C1J engine failures above 250hp

[olidaviesuk]

Hi All,

Would just like to pick your collective brains - for all those who have run the C1J over 250hp and had bottom end failures - very interested to know what fails and why, I suspect a substantial amount will be either cracked liner, or det issues from fuelling (or the carbs inability to fuel properly at that power level.) Particulary interested in conrod bolt (or rotating mass failures - and exactly what fails and why - I'm speccing an engine for next season and
am thinking that std rods and pistons will probably be ok with efi at that power level. providing the rods have arp's, but interested to hear how other people have got on.

Cheers

Oli

[Woznaldo]

Oli, I'm no expert, but as you say, most will be cracked liners (bad fuelling). That said, a fair few rods have gone south too. You could probably get away with std on a road car, but be upgrading on a race engine that will be getting the full beans all day long.

[SCHWARTZ]

I wasn't running that much power but a head bolt snapped, looking at the Volvo lump the bolts are huge compared. May be worth fitting bigger head bolts.

[Brigsy]

I hear tales of ring lands failing over 25lb's boos, possibly down to poor setup, who knowt. Ive never had no problems on my own engine though.

I would probably go for forged rods and pistons, as a hell of a lot of boost will be needed to make over 250hp.

[Mart]

Liners, rods, crank & bearings will be fine. Piston ringlands will be the key factor with regards to durability/reliability.

A set of J.E's would be on my shopping list if aiming for that level of power & beyond.

[Brigsy]

Liners, rods, crank & bearings will be fine. Piston ringlands will be the key factor with regards to durability/reliability.

A set of J.E's would be on my shopping list if aiming for that level of power & beyond.

Did you have problems with the original pistons at higher boost levels mart? I can remember talking to somebody about it

[5teve L]

Did you have problems with the original pistons at higher boost levels mart? I can remember talking to somebody about it

Did Mart post ?

[Mart]

Did you have problems with the original pistons at higher boost levels mart? I can remember talking to somebody about it

Aii mate. I've always said, imho & from experience, that Tarabusi pistons were the more durable 'o.e' piston, but at high 20's+ psi boost, even the ringlands on those will eventually collapse.

For sustained reliability, you really need forged pistons at that level & beyond, again, imho.

J.E's + Total Seal rings ftw

[R5MJH]

my 1st tungy 5 ran 25psi boost daily with no probs on standard internals but i wouldnt advise it, but the carb was setup properly, the only time i had problems was when it ran above 25psi, i cracked the liner, blew water pipes off and had head gaskets go almost weekly lol, but in those days perfect circle were mainly used for oe, in mikes build on the current 5 we used tarabusi liners, pistons and rings, and he runs this current @14psi and theres not one drop of oil leaking anywhere, and he thrashs the heck out of it everywhere, we had it briefly upto 20psi with no problems too, as mentioned anything above 20/25 psi is at your own risk lol

[Logg]

Wow are you guys in your race cars really at this sort of power levels. that's really impressive.

I've been playing with 20-25 psi in a road car for a 8-9 years the only fail I've had that can be put down to the engine its self was a dropped valve.

I cracked a ringland but that was due to split pipe on the actuator and unlimted boost. A couple of head gaskets but that was carb tune related. Knocking bottom end but that was lack of oil.

I hope writing that's dont make my engine **** its self now. LOL

[TNT ANDY]

Lol Andy' you keep testing to destruction chap.

[GTphil]

I have had a few engine failures, a dropped valve, and a valve guide that slipped out of the head down the valve stem got smashed up by the valve sending 10 or so bits of metal into the combustion chamber and turbo

I also had a set of pistons from my first engine where bits of the ringlands ended up in the sump, this was more than likely down to a poorly set up carb.

All of the above where whilst the lump was running 22psi +

For that sort of power level you will need some revs, so upgrading the valve train as well as the pistons as best you can would aid reliability imo.

[Alex]

When my engine had it's little moment it was due to a cracker liner. That was at about 22 psi on a 118k engine.

[olidaviesuk]

Interesting stuff - I was expecting cracked liners and dropped valves/valve heads coming off - but really surprised at the lack of rod bolt failures... thought there would have been quite a lot of those happening above 200hp at higher rpm. The ringland failures surprised me mart.. would have expected them - but at a point where the engine was under more stress than at 250hp - probably why martin faulks was looking at the bmw mini cooper piston when he was looking at the C1J in his engine build project... Oil sprays could be handy too given a convenient oil gallery...

[Logg]

I think in the later years of bb turning there engine builds used under piston oil spraying.

[SCHWARTZ]

Maybe utilise the sprayers from the b18ft

[Sparkie]

at higher revs i found that the pistons wore the std liners out at the top and bottom fo the stroke quite quickly.

[Dave Reed]

The thing you've got to look at here oli is the type of use your engine is going o be getting.. Road engines won't always be on the limit with high down shifts etc.

I'd have a good dynamic balance done with some arp's holding it all together. Get a much weight as you can put of the rolling mass.

I'd also look at the valve trian, a set of double valve springs (vauxhall 16v ones fit well . is a must and larger push rods too (ford pre cross flow are a good fit) also enlarge the holes in the head..

