I took the falcon down to the local goodyear tyre & auto this morning to get a nail removed from the front tyre and discussion turned to corolla's and k motors. He told me he had built and raced a reliable n/a 3k with 165hp @ 8000rpm at the rear wheels, dyno tested. The 3k wasnt in a corolla but in some type of sprint car and it ran on methanol (sp?) but would still have similar hp on premium I would think.

 

The guy says he spent a heap of time, money and a few blown k blocks finding the right set up but when it was done he could run the engine at 8000rpm continuously for the whole race meeting for the whole year without a rebuild. Said it would actually spin up to close to 11,000rpm if he really pushed it but was of no benefit to do so.

 

Best of all he has all the specs at home includin the dyno charts and has offered to share them with me if I want them. Some of the specs include 3k block rebored to 1220cc, mazda 121 pistons, 5k head, twin webers with fuel regulator and a whole heap of other assorted bits and pieces. He claims it can be built for about $1,000.

 

Now I just need to convince the Mrs that it's worth spending even more $$$ on a car that will sit in the garage more than it gets driven.

 

Mmmmmm......165hp 3k motokhana corolla, watch out Colin :down:

that sounds rather intruiging...

Some of the specs include 3k block rebored to 1220cc, mazda 121 pistons, 5k head,

Funny you should say a 5K head on a 3K motor... when everybody is saying to go a 3K bigport head on a 5K motor! :down:

 

But that engine sounds tough as! And 8K rpm?? Perfect for motorkhana :)

wow..try get those dyno sheets and specs that sounds pretty cool :down:

a thousand dollars? yeah, maybe with cost price on all parts, and doing machine work in your own time with equipment you can use for free! paying even trade price, plus machining costs, you'd easily be looking at over double that

 

methanol would make a big difference too. and in a street car, it would be an undriveable, torqueless pig of a motor. it probably comes on cam at about 5000rpm

 

please do bring to light some actual facts and prove me wrong, but this sounds like a dream to me. there's a big difference between a race-only engine and an engine capable of being driven comfortably on the street

Well he is a mechanic by trade and he did do all the work himself including machine work. I think the motor was in a minisprint car.

 

I might give him a call on monday and see if I can get some more info off him about the engine specs.

 

As for street driveability well I am not that fussed as my car probably wont see the street for a few years, strictly motokhana & autocross.

 

 

 

 

Oh and he said no one would probably believe it :P

i believe you can get a 3k to make 165hp naturally aspirated

 

i don't believe it's going to be a very useable car in motorkhana, a motorsport where you barely get out of first gear, and having throttle response across the entire rpm range is a useful thing. nor do i believe such an engine would suit a street car. it's a specialised, high-speed circuit racing engine, and nothing else

 

i also believe you can get a K motor to hit 13000rpm, i've heard of this happening and don't doubt it for a second. however, doing this won't make your engine last very long at all

 

we all know from others' experience that the blocks suffer from poor harmonics above 8000rpm and crack, and the the crank and rods will weaken substantially above 9000rpm in a 3k, and 8000rpm in a 4k

My father raced a 3k ke20 back in the 70s with 79 mm trd pistons and trd rods(1293cc)trd valves,springs,retainers,pushrods&cam he spun it to 9000rpm and ran it on methanol the jets are HUGE he said it gave the engine about 30% more power over running on avgas but i doubt he had 165hp.

Edited June 29, 200521 yr by blown 5k

As for street driveability well I am not that fussed as my car probably wont see the street for a few years, strictly motokhana & autocross.

You don't want a peaky pig of a thing for motorsport, motorkhanas or otherwise. The beauty of my 3K is usable power from 2500 to 7500. Flexibility is what you want.

 

BTW, I believe 165 for a minisprint, but methanol and all the other tricks those guys are allowed will do that. You'll never get it out of a road motor.

how high can 5k's be revved before the blocks fall apart?

4k blocks suffer from bad harmonics above 8000, so that or below

 

a general rule of thumb for reciprocating parts strength says not to rev a 4k cranked engine (which is 5k as well) past 7600rpm

 

doug has built a 4k then a 5k with the same cam, and says that a 5k is like a 4k, with more power, and shift the powerband 1000rpm lower

 

so really, there's no reason to rev a 5k past 7 grand, even if it will do 11000rpm when you want it to

Ahh well i`m going to try and spin my new 5k race engine to 9000 rpm and make power there,i`ll let you know how long it lasts for before it goes bang.

Oh dear!

 

165 hp (at rear wheels!) from a 1220 cc N/A 3k = Total Bullshit

 

Even on Alcohol.

 

NASCAR engines can't even manage that kind of hp/litre output.

actually NASCAR V8S are about bang on that figured... unrestricted they run 800hp. thats 137ish per litre...... 1200cc 165hp, 137 per litre....

 

a sprint car engine eh..... i can belive that. maybe not the price though.... a new weber would chew up all ya budget!!

 

and methanol.... you need twice as much methanol as you do petrol. and you need a dedicated alcohol fuel system. thats tank, lines, fuel rail, pumps and carb

Edited June 29, 200521 yr by Mr Revhead

Actually,

 

The NASCAR engines used in the Winstone Cup Series have the highest outputs of between 750 and 800 hp this is between 129 and 136 hp/litre. Other NASCAR series engines can be down to 600 hp.

 

These engines are run for 30 minutes on the engine dyno before max hp readings are taken. Point is, these hp figures are at the engine not the rear wheels. The 3k was quoted as having 165 hp (from just 1220cc) at the rear wheels.

 

$50-100,OOO US is spent on building each NASCAR engine.

 

I'd like to be wrong but I just don't believe it.