aan engine. more revs??

[nicksonmsport]

Im told std aan engine will do 7500 rpm. What is required to up the revs safely so I can make use of large turbo to best effect.

Many thanks
nick

[Rusty]

Valve springs, retainers, tappets to solid lifters, cams and flow work up top. Usual lighten, balance & even dry sump down below.

[nicksonmsport]

What sort of costs involved in that lot? And what cams do people use?

Any dry sump kits off the shelf? If so cost?

Cheers

[Rusty]

Head £1500+ Cat Cams + adjustable gears, £1000+, engine £5000+, dry sump £2500+... ish.

Schtick, DBillas, Cat Cams, Dahlback & various Swedish mentalists for cams.

[nicksonmsport]

Cheers. Does oil pump start to cavitate at higher rpm then? Warranting need for dry sump?

[caterpillar]

use dry sump = more hp (ca 15%) and you are shure the oilfilm will not fail... if so, you need a bicykle, limp mode home

[Error404]

Personally I wouldn't go above 7500 on the stock oil pump.
High revs are not really what these engines are about IMHO.

[nicksonmsport]

I agree I would prefer not to spend another 5k plus for an extra 500 or 1000 revs. Was just getting an idea if it was worthwhile if it meant a wider power band.

Engine needs rods installed anyway so wanted to plan engine build before it came apart. Will be doing head studs and rod bolts etc.

[Quattronaut]

I thought you wanted to build up the engine new?

When you already wanted to do that, it´s not that big thing I guess. Rods, pistons, crank can be lightened when they´re out. So the only thing is change the head to mechanical valvetrain. If you build it up complete, it´s no big deal buying solid lifters instead of hydros, and headwork is headwork.

The usable powerband for cars under 500-550hp is not really increased IMHO by giving more revs. Usable powerband is in most times around 3500 rpm difference between "kick" and "choke", and those turbos which are for good 500hp kick in between 3700 and 4200 rpm in a well done and good mapped motor. No sense in higher revs, when your turbo starts to choke from 7200 rpm. To really use the higher revs, you need a bigger turbo, that for example boosts at 4500, and then you got peak power at 7500 or still bit later. But that is far more than 500 hp, there we´re spaking about 600hp+.

Lehmann, Hohenester and others say, that 540hp is the limit of a 20vt with hydros.

[nicksonmsport]

Engine is already built. It was built by previous owner. I intend to strip it ans install rods and arp fixings then bolt I back together. Items have already been balanced. Just wondering if it were worth upgrading the valve train to allow the engine to rev higher, but tbh if 7500rpm and 500bhp are perfectly achievable without the extra costs involved in top end mods etc, then I will just stick with it as it stands.

[Thuppu]

Lehmann, Hohenester and others say, that 540hp is the limit of a 20vt with hydros.

How would the tappets know how much hp the engine have? I would say it's more like rpm related how much the hydro tappets can handle. 8000rpm have been proven to work fine with hydro tappets and stock oil pump. I would use stiffer valve springs though, especially if you use higher lift cams. But like told, there is no point in rising the rpm limit if the engine shokes badly at high rpm's

[Quattronaut]

IMHO stock hydros are usable to 7500 rpm, some aftermarket lighter ones till 7800 with better springs- but in this rpm range their use is risky, and they will be worn out fast. And we are not speaking about a car that is used on street and driven normally all the time, and that is in real high revs from time to time. We are talking about a track and race car, that will be driven in high rev ranges most of the time. I for myself do not think that hydros are usable that way real safe.

I meant the 540hp that way, that peak powers up to around 540 hp are reachable with stock valvetrain, hydraulical tappets, no need of solids. Only when you go higher, you will need mechanical valvetrain. And I am not only speaking about damage, but also about sense- turbos, that are able to do 600hp, are that big, that boost will be at 5000rpm- when the rev limitter cuts it off at 7200, you are running into rev limitter at full boost, that can cause several damage; and the usable power range is senseless, only 2000 rpm range.

[Albert]

I some aftermarket lighter ones till 7800 with better springs

What hydros would you recommend for race car that can handle 7500-7800 rpm abuse ?

[elaw]

Just FYI if you're thinking about switching to lighter hydro lifters, you might want to read this first: http://www.theprojectpad.com/viewtopic.php?f=32&t=1263

[Albert]

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