Oops!!Just hit 6480rpm with the wagon in first gear!!

[Stav]

My car has an automatic box.I am still counting my lucky stars today guys. I was tuning the wagon up a little today and discovered that at 5500 to 6200 rpm my car was running very lean at 13.9 to 1 af ratios. I pulled over somewhere safe and put some fuel in .I then drove the car for a few minutes to warm it up. I pulled over to side of the motorway and when the opportunity came I logged the cars' tune at wot ..Well I ll be darned if I know how it happened as my rev limiter is at 6200 rpm but the car just loved my adjustments pulled like a jet in first gear and then bang bang...I thought I blew it up.. I pulled over in a safe spot and reviewed my data log. Phwoar!! It actually spun up to 6480 rpm!! It had gone past the 6200 rpm cutoff for some reason .

The bottom end on the wagon is a second hand stock item.The head has heavy duty valve springs and reco head.

What could possibly break in the bottom end is my main question? It was a bit scary..

[blueoval]

I dread to think Stav.

But anything that bangs at high revs is not a sound you would want to hear, ever!

I can only assume worst case scenario, valve bounce or worse, perhaps bent rod?

[TOASTED]

lol whoops.. sorry thats not funny at all

[Stav]

Originally Posted by blueoval

I dread to think Stav.

But anything that bangs at high revs is not a sound you would want to hear, ever!

I can only assume worst case scenario, valve bounce or worse, perhaps bent rod?

The rev limiter did kick in .I hope it was what the bang was .I drive the car easy so I havent experienced the rev cutout many times.I am sure it was.
It is still driving nice and normal afterwards as well.Seems normal..no noises or anything like that.
Is 6500 rpm dangerous for a stock bottom end?

[Stav]

Now that I think of it ,it must have been the limiter...bombom bom then felt like power was being cut ...

I have to wonder a few things now? Should I raise my rev limiter to 7000 rpm and take advantage of the torque or will I blow this engine as well?

[Stav]

Just got off the phone with my head reco man. It was definately the limiter. Also..I will be raising my rev limiter to 7000 rpm after that astounding run..looks like I may still have some more curry left in the wagon to come.

[FGII-XR6]

just shows how strong the 4.0 I6 is

[HLC]

i reckon anything higher than 6500 will result in something flying out of your bonnet. i'd leave it as it is and take it to WSID to see what happens.

[blueoval]

I think you should keep ya rev limiter to a level where you feel is safe.

Unless you engine has been built to handle high rpm, I wouldnt push it.

It sounds like the rev limiter now you have mentioned it. Keep the rev limiter at the original limit you have. They do restrict power once you hit the limit. Thats what they are designed for, to stop high rpm damage.

Its up to you mate, but I would err on the side of caution

[Stav]

My head bloke said that they should be good for 7000 rpm Maybe wise to limit it at 6600rpm to be a bit more conservative.I ported the head and they did the new guides for me and skimmed it.I trust these guys.

The springs are made to take 800 lift and can rev very hard.The bottom end was my concern.

I dont want to hit the 6200rpm rev limit in frst at wsid.It will kill the potential of the car.It went off the rails so to speak.

[Mr Hardware]

you're keen mate. I don't like going past about 4800rpm, just starts sounding angry and not nice. It's a friggin I6, no-one buys them to get 100% out of. They buy them cos they're strong and reliable, not cos they're a performance motor.

[XCSEDAN]

has the bottom end been balanced? are the stock rods forged or just cast? another thing is the main caps, if they dont have a decent bolt kit on them they may let go...

if your bottom end is all stock, and you blow it (assuming you dont do any damage to the head) you could just buy another bottom end and block if something goes bang...

the head sounds like the expensive bit, how much have you invested in it?

spin it up to 6600 and see what happens, and get a more accurate rev limiter!

