deg
exh dur @ .050" 318 deg
Lift int .615
exh .660
lope sep 106
isky cam, isky anti-pump up hydraulic lifters
on a 1.7:1 rocker, full roller from Harland Sharp.
Rocker stud girdle from mondello olds, and valve covers to clear them.

Obviously head work in order to run the adj. rockers, custom push-rods, hardened, guide plates came with the rockers.
Offenhauser intake, 800 spreadbore holley (worked)
much P&P, bigger valves in W-31 stock head so no need to revalve, black oxide guides and seats, titanium retainers, 10deg locks.
I remeber my valve springs were only a 2 spring set-up, sorry i can't remember the lbs or install height. It's been a long time.
I was 13.7:1 comp on sunoco blue 260 fuel.
Head work was enormous! Shaved down a bunch to raise compression, still was running the stock flat piston 10.5:1. Had the exhaust ports heavy P&P, center divider was cut out, welded in plate and knife edged, flow matched....it ran me over $5k in head work alone. That's why I LOVE the prices on WOT's P&P work!

Headers has 2" primaries to a 3.5"x31" collecters. Let me know if that helps. Pretty much all I can remember.

I used to get a bunch of stuff from Brown Racing. They use to supply all the Olds cam-am engine gear in the '60's. Haven't seen them in years and never on the net. If anyone finds them it would be great!