how high should my 5 rev???

[leesaunders1981]

I have a piper 285 cam fitted with uprated springs etc, standard comp, does any body know how high i should be revving my engine untill as there is no rev limiter???

[dangerous dave]

do you have an AFR guage fitted.. you can rev the car as far as you dare, but if your fueling runs dry:crap:

i've taken a standard engine with a t2/t25 17psi to 7k maybe abit more and it was still pulling, no problems at all.. same engine took a t28 18psi to about the same, maybe a touch more to get some power out of it as the standard cam wasn't exactly working well with the t28:D

[leesaunders1981]

yes mate have a AEM wideband, running a full T25, i ve been revving to 7k with no probs buts seems it wants to go more....

[dangerous dave]

yes mate have a AEM wideband, running a full T25, i ve been revving to 7k with no probs buts seems it wants to go more....


its your car, you take the risk.. id go to 7200 all day long, im even gonna push my new engine to 8k, but much further? i dont know..

see what others say..:)

[Tony Walker]

personally i wouldnt regually rev past 7000, my soft cut is at that and hard cut not far after. without a revlimiter id keep it below 7, i wheel span in the wet before i bought my limiter and my rev counter pretty much hit my boost gauge lol. it also saved my engine when my throttle jammed open.

[Os8472]

i rev mine to 7k, befor going efi it revved to 8k once, wasn't nice.

If you ask Sparkie though he'll say its good for 8500rpm:eek:

[leesaunders1981]

So we are saying about 7k to be on the safe side???

[Andrew Cooke]

from the cup manual:

"The valve collets are designed to operate at a maximum of 6500rpm. If this speed is often exceeded we recommend that the collets should be replaced at frequent intervals"

[SCHWARTZ]

the push rods dont like it much after 7000rpm ish mine decided to bend as have a few others. no just me then:laugh:

[Andrew Cooke]

the push rods dont like it much after 7000rpm ish mine decided to bend as have a few others. no just me then:laugh:

piper cam?

[djinuk]

I rev to about 5800 and then bottle it. :P

[Sparkie]

i rev mine to 7k, befor going efi it revved to 8k once, wasn't nice.

If you ask Sparkie though he'll say its good for 8500rpm:eek:


it can be done, but as i've mentioned before it will wear your engine out very quickly.
oil pressure needs to be high at those kinda revs. 10-15psi per 1k revs i read somewhere. most gtt's stop at 45-60psi

[youngscottie]

would it not be worth getting the car on the rolling road
then look at your graph where the power starts to tail off
theres not much point in reving past that as theres little gain to be
had from the extra revs:confused:

[Ian S]

from the cup manual:

"The valve collets are designed to operate at a maximum of 6500rpm. If this speed is often exceeded we recommend that the collets should be replaced at frequent intervals"
Is that for both inlet and exhaust? IIRC, one of them, I forget which, has only one groove in the valve.

With my standard cam the engine more or less lived at 7000rpm for the 10 years I had it which included about 13 runs at the Pod taking it to 7500, where is was sweet and nice. A couple of years after Pod, so not directly Pod related, a collet came off and the valve dropped into the chamber denting the piston a bit and slightly cracking the head around the guide.

So then I fitted the newly assembled C1J engine that I had standing by. That contained the Piper 275 and a whopping turbo. That engine didn't 'make boost' until 5000rpm in first, so again it lived at 7000 to 7500 for 2 years until a collet again came off. Or a valve tip snapped off at the collet groove. Could really be sure. I was a bit harsh at the higher revs. A pals one, with nice head work and not the standard air cannister and the 285, was without that strained sound and feel and whisked around to the red area with effortless ease. About 5,500 was where mine got a tad harsh. My tappets were adjusted.

According to the OE gauge it made about 6 Bar oil pressure. 88psi. I put that down, a bit to the all new engine bearings, but particularly to the very close fitting new turbo bearings. Used Mobil1 0W40. That did make it smoother and not holding back when cold.

Anyway, that collet info would have been useful to have before the event(s).

Thanks for sharing it, in case I ever get a c1j going again. :)

[Andrew Cooke]

it says collets, so I assume all collets.

It does also mention about updating the valves, collets and caps on 85-86 cars with later parts.

At the end of the day you take your chances, the odd squirt to 7K is not the same as racing at over 6500.

[Ian S]

it says collets, so I assume all collets.

It does also mention about updating the valves, collets and caps on 85-86 cars with later parts.

At the end of the day you take your chances, the odd squirt to 7K is not the same as racing at over 6500.Further good data. :) And interesting as I was unaware of a difference between earlier and later parts.

