99blancoSS

iTrader: (115)

Mods I know you'll move this, I just needs some answers.
I want a solid roller 402-416 that spins at 8000-8500 rpms all day long. If I decide to drive it at 7500 rpms for 8 hrs I want an engine built to take it over and over and over.
Is this realistic? IS there a point at which rpms becomes far to much money. What is that point? Most of the engines built on here are drag motors, explosive power for short periods of time. I like listening to the engine at 7000 rpms and am having trouble hitting the limiter so I want more rpms. Tony Mamo has a 383 solid roiller I think 7500 rpms is the limit. IS that the practical limit unless you get into titanium?

Any sponsor see's this please pm me if you want. I want some education on this. I've pm'ed 3 sponsors about it and only one was willing to talk to me about it so far. Why wont anyone build me a solid roller? THis is a weekend warrior car. I dont mind adj lash.
IF its a retarded request then explian why. I already know a hydro setup can be very stable at 7000 rpms. I have one.

ALLBOTTLE

iTrader: (13)

High RPM motors ave very expensive to build, the quality of components is critical.

It's one thing to be at 8krpm for 2-3 seconds but sustained periods of time not only take a toll on the short block but the oil pump as well. The direct drive oil pump is not suited for sustained high rpm use, a drysump oiling setup would be critical

For that sort of application you are going to wan to the lightest rotating assembly you can find including lightened crank, billet or titanium rods and super light pistons. Also mean piston speed is going to have to be close watched. a 4" stroke is going to be killer. You can build a short stroke large bore motor to help with piston stability like CUP and C6r(4.180 bore/3.875 stroke) motors use.

Lifters are just 1 part of the equation, a hydraulic lifter can only take so much spring pressure before it will collapse, so that will tend to limit the how aggressive a a lobe you can use. with a solid lifter you can use a more aggressive faster ramping lobe because you can get a spring with 250lb seat pressure and 800lb open.

Just like you said above, Tony has a 7500rpm LIMIT, that by no means does it mean that it operates at 7500rpm for extended periods of time. Even GM has chosen to build the C5R/C6R to operate below a certain RPM range ( it increases the probability of the car successfully completing the range and allows for more readily available power with less shifting. (590hp @ 5400 rpm/640tq @ 4400 rpm)

99blancoSS

iTrader: (115)

So basicaly my rpm "want" is really not in the budget unless I've got Katech money to drop. Is there an advantage then to a soild roller over a hyrdo knowing that it will be driven at sustained rpms?

SO the best way to attack it is big bore less than a 4" stroke. That leaves either a sleeved motor or iron block which I wanted to avoid but sleeving adds cost.
Thank you for the help. It gives me somewhere to start.

If I used katechs 3.819 crank with a 4.125 bore what is that? They have it listed as a 396 and 408 crank. It looks like the 4.125 bore would be a 408?
I guess that wouldnt be optimal for what I want so what about the 396? How do I get that?

mrdragster1970

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My only thought is who cares what rpm it spins, & how long?? Build the engine to the power you want, with the rpm as low as possible. My big blocks are made to spin 9000-9200, but that's only for 6 seconds, and they cost $30,000 plus.

The things mentioned are great points, light valve train, top of the line everything, big bore, small stroke ect. Just remember, RPM eats springs. Adjusting the lash is the least of your worries with an engine like you want. Good luck.

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99blancoSS

iTrader: (115)

All good info, I need to be educated about what I'm looking at. I like rpms is all i can say. Its music to my ears when I'm in the right driving mood. Corners, straight aways, corners. I keep the rpm high in the corners. Explosive power off the light is nice but I find myself doing more on a roll than from a stop. But my car is 4050 lbs from a stop with a heavy *** drivetrain. I really like my current power band 4000-7000 rpms but am looking for what everyone wants .. ridiculous rwhp. But I dont like losing traction off the light which is why I like the current combo but want more power up top and a little more down low. Not a lot more down low, just a little more to help get it moving. Isnt any good if all I do is sit there and spin.
I dont get time to go to the track. I get basicaly one day or two a week to go out and thrash on it. Rest of the time its getting zaino'ed. Weekend warrior. Was a daily driver but has evloved over the past 2 years.

