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Ok...
The b18b seems to yeild better compression through and through...
If i have a std b18c...
I moved all the parts over to a b18a..
The b18a would produce more power?
the b18a/b has a 1.8mm longer stroke than a b18c
is longer stroke better? and would it be as happy to rev?
thanks dan
how does the b18b yield a better compression?
longer stroke is going to mean more inertial load on the rotating components in the bottom end, which means you can't rev as high.
Quote:
Originally Posted by saxman
http://www.c-speedracing.com/howto/c...c/compcalc.php
try it with any combination.. the b18a/b yeilds more compression throuhg and through
so does that mean a hybrid b18a with b18c is better then a stock b18c?
higher compression isn't necessarily better though... especially when a .1-.2 increase is a result of sacraficing necessary features that help protect against detonation. The longer stroke is also going to reduce your usable rev range, and in a motor that relies on reving to make power, I would bet your peak power, at a safe level, would be less than using the b18c block
I correctly built LS/Vtec will rev to 8500rpm all day with no worries so I dont see the revs a problem and all this bullshit talk about stroke and rod ratio's not allowing the engine to rev and stay together is internet hype.This link is to a very good thread about LS/Vtec engines and how to build one correctly http://www.honda-tech.com/zerothread/1676914 .If I had the choice between a B18C and a LS/Vtec I would personally use the B18C engine if I already had it in my car.I have 3 B18A Vtec engines in my workshop now that we are building and 2 of them are for racecars and the 3rd one is for a streetcar.And with higher compression gain a correctly built engine with the right tuning can run higher than STD but what Saxman is saying is correct compression is not everything combinations are the way to good power.Quote:
Originally Posted by saxman
Regards Dyno Dave
A longer stroke means more interial load on the rods... means you can't rev as high as the same set up with a shorter stroke. Will the r/s of an ls/vtec be ok for 8500? Maybe...
Is it putting more load on the bottom end components than if there was a shorter r/s? Without a doubt.
Personally, I wouldn't run a stock bottomed b18a/b motor at a higher rpm if you haven't upgraded the bottom end to some degree.
cool... longer stroke give more compression... however longer stroke is not as rev happy since it requires more movement..
pretty mucha catch 22... build quality is still also somehting to consider.. hmzz...
What the hell does that mean? If it is indeed a typo, then it makes even less sense...Quote:
Originally Posted by saxman
Longer stroke = Greater torque = Same power at lower rpm*
*However, 1.8mm out of 87 will yield 2% more torque and if you do take the extra stroke then you can theoretically make the same peak power at 98% of the rpm. Negligible much?
Having said the above; Many many honda-tech goers run the LS crank in their built motors and rev to 8,500 and beyond all day.
Bottom line, you'd be wasting your time really. Keep the B18C block and just get some higher compression pistons if thats your bag.
was a typo... was supposed to say "inertial"
The most damaging load on a rod is the tensile load caused by inertia. The longer the stroke, the greater the acceleration of the piston per given rpm. When you have the same weight piston moving a greater distance, at the same high rate of speed, the inertia of said set up increases, causes more tensile load on the rods. This is what breaks bottom end components(short of detonation due to incorrect tuning/other issues... but that's a whole other discussion).
So is all this you should not do stories based on experience or a story you read on the internet or because someone said that it just wont work.Dont get caught up in internet stories about all the technical reasons why this or that engine wont rev or wont work.There are plenty of LS/Vtec or B20/Vtec engines running around that will make more than enough RPM/power to keep you happy.If it makes anyone feel better I am doing a LS/Vtec for my own car and I will be more than happy to turn it to 8800rpm with stock rods and a set of ARP rod bolts in them.Torque will make the car move quicker and the more you make at a lower RPM the better the car will accelerate so in a STREET BASED car where do you need the torque at 4000rpm or 9000rpm? guys you must remember torque makes HP,HP does not make torque.
Regards Dyno Dave