Escort Sigma 1600 Race Car

[Roadsport]

Re: Escort Sigma 1600 Race Car

Looks better with carbon than with cardboard
Looks like an rwd engine now.

[Roadsport]

Re: Escort Sigma 1600 Race Car

The true trac converts the torque to the wheel with best grip. At a race trac it means it wil apply the force to the outer wheel rather than try and spin the lighter inner wheel.

But as Graham stated it requires both wheels firmly on the ground or its like an open differential. This, I hope, will not become an issue since I have this same problem with my current LSD and have pretty much sorted with stiffer front springs.
This corner here was the only one I had some slip if I took the line too in.

[Tristan]

Re: Escort Sigma 1600 Race Car

thats a gorgeous picture. New desktop background , I think..

[Roadsport]

Re: Escort Sigma 1600 Race Car

Anyone know how low piston compression height would be possible? I'm looking in to improving the crank ratio in the future, and lowering the compression height is quite essential.

[Graham]

Re: Escort Sigma 1600 Race Car

i think your find my bmw piston is pushing it, 25mm with a 22mm gudgen pin so thats only 16mm of piston above the pin, not enough room for 3 rings though!

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

Your old pinto had 5.7" rods, and the pistons to suit have about a .945" CH with a .928" pin inside the oil ring, and a support rail/ring on the bottom to support the oil rings.

In metric that is 144.78mm rod, 24mm CH, 23.57mm pin

With a 1mm top ring, 1.2mm second and 22mm pin you could use a CH around 23mm with a 3 ring combo, that's about the limit as the rod would be quite close to the bottom of the piston crown, with a 20mm pin you would have a bit more material between the rings.


Pic you sent me of your old 5.7" eagle rods + wiseco pistons





What rod ratio are you currently using in the SE?

I think about 1.8 to 1.9 to 1 is about optimum for a high rpm race engine, the higher the rpm the longer the rod needs to be, F! engines use a very large rod ratio, something like 2.5 to 1 if I can remember correctly.

Would be very interested to know what happened your old engine, why the crank snapped, was it at no4 big end?

Good luck with the build, I hope you find the extra power you are searching for

[Roadsport]

Re: Escort Sigma 1600 Race Car

All Zetecs have quite poor crank ratio. The SE has the highest but still only 1.68:1

Its a tricky feature to imrove due to the long stroke and allready very low compression height of 25mm. Id need a 10mm shorter pistons to hit 1.8:1. Only is it even possible to manufacture pistons with 16 mm compression height?
Other option would be to modify the crank, or have one made or find out could I use the smaller Zetecs cranks

[Graham]

Re: Escort Sigma 1600 Race Car

have some pistons made with one compression ring?

[Roadsport]

Re: Escort Sigma 1600 Race Car

have some pistons made with one compression ring?

I'm allready asking around for quotes.

Other, and the cheapest, option would be to use 1400cc crank. If possible that is, but I believe It could be used in a 1600cc block.
That would make the engine 1499cc and a 1.86:1 ratio. And I could shed a 45kg's off the car. Weighting in at 825kg. I could use the existing pistons and only have new connection rods made.

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

With a single compression ring the limitation will be the small end diameter of the rod vs the piston crown thickness, you only need about .5mm clearance, if the small end measured say 29mm with a 20mm pin, that is 14.5mm rad + 5.5mm crown thickness + .5mm = 20.5mm CH

With your raised top pistons you could go shorter than that, machine 2 or 3mm from the underside of the dome and let the rod go up into the relief, having a 5.5mm thick crown (plenty of material left for strength), with a single top ring and a 20mm pin you could get it down to 17.5mm, I think that's about the absolute limit, 7.5mm shorter than your current pistons!

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

Another option may be to use a 1700 puma block?

They either have a longr stroke or a larger bore, can't remember which, if its bigger bore then maybe use a 1400 crank and a 1700 block to make near 1600cc?

[Roadsport]

Re: Escort Sigma 1600 Race Car

Another option may be to use a 1700 puma block?

They either have a longr stroke or a larger bore, can't remember which, if its bigger bore then maybe use a 1400 crank and a 1700 block to make near 1600cc?

The 1,7 has bigger bore and stroke. Using Puma block and a 1400 crank would give 1538cc but I'd need to invest in a set of new pistons and cons. Plus the 1.7 are not as plenty as the 1,6 and they have alloy cylinders with nicasil coating so a lot of hassle to get the bores honed if scored.

The Zetec se Pistons have 18mm pins. So maybe I could squeese 8,5 mm out of the pistons. Making 1.79:1

If I'd go for the whole nine yards And ad an Farndon crank and a rebore I could get it all. With 20mm CH. Would cost a lot of money though but would be an absolute screamer.

[RWD fords rule]

Re: Escort Sigma 1600 Race Car

Looks like pistons and rods are the best way to go then, yeah I beleive you would get them 8.5mm shorter with 18mm pins, maybe even 9mm shorter depending on the outer diameter of the small end, I think 1.8 to 1 rod ratio or so would work a lot better than 1.68, has to be worth a nice bit more top end power.

[Roadsport]

Re: Escort Sigma 1600 Race Car

Right, back to the current evolution.
Did some more tinkering today. A long overdue overdrive water pump pulley.
Well the picture of it anyways. I'll pick the material up on Thursday and drop it off to the machine shop on Friday.

[Tristan]

Re: Escort Sigma 1600 Race Car

haha I did much the same with my Zetec Se pulley , only I just drilled holes in mine!