Ratling noise??

[homer]

my 94 astina (pop up lights) - 4 cylinder in line 16 valve SOHC
make a ratling sound on the gear nobe once I drag it to 7500 rpm,
anybody experience this before...

mods: k&n pod filter, 4-2-1 and low restriction muffler, koni shocks & lower springs.

been bugging me for a while now... try a few things like:
adjust timing
change better plugs (platinum)

anybody can help....

[Aaron]

Rattling from the gear knob at 7500rpm?

Are you sure it's not pinging/knocking or valve bounce?

erhaps 7500rpm is a littel excessive for the fuel quality you're running?

[Toyboy]

Yeah i get a slight rattle from the gear knob area to when i rev it to 7000rpm and clutch it,mine isnt a pinging rattle but :P
I cant see the point in reving it that far unless you have internal work(cams etc) done on your motor dude,it wouldnt be making any power after about 6800RPM,so it would be point less strangling it like that :lol:

Catch ya :D

[homer]

I am planning to change the cams but if this thing continue to happen
than whats the fun if every time I have to hold the gear nobe real thight
when rev is high...

any ideas,

will a higher octane fuel help,how much octane boaster to use on 60 litres?

anybody got any refrences on mod cams, valve etc... basically I'm trying to mod the stock engine.

Many thanks in advance...!

[bRaDiNhO]

1. 7500rpm?!?! How often u getting there.... redline is 7000!
2. I get rattling from my gear know at anything above 2500.... i'm missing one of three screws that keeps the knob on the shaft. Mine is aftermarket tho, can't remember if the standard was twist-on or screwed.
3. If you are that high in the revs your hand should be on the knob anyway, considering u should be about to grab the next gear.
4. Mods on 1.8SOHC? You will pay about $1000 for a decent DOHC motor that pumps out a fair few more kw than the SOHC. Cams are about the same price, if not more. And i'd say HP increase will not be as high. Even better do a turbo transplant, plenty of people around to talk to about that. If you are really keen on a hi-po n/a motor, check out the MX5 forums for 2nd had race engines... there was a 1.6 race motor with something like 150kw for about $500 at one stage. I made another post about a new 1.8 race motor for $7000 i think.... wouldnt do that, but plenty o good second hand engine conversion options.

[homer]

I'm going for higher rpm instead of more power... I don't think I want to debate that in this topic the pros & cons.

I have rev it to 8,000 rpm which is the max on my meter at the moment, but the only thing is the gear knob start shacking real bad after 7,000 rpm.

Want to know if anybody got the same problem and have a solution.

Engine transplant is not an option for me as I like to mod things instead of dump in a powerful engine and overwrite all the characteristic the car have, I find that more fun but also more troublesome!

Lucky enough I have a mechanic who share the same view so we are both in this little self experiment. He drives a proton 1.5 litre cab and 8,000rpm is not an issue, but we are still looking for a solution to my car.

Well I think I am out of line here, just want to know if anybody got any suggestion or ideas, I'm willing to try anything, two heads are better than one, 3 heads is better than 2...

ps. will try high octane this week but still trying out the right quantity to use.... thanks aaron for the idea :)

[Toyboy]

I'm going for higher rpm instead of more power... I don't think I want to debate that in this topic the pros & cons.
Dont quite understand you man,you want more RPM but no more power :lol: More RPM means MORE engine wear,and if its not making any more power at the higher RPM why bother :?
BTW if you want a engine that likes to rev to 8000rpm and beyond buy a Honda,least it will make power all the way to those RPM's :wink:

[homer]

I think to clear things up, i am not into engine transplant that will bose your car 50 bhp or even more with a turbo...!

I want to mod the stock for power, and upping the standard rpm is just an idea (any other ideas and suggestions are welcome), of course I want more power who doesn't but I am not giving up the stock engine for another.

Hope this clear things up a bit, I'm trying to squeeze out as much power as I can from the stock engine with some minor mods... :)

[Pernod]

I dont think anyone else takes their stock engine to that level so you might struggle to find anyone to help.

Out of interest, have you put it on a dino at that many revs? I would love to see what the power curve looks like - I have a feeling that it will be rather flat towards the top? (but you wont catch me driving mine anywhere near that!)

Are you currently using the standard box? My guess is that it simply wasnt designed for that many revs and that the rattle may just be caused by wear and tear - how old/how many KM's has it done? When did you last change the tras oil?

[homer]

Never done a dino before.

Last time I change trans oil a few months ago... can't remember do it every second time I service.

the car has done 170,000 km's

I not saying the way I mod will work, but I am just trying out my options, if I blew one of this stock off it is dirt cheap to replace them compare to the more premium engines.

Just trying to have some fun...! aren't we all...

[Cosmo Dude]

If the standard engine redlines at 7000 rpm. Mazda wouldn't have balanced the engine to the revs that you're doing.
It is time to think about re-building your motor before you do some serious damage.

Rod

[BigMal]

Recomend adding a Main Bearing support plate off a late model
MX5 BP or GTX for better stability at higher revs if it will fit in the
SOHC sump. Agree with everyone else raising the RPM limit on a
motor is not a cheap thing to do when reliability is priority. Rattling
in the motor could come from many sources at those revs could be
a cracked engine mount or maybe the bushes at the back of the shifter
under the car. For a fair dinkum 8000rpm screamer you need to
have everything balanced and using high perf bolts. Cam lifters would
need to be special high rev/increased tension otherwise your motor is
just an accident waiting to happen.

Regards

Mal

[Rupewrecht]

have you put it on a dino?

where'd you find a dinosaur willing to have a car put on him? :P

you dont want more revs, man. More revs does not equal more power.

bolt a turbo to an engine and it'll probably use the extra revs*, but the engine has to built to withstand those sort of revs.



*as i discovered when my revlimiter was accidentally set to 8k...and still pulling like a schoolgirl!

[homer]

anybody here mod engines?

[homer]

Thanks for the advise BigMal :lol:

[ezin]

Most engines from japan are balanced damm well! i dont think balancing an engine will make it hold together that much better at high rpm's! its a 99% chance the rod's will stretch under such speed! This happens when the piston is on the exhaust stroke and has very little pressure on the top of the piston! this as uz can imagine will cause a nice bang and a big mess! I would take the rods out and replace them for some aftermarket ones that are designed to handle the speed! That way the thing should hold together to 85-9000rpm! dont forget to change the cams and port the head to flow at such high speeds! Enjoy the high life!

[homer]

Look like a have myself some busy months ahead... :lol:

Thanks for the advise ezin.

[Cosmo Dude]

Don't forget that an engine is the combination of all its components. You will need to make sure all parts are upto the job, crank ballanced and able to keep up the lubrication.
Conrods are strong enough to hold onto the pistons at the speeds you anticipate.
Pistons that are light enough not to rip the top off the rods.
Cams, valves, porting and valve springs that will work together. Then there is the exhaust.
I'm sure others will remind you of more components.

Rod

And then there is the ECU