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Tired Engine. How Much Difference Can It Make?

Psymon

By Psymon,
in Engines & Forced Induction

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Psymon Mentor

Psymon

Posted
Posted

Browsing the forums this evening i came across this thread which got me thinking.

How much difference in power output does a tired engine make? The thread i linked to above shows r32matt's awesome dyno result from relatively simple mods. Obviously his AFR's aren't overly rich as is common with modded Skyline's running a standard ecu which would have helped a lot with his good result. However a couple of people mentioned a fresh/good condition engine could have been a contributing factor.

I too have a 32 with an RB20 in it with very similar mods. Mine has a 3" turbo back exhaust and has had the standard ecu remapped. Also it is an auto ecu which should add some extra bottom end due to some extra base timing. I have never had it dyno'd but it doesn't feel like it would be anywhere near that power figure. Even with the ecu re-map it is still running very rich and an SAFC is next on my to do list but i still don't think this will get me to the 190rwkw mark. The car is a 91 model and as far as i know is the original engine. I know for a fact that myself and the previous owner have taken good care of this engine but i'm starting to think that its getting a bit tired.

So just how much difference could there be between a freshly built engine (to standard specs, compression etc.) and one thats got a few years under its belt (not a complete shitter engine that burns oil and sounds like a diesel :)).

Simon

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Engine's that are tired, will make less generally.

Healthy motors are a good thing.

That said, dont read too much into that other thread mate :)

Come on, 200rwkw on 12psi, no chance.

You'd expect a very low 13, i bet it doesnt get close.

Anyway, how much the difference is, depends on how stuffed the motor is really.

I had one bad cyclinder for a while (which turned into 3 eventually) and it was down around 40-50rwkw when i lost comp in two of em.

But thats rebuild stage then.

So just "tired" maybe 10-20rwkw give or take.

Its hard to measure to be honest as no two motors are identical.

dead32 Mentor

dead32

Posted
Posted

theres alot of contributing factors that affect dyno readouts e.g wheel size, tyre presure, ambient temps... my car made 196 on 14psi btw, thats on 18's with 40psi in em, first up if your car isnt and auto i would piss that comp off,, you will never get the ignition timming correct, to adavanced is no good, auto comps run 5deg advanced then a manual... as for the freash engine thingy, if the motor makes better combustion its gona make better bang, pretty simple :)

jazza08 Mentor

jazza08

Posted
Posted

An engine with higher compression is always goin to make more power than the same one thats tired and has lower compression as the 'bang' is not as strong.

Someone mentioned 10-20rwkw (13-25rwhp) i didn't realise it would be that much! Every situation will be different of course but i expected 10-20rwhp...? What i love about newer motor's is how much smoother they are in cruise etc!

SilverECR33 Veteran

SilverECR33

Posted
Posted

10-20kw .. it can actually be alot more than that.

Top Gear did a show where they each had to buy an old sports car.. was interesting to see. exactly how much less power each car had,.. from since the time they came out, to when they stuck each old sports car on the dyno.. 1 was about 100hp difference.

but i bet also the fuels that they ran on back then were alot different to todays fuels also.

so there is alot of different, things that can make up the difference. i.e internal wear/clearence, compression/ timing/ fuels. and obviously, the wear of the cars drive train!. drive train makes big difference on dynos. if the drive train is worn. ie. diff and trains, or gearbox, and clutch etc. could also definently cause loss of power to wheels. on top of a worn engine :)

siksII Grand Master

siksII

Posted
Posted
10-20kw .. it can actually be alot more than that.

Top Gear did a show where they each had to buy an old sports car.. was interesting to see. exactly how much less power each car had,.. from since the time they came out, to when they stuck each old sports car on the dyno.. 1 was about 100hp difference.

but i bet also the fuels that they ran on back then were alot different to todays fuels also.

so there is alot of different, things that can make up the difference. i.e internal wear/clearence, compression/ timing/ fuels. and obviously, the wear of the cars drive train!. drive train makes big difference on dynos. if the drive train is worn. ie. diff and trains, or gearbox, and clutch etc. could also definently cause loss of power to wheels. on top of a worn engine :)

those cars were not tired in the sense that this thread is talking about, those cars were on the brink of falling apart and blowing up, they were all cheap shitters.

  • 3 weeks later...
SilverECR33 Veteran

SilverECR33

Posted
Posted (edited)

hahah yea true they were shitters ay.. well not really shitters , they werent too bad, only james one was crap :).. i mean those cars to us guys would be ok. they were good examples of tired engines but!!..

Edited by silverbulletR33
iz32 Community Regular

iz32

Posted
Posted
lmfao.

I was taking the piss. :)

hehe... proof is in the RB20... :(

its still going with no bottom end knock or anything, still making the HP, still painting the under side of my car in shades of mobile1 .... (albeit im currently on the hunt for a new donk)

as long as they are well oiled and fueled RB20's just keep on going........ tired motor BAH! :)

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