WooDooUKs ReVolvo Project Trackday 2

[germ]

im told, the smaller valve/ design of the head increase torque significanly over that of the standard f7r head/bottom combination. also the coil s are a apain.. had too much stella need sleep lol

[foggyjames]

Unless I'm going bonkers, smaller valves are never a good thing for power. I'd also be interested to know what exactly the advantage of the 'P' head is over the 'R'. I presume it's not just the cams, or people would just swap them (unless they're not swappable...)...?

cheers

James

[germ]

foggy there you go again on a "power" hunt..its torque, like longer manifold stacks ora more restrictive exhaust mani..it increases torque..does nothing for top end power tho.. im affraid its around 147 hp.. that is lower down in the rpm and torque is quite alot more again lower down the rpm range. by tweaking this to your advantage (hill power do a good job of this) you can get a really nice power band/torque curve.

When martin gave me a ride in his hybrid it was amazing..seemed to pick up much better than the standard f7r.

[classicswede]

Small valves do nothing for BHP or Torque. It could be something along the lines of valve angles or port shapes or combustion chamber shape but valve size will not be the reason for better performance.

[jtbo]

I love to bash Honda, from 2007 CRF450R sales bulletin:

New smaller exhaust valve for improved flow and smoother power delivery.

Right, as everyone knows, people who seek more power put smaller valves to head so it would flow better

I guess small exhaust valve had most to do with emissions, also part of above is true as closing small exhaust valve does not upset swirl of mixture as much and could help to burn fuel better, but I doubt that benefits of that are exceeding disadvantages when focusing to power and torque.

Longer manifold runner give more low end torque only because of those intake pulses (when intake valve is closed, it send pressure wave towards intake manifold, which runs back and forth, there is certain rpms where pulse arrives back to intake valve when it is open making more air to go into engine) having smaller frequency as air has to travel longer distance, thus optimum rpms are lower. It is not because of intake being more restrictive in that case.

But there is lot that I don't know, but I know that air that goes in has to come out, if there is restriction at some point there won't be so much air and it is possible to add only little fuel to air, more fuel is not helping, so engine has to work in balance.

[foggyjames]

I doubt a hybrid makes more torque (unless the CR is higher as a result)....more likely the cam specs make it more gutsy at the expense of high RPM power. The only real way you'll make more torque but less power is by doing something to reign in the power...i.e. you're throwing away power by limiting torque at high RPM. I'm talking about things like putting an undersized intake / exhaust on, putting in a really lame cam (or cams), or adjusting the cam timing dramatically. Anything you might lose down low by tuning for power (on the same platform) will be massively outweighed by what you gain up top.

You can only make a naturally aspirated engine of a given displacement and compression ratio make a certain amount of torque (I can't think of many production 2.0 NA motors with much more than 150lbft of torque...race motors with high compression will make a little more), so beyond that it's a matter of sustaining that torque as close to your max RPM as you can, hence making good power. That's how a Civic Type R (mk1) makes 200bhp while my 343 makes somewhere around 150bhp, despite having exactly the same 145lbft peak torque...the Civic holds onto that torque at high RPM better than the 343...mainly thanks to the awesome cylinder head and cam arrangement. The stock 8v Volvo head just can't flow enough air above 5krpm.

Of course if we're talking about a daily beater for pottering around in, it's a bit different (hence why diesels are so nice for DD use), but these are supposed to be race cars, right?

If we could get some dyno numbers (stock F7R vs hybrid), we could perhaps start to make some sense of what's going on. Do the hybrids really make more torque, but maintain the same peak BHP figure (probably compression ratio), or do they make the same peak torque lower down the RPM band, and less peak power (different cams, probably)...or something else? If we got some numbers, we can probably work it out.

cheers

James

[jtbo]

But that civic won't move unless you have 5000rpm or more

Stroke:bore ratio had something to do with torque and rpm, can't remember that all, but there were quite few things to consider.

Also 4 valves is bad for low end, that has to do with mixture filling cylinder, valve closing effecting swirl and such things and it matters, unless one is accelerating only at straight line. Advantage of two extra valves comes at higher rpm.

Quite meaningless anyway.

Isn't hybrid increasing displacement? That would increase torque naturally.

[foggyjames]

Traditionally, longer stroke meant you couldn't spin the engine as fast. Nowadays, that seems to have been overcome by the use of stronger components, and most high performance road car engines have larger stroke than bore. More stroke means more force per rotation...hence more torque.

The thing people seem to get excited about nowadays is rod/stroke ratio...which in practical terms tends to refer to piston weight (as a longer rod for a given stroke will need a shorter and hence lighter piston). It also has to do with the angles involved, as when the rod gets longer, the angle at which it's presented to the piston decreases. In other words, the current trends are as follows: relatively long stroke and narrow bore for torque (and to make the engine smaller!), relatively long rods, and relatively short, light pistons. Designers only seem to bother with big bore / short stroke engines now when when we're talking about seriously high revving stuff - bikes and race engines...10k RPM+, etc.

This is where engines of the 70s and 80s are now pretty old fashioned. You can slap a 16v head on a redblock, but the geometry of the bottom end is still 35 years old. A few companies make long rods and short pistons for redblocks, for example...to modernise them a little. Next to stock ones, the difference is quite comical! Light pistons make high RPM much kinder to the engine. You can beef up the standard rods, but if the pistons are still massively heavy, no amount of forging is going to make them happy to sit at 7500+ rpm for an extended period.

F7R and a hybrid have the same displacement. Obviously a hybrid has greater displacement than an F7P.

cheers

James

[WooDooUK]

Well Managed to find an Engine! Will be picking it up in the next few days,

Its a Complete F7R From a Clio Williams! and the Ecu
Bit more money than i wanted to spend, but im still going to rebuild the F7P and sell that on (anyone interested? )

Also whilst doing all this im going to fit a Remote Oil filter, and i might also fit Mechanical oil Pressure gauge for Piece of mind

[340GLT]

I mite be interested in your 1.8 16v before you rebuild it if your interested?
Adam

[WooDooUK]

I mite be interested in your 1.8 16v before you rebuild it if your interested?
Adam

Another one!?

Surely you cant have a use for a 3rd (that i know of )

I will speak to you later about the engine.

[germ]

This has turned out to be a really interesting topic.

im only going by what the renault dudes say and by the rides ive been lucky enough to get from a couple of members, ohh and the guys at hillpower. its all quite mysterious as noone really wants to let the secret? be known and tend just to say do hybrid=win.

im sure everything will become clear in time, hopefully someone here will build such a hybrid? and get some dyno runs done against serveral differnt types of F series engines?

145lbft mine is 135lbft(so it says in the leaflet)...git.. i spose that shows the redblock v frenchy stuff war..is won by the redblock.


Nice work finding a williams engine and ecu! should be fun

[340GLT]

Germ you know i'm running a hybrid right?
Adam

[germ]

What WHat What...im a noob lol *i'll go hide in a corner till the dust settles.... *

[volvosneverdie]