Have read a few threads regarding compatibility of hydro bottoms and solid heads, bu none seemed to draw the conclusion I was after

So, will a solid lifter head go onto a g40 bottom end without faffing about with the oil and water channels etc?

what are you doing now LOL :)

It sure will. Not the other way around though, Putting a hyrdo head on an originally solid lifter head'ed bottom end will cause oil starvation due to an in-sufficient oil pump.

A mechy head'ed G40 would be a pretty good way to go.

One thing though, the mechy heads have the combustion chamber in the head, so putting a g40 bottom end on say a HK head would equate to a very low and un-useable C/R

You would have to either use a non-g40 bottom end, best bet would be a 3f or ABD as these will get you the most power.

Nice idea

Bum. I liked the idea of a solid head to achieve higher revs. Hmmm, and way to get around the low CR? I have the g40 bottom end sat doing nothing atm.

How about flat headed pistons to raise the CR back up? Are there any standard pistons that fit the G40? (i.e. how does the g40 acheieve the 1341cc capacity over the 1275cc? Is it piston crown/stroke/bore?)

Oh and harris.racing, i was going for a solid headed g40 turbo. Maybe in a scirocco or golf mk1 cab now the Falcon is dead

The standard capacity of a PY engine is 1272cc , 1341cc is overbore or a different block i thought?

overbore and bigger pistons usually accralite or forged

low compression? MORE BOOOOOOST

Potentially, but off the boost it'll be undrivable.

Aha, I always suspected the G was the same as standard 1.3. How is the CR reduced to run boost, but the capacity maintained at 1.3?

C/r has no direct link to capacity. The g40 has a larger volume combustion chamber, giving a smaller ratio. This is down to the pistons.

Have you read up on compression ratio?

This would not be a good idea using a G-lader on a 65mm pulley

It is do-able though, even a flat faced solid lifter cylinder head out there. Just needs slight modification to fit. Someone on here has a solid lifter 3F engine :-) Personally, I would fit a 16V head if going turbo though. Bit more work/cost, but a lot more benefit for performance scope.

Potentially, but off the boost it'll be undrivable.

Aha, I always suspected the G was the same as standard 1.3. How is the CR reduced to run boost, but the capacity maintained at 1.3?

man up! lol, if it was turboed imagine the surge of power youd get at a certain rpm. hahha would be fun!

You'd be making about 20hp with the CR that low.

Have read a few threads regarding compatibility of hydro bottoms and solid heads, bu none seemed to draw the conclusion I was after

So, will a solid lifter head go onto a g40 bottom end without faffing about with the oil and water channels etc?

I want to do the same thing as you. You can get flat bottom solid lifter heads from a couple of certain polo models, and they'll bolt straight onto a G40 bottom end with no change to the combustion chamber. But I am wondering about what solid lifter camshaft would be suitable to use? Because it would be good if there were a factory cam which would be suitable for use with boost, rather than having to go about getting a custom one ground up...

16v KR distributor fits into the solid lifter heads, and has a hall sender plug which the G40 loom would plug straight into. The only other issue is the cambelt.

Gaz on here has managed to swap his bottom pulley to convert his ABD/Solid lifter head engine to square tooth, or the other possibility is to make a custom cam pulley to convert the whole engine to round tooth.

Anyone have any knowledge about suitable cams for a Solid lifter head on a G40 engine?

Cheers,

Arun

Edited 15 July, 201115 yr by Phataz1

Newman cams offer solid lifters. I assume for use with their cams in hydro heads.

I've heard that the solid lifter heads have smaller valves and ports than the 1.3 hydro heads.

Edited 15 July, 201115 yr by varnish

What code is that then arun? this has interested me as well now , however, i would probably just use a normal non-PY bottom end for budget reasons, they can handle a bit of boost no problem as tommo proved. Using a solid lifter head with the combustion chambers around the valves, giving me a suitable CR, would have to calculate it however...

Another good reason for using a non-PY bottom end is that you can already get it in square tooth form such as the MH and 2G.

Regarding camshafts, as far as i'm aware on tommo's he used a normal ABD component?, If that's the case then i would just go for maybe a GK cam?

The ABD camshaft is the same as the 1.3SPI engine found in mk3's, and by all accounts is nothing special. So it you should be able to see decent power with a pretty mild camshaft.

