The V8 Owners Forum -

I need to build a race engine max BHP 220-230.
What would be best a 3.5 or a 4ltr.

Its only going to be used on the track in a race series.

Your target is about the limit for a sensibly tuned 3.5

There ain't no substitute for cubes and what's more races are won with torque. Torque provides acceleration out of corners.

You can have a high BHP motor with hardly any torque but a shed load of revs....a nice motor this ain't!


AJMHO,

Pete

Normally bigger cubic capacity is better as it gives more torque

But the bigger you go the less the engine likes to rev so you could end up needing to change gear mid corner after "running out of revs"

Make sure you thus know what your rev range will be in the twisties - may need to alter geabox / diff ratios too to match where the engine will make the power.

I have a 3.9 in the GT40 and it's fairly heavily worked and has dyno papers for the engine at about 265hp but it is a pig less than 2000 rpm uness on the power. It also is very loud bcause of the exhaust valve timing - another thing you need to keep in check on a race car (damn tree huggers building old folks homes on racetrack noise paths)

Ian

.....just had a look at my plot from Emerald,
276hp@ 6100rpm,
and
253ft,lbs of torque @ 5100rpm and over 130ftlbs at 2000rpm,

Thats from a 3.9, with a fair bit of work, but NOTHING special apart from Throttle bodies
Shame its in bits at the moment, but it is starting to come back together, better and stronger.
Ian

oh fooooooooook

thev8kid wrote:oh fooooooooook

TeeHeee better buy a bigger bottle of gas then Tony

nah can't afford fook all at the mo mate,
still paying off bills from earlier in the year after a death in the family.

you got no worries from me next season,

Ok a 3.9 or 4.0 it is then.
So best Idea due to the BHP limit would to build it for torque.

Any advice for this would be handy.

I will be going Injection with a emerald.
Plus planing to make my own plemum, with tripple throtle boddies

Thanks
Leigh

I will be going Injection with a emerald.

Do a "Your Garage Scene" about your emerald project for the dumbos like me please mate

I should be Emeralding my V8 AND Megasquirting my son's 3000 this winter so I need pathfinders like you desperately. Be prepared for many questions. If you can wait for the Autocar show at the NEC in January I think they do a show discount

Muchos gracias in advance

Ian, what sort of pathfinding do you require??

Well I've never done one before Either.

But seems to be the best way to go esp if you want to keep upgrading.

The plan is to start in group C limited to 220-230 BHP.

Then if I do ok upgrade the engine and move up to group B.

I do have a friend that's currently doing it so will be getting some help from him.

Probably the basic fundimentals for your engine would be Buy once not twice, upgrade to your final spec on the basics, make it strong enough to exceed your final plans, although it may appear to be overkill initially building a bottom end to cope with 325 hp when you are only producing 240, In reality the bottom end of the Rover is pretty good in stock form, my 3.9 has sat a 7k many times, The basics I would be looking at for the bottom end would be ARP bolts and studs throughout, rod bolts, mains and head studs, one personal choice would be a lighter Steel flywheel as I have seen a couple of flywheels explode.
Stock HRC rods seem to be OK and the pistons are not too bad either, but a nice set of Accralites would be beneficial, just a tad expensive, ballancing will also help with lognjevity, if you go the route of ARP rod bolts, the rods WILL need checking for ovality