When the GTT was functioning, when I drove over to my relatives, about 10 miles of country lanes, I'd barely drop out of the red, though obviously not all the time at WOT. Sprints and hill climbs often only last for a minute or two so my engine probably had a harder time than sprint racing. Though I would let it warm up a but first as I 'cantered' out of town. Though at a relaxed pace all the way the oil didn't reach 90°C until I arrived. So it wasn't fully warm at first. The oil would soon be at over 110°C once on the power.

So, anyway, the 2nd engine's collets lasted that usage for 2 years at maybe once a week, all be it with a lower lift cam.

So there's little to worry about regarding un-due wear, if you only occasional use it. Provided your engine is good for it that is.

[Slim]

I also have a t28 and piper 285,, only runnning 16psi at the moment. But it seems as the power drops off after about 6200 :(

is there somthing wrong somewhere?? maybe more boost would put the power up further?

[Ian S]

Mine was naff below 18psi.

Came to life at that with a step change and got into it's stride at about 24psi.

[Slim]

ye maybe its boost related.. better turn it up lol

[dangerous dave]

ye maybe its boost related.. better turn it up lol

we had that on my old car, turned it up from 10-12 psi to 15 and there was little change, but from 15 to 17psi and the car was flying.. :cool:

its all about the boost..

i always expect going past 6500 will wear things out, these cars and engines for many years were just day to day town driving cars till we got hold of them, now there running more boost and more revs, bound to let go in the end..

im gonna get my power up, use the revs as i see fit and if it goes pete tong i'll deal with it..

[rs250nut]

Shame the c1j as such a weak valvetrain, the bottom end has got to be good to 10k+rpm

[tiff_lee]

Shame the c1j as such a weak valvetrain, the bottom end has got to be good to 10k+rpm
This may sound stupid and I have no idea of the practicality or what the cost involved would be but would it be possible to fit a 16v head onto the c1j block like they do with the A+ series engines in minis?

[Rob@Backyardracing]

would it not be worth getting the car on the rolling road
then look at your graph where the power starts to tail off
theres not much point in reving past that as theres little gain to be
had from the extra revs:confused:

:agree: correct completly pointless over reving a motor, but also even if your torq is tailing off, HP will still be made as the engine is still gaining rpm, but the hp will gain at slower rate depending on how fast the torq drops off of course... Also gear ratios is a key roll in all this too as you allways want to pic up peak power again... The more you rev it the more revs it will drop on a gear change and a bigger range of power band you will need to generate to keep the ball going as such and so on etc....

[J$£5GTT]

from the cup manual:

"The valve collets are designed to operate at a maximum of 6500rpm. If this speed is often exceeded we recommend that the collets should be replaced at frequent intervals"

:agree: me an the M replaced one of mine,had a cracked spring retainer and another retainer was being held in place with just barely half a split collet...going to fit a rev limiter as i very sure thats what caused it.

[Sparkie]

This may sound stupid and I have no idea of the practicality or what the cost involved would be but would it be possible to fit a 16v head onto the c1j block like they do with the A+ series engines in minis?

a few years ago there was a guy on here from america, who claimed that he was working at putting a suzuki swift head on a c1j block. didnt go anywhere and he disappeared.....

[Ian S]

would be but would it be possible to fit a 16v head onto the c1j block

Why bother?

You'd have to block up the old cam's oil ways.
Get the head bolts through without damaging anything or make good all the damage.
somehow get drive to the two new cams.
Do something about the water pump and getting the water through the head and block.
Drive the alternator.
Much else I expect.

Or

You could just throw in an existing 16 valve engine that will be better designed, eg, with oil spray under the pistons.

[Spooky]

Exactly Ian, F4R FTW :D

[tiff_lee]

Why bother?

You'd have to block up the old cam's oil ways.
Get the head bolts through without damaging anything or make good all the damage.
somehow get drive to the two new cams.
Do something about the water pump and getting the water through the head and block.
Drive the alternator.
Much else I expect.

Or

You could just throw in an existing 16 valve engine that will be better designed, eg, with oil spray under the pistons.
Why bother? don't ask me i'm not going to do it, I was merely asking if anyone had tried it since it was commented on that the valvetrain was the weak link and seeing as people put 16v heads on 1380 a series engines I assumed it was a possibility.

[Mart]

a few years ago there was a guy on here from america, who claimed that he was working at putting a suzuki swift head on a c1j block. didnt go anywhere and he disappeared.....

:laugh: Craig wasn't it? Another failboat...