higher compression c1j

[redtoplee]

hi guys. I've been offered an engine my mate built a few years ago.
its a c1j its had 1mm skimmed off the block and liners to make the ratio 8.3.its got a 300 piper cam and vernier pulley.uprated valve springs.also has a genuine cup car baffled sump.

what you reckon that would be worth?

also what is the advantage of raising the compression? because i understand that a standard bottom end can go over 200bhp anyway.

lee

[michael tierney]

the higher compression raises the low down torque(makes the engine more efficient)the snag is when u turbo charge it .....because of the AEI unit(std ignition curve) it will pink or detonate earlier ,unless you can find some way of controlling it....mappable ignition....water injection....so if your running a carb you're better off with the standard compression......or very near it!

[redtoplee]

the higher compression raises the low down torque(makes the engine more efficient)the snag is when u turbo charge it .....because of the AEI unit(std ignition curve) it will pink or detonate earlier ,unless you can find some way of controlling it....mappable ignition....water injection....so if your running a carb you're better off with the standard compression......or very near it!

thanks for the info...
but what sort of power would it start pinkin? would u have to run as much boost to get the same power from a standard compression engine?

lee

[redtoplee]

what i mean is. I've just brought a proven 230 bhp engine. its standard compression but a rebuilt bottom end with a piper 285 cam..its got a t28 blah blah blah.
but if i was to also purchase this other higher compression engine and stick the t28 etc from the proven 230 bhp engine would i be better or worse off?

lee

[michael tierney]

what i mean is. I've just brought a proven 230 bhp engine. its standard compression but a rebuilt bottom end with a piper 285 cam..its got a t28 blah blah blah.
but if i was to also purchase this other higher compression engine and stick the t28 etc from the proven 230 bhp engine would i be better or worse off?

lee

if you put the t28 on to the higher compression engine it will detonate sooner.....so you'll be worse off!.....the 230bhp engine can produce this power because it has standard compression.the higher compression engine is more than likely only higher because it overheated at some stage and the head had to be skimmed(overskimmed)

[redtoplee]

if you put the t28 on to the higher compression engine it will detonate sooner.....so you'll be worse off!.....the 230bhp engine can produce this power because it has standard compression.the higher compression engine is more than likely only higher because it overheated at some stage and the head had to be skimmed(overskimmed)

my mate said it was skimmed off the block and liners.the head is unskimmed.:confused:

[Ian S]

Big Jim Racing did, possibly started, the block skimming. AFAIK, he was the only one doing it. Many of those cars ran mappable EFI and at least one made nearer 280BHP or so without NOS. Another over 240BHP, and that was with a carb and OE Renix ingition. They weren't simply a skimmed block and liners, quite a bit more to it.

I drove the latter and it was very linear, like a non turbo engine (also, it had a VNT), but went a bit faster than my T28, etc, setup, doubly especially off boost, that was it's strength, it could pull a car or two's length on my car whilst I was trying to find the grip and control the wheel spin.

[turbo ted]

That was ms Motorsport trick that big jim or ctm done for ms skim the block and machined the head too so pistons went up into the combustion camber in the head, all engines where setup with t28 turbos and vnt turbos with carbs so it can be done;)

[philr5t]

I can't really see 280hp being achieved on a h/comp engine especially with a carb and the standard coil pack? Efi most definitely but it still will need a large turbo to make 280+ hp

[redtoplee]

so this could be a possibility for me then. if i buy this engine with the 300 cam,stick on all the other stuff i have from the 230bhp engine.maybe it will lose some of that lagg. :rolleyes:
I'm not looking for more horse power doing this.its also just a newer built engine..

[Ian S]

To find out:
Are the pistons dished,
Do the pistons protrude? How far?
Was it really a whole mm skimmed of the block and liners? Who did it? If you crack a liner it'll need to go back to them for the whole thing to be done again to get the new liner to match.

If they actually do protrude, you'll have to be especially careful with the head gasket or the pistons will hit it somewhere.

Can you be sure about the rest of the assembly? New seals and fitted cleanly? Crank wear? Bearings, etc. Oil seals and cranks wear? Oil pump.

8.3 is not a high ratio. I think the Big Jim ones were more like 9:1 or 9.5:1.