[The Monty]

I have spun the Monty to 6600, as it read on the tacho anyway.
The next four runs registered at 6400, stock everything, bar intake exhaust and tune. I hit no limiters on those runs, but have hit them before, and what you described is hitting the limiter.
It didnt make any wierd sounds, or blow smoke (was filmed), or slam into gear, so I dont think there is much wrong with it, other than with me, spinning to 6400 is breaking the 100 kmh speed limit, lol.
Just dont do it often, and have the mentality that if it breaks, a whole low K AU engine is $400 from the wreckers.

[The Monty]

I should mention, that I didnt hit those in first, but in second, as I crossed the line.

[Stav]

Originally Posted by XCSEDAN

has the bottom end been balanced? are the stock rods forged or just cast? another thing is the main caps, if they dont have a decent bolt kit on them they may let go...

if your bottom end is all stock, and you blow it (assuming you dont do any damage to the head) you could just buy another bottom end and block if something goes bang...

the head sounds like the expensive bit, how much have you invested in it?

spin it up to 6600 and see what happens, and get a more accurate rev limiter!

The bottom end was second hand 160,000 km travelled.All stock. I didnt use the tacometer.I used a datalogger which is accurate.
I spent 12 months porting it myself the head.It had new guides installed,hi lift springs and from memory chrome moly retainers. The springs can handle big lift and big revs. I upped the compressiom a tad as well. I dont like revving the guts out of the wagon as it is daily driven work car..but it is nice to drive. It rarely sees over 5000rpm as I want it to last.
A whole au engine can be bought for 600 dollars.

[StealthAu]

Get it on the dyno, see were power starts to die off and set limiter accordingly.

[Windsor220]

Originally Posted by Stav

my car was running very lean at 13.9 to 1 af ratios.

Wouldnt 13.9 make it rich?

[EvilChief]

what ecu are u tuning?

most cars have a soft and a hard limiter

the soft limiters are either cam timing retard (in VCT) or fuel cut and set about 200 to 300rpm below the hard limuter, which is ignition cut.

the banging sound most likely was ur hard limiter, if it was something more serious it wouldnt idle

[honer]

Originally Posted by StealthAu

Get it on the dyno, see were power starts to die off and set limiter accordingly.

^^^^^^^^^^^ Thats how its done and what I'd be doing.

[EvilChief]

Originally Posted by Torxteer

Wouldnt 13.9 make it rich?

i wouldnt call it lean lean, but its not very rich either.

personally i target around 13.5:1 on NA cars in top end and adjust timing accordingly.

turbo cars cop around 12.5 to 13.0 :1 with appropiate timing

[Stav]

Evil chief..I agree with you on this one.If it was serious engine damage then the idle would most likely go stupid and i would hear clanking sound of metal to metal contact. I am tuning the eecv which has its limiter raised to 6200 from from memory.I have chucked the interceptor on top and have been fiddling with it for around 8 months now.

I really hate dynos with a passion and so it will be unlikely to go on.I can tell just by driving the car at if my adjustments are working or not.(with the aid of my data logging equipment) The only thing I need now is to buy another gtech pro meter for fine tuning to a higher scientific level.My last one was stolen:(

[Stav]

Originally Posted by EvilChief

i wouldnt call it lean lean, but its not very rich either.

personally i target around 13.5:1 on NA cars in top end and adjust timing accordingly.

turbo cars cop around 12.5 to 13.0 :1 with appropiate timing

My car seemed to flatspot with 13.5 air fuel ratios but I suppose some cars are different.I added some fuel and left ignition timing alone.It felt much more responsive.For just an enthusiast I am treading lightly and taking notes. My main objective is reliability.For the 1/4 mile I would be mad to have the car hit the limiter when it is producing more and more torque.I will drive the car around and give it a few safe blats to see if the car keeps pulling like a jet to the limiter and decide accordingly.

