ali123

Thanks guys I've contacted everybody mentioned in this thread. If there are other people you guys recommend who are good with high rpm valve trains please let me know.

Thank you

HISS

iTrader: (52)

I think it's doable, but reliability would be an issue. The key here would be weight, or lack there of.

dckmn52

I don't see why everyone thinks OPs goals are so unattainable. It's just expensive.

Camshaft selection before having a combo figured out is going to be a massive problem. That cam will likely fall off well before where he wants the power.

Keep the valves light and the rest solid. Ti valves. Jesel shaft rocker arms, tool steel hardened pushrods with a large wall thickness, solid lifters, large dual springs, belt drive to dampen harmonics.

Then the intake system. Sheetmetal, ITB, or even a tunnel ram setup with twin 4150TBs would be cool.


It'll make power, it just requires some thought, and some money

1CAMWNDR

iTrader: (21)

Then why would you need 8,500 rpm capability? Knock that back to a 7K rpm max and spec heads and cam that make excellent power for your small cubes between 4K and 7K.

It will make for a much better STREET driven car.

Fraser588

OP: Besides what type of cylinder heads you plan to use.

1. What type of engine computer do you plan to use? Crank Trigger?

2. Wet sump or Dry Sump?

I had a customer build I'll post later on that peaked 803hp@7200 rpm and went to 8000rpm. Solid roller/wet sump.

Do your pistons have gas ports? What is the rod journal size on the crank?

KiwiKid

Hi Fraser,

If that engine is normally aspirated I will be most interested to read that post, as you already might know I am building a normally aspirated short stroke 3.625 large" bore 4.185" engine aiming for 800BHP @ 8000RPM. and whilst I am probably a month away from that engine being bench dyno'd, its taken me 8 months of research and time to gather together what I believe is necessary to make that sort of horsepower reliably for endurance road racing.

One thing that I can say for sure is that it cost a lot of money to get an engine to hang together at the sort of performance numbers we want to achieve if you are going down the normally aspirated route.

However if Ali, wants to truly hear an Ls engine scream he doesn't have a lot of choice but to go down the normally aspirated, lightweight component, high vacuum dry sump etc route as I have done LIMO, and that just cost's a lot of money in any bodies language.

Cheers,

Mark.

imma_stocker

iTrader: (19)

Dry sump oil system?

How many rpm can the factory style Melling pump handle before it cavitates?

KiwiKid

Hi Imma,

With respect I think you might be missing the point, the point in this instance, being that in order for an engine to be able to rev freely to 8,000 RPM and more, one needs to cut down on parasitic loss's, and removing oil from the crankcase under high vacuum [by at least a 3 vacuum stage dry sump pump] is a proven means of gaining both horsepower and rpm as it allows the rotating assembly to spin with as little drag as possible.

Cheers,

Mark.

HISS

iTrader: (52)

I like the idea of a short stroke large bore, should make for a rowdy little motor. Similar to what used to be in vogue with the 377 sbc.

imma_stocker

iTrader: (19)

Right, I agree. My angle is this, the same high vac crankcase can also be created by other means. Because a dry sump system costs a lot $$$ for those who need to convert from wet sump, I question if that kind of money could be spent elsewhere while keeping a factory style oil pump/pickup/pan.

Heard the crank to oil pump rpm ratio is 1:2 so 8,000rpm crank = 16,000rpm pump.... not exactly what GM engineers had in mind I'm sure lol Could a large enough accusump system solve the caviation problem? More importantly, when is cavitation a real problem?

For those who don't know, HIGH VAC conditions in the crankcase yield results. Higher the better sort of deal to the point of race motors needing to turn the main seals backwards to keep them in place, otherwise it is possible to suck it back into the motor. The key is you must create enough vac to start seeing benefits, then the efficiency spikes until you find the plateau.

Thanks!

Fraser588

Around 7500 rpm in drag racing appears to be a point where I've heard people spin rod bearings etc. with factory pan/oil pump. You can gain some control by using an external oil pump. Also if you're using a belt drive.

Typically the factory ignition doesn't hold up past 7500 I recall, that point typically use a distributor/crank trigger BS3 and again... belt drive.

