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Kris, we've got some questions for you


Guest Anonymous

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Guest Anonymous

thank you all for the answers.

excpecially kris, the engine man!!

but we have still some questions:

we have the stock pistons, so do you have some pistons you recomend, brand or weight?

and the con rods, lightned, and polisched schould be ok then?

about the aluminium flywheel then, the flywheel on www.peaco.com, are they good? i mean wheight, strengt and durability( also when we use the car at daily use, not always but sometimes?

many thanks for the answers on the previous questions.

Tom, and Danny

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Guest Anonymous

rodpiston.jpg

If you've got stock pistons then you are probably not running 10.5:1

unless you've changed your head design or something. The most they

ever made was a 10:1 euro ti piston which I have 4 sitting on my desk.

Ok If you weigh that piston... you know what.. it's heavy!! Very

Heavy!! and your going to ask a connecting rod to throw it up and

down 6000 times a minute... yeah talk about that for load... now

with that load on the rod.. you also expend energy the motor makes in

rotational losses and extra reciprocating weight inside the engine...

The motor is less efficent because it's throwing around an extra

kilogram in weight in just the pistons.. I race preped my rods and

removed about 35 grams per stock rod. I was more concerned about

end to end balance and didn't want to remove to much. My race

preped rod weighs in at 682grams where a stock rod weighs in at

717grams. 5% lighter. I also have a lightweight mechart 02 racing rod

which weighs 536 grams. 25% lighter. The picture above is of the 3

rods side by side and of the two pistons.

For your application I'm not sure if you want to go with a racing rod. If

money is not an object then by all means I would go with a racing style

rod. Crower, Paulter, and Carillo all make nice rods for a m10. You

can see a little weight savings can add up. If I save 35 grams a rod

then I save 140 grams in reciprocating weight. Now if I use those

mechart rods in an engine. I save 724 grams!!!! Thats more than a

whole stock rod originally!! Now we get into pistons. My 89.48 10:1

euro piston weighs 721 grams with a stock piston pin in there. My

piston that I will be using in the latest engine is a lightweigh mahle

hemi sport pistons with light weight titanium wrist pins. It weighs in at

508grams with that titanium wrist pin. That is a weight savings of 213

grams per piston!! 852 grams total for all 4!! Now if we add that up

with the connecting rods and the pistons we have a 1576 gram lighter

assembly. It has been said for every 1 kilgram you save in the

assmebly you generate 5hp. Whether this is true or not. The lighter

weight will generate more HP out the back. Now with that in order.

You aproach your crank shaft. It weighs about 39lbs and that is all

rotational mass. Some of the worst kind to accelerate. A knifed edged

crank shaft would be the solution. It will be much lighter. Like more

than 5lbs lighter. That is the same as like putting on an aluminum

flywheel. Speaking of that. You should get one! They make an

incredible difference in acceleration. Espically at slow speeds. Now

you've got that flywheel. Please don't slap a heavy clutch pressure

plate on it. Get like a spec clutch with a lightweigh mod. The more

weight you take off there that is rotational mass the faster the engine

will rev. Ok back to the engine. Your valve train. Since you're running

a rally engine I would think a nice 284 or 292 cam would work. I

would go with like a 4.50 rear gear. Ireland Engineering can make one.

or a 4.11 if that is all you can find. Now see we got off topic for a sec..

valve train.. great power between 3500 and 7k sounds all like a

schrick 292 to me. I would get new stock valve springs and titanium

retainers. This engine is going to be driven hard for long. you don't

want it to crap out on you. I would just give it a brief smoothing over

on the ports. I would not enlarge the ports much at all as they give

great flow for the setup you are looking for. The carbs like I said need

to have about a 34mm choke on them.. That gives mad sick torque

down low.. Enjoy!

Kris

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