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Pinto compression ratio
brianm - 20/4/03 at 09:04 PM

I'm building a Lowcost with a 2 litre pinto engine, which will run on fuel with a RON (octane) of about 115, so I want to increase the compression ratio (and adjust timing ) to take advantage of this. Any Pinto experts here, or can anybody point me to an appropriate group, that can tell me, i) what kind of CR I can go to with 115 RON without pinking, and ii) how much can be safely shaved from the surface of a standard 2 litre head,giving me what sort of ratio? I understand the 1600 head has a smaller combustion chamber, but does it have smaller ports and valves as well?

Stu16v - 21/4/03 at 12:02 AM

quote:

I'm building a Lowcost with a 2 litre pinto engine, which will run on fuel with a RON (octane) of about 115,


115? My local garage sells super-unleaded with an octane rating of 97. Do you live next door to an alcohol factory?

Kin 'ell, good old 5 star was only 100 octane IIRC....

Can you get us some????

[Edited on 21/4/03 by Stu16v]

CairB - 21/4/03 at 08:37 AM

There's a guide in David Vizards book - How to Modify Ford O.H.C. Engines (IBSN 0 86343 0856). At 115 octane your off the graph and looks like a CR in excess of 15/1, other factors influence.

brianm - 21/4/03 at 09:24 PM

quote:
Originally posted by Stu16v
quote:

I'm building a Lowcost with a 2 litre pinto engine, which will run on fuel with a RON (octane) of about 115,


115? My local garage sells super-unleaded with an octane rating of 97. Do you live next door to an alcohol factory?

Kin 'ell, good old 5 star was only 100 octane IIRC....

Can you get us some????

[Edited on 21/4/03 by Stu16v]

brianm - 21/4/03 at 09:41 PM

quote:
Originally posted by brianm
quote:
Originally posted by Stu16v
quote:

I'm building a Lowcost with a 2 litre pinto engine, which will run on fuel with a RON (octane) of about 115,


115? My local garage sells super-unleaded with an octane rating of 97. Do you live next door to an alcohol factory?

Kin 'ell, good old 5 star was only 100 octane IIRC....

Can you get us some????

[Edited on 21/4/03 by Stu16v]


Sorry about the post below - hit the wrong button.
The 115RON fuel, which I already use in two saloon cars, is readily available throughout the UK at about 1200 outlets, and costs about half as much as that expensive 95 odd octane stuff that I suspect most of you use. It's called Autogas or LPG. The difference between the Lowcost engine and my other two cars is that they are duel fuel, but the Lowcost will be LPG only, so I can take full advantage of the increased RON. The gas gear comes with it's own ECU and is easy to set up with a laptop and the appropriate software. Much easier than twin carbs or modified fuel injection. Anyone able to answer my queries on the Pinto heads?

bob - 21/4/03 at 09:51 PM

Might be best to have a chat with vulcan engines as they are the main pinto head builder,or even burtons.

http://www.vulcanengines.com

Hope this helps

brianm - 21/4/03 at 10:23 PM

Thanks Bob. P.S. My 3 year old (whom I'm building the Lowcost for) loves your avatar

jollygreengiant - 21/4/03 at 10:51 PM

Why skim a 2.0 head?

All pinto's use the same head and block configuration, the head heights are the same, the water way/oil way configuration is the same. So unless you are using an injection head, why not use a ported, big valve and gas flowed 1.6 head? the logic in this is as follows...... the combustion cambers for the pinto is all in the head so a 1.6 has a smaller combustion chamber than the 2.0. This then takes the compression ratio up from about 9:1 to about 10.5:1. the head face will only need a flash over to clean it up and you will not weaken the casting by removing any serious amounts of metal. The best head to go for is the 1.6GT head as this had 2.0valves & cam as standard.

The beauty of doing it this way is that you can spend all your money on making the head breath right and the compression ratio goes up for free!.

Hope this helps Brian

Enjoy.

brianm - 22/4/03 at 05:52 PM

I was thinking of skimming a 2 litre head because I have one. I have bought a book rolling chassis, with a 2 litre injection engine and box, but the injection manifold is far too high, so I want to ditch that and replace it with a carb manifold fitted with a gas mixer. What's the difference between an injection head and a carb head? Will the carb manifold fit? I don't really want to do any more work on the engine than necessary to make it run on gas untill the car is finished and SVA'd.Enough to get on with with the rest of the car, although something like a head swap would be OK!

theconrodkid - 22/4/03 at 05:56 PM

if you want to get rid of the injection inlet manifold,i want 1,chopped mine a tad too much

jollygreengiant - 22/4/03 at 08:00 PM

Injection heads are better gas flowed heads, but the head to inlet manifold ports are pear-shaped to allow for the injectors in the manifold and to give the as straight a shot at the back of the valves as possible. On carb heads the ports on the inlet side are all round. Generally manifolds (although some would argue otherwise) are not interchangeable between the carb and injection because of likely air leaks. However thereis a company that makes an adapter plate to allow carbs on an injection head ( I believe about £80 - see previous posts).

If you skim the head, then technically you lower the head (and thereby Camshaft) in comparison to the block. This will slightly alter the cam timing so you should theoreticaly have to buy a vernier cam kit to set the timing right. If you wan't to do it on the "cheap" then it could be argued that to replace the head with a Carb 1.6GT head would be the cheapest option. Generally the heads don't need skiming just the head face cleaning. Get the valve guides & seats sorted, have the spring seats lowered & modified to take the later CVH type oil seals, double valve springs with the head seats lowered to allow for a higher lift Cam. Put it all together with a std (or mild/fast road cam if funds permit) and enjoy. If funds permit a bit later the camshaft can be replaced with a faster cam cos the head is ready to take it. Also youv'e still got your injection head to keep or sell on as you see fit.