So yes above 7500rpm it starts to get expensive. Unless you go Distributor/Carb route. I'm not saying you couldn't go to 8000 rpm but the it shouldn't be spending much time there with the factory PCM/24x. E38 PCM/58x reluctor could add some high rpm reliability.

Belt drive you're left with only external oil pump options, dry sump can use a scavenge stage to pull crankcase vacuum.

So Ali123.... Your engine block is machined already for a belt drive? If it had any kind of shortblock design for "up to 9000rpm", it should use a belt drive.

Fraser588

Mark, the engine was/is naturally aspirated, basic specs.
434ci, 14:1 compression
4.155" bore
4.000" stroke
Mast 305cc heads/Ti valves/Mast CNC intake
273/289 .803/.824 110*

Here's a link to the post on this engine:
http://www.ls1.com.au/forum/showthre...28#post2066228

I'd say the remarkable part is, 800hp was made with off the shelf parts.

I'm not here to sell anything (unless you want a 4,210ci CAT 3516 lets talk
This is just an example of what I know regarding high rpm LS build. Brian Tooley would be
best one to talk to for spec'ing this out.

Fraser

lil john

8500 rpm with a LS3 is very simple....
1st) Good set of ported Ls3 heads
2nd) Heads Machined for shaft mounted rockers....
3rd) Ls7 Titanium valves turned down or hollows your choice.

The short block NEEDS to BLUEPRINTED.

Call in on a cam.....Depending on how big but around 279 to upper 260's all depending on crank size.
Cheap Super Vic or Holley High rise intake.
You could run around 12.2 Compression and still run pump gas.

The only thing that is hard is keeping down EXPENSES......


This could all be done with a 408-454 and get 800 fwhp or a stock LS3 (that got 8300 rpm and 800fwhp) as I've posted before.
Cam duration and good valve train will get you there easy..
What will cost the most is the SHAFT MOUNTED ROCKER ARMS...GOOD springs next up to bat ...Light weight valves ........


Main thing I hate to say, is buy the best pair of lifters (they will set you back $1100 E-z roll bearing less lifters).. a lifter will go before a ARP stud. I purchased these and said no on shaft mounted rocker arms and used Comp adj stud mounted rockers..... Mine are in the shop getting worked over ..larger studs, springs....etc. Need to call Joe at Jomar to see if he made the LS3 stud girdle that I asked about. With this same cheap set up...It's not the best Vs Shaft mounted ...but known to hold up to 8500 rpm at which studs become a factor. Stud girdle helps tie the studs down like a shaft mounted rocker arm sys. for cheap.

lil john

also don't go over 800 lift, springs will get hard to find and very costly...btw

smaller spring pocket.





Ok so what type of rear end gear would you run with this with either: auto with stall or manual trans?

KiwiKid

Wow 14:1 Compression, you must be using some really good fuel to run that high in the comp. I have been that high in the comp years ago with our 310ci SB2 when we ran SCCA TransAm car's and fuel octane was free, we used to use VP fuel, though I cant remember the specification I just remember it was expensive!

Cheers,

Mark.

Fraser588

Its not that bad because of the cam size and overlap it blows off alot of compression out the exhaust. You could potentially run a setup like that on E85. Don't suppose you have E85 in NZ? I could care less for E85 and would prefer 110 octane but while its $2.50/gallon at the local fuel station for E85 i'll take advantage of it.

KiwiKid

Hi Fraser,

No we don't have E85 in New Zealand the maximum Ethanol content you can buy in this country from the pump is 10% Ethanol.

As I said In TransAm we used to use VP's 110 but strictly for racing purposes, as it was way to expensive for the road.

Cheers,

Mark.

Fraser588

IDK what Lil John was banned for but this list is very over simplified. 2nd you don't need to machine LS3 heads for shaft rockers (?). 3rd you don't want to use hollow valves with solid roller, spring pressure will break the valve in half. Its an unwritten law when I was at AES over 7500rpm we would recommend Titanium I&E valves.

Blueprint shortblock? You could blueprint any engine, doesn't mean it has to be of any higher specification.

Overall poor advice. Doesn't address any of the additional hardware needed for 8500+ rpm, oil system, PCM etc.

If I was building an engine for 8500rpm I would've started with a 4.125"+ bore size, able to use better flowing cylinder head 400+cfm, something like Mast Inline head. Of course you can rig it up where an LS7 style head is used on a small bore, compromise.