Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
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Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
just to be somewhat helpful... anything above 12:1 needs a decent tune... and many here have proven that Honda's are tune dependent.
On another note, I know of SR20s that run between 12:1-12.5:1 untuned on 98ron sweet BUT with big cams in the vicinity of 275-290* duration.... just remember that dynamic compression ratio changes with longer duration camshafts and overlap. you will also want to run a tad richer as a safety margin... but again from a few things i've read from the internet (yes intarweb is full of varying info so beware) in regards to the s2k motor, it's fairly detonation resistant due to head design so again thats something to consider.
How do you plan on achieving this compression raise? but no matter what get it tuned and you'll be fine and reap the benefits of additional torque
I agree though that this thread should either be in the All motor or S2k forum as i'm pretty sure flow dynamics of the F series is vastly different from the more common K/B/D series motors that people work here.
Quote:
Originally Posted by aaronng
WTF does that even mean?? English isnt ure first langauge is it?
I wanted to hear from ppl who have built engines with high compression. Usually turbo set ups run low comp. so i figured all motor was a given,but hey this is Ozhonda. :(
Thanks for the input dsp26. I'll be running about 12.4:1 with oversized TODA pistons and a different head gasket. Obviously a tune is in order. Just wanted hear from some of the engine builders that post in all motor.
also ok-ish but you should not depend on the knock sensor as it is an electrical device that retards WHEN it detects ping... what a tuner/builder should achieve is the prevention.Quote:
Originally Posted by EG5[KRT]
same as a rev limiter... it is electrical based when you reach a certain rev... but what happens if you redlined 5th and shift to 1st/2nd... revs will exceed beyond the electrical disabler being the rev limiter and blow your engine anyway as the revs had no way to climb to that threshhold, but rather start somewhere where it already exceeded the point of the limiter
Piston design is crucial since the piston forms the bottom of the combustion chamber, I have heard of B series engines in the states running 13.5+ static compression with well designed pistons on pump fuel.
dsp26 is correct, cam size also plays a big part, at the end of the day it's the dynamic compression which actually matters. It is possible for an engine with 13:1 static compression and an overly large cam to have the same dynamic compression as an engine with static compression of 10:1
Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
Lets read that again shall we.......
Im asking about comp. ratio in the low 12's in an ALL MOTOR section on a honda fourm. To my knowledge no hondas run that stock. I have a car that comes stock at 11.4:1. I was aiming the question at ppl who would already have prior knowldege of this,(hoping to get a helpful response)Hence i originally posted in all motor. For those who know that the s2000 comes out of the box at 11.4,im obviously enquiring about RAISED compression, and that i would have no avid interest in how a standard car with a similar compression ratio, deals with pump fuel. Obviously there would be no issue as it would severely cripple the car manufacture's sales, if a standard car had knocking and detonation problems. We could then go into themes including loss of revenue, GDP and econimical issues, jobless factory workers and so forth ....
Many All motor b18's and k20's etc.. run high compression so..... I posted this question in All Motor, where we see alot of engines running ratios like this. I intentionally did not specify engine model, and posted in all motor,as i wanted numerous answers. I also did not specify engine model or post in the s2000 section,as no one here with an s2000 is running a ratio that high. All Motor is also known to have engine builders themselves post there, their input would have been valued.
My intention was to enquire how members find it,to frequently run modified engines with high compression ratios that are subsequently, higher than standard. This is realised by other ppl who have posted in this thread, whether it be words to the effect of "good luck getting an answer amongst a bunch of dumb shits" or actually contributing with an answer. It seems the only ppl having trouble understanding my question are u and ure buddy. But hey.....this is ozhonda. I posted the same question on s2ki and guess what?? No trouble getting an answer there,but all the memebers there have opposable thumbs,might be a contributing factor?.
I wanted input from actual ppl who have RAISED compression to this level. I didnt want a slinging match with linguistically challenged moderators.
So for the record,to be clear and concise, anybody that has RAISED the compression ratio of their engine to around 12.0:1-12.5:1, your contribution would be appreciated in leaving comments regarding the grade of fuel available at the pump,or any other issues realsied, regarding detonation or knocking. :)
Ahh, much better. :thumbsup:Quote:
Originally Posted by WhiteAP1
Moving to All Motor. :)
You should be fine running that comp on 98 provided the tune is good. I used to run a Pug 205GTi on 98 which had 12:1 comp and it was an old 8v SOHC engine with a poor chamber design. Admittedly I had a big cam (296deg duration) and quad throttles.
On a far superior engine running the same comp or more shouldn't be a worry if the tune is right. Not so sure about doing it with standards cams though. That may push the boundaries a little. You may need some cam to reduce the dynamic compression as was mentioned in a previous post.
its not the COMPRESSION ratio that changes a cars drive ability - its the parts that are needed for higher compression that change it.
IE bigger cams etc.
i think u will be fine just make sure u have a great tune and quality gear to support it, i'm looking at running a k20 frank 12.5 maybe 13 on pump gas for a future project, one of my worries is the fuel being consistent and actually 98. Check out some us forums heaps of info there, quite a few run this comp on street engines and pump gas. Prolly also good to talk to dyno dave and yonas will have an idea from his experience too.
Its not the parts im worried about, the engines built for 12.4,both head and block have been upgraded accordingly. The quality of fuel, or lack there of, was my concern.
I just wanted to hear from others, to pretty much confirm what i thought already. Spent plenty of time on the US forums, and yeah they run higher ratios on pump fuel also,even with their quality of fuel. Its the AU grade of fuel i was curious about.
Rating-wise, our 98 is the same as their 93. A large proportion of their pump fuel has at least 10% of ethanol in it. So in that respect, our 98 octane is better than theirs. Sulfur-wise, they get their fuel from the same souce as we do.