High Comp Engine

[blandy 29]

Been doing alot of reading over last few days regarding 1.9 8v tuning

I see a popular choice is to add 1.6 pistons and a 300deg cam to a 1.9 to achieve around 175bhp

 

What id like to know is whats needed to go higher i.e towards the 200 figure?

 

I know its not cheap etc and a 16v is the cheaper option but hopefully myself and a friend will be looking to build in order to race hence the 1.9 option to stay in a sensible class but have jenvey 45's etc to go onto the car.

 

The rest of the car will be pretty much sorted ready to go as if we do it the engine will go into my current car.

[welshpug 1,621]

lighter pistons and rods, the standard 8v stuff is quite strong and well balanced but a little heavy, longer rod will enable a lighter piston, possibly bump the compression a bit more.

 

there will be double valve springs anyway to allow for the increased lift, so they will cope with the rpm you inevitably end up needing.

 

also properly optimised intake and exhaust manifolds rather than off the shelf stuff will add a few bhp and broaden the power band.

 

off the shelf inlet manifolds have pretty sharp angles as they are particularly short to enable the flat mounting of carbs, go longer on the inlet and you can introduce a much more gradual curve, and use shorter trumpets & bodies.

 

 

a properly done head for the target bhp/use will help a lot.

[blandy 29]

Did notice the inlet manifolds were particularly short as compared to the satchel type on the 16v's etc.

 

Again i can find alot of info regarding upping the capacity on the 16v's as this has always been my plan but with the addition of another paying participant the idea of building something to compete in seems alot more interesting/viable. just glad its now as so far only brought the crank for the 16v enigne

[dcc 855]

Basically headwork, pistons and rods - get a target cr and build exhaust and inlet to suit cams.

 

In a nutshell, dropping circa 10k in to an engine to get magic numbers is what you should expect.

 

Though with that spec you'd be closing in to 220-230bhp id imagine. I have seen a 190bhp 1.9 8v and one with unknown power, the gearboxes are what truly what separates these motors

 

My modest but solid 8v is racing in Ireland now!

[oak tree garage 1 1 Cars]

personally i have found that decent pistons head work and manifolding is the way forward ,not had a problem with standard rods if balanced ,but if your cam works at more than 8k rpm might be safer to have rods as well , best gains in the head were bigger in and exhaust valves and manifold lengths to work with the cam as stated above

[blandy 29]

I see the figure of £10k floated around a lot but in terms of spec that's about it - although would be very intrigued to where the 10k is spent allthogh guessing that is everything including inlet/exhaust bodies and management etc

 

I'm not going to do anything near that kind of money (have got bodies and management etc already) but am a firm believer in the right components. I guess the cam is the place to start and then build the engine to the correct compression/clearance?

 

I know of 3 around the 200 mark but not got any info on spec as there race cars so not to liberal with the details for obvious reasons,

[Miles 331 1 Cars]

As odd as it sounds hopefully got a head going to Slarks soon for some work, although Mini people a mate of mine who's built quite a few race winning engine's has had head work done here, Bottom ends really need pistons and rods with head you can get 200 ish without spending a huge amount, Long inlets do work well as my other mate has carbon inlets on his done by mass and on the engine dyno saw 243bhp and that was 15+ years ago now

[blandy 29]

definitely some serious potential

[dcc 855]

You need to think abiut your intended use of the engine too - i.e. hillclimb would want more mid range, tarmac track days would be more inclined to use higher revs.

 

You might find it prudent and more effective to use forced induction.

[blandy 29]

would be to fit into a race series so hence n/a and looking towards the 8v potential