[EvilChief]

AFAIk the interceptor does not allow to make adjustments to your throttle pumps, so once you lean certain areas out, the enrichment from a throttle pump may not be enough any more to overcome a flatspot, so you may be forced to a tad richer in that area.

also once you lean an area considerably off, you need to adjust your timing in that very same area as well.
for example:

in the 3000mark to 4000 mark you pull AFRs from factory rich 12:1 down to 13.5:1, you will need to advance you ignition timing slightly, to compensate for the time it now takes for the AF mix to ignite completely (the leaner a mixture the harder it is to ignite, hence ignition point needs to be forfitted, but very carefully listen for rattle/pinging)

that should take care of your flatspot
second problem you may or may not face is the inability for the interceptor to go beyond certain ignition retard or advance. i faced that barrier when tuning a turbo falcon, in which i wasnt able to to remove more than 17 deg of timing and still was too much.

[stiddy]

Pfft, break something in the bottom end at 6400rpm? kidding right? lol dont worry stav... takes a little more then that..
The AU I6 bottom end is a very tough unit stock, you would be able to spin it to that every day if you wanted to. Plus 160,000k bottom end is just run in lol.. again, dont worry.

[HLC]

Originally Posted by Stav

Evil chief..I agree with you on this one.If it was serious engine damage then the idle would most likely go stupid and i would hear clanking sound of metal to metal contact. I am tuning the eecv which has its limiter raised to 6200 from from memory.I have chucked the interceptor on top and have been fiddling with it for around 8 months now.

I really hate dynos with a passion and so it will be unlikely to go on.I can tell just by driving the car at if my adjustments are working or not.(with the aid of my data logging equipment) The only thing I need now is to buy another gtech pro meter for fine tuning to a higher scientific level.My last one was stolen:(

stav, the bum-o-meter is no comparison to a dyno. 50 bucks will give you 3 runs or whatever, the number at the end is irrelevant. but knowing where the car stops making power is a handy bit of knowledge to have.

[xr8ute]

Its the top end that would cop a hammering at those revs, but your heavier springs will help there....

I used to hit the limiter heaps in th ute, because it is at only 5500rpm in the AU1 XR8's. Its not good for ET thats for sure...lol.

Dont be afraid to rev it Stav

[Sonik]

I hit 7,500 tonight!
In the Magna though.. Never been above 4.5k in the falcon.

[Sox]

It's not likely that you've damaged anything, not because it's bulletproof, but because you've driven it and it's appears fine. If something had gone wrong, you'd know.
As for setting the limiter to 7000rpm, I'm not so sure on that, firstly because an old engine like you have is likely an accident waiting to happen, and secondly it is almost certainly falling off the power well before then.

Their is simply no point in revving an engine much beyond it's power peak.
Get it on a dyno, yes dynos are just fine if you use them correctly, and find where the peak is. Then adjust your limiter 200-300rpm higher.

With a fresh engine, new rings, bearings and perhaps a balanced bottom end, I would imagine 7000rpm is safe enough for the I6, but still wasted if the power peak is 1000rpm less.

Rick.

[Stav]

I just loved the way it screamed up the motorway..it was the bang limiter which amazed me even more??6200 prm limit and I hit it!! Went past the darn thing!!

[Stav]

Originally Posted by Sox

It's not likely that you've damaged anything, not because it's bulletproof, but because you've driven it and it's appears fine. If something had gone wrong, you'd know.
As for setting the limiter to 7000rpm, I'm not so sure on that, firstly because an old engine like you have is likely an accident waiting to happen, and secondly it is almost certainly falling off the power well before then.

Their is simply no point in revving an engine much beyond it's power peak.
Get it on a dyno, yes dynos are just fine if you use them correctly, and find where the peak is. Then adjust your limiter 200-300rpm higher.

With a fresh engine, new rings, bearings and perhaps a balanced bottom end, I would imagine 7000rpm is safe enough for the I6, but still wasted if the power peak is 1000rpm less.

Rick.

True..I just am the not so biggest fan of dynos any more.I might just set it at 6400 rpm and see what happens.The acclerometer should let me know what works.

HLC..my bumometer is a good one.Trust me I can tell more power after the thousands of hours of fiddling with the car.