[redtoplee]

Standard compression c1j
73.5mm cylinder head with piper valve springs
285 piper cam dialled in at 113 degrees.
Adjustable timing pully
Fettled carb
Campus crank pully and alt belt
Large front mounted intercooler
Simplified vac pipe and breather set up
BMS downpipe
Full 2.5 inch exhaust system
Efi fuel pump
Rising rate malpassi fuel regulator.

if i was to swap the the standard compression engine (spec above) and stick in this higher compression lump with this spec,would it be any good?

lee

[James5]

Standard compression c1j
73.5mm cylinder head with piper valve springs
285 piper cam dialled in at 113 degrees.
Adjustable timing pully
Fettled carb
Campus crank pully and alt belt
Large front mounted intercooler
Simplified vac pipe and breather set up
BMS downpipe
Full 2.5 inch exhaust system
Efi fuel pump
Rising rate malpassi fuel regulator.

if i was to swap the the standard compression engine (spec above) and stick in this higher compression lump with this spec,would it be any good?

lee

I ran a similar spec MSM engine some years (heavily skimmed head) back on a VNT turbo and it would heavily det at anything over 24 psi of boost, I had to retard the TDC sensor (retarded the ignition). if I left it in std position it would det and H/g would fail within a few mile's done that twice.
Ideally if you are wanting to run the Higher comp engine you are going to need a decent ignition map as the AEI is a generic ignition curve that us GTT owners have got away using on a variety setups but it's very risky so mappable ignition is the way forward.

From memory I made 199bhp @16psi on my MSM high comp engine and that was with a bad setup, water injection dampening spark and a heavily overfueling carb. Ended up ditching the water spray, ditch the large venture carb to a std but custom carb and was running 24psi manifold and the car was much much quicker just never got it RR again.

[Matt Cole]

I know the French have done an adjustable Renix AEI module? Info on here.:)

[Trevhib]

I know the French have done an adjustable Renix AEI module? Info on here.:)

Thread here:
http://www.rtoc.org/boards/showthread.php?t=32249

Advert here:
http://www.rtoc.org/boards/showthread.php?t=35618

I think the general consensus was that these are awesome but quite expensive.

I wonder if Sebastien (Xenon), is still doing them or how things have developed over the last 18months? I can see he's still a member. :agree:

[Fordy]

Modern turbo engines run N/A compressions.

Look up the vag 1.4tfsi. Small turbo and huge compression.

a compression of 8.5:1 would be a nice simple setup, shame we can't buy forged Pistons with that ratio :(

The Aei needs ditching works well.... But it's the 21st century now. a simple MS2 megasquirt or adaptronic ecu will make your car amazing and upgradable in the future.

[philr5t]

Mine is a h/comp set up cammed with a Vnt running Efi strong engine all forged with steel liners and mad 309hp@32psi it also made 217hp@12psi and is quite a handful to keep in a straight line, I did manage to blow a metal head gasket though and this could of been due to a turbo spike or lack of clamping on the cylinder head. It's since been running 27psi and there has been no issues but running really rich, plans are well under way at the mo to run more boost with less wheel spin and hopefully some extra power will be found, can't beat loads of power out of a 1.4 with no gas got to love the little c1j

[redtoplee]

Do u think I could use this higher compression engine? Or keep the standard compression engine? But 1 day I will probably introduce efI. When I learn more about it and what it costs:crap:

[Ian S]

It seems a bit like you need some local, hands on, help, advice, guidance or this engine swapping might not work for you.

Yes it might all bolt together and run, but it might detonate to bits on first hard use. Or run very badly, or leak oil everywhere. or run so rich that fuel gets past the pistons into the oil and wears out the turbo bearings in a few miles. Or metal particles get into the turbo bearings and wear them out in a few miles because the engine was not clean internally.

There are many things that can go wrong with modified engines, never mind very modified high boost, and usually do when not under the guidance of a competent engineer.

You need to find out exactly what your buying.

It sounds a bit like you're just relying on optimism and luck to get it working. Never mid working well.

My advice is that you find a competent engineer or business to help you, or read all the books and learn all the maths so you can do it yourself.

These forums are good for maintenance and small modifications. But you're proposing something far beyond that. You need to perhaps get the bottom end up to Scoff, or someone like that, and pay him to take it apart, inspect and de-bodge it, put it together and make sure it all works, then fit EFI and map it.

[Trevhib]

:agree:

[redtoplee]

It seems a bit like you need some local, hands on, help, advice, guidance or this engine swapping might not work for you.

Yes it might all bolt together and run, but it might detonate to bits on first hard use. Or run very badly, or leak oil everywhere. or run so rich that fuel gets past the pistons into the oil and wears out the turbo bearings in a few miles. Or metal particles get into the turbo bearings and wear them out in a few miles because the engine was not clean internally.

There are many things that can go wrong with modified engines, never mind very modified high boost, and usually do when not under the guidance of a competent engineer.

You need to find out exactly what your buying.

It sounds a bit like you're just relying on optimism and luck to get it working. Never mid working well.

My advice is that you find a competent engineer or business to help you, or read all the books and learn all the maths so you can do it yourself.

These forums are good for maintenance and small modifications. But you're proposing something far beyond that. You need to perhaps get the bottom end up to Scoff, or someone like that, and pay him to take it apart, inspect and de-bodge it, put it together and make sure it all works, then fit EFI and map it.

Thanks mate. Will have to do that.