1997bird

iTrader: (2)

One other thing to think about is what aftermarket injection system do you want to go with if you spin your motor 8k. The stock pcm on a F-body will only let you rev 7000-7200 and then it is out of a fuel map from what I have been told. The Y-body on the other hand has a 8k map, again what I have been told.

bore x bore x stroke x # of cylinders x .7854 = cubic inch

99blancoSS

iTrader: (115)

ok 4.125x4.125x3.819x8x.7854= 408.299

Most 408's are a 4" stroke and smaller bore. Is there a reason for not going with a big bore 408? What am I missing ? Is it because its cheaper to go with an iron 408?

So if went with a 4.125 bore and the 3.819 crank what would be the results? Smart or not?

ALLBOTTLE

iTrader: (13)

a Conventional 408 is a 4.030 bore 4.00 stoke.

Why are you so set on a 408? if you are really trying to build a motor that will live at 8500 rpm you should be looking at using something like a 4.180-4.200 bore and a 3.25 stroke from a 4.8 truck. This will let you use a much longer rods to alleviate the side loading and rod angle problems and keep mean piston speed down.

With a 4.180 bore you would have a 356ci a 4.200 bore would give you a 360ci

Be ready to to spend 25-30k on this motor if you want it to run at 8500 rpm for any period of time and make decent power. Your Intake and head combination is going to dictate how much power you make.

99blancoSS

iTrader: (115)

I wasnt set on the 408 just throwing it out there. It seems whaty I want is not really practical. No problem I needed to know. Thank you all for the help.

gun5l1ng3r

How does your car weigh 4050 Lbs? Thats massive, do you have lead drivetrain parts?

Also, I would take a look at Katechs 5.7L Sneak Attck Motor. It only has a 8000 RPM limit (not sustained) but has LS7 heads with a hydraulic cam. It has a bigger bore with a smaller stroke.

LSGunZ28

iTrader: (8)

not trying to be a smart ***, but it = displacement, not cubic inch or liter, those are units in which you use the measurements.

DONAIMIAN

iTrader: (18)

Keep in mind that those motors breathe through two 3X.Xmm restrictors.

DONAIMIAN

iTrader: (18)

Whoever told you that hasn't tried because its been done many, many times.

And to the original poster, plan on going dry sump. Aviaid makes a nice system that still allows use of the a/c. The motor that I originally wanted to build was a 398 all bore (stock crank) with a solid LS7 top end. If you could afford it, I would go that route.

1997bird

iTrader: (2)

Well so that I know, is there a fuel table past 7200 rpm in the stock ECU or just a spark table past that point. If the fuel table is not there past that point how do you "tune" properly past there?

1997bird

iTrader: (2)

Yeah well, I put it into laymen terms of understanding.

C6Dude

Ultra light Components are key to High RPM reliability.
Especially in the valve trane dept. With high RMP driving , Valve Spring life is drastically shortened and springs must be changed regularly to prevent a cotastrophy.
Rotating assembly must be balanced perfectly and crucial to engine life.

I spin my LS402 to 7450RMP with AFR 225's and Comp Cams 921 Springs.
Cam range is 2700 to 7300.

Heres an HP tuners screen shot of the RPMs



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GMC_DUDE

Do you mean the main VE table? On my truck it goes to 8000 rpm, as does the spark table. All other fuel tables are based on airflow rather than RPM.

1BadAction

iTrader: (10)

Or just buy a badass high perf merc 2 stroke, run it on a dyno all day, and be done with it.
http://www.youtube.com/watch?v=mM9l774zLo4

blackz93

iTrader: (2)

1997bird must be thinking about an LT1.

gun5l1ng3r

Is that a 6 cylinder 2-stroke?!

It rumbles like a V8 at idle, but screams like a F1 motor!!!