Also, the 268/268* newman camshaft i'm using at the moment is actually intended for a G40 or G40T but works well in normal N/A applications so they must be quite compatible.

C/r has no direct link to capacity. The g40 has a larger volume combustion chamber, giving a smaller ratio. This is down to the pistons.

Have you read up on compression ratio?

Yeah, the ratio between the volume at tdc and (I guess) bdc. Therefore the CR must be related to the volume/stroke etc to maintain it. I'm struggling to find the words to explain what I mean right now, but I'll accept I may have it wrong.

But 16v turbo does sound very interesting, not something I had considered. Ate these heads flat bottomed?

Also, the 268/268* newman camshaft i'm using at the moment is actually intended for a G40 or G40T but works well in normal N/A applications so they must be quite compatible.

Actually the other way around! The 268° deg cam and similar items in their range are designed for the N/A Polos, but it just so happens that N/A cams work fairly well in turbo'd cars - and the 268° is a good match for a K03 turbo on a G40 engine. Put one on a G-lader powered G40 though and it'll be a sack of shit.

Tommo used a gt cam i think

I have a mk2 solid lifter head on an ABD bottom end, the square tooth pulley for the crank is a late mk2/early mk3 item (just prior to the changeover to round tooth). I have had bigger valves cut as the inlet valves are smaller (34 vs 36) ports are the same or at the least very very similar. exhaust valves are the same.

The flat mech heads are fitted to HK (83-85 1272cc) and GL (81-85 1043cc) engines.

As said above the KR dizzy has the right distributor drive to fit the mech head as well as the correct trigger wheel spacing to run GT or G40 management.

The only custom thing I've had to do to run mine is drill and tap the thermostat housing for a blue temperature sensor. For this I had to find a threaded temperature sensor. Some vauxhalls from the early 90s use the right type of sensor with the correct plug for the polo loom.

finished article:

List of factory mech head cams:

http://www.clubpolo.co.uk/forum/index.php?showtopic=67971

I think some of the pov spec mech head cams run no valve overlap

C/r has no direct link to capacity. The g40 has a larger volume combustion chamber, giving a smaller ratio. This is down to the pistons.

Have you read up on compression ratio?

Yeah, the ratio between the volume at tdc and (I guess) bdc. Therefore the CR must be related to the volume/stroke etc to maintain it. I'm struggling to find the words to explain what I mean right now, but I'll accept I may have it wrong.

But 16v turbo does sound very interesting, not something I had considered. Ate these heads flat bottomed?

That's how it seems,

But the displacement of a piston engine is measured from the total volume covered by all pistons in 1 cycle. So thats just the bore multiplied by the stroke.

Difference in combustion chamber volume therefore has no link to displacement, it only effects the maximum pressure caused by the compression. The higher the ratio, the higher the pressure.

I'm sure you know this, just getting a bit carried away

Edited 15 July, 201115 yr by MaxMax

Also, the 268/268* newman camshaft i'm using at the moment is actually intended for a G40 or G40T but works well in normal N/A applications so they must be quite compatible.

Actually the other way around! The 268° deg cam and similar items in their range are designed for the N/A Polos, but it just so happens that N/A cams work fairly well in turbo'd cars - and the 268° is a good match for a K03 turbo on a G40 engine. Put one on a G-lader powered G40 though and it'll be a sack of shit.

Are you sure?

I ask because when i purchased it, the spec sheet stated it was for turbo g40 engines, and when i asked they said exactly what you have quoted.

It's designed for F/I but works well in N/A

Yeah, I've had a few now, so I'm struggling for the best way to explain what I mean. Regardless, 1.3 16v turbo sounds fun. Do the afh heads fit the 1.3 bottom ends?

I think some of the pov spec mech head cams run no valve overlap

Is this what is required for using a G-lader Gaz?

Cheers for the additional info

Ahhhh, just had a think about what you said maxmax, is that the def of capacity then: distance travelled by all 4 cylinders in one stroke? Makes sense then how CR is not related. Tanks for that, clears a lot of things up

I think some of the pov spec mech head cams run no valve overlap

Is this what is required for using a G-lader Gaz?

Cheers for the additional info

I believe so, I seem to recall a discussion years ago that talked about similar issues that went along the lines of too much overlap just means the boost goes straight through the engine, while on a turbo this is less of a problem as it helps spool the turbo. I'll admit I don't know alot about the subject but thought I'd mention it anyway. :)