30 replies to this topic

[Guess-Works.com]

Pistons are different because of the longer stroke of the crank, this is only the pin to crown height otherwise the pistons would come out of the top of the block. Apart from that the 1098 and 998 are pretty much the same..

 

The original 1098's ran a slightly different head (12G202) but the last of the 1098's ran the same head as the 998 in A+ format.

[Cooperman]

The basic design is the same, but the stroke of the 1980 is much greater. Big end and main bearing diameters are the same.

 

Consequently the 998 is capable of revving much higher without risking exceeding the crankshaft limit.

 

Revs make top end power, capacity makes torque. That's a simplification, but it gives an idea.

[Fozz]

So concrete, the only difference is the piston? There is no difference between both cranckshafts and conrods? am i correct guys? Many thx for the help.

[Cooperman]

To get a longer stroke requires a different crankshaft. If the 'throw' of the crankshaft was not greater, there would be no increase in capacity.

Con-rods are different too.

 

Best bet is still a 998 bored to +0.080" giving 1060 cc.

[Guess-Works.com]

1098 and 998 share the same conrod, the piston has a shorter pin to crown height

[Fozz]

Hmm, cooperman says...conrods are different too....guess works says they share the same

so the main difference will be the cranckshaft and the pistons?

No pics possible about the pistons and cranckshaft difference?

[Cooperman]

Yes, my error, not rods, it's pistons which are different plus, of course, the crankshaft which looks similar but has a much longer 'throw'.

Not a lot of point in having photos as they do look similar. Just some dimensions change to give the increased capacity of an additional 25 cc swept volume per cylinder.

[Fozz]

Ok guys...same conrods, but different pistons and cranckshaft...many thx for the help and reply!

[Langers#56]

Is it "Possible" to Build a 1098CC Engine from a 998? as over the life of my car, Someone has done an engine swap and there is no engine number on the Block?

as I would be looking to do Straight Cut Gears also?

[Cooperman]

A straight cut box would be a mis-match with a 1098. The 1098 is a low-revving engine due to the crankshaft limitation but it gives a wide torque band. That SC box is for high revving engines with a narrow torque and power band. A 1098 needs the standard wide ratio gears with a high FDR

[Spider]

They also had different Camshafts, the 1098 had a slightly longer duration.

[timmy850]

Is it "Possible" to Build a 1098CC Engine from a 998? as over the life of my car, Someone has done an engine swap and there is no engine number on the Block?

as I would be looking to do Straight Cut Gears also?

Yes, they have the same block, so very easy to put a 1098 crank and pistons in. 

[G'Racy]

Interesting. If an increase in torque is your goal at say 2000 - 5000 revs rather than increased bhp at 6000 - 7000 revs is it better to stroke it or overbore to 1060cc? what if you stroke it and overbore, I already have a 12g295 head (skimmed to suit 998cc) and a SW5 cam, how would these suit if I stroke my engine to 1098?

[Cooperman]

If you bored to 0.060" and fitted a 1098 crank you would have around 1160cc. With an sweet & a 295 gas flowed head with bigger inlet valves it would be a high-torque engine. You would need a good inlet &exhaust system.

[Langers#56]

If you bored to 0.060" and fitted a 1098 crank you would have around 1160cc. With an sweet & a 295 gas flowed head with bigger inlet valves it would be a high-torque engine. You would need a good inlet &exhaust system.

Could you do Straight Cut gears with this, your gonna have to slow down a bit. I've got some engineeering knowledge what is a 295 gas flowed head