Under piston spray is a definate winner also.. Along with a baffled sump Or of money isn't really an object then dry sump it.. I don't know what the standard oil pump is safe to rev to, but I bet 7k is almost its limit.

You also want good quality bearings.

Cam.. I'd go for a custom jobby that gives a nice torque curve as opposed to max power.. Something like the piper 270... With a little overlap as possible..

Some good head work and bigger exhaust valves.. I'd just port match the inlet and open out the exhaust..

It's worth also adding an extra breather to the block too, the old mechanical fuel pump blanking plate is a good place (just make sure you baffle it)

I'd also up the comp ratio too since your on efi, maybe as high as 8.5:1 to 9:1..

Forged pistons is a must imo too.. Also some total seal rings.

I never really had any failures with the efi but by then very thing was uprated including the liners. With the carb I only ever split one liner, but that was running gas at the time so cylinder pressures would of been massively high

[Woznaldo]

The thing you've got to look at here oli is the type of use your engine is going o be getting.. Road engines won't always be on the limit with high down shifts etc.

I'd have a good dynamic balance done with some arp's holding it all together. Get a much weight as you can put of the rolling mass.

I'd also look at the valve trian, a set of double valve springs (vauxhall 16v ones fit well . is a must and larger push rods too (ford pre cross flow are a good fit) also enlarge the holes in the head..

Under piston spray is a definate winner also.. Along with a baffled sump Or of money isn't really an object then dry sump it.. I don't know what the standard oil pump is safe to rev to, but I bet 7k is almost its limit.

You also want good quality bearings.

Cam.. I'd go for a custom jobby that gives a nice torque curve as opposed to max power.. Something like the piper 270... With a little overlap as possible..

Some good head work and bigger exhaust valves.. I'd just port match the inlet and open out the exhaust..

It's worth also adding an extra breather to the block too, the old mechanical fuel pump blanking plate is a good place (just make sure you baffle it)

I'd also up the comp ratio too since your on efi, maybe as high as 8.5:1 to 9:1..

Forged pistons is a must imo too.. Also some total seal rings.

I never really had any failures with the efi but by then very thing was uprated including the liners. With the carb I only ever split one liner, but that was running gas at the time so cylinder pressures would of been massively high

I think these mods are pretty sensible and I'll again agree that a race engine is a different kettle of fish. While on a road car the std Rods and Pistons may survive just fine and on the occasional drag run, the sustained high rpm high boost abuse will take it's toll and 250bhp is probably the safe limit on a road car.

There is the added advantage when running forged pistons and H sect rods, there will be less rotating mass and therefore less loads on the bearings (boost load aside). I'd go with some ARP bolts too. It may be over kill, but I'll bet the increased safety margin will be worth it.

Running higher comp ratio will give you better throttle response, allow you to run lower boost for the same power and therefore keep the charge temps a bit lower.

I didn't even think about under piston oil spray, but again for longevity it's probably a good mod. I couldn't say if you'd need to up the flow volume with a different Oil Pump when using spray, but it's possible.

An Electric Water Pump might provide a more constant temp and remove the fan belt issues?

H Sect Rods GBP500
Forged Pistons GBP500
Under Piston Oil Spray GBP???
Head Work GBP750

You pays your money and makes your choice.

[olidaviesuk]

Good shout Dave - at the moment i'm in a halfway house spec - with a heavily spec'd top end - steel valves etc etc.......baffled sump and a few trick bits done to the bottom end too. But have been debating just how far to take things with the bottom end - theres been some really useful info in this thread - in an ideal world you'd have a complete steel bottom end - but not much change from £2k if you do that...

Quite interesting about the cam - I've got a catcam 320 kicking around that I might try as a comparison..

The thing you've got to look at here oli is the type of use your engine is going o be getting.. Road engines won't always be on the limit with high down shifts etc.

I'd have a good dynamic balance done with some arp's holding it all together. Get a much weight as you can put of the rolling mass.

I'd also look at the valve trian, a set of double valve springs (vauxhall 16v ones fit well . is a must and larger push rods too (ford pre cross flow are a good fit) also enlarge the holes in the head..

Under piston spray is a definate winner also.. Along with a baffled sump Or of money isn't really an object then dry sump it.. I don't know what the standard oil pump is safe to rev to, but I bet 7k is almost its limit.

You also want good quality bearings.

Cam.. I'd go for a custom jobby that gives a nice torque curve as opposed to max power.. Something like the piper 270... With a little overlap as possible..

Some good head work and bigger exhaust valves.. I'd just port match the inlet and open out the exhaust..

It's worth also adding an extra breather to the block too, the old mechanical fuel pump blanking plate is a good place (just make sure you baffle it)

I'd also up the comp ratio too since your on efi, maybe as high as 8.5:1 to 9:1..

Forged pistons is a must imo too.. Also some total seal rings.

I never really had any failures with the efi but by then very thing was uprated including the liners. With the carb I only ever split one liner, but that was running gas at the time so cylinder pressures would of been massively high