I hope this helps.

Enjoy.

brianm - 24/4/03 at 11:05 PM

quote:
Originally posted by theconrodkid
if you want to get rid of the injection inlet manifold,i want 1,chopped mine a tad too much

Sorry, don't want to get rid of it just yet untill I've sorted out exactly what I'm doing manifold wise. Your post on chopping your manifold intrigues me. Anyone care to elaborate on how this can be done and what it ends up like?

speedthing - 27/4/03 at 01:07 PM

1.6 pinto heads do differ slightly from the 2.0 best thing to do is check the 2.0 head gasket with the 1.6 head i think some of the water ways and poss oil differ slightly
2.0 fuel injection heads can be interchanged with carb manifolds you just use the carb manifold gasket i have done this on my 2.0l capri used the old twin webber and left in the fuel injection cam with no probs and ran it on unleaded with no mods to the timing ran it for 30,000 miles before i sold it and it pulied like a train under acceleration so it can be done!

[Edited on 27/4/03 by speedthing]

theconrodkid - 27/4/03 at 01:18 PM

brianm,look at cairb,s site there are pix of how to do it properly

sg_frost - 28/4/03 at 10:12 PM

thought fitting a gas conversion to a car was expensive, if so, why are you worried about spending a bit on the head to get it right????

jollygreengiant - 29/4/03 at 07:04 AM

quote:
Originally posted by speedthing
1.6 pinto heads do differ slightly from the 2.0 best thing to do is check the 2.0 head gasket with the 1.6 head i think some of the water ways and poss oil differ slightly
--------------------------
Nope I've been down this road & done it. 1.6 heads same size as 2.0, only difference is on combustion chamber size and valve sizes, unless its a 1.6 GT head then the vavles are the same as 2.0. The heads bolt straight on and it takes the compression ratio up to 10.5/11:1, but you do need to get the head ported a bit to make the most of it. Went like sh*t of a sh*v*l on twin 40's(MK3 2.0 Estate).
------------------------

2.0 fuel injection heads can be interchanged with carb manifolds you just use the carb manifold gasket i have done this on my 2.0l capri used the old twin webber and left in the fuel injection cam with no probs and ran it on unleaded with no mods to the timing ran it for 30,000 miles before i sold it and it pulied like a train under acceleration so it can be done!
----------------

Had this argument before in previous posts my only comment is that you were lucky.
------------------

[Edited on 27/4/03 by speedthing]


The way that I looked at it is you want to up compression that means replacing head one way or another, either way, unless you get an exchange head, you should be thinking about valve guide replacment and valve seat recuting/replacement, so after that a set of valves and valve springs are not that expensive and it just makes sure that your new/replacement head is right, technically the the only extra(s) on the job would be any porting and spring seat height adjustment/modification and if that is done with at guide replacement then the cost should be negligible.
Enjoy

speedthing - 29/4/03 at 06:21 PM

i have also done the 1.6 head thing on the 2.0l block i found that the 2.0l head
gasket and i think the water ways overlaped slightly so i had to open them
out slightly to match the gasket
the 1.6 head goes well on a 2.0l block
if you plane the 2.0l head by 1.5mm
you should get 10.2:1 which isn't bad
just make sure that the head is at standard thickness first
as for the inlet gasket this has been done to 3 other pinto engines in the local club
the trick is to make sure that the inlet manifold is perfectly flat and use the genuine ford gasket for the carb inlet maifold as the injection one overlaps the
outer edge of the carb inlet manifold
also the new ford gaskets come with silcone seal on also this head mod has been done on hundreds of capris in the
cci and no one has used that adapter as
far as i know

brianm - 29/4/03 at 11:06 PM

quote:
Originally posted by sg_frost
thought fitting a gas conversion to a car was expensive, if so, why are you worried about spending a bit on the head to get it right????

A basic LPG system will cost me about £250 or £360 with an ECU controlled, laptop set up system. Offset the cost of ally petrol tank, lockable filler cap, twin Webbers, etc., and it doesn't cost that much. Then, of course, half price fuel every time I fill up, and no emissiions problems at MOT.
It's more a time thing than not wishing to spend money on the head at this stage - want to get the thing finished and SVA'd.Might ditch the Pinto for something lighter then anyhow.

david walker - 30/4/03 at 09:19 PM

Something odd about an LPG Se7en. Bit like the diesel ones often talked about but never built. If you've been on the LPG fitting course you'll know not to fit a Zetec later - valve seats will be quickly eaten away!

Not wanting to perpetuate the old carb manifold onto injection head argument, I've done it/seen it done literally dozens of times and luck doesn't come into it. As "speedthing" says, providing you use the correct gasket you won't have a problem.

The reason that 1600 heads are prefered on full blown racers because there is more meat in the ports and combustion chamber to play with when gas flowing. 2 litre heads have too big ports (too slow gas speed) and better flow rates are achieved by modifying 1600 heads.

In restrcited race formulae such as F2 Stockcars, 2 litre Hotods etc, where a 2 litre head must be used then 60 to 80 thou can be safely planed off the head thickness. A vernier timing pulley then however becomes necessary.

speedthing - 30/4/03 at 09:52 PM

thank u mr walker