^^^hmmm interesting
redlining your motor wont kill it instantly. for example: while pit crewing this summer for SPI, we installed a calum ECU on the race car, a 95 200SX with a FWD SR20DE. the stock redline was 7200 RPM and with the new ECU, it was raised to 8000 RPM.
Vic took full advantage of the new redline and as a result, the car posted times at mosport nearly 2 seconds faster than previous personal records for that car.
however, the motor only lasted another 5 (i think) race weekends before one of the connecting rod bolts (a known weakpoint on SR’s) let go while decelerating, and the motor blew. it very well could have been it’s time or the failure could have been from excessive strain, caused by the increased redline.
had we replaced the rod bolts before-hand with ARP pieces, the motor may have lasted another season. or not… a different part could have blown, likely a connecting rod cap or another piece of reciprocating mass in the motor.
most high rpm failures happen when inertial loads are placed on parts, that exceed the intended specs. just like in construction, you build a bridge to hold 8 times the maximum posted weight, you will forge a connecting rod bolt to withstand X times the maximum forces. so using the bridge example, if u put 8 times the maximum weight on it, it WILL definatly break, if u stay below the posted maximum weight, it should never break, but if you’re somewhere between the maximum and 8 times the maximum, it wont break right away, but eventually it will break.
to say that a rev limiter will save your engine is not completely true. if you are in first gear accelerating at full throttle and bounce off the rev limiter with the car still in gear and tires at 100% grip, it sends a jolt throgh your driveline that could damage your motor. imagine the entire weight of your car, multiplied by the transmission, transferred through the drive shaft, placed on 4 tiny, aluminum, rod bearings.
also, when an engine accelerates, the pushing and pulling forces on the crank shaft are transferred smoothly through the bearing , through the thin layer of oil that lines the bearings and to the crankshaft in a circular pattern, never truly head on. oil pressure must be maintained so that on a molecular level, the bearings never actually touch the crank. if they do, you run the risk of spinning a bearing. loss of oil pressure under load, sucking up water, detonation, excessive RPM or a strong enough jolt, or any number of other reasons could cause the bearing to touch the crank.
finally, regarding high RPM operation, it is not always beneficial to seek a higher redline in the first place. there is a formula that takes into account: engine stroke, overall displacement, rpm, and other factors, producing a graph on which, efficiency begins to decrease after a certain RPM.
Are you talking about simone perfornamce in newmakret ? vic ? i take my 240 there a few times, good guy and people working there, anyways i see what you all are saying still makes me wonder though
yeah, same vic
Hanzz is dead on…but…
the redline of a motor is verrrrry different than the rev limiter
a rev limiter is a manufacturer precautionary tactic to limit rev’s beyond a given point…
that said a 5yr old computer may be able to run a 1yr old motor…BUT…
if in 5 yrs the internals have changed design spec and are now a little weaker but still dimensionally the exact same
(like changing valve construction material but not anything else)
then the redline on the new motor may be lower…
installing the older computer moves the rev limiter up as the OE redline WAS higher…your new motor may very well break very early now…
high rpms come from precision balancing and precision machining…
lightening internals makes it easier to balance.
because
at high rpm’s the rotational enertia is taken into account…
so a 1 lb item at 3k rpm’s acts like a 10lb item
(only an example as size makes a difference too).
balancing 10lbs takes more weight to balance if it’s off manufacters perfect spec…
balancing a small item that will weigh 10lbs (including enertia) is harder to do…as you gotta find somewhere to put the heavier metal or balancing weights etc…
reducing the overall diameter helps in balancing as well
a bike crank can be made to be stable at higher RPM’s
by just improving the precision of the counter weight placement, or balancing weight location, or balancing weight shape profile…
or basematerial…if you can do this get D2 tool steel and see a 10-20% increase in redline as trhe crank can be made smaller but still weight the same or less as the material is waaaay stronger. and therefore won’t flex at higher rpm’s
but the best way is reduced diameter…(for the most part)
the easiest is lighter weight…just like balancing a tire.
anyhow…
depending on motor internals etc you may be able to raise the redline with more accurate spark / fuel timing but the effect would be minimal…
internal upgrades such as
forged instead of cast crank and cams and connecting rods
profile improvements for structural (Ibeam rods instead of OE)
higher pressure / spring rate / lighter valve springs
cam overlap / design profile / lobe and bearing width etc
valve diameter / # of valves / material / seal profile (3 or 5 angle)
main bearing design / material / journal and lube profiles
design fault repair (the connecting bolt upgrade hanzz spoke of etc etc)
etc are the ways to increase redline the easy-est for reliability.
next would be blueprint machining and balancing.
(this used to be done by ensuring the head cam journals were perfectly centered and aligned for straightness etc)…its worth quite a few ponies at the super high end engine building level.
sleeving the cylinders with high grade materials
where you boar out the entire cylinder wall and replace it with a sleeve (stainless is most common)…imagine running V8 pistons!!
ther is many more things depending on cash flow…
once you get to these levels your talking some major $$$$ for a motor
just swapping a computer will not increase the redline
it can increase the rev limiter but rarely increases redline more than a bit as …most often…
newer motors in a series (ie 1998 2.4L and 2000 2.4L) are weaker unless it was designed as a performance motor…then sometimes its better made…usually because of recalls, complaints and hp claim increases…
reducing the rev limiter will help protect the motor but only if your wife / buddy borrows the car…
this is why some tach’s have a backlight that changes colour to yellow and then red for a shift light…
if you are pushing your motor that hard…pay attention or buy an automatic…
there is no safe way to seriously increase hp and race and protect your motor without a stupidly expensive computer with a voice to say
“danger will robinson…danger”
or some kind of cruise control type system to kick in or a throttle position stop…but this sucks as, in different gears etc your throttle position doesn’t = rpm’s