tinkerbell

i am def. doing a K conversion in my VTiR DC2,

i have a full K20A2 and a full K24A1 and a 5 speed K tranny and will be using Hondata K100 ecu...

i love the concept/potential of 86x86 bore/stroke, but i am tempted by the idea of HEAPS of torque with the 'stupid big' K24 99mm stoke.

but has anyone used a K20/K24 for continuious high RPM circut racing ie 10+ full noise laps etc...

i have built a B20VTEC before (stock internals) and have reved it over 8500 on the circut without drama, on one track day i had rev limiter set to 9k and it felt fine.

the B20B R/S ratio is similar to the K24A R/S ratio (1.54ish), so can i compare apples to apples or is the K inheirently different to the B series frankies???

any input would be most welcome

tinkerbell

sorry, a AUSDM DC2 VTiR = USDM DC2 GSR

Nikos

I would imagine a stock K frank would be ok for race circuit but not ideal for drag racing du to the lower rpm redline

I have not seen any times yet on 1/4 mile of one

bluebird

I have... 9.89 from Skunk2 RSX

nickzed20

the R/S ratio has little to do with the revibilty (aspecially in this extremity of cases)

the 99mm stroke forces the piston to travel that distance per one half revolution, and a lower 86mm would be that in one half also. therefore at the same RPM, your 99mm engine will be putting more force on the rods, piston pins and pistons.

if done right, its not a huge problem; however i dont see 10,000rpm comming from it without a crazy lot of money invested


Modified by nickzed20 at 6:36 PM 11/27/2004

tinkerbell

hmmm, seems like no-one really knows yet???

nick - why are R/S ratios not relevent to the K series frnakenstiens?

JDogg

r/s ratio dosnt matter... piston speed is far more important than r/s..

99mm stroke is gona create some REALLY high piston speeds and stuff will break.

id stick w/the k20

tinkerbell

so piston speed is the real concern!

the bore/stroke ratio is also aweful - (i just worked out)

B18A = 0.91
B81C = 0.93
B20B = 0.94
F20C = 0.96
B16A = 1.05

K24A = 0.87
K20A = 1.00

bore/stroke ratio is a good indicator of piston speeds and also revability - with anything over 1 being a great revver at the sacrifice of lowend torque.

so yeah, the k24 = torque the k20 = revs + top end power

JDogg

bore/stroke ratio is even more useless than r/s ratio...

that has nothing to do with how well it will rev.....

tinkerbell

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">that has nothing to do with how well it will rev.....</TD></TR></TABLE>

really?

on what basis do you make this comment?

JDogg

think about it... why would a change in the bore (how big AROUND the piston is) have anything to do with revability..?? what does it tell you about piston speed... NOTHING. look at ur math... b20b and b18b have different bore/stroke ratio, but they will have the SAME piston speed because they have the same rod and hte same stroke.

the reason it might "seem" that a bore/stroke ratio might matter is because the only way to get any displacement and still have acceptable piston speed is to have a bigger bore. stroke is the biggest factor in revability of an engine and the only one you need to be conserned with.. period.

tinkerbell

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">think about it... why would a change in the bore (how big AROUND the piston is) have anything to do with revability..?? what does it tell you about piston speed... NOTHING. look at ur math... b20b and b18b have different bore/stroke ratio, but they will have the SAME piston speed because they have the same rod and hte same stroke.

the reason it might "seem" that a bore/stroke ratio might matter is because the only way to get any displacement and still have acceptable piston speed is to have a bigger bore. stroke is the biggest factor in revability of an engine and the only one you need to be conserned with.. period.
</TD></TR></TABLE>

so a engine with a 86x86 bore/stoke will have the same piston sideloading as a engine with a 50x100 bore/stoke?

and be able to rev as high?

why do F1 engine have bore/stoke close to 100x50 and rev to 18'000rpm?

you say bore or 'aroundness' doesnt have any effect on revability?

i think it might...

JDogg

f1 engines ahve a huge bore and a small stroke... similar to motor cycle engines. they are like that simply because they need the short stroke so the engine can rev. the big bore is so it will have enough displacement... it has nothing to do with revability...

tinkerbell

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">f1 engines ahve a huge bore and a small stroke... similar to motor cycle engines. they are like that simply because they need the short stroke so the engine can rev. the big bore is so it will have enough displacement... it has nothing to do with revability...</TD></TR></TABLE>

oh, OK.