[G's LJ80]

Hi guys I'm new to this forum stuff and was hoping someone could tell me if i can convert my F8A 797cc motor from my LJ80 into a F10A 1000cc but I still want to keep the original block? can it be done and how? can I just replace the head? also would it need to engineered to get it registered?
Sorry I'm not overly mechanically minded but i do pick things up pretty quick
cheers

[2stroker]

You can fit an F10a but you can't make an F8a into an F10a. The block is taller in the F10a as the stoke is longer. Where are you located.

[scottiej]

I had this discussion with someone on lj10 about this, we didn't physically measure the block height but the different stroke looks like it's actually achieved with the Conrods and pistons so it should be possible.

http://www.lj10.com/forums/viewtopic.php?f=5&t=6777

[G's LJ80]

Cheers I can't read that page as I'm not a member. I'm located in kalgoorlie wa. Iv looked around abit but I'm thinking maybe il just keep it all original the car is complete just in bad shape so it's going to take a lot of tlc haha and looking for bits and pieces to replace! Would anyone know what kind of top speed you get out of a 787cc motor?

[2stroker]

This info is from an old post.

F8A - 797cc, bore 62mm, stroke 66mm
F10A - 970cc, bore 65.5mm, stroke 72mm

The heads are interchangeable, the combustion chamber size difference is negligable however the valves and ports are bigger in the F10A head, the F10A block is taller than the F8A block to allow for the longer stroke.

[UBZ]

Quote:

Searching the web i found the compression heights for the engines

F8a piston compression height is 27.5mm
F10a piston compression height is 24.5mm

So with the longer stroke of the F10a being 6mm and that would make the piston be 3mm higher at the top of the stroke Suzuki
has lowered the compression height of the F10a piston by 3mm to keep the block at the same height as the F8a

The blocks/heads are the same height .
I measured as well to make sure it was ok to use a F8a for mockup work in place of a F10a

[G's LJ80]

Ok thanks guys but I'm thinking of maybe keeping it original with the 797cc motor would anyone know what the top speed of these are? I'm located in kalgoorlie wa

[sideways]

2stroker wrote:

The heads are interchangeable, the combustion chamber size difference is negligable however the valves and ports are bigger in the F10A head, the F10A block is taller than the F8A block to allow for the longer stroke.

I measured all this up the other week to see if there is any advantage to using an F10a head.

Inlet valves are 31.6mm on both.

Exhaust valves are 27.7mm on both.

On both the inlet ports measure 23.7mm diameter, measured inside the port past the machined bell.

Exhuast ports are 24mm wide x27.5mm high, measured on the gasket face.

Cams appear to have identical profiles, the rockers are identical and the rocker shaft spacing is the same.

The combustion chambers are pretty much the same except the F10a heads (or at least my F10a heads) have a machined cut about half a mm deep that matches the bore. F8a heads have this cast in to match their bore. I don't think there's actually any difference in the combustion chambers aside from that, if you measure the distance from the rocker cover surface to the head gasket surface and take that difference into account (to account for machining ect) than the chamber depth varies a very small amount. The 2 piece (F8a) heads in scottiej's post on LJ10.com have been skimmed (IMO), hence the perceived difference.

Both blocks measure the same height, 223mm. I've got some rods kicking around somewhere, I'l measure them up if I find them.

As far as I can tell there is no performance advantage (or disadvantage) to using and F10a head over an F8a one. The only difference is the front oil seal housing and the cut for the bore size. Of course the F10a/1l sierra exhaust manifold is about 8000000000 times better designed (being a 4-2-1 design, like most extractors) but it doesn't fit in an LJ (chassis in the way, if you merged it early like a Maruti does for the cat converter then you might get away with it, I can't remember how much clearance there was though). Both engines breathe through a 32mm carby. The carbs have different venturi designs but I think the surface area is roughly the same.

I've read a number of times you can convert an F8a into an F10a, I don't know if I'd trust an engine with a 3.5mm overbore though. 303zuke said LT250f pistons will fit in an F10a, giving some larger over bore sizes and potential for a massive 1.1 litres (huge! ).

Using F10a parts to increase the displacement of the F8a would require an engineers certificate but you would never ever get picked up for it. Putting an F10a in would obviously need an engineers certificate too.

[2stroker]

Sideways, I will have a look on weekend, I am pretty sure that the port difference is even noticeable to the eye. You may be measuring two F8a heads, they both have 800 on the inlet side of the head toward back, an F8a head has a Suzuki style "S" on same side in middle and the F10a head usually has "S 2" but in a normal S not stylised Suzuki "S"

[303zuke]

There was some discussion re the F8A/F10A head differences in THIS THREAD.

The inlet and exhaust valves have the same part numbers, while the inlet manifold and exhaust manifold gaskets are the same, so I would expect identical port sizes. The only difference which is readily obvious is the timing belt cover stud positions near the cam seal opening.

[sideways]

I have 4 heads off engines here, 2 F8a and 2 F10a. I've compared all.

Interestingly, one of those F10a ones is an aftermarket/replacement head. It does have a difference in the exhaust port, there's a lump cast into the lower left corner about half way along (I meant to mention this before!). Other than that, aside from looking like it's cast out of cement it's exactly the same as the other F10a head.

My LJ has a type 3 1l engine in it, I'm pretty keen to pull that apart and see what they've changed over my 2 type 1 engines. With the smoke it blows, that probably wont be long.

What's the difference you mention between the ports?

[Edit:beaten in thread 303 linked]FWIW with the 800 markings, only the 1l (one piece) heads have those. I don't think I've ever seen an LJ head with 800 on it (and certainly, the 3 I have here don't) where as almost every F10a head does. And yes, the 800 marked heads have the machined chamber for the F10a bore size. I'm going to assume it was Suzuki covering our arse for F10a conversions in LJs. [/beaten]

[JrZook]

sideways wrote:

I don't know if I'd trust an engine with a 3.5mm overbore though

When its running I'll tell you how my experiment holds up