Race engine parts configuration.

[pingpong]

Having been impressed with the level of knowledge and help already recieved from this community let me pitch another curve ball in the direction of those expierenced with f4r engine builds - specifically for competition requirements...

As mentioned in a previous thread this is the current rough engine specification:

Originally a Clio 182 road car.
Jenvey ITBs, fuel rail & ITG filter element.
High compression pistons.
Forged conrods.
Balanced throughout.
ARP throughout.
new seals, gaskets, followers etc.
CatCam Valve springs
Single piece valves
422 CatCams with VVT.
Headwork of some description; based on ph1 head.
Lightly skimmed, rehoned, 3 angle valve seats.
4-2-1 exhaust manifold.
Alternator & waterpump are only Aux Losses.

Other important info - rpm limiter around 7700 - 7800, thermostat controlled oil cooling.

Bold marked components above are still up in the air a little as I have had very mixed reports on engine character based on different combinations of components.Our main rpm band of interest is 5.5k to 7.5k - maximum torque during and maximum BHP toward the end of this band.

Give me your insight on parts, compression ratios, output approximations, engine character etc.

Look forward to reading your advice!

 

[Chip-mk1]

Single piece valves are a must IMHO, hell we've even put them in my mrs road car which is only a relatively mild engine build and while we have got it revving to 7850max it is only used normally in 5-7K even when she tracks it. The standard ones can fail at 7500rpm even on a standard engine eventually, so I wouldnt consider using them in an uprated engine, especially one where you are investing money in the cylinder head.

As far as pistons and rods go, the standard CR is reasonable for the rev range you are after, so no massive need to upgrade from that point of view, but from a reliability point of view I would certainly recommend it, Ive seen quite a few of these engines have piston failure between the rings now, and its always down to a casting imperfection, its literally a lottery if one or more of your pistons (which are poor quality and full of air bubbles) happens to have a weak point in a crucial spot or not.

If you do upgrade the pistons to forged items it will give you the clearance you need for the 422 cams as well, although for a useable range upto 7500rpm, the 422 cams are a little overkill really, 421 work very well in that range too and will also pull cleanly from lower down for those times where you end up slightly misjudging a corner and end up coming out at lower rpm than intended, so it depends on just how bothered you are about that peak figure or not.

With regards to VVT, I would certainly go for it, but I would over advance the inlet cam statically as well if you do have pistons with enough clearance for it, that way you can run loads of advance in the midrange and then turn the VVT off at the top of the rev range where its not wanted for peak power.

210-215bhp is a very easily ballpark to end up in with 421s, and with 422s you should just about get above 220, going much past this isnt easy as you end up needing to rev further than you are talking about, and that ends up expensive.

 

[Chip-mk1]

PS, this is what I mean about the ringland failure on the pistons:

Oh and here is a sexy cylinder head picture from a recent build I did, his work is superb, sorry I dont have better ones showing off the ports etc though
As you can see, we used supertech valves for that, and really you want uprated springs if you are reguarly over 7500rpm although you can just about get away with standards upto 7800

 

[pingpong]

Thank you very much chip, very useful information!

Is there a rod / piston combination that is generally recommended - What are the main options?
Are there a variety of compression options avaliable with regard to the pistons?

 

[Chip-mk1]

11.8:1 is a popular compression choice for use with the sort of RPM you are discussing, by the time the block and head have each been skimmed its normally more like 12:1 anyway, but there are much higher available.

What fuel will you be using? If its a road fuel I personally would probably stick at those pistons, but if its a race fuel then I would go much higher.


Engine dynamics are pretty keenly priced for rods and pistons, Ive used theirs before on a couple of builds and theyve been fine, they are wossner pistons and generic steel rods IIRC

 

[pingpong]

98 Ron would be the fuel used.

This was a package I had in mind:

http://www.performanceenginecomponents.com/products/product.asp?id=250356

 

[Chip-mk1]

If its always on 98, 12.6:1 shouldnt cause you problems, but the gains over 11.8 will be only at the very top of the rev range.

 

[pingpong]

Valves - the only brand I can find seem to be supertech; correct me if I am wrong but they do not appear to be 'single piece'; is there another brand that does produce one piece valves?

 

[BIGASH]

I've been looking into this over the last week and the super tech seem to be single piece for the inlet and then two piece inconel for the exhaust. K-tec sell some but I think they are the same super tech ones

 

[pingpong]

I believe they are James, but branded as KTR Sport which I think is a bit cheeky - they also seem nearly twice the price of other suppliers!

 

[BIGASH]

Yes I saw another product they sell the other day at twice the price of elsewhere but people still seem to pay it lol!

Will be interesting to see how you get on with this spec as I am just working through an engine spec for this winter albeit i'm not planning at the moment to do rod's or custom manifold though, but just looking around and learning at the moment

 

[Fred@BTM]

^you do as i say ;-)

 

[BIGASH]

^you do as i say ;-)

Haha perfect saves me the hassle of looking round then

 

[Chip-mk1]

Although super tech exhaust are two piece they are joined a lot further up the stem than the standard valve so it makes them far less prone to splitting in half, as that part of the valve sees far far less heat and is better cooled by the guide.
More than adequate, even for most turbo applications.

 

[pingpong]

Right team, lend me your brains with this one.

I am going to go steel internals; so this provides me with 3 options:

12.6:1
11.8:1
stock

I also have the choice between the following 3 camshaft profiles (Catcam owe me a replacement set so restricted to that brand.)

421
422
423

or am I correct in thinking... With solid lifters I could move to the following:

521
522
523

Any feedback / expierences to share?

Again; ITBs with longest runner length possible; 421 ex manifold, 98ron fuel, aiming for maximum torque in 5-7.5k band, don't want to compromise reliability for extra output, for instance, if the 5xx profiles push the valve train too hard.

I'm afraid I can't read cam profile specs to understand what sort of impact they may have on performance.


Many thanks.

 

[Dan519]

422 or 423 with high compression. You can rev to about 7800 before you get to the point of lifters going soft/filling with air. 421s would be under speccing and holding back the potential.

I would go with 422s I think

 

[pingpong]

Dan, thanks.

What kind of difference in power delivery would you expect between the 422/23 profiles? Just trying to gauge engine character.

No word on the 5xx series - need far higher RPM?

 

[Fred@BTM]

We've just finished an engine with 423's that made 242bhp @ 7000rpm (engine dyno)

 

[pingpong]

Thanks Fred, what CR?

 

[mark123]

I think this is the guy Fred built the engine for?

Similar spec to what you are talking about.

Dyno results http://www.cliosport.net/forum/showthread.php?540049-newbie-with-a-clio-cup-race-car/page35 spec is earlier in the thread.

 

[Fred@BTM]

i've got the true measured data at work, it was knocking on for around 12.7ish from memory