Research for new RV8 engine build - std TVR or oversquare?

[dnb]

I'm about to put a new cam in my Griff. The spec for all this is pretty well decided but it got me thinking about what would be a good bottom end spec for the next engine in anticipation for when I "need" it...

Here's the rules:
It'll start out NA, but I would like to allow for supercharging at some point in the future
Capacity should be around 5 litres. (5.1 is too big for my insurance company unfortunately)
Heads will be modified versions of the TVR heads I have already.
Use will be daily driver, "fast road" use and the occasional track day.
Having the car able to rev a bit more easily would be nice. As would having an approx 8k redline.

So, do I go for a crossbolted block with 96mm top hat liners and a standard (at least in dimensions!) 86mm Range Rover crank to give a 49xx cc short(er) stroke engine, or stick with the TVR crank (90mm) and the TVR std 94mm block?

Or is it not worth worrying about the geometry too much since the valve gear is the limiting factor here?

Any insight welcome

[mongoose]

I must admit,the larger bore/stroke ratio appeals to me.I had a chat with Rob(v8 racing) recently about a 5.4 conversion,but i cant get sticking to 5 litre out of my head.I like the thought of a high revving/power higher up the rev range type motor .I'd still like Rob to do the conversion,as it's all about building in more reliability for me.
96mm top hat liners,roller rockers,proper crank etc

[Boosted LS1]

If your block and crank are good I'd stick with them for the time being. Choose a modest compression which you could lower if using buick 300 heads assuming you can find some that aren't shagged. They would have to be overhauled anyway as they're pretty old. Or you could just build aiming for 9:1 or a bit less and run modest boost (5-7 psi) with some water injection as and when you need it. Invest money in the pistons rings and stuff in the block.

Boosted.

[dnb]

The point is to keep the car on the road as-is for the moment while I build the new engine up. I then have the car off the road for the minimum time. (In theory at least!)

[v8 racing]

The only way of building a motor to produce good power now and swap to a blower in the future is to have big cc's in the piston and then skim the nads of the heads, when you put the blowers on you can then lower the cr by fitting large heads, personal i would stick with what you have untill you decide what you are going to do? building an engine for a blower is totaly differnt to building one n/a, the cam etc... plays a massive part as do the heads, the capacity of the engine also plays a big part, n/a make it as big as you can, turbo just run more boost fo the same effect?!

[dnb]

The supercharger is not a definite - It requires SWMBO approval, which is not likely to be given. (She said "NO" in a very loud voice ) So it should be removed from the future spec.

I'd expect to be changing a lot of the engine (pistons, cam, maybe rods etc) if the supercharger appears anyway as I know there is no way to do both NA and forced the same way. (Remember my car background is Impreza WRX tuning )

Back to the question of how to make the engine rev more than the "long" stroke TVR unit...

[v8 racing]

forget about the myths of long stroke motors not revving its a load of crap!! my 5.5's which run a 94mm stroke are happy to 7000 rpm, i also know of chevy motors that run over 100 mm strokes that rev to 8000+ rpm, its all to do with the internal mass of the engine not the size

[Boosted LS1]

dnb said:

I'd expect to be changing a lot of the engine (pistons, cam, maybe rods etc) if the supercharger appears anyway as I know there is no way to do both NA and forced the same way. (Remember my car background is Impreza WRX tuning )

You can build a good bottom end for n/ which will take low boost. At the end of the day it depends on how much boost you want and what capacity you intend to use. A stock 4.6 would be quite good or a 4.6 with bowled pistons would be even better. No need to change rods. Wrx's aren't like rovers.

Boosted.

[dnb]

You mean they don't have so many chocolate components in the engine?

[Boosted LS1]

dnb said:

You mean they don't have so many chocolate components in the engine?

In the scooby or rover? Seriously, rods don't fail with boost or stock rpm's. You need decent pistons in a rv8 and then you can crank in some boost

Boosted.

[dnb]

Sounds the same rules as Scoobs then... Maybe 24psi isn't such a good idea on a Rover as it is on the Scoob?

Will you lot stop tempting me with forced induction please? Nic'll really not be happy with me when she reads this thread.

[wheeljack888]

Hi v8racing/BoostedLS1

I know you use forged pistons and H-beam rods on the 5.5 engine but do you use the existing crank-damper/pulley or some really fancy racing american billet-job.

Cheers

Phil