Spec Focus piston?

[brads03zx3]

Maybe +-.2 compression (or a similar small range)

[recar]

Originally Posted by brads03zx3

Maybe +-.2 compression (or a similar small range)

This would save some money, most popular piston offerings are 9.0:1 and 10.5:1. Any other compression ratios have to be made.

[BUR_ZX3]

I might suggest that on a zetec a 10.5:1 compression ratio, however achieved, be allowed. (although with the weight to power ratio thing.... I suppose it'd be moot)

[brads03zx3]

But that would pretty much require a rebuild for every participating zetec. Nearly 1 full compression point will drastically change the powerband of the engine.

[BUR_ZX3]

Granted. But unless someone wants to start producing economical rod/piston combos that feature stock compression... I don't see much alternative.

If one of the goals is to keep it low cost (which I certainly can agree with) we have to think about being able to make the engines last.

Granted, nobody has let go, but has anyone run a full season racing yet? (Does Leo even?) And even as such, Leo has far more resources available to him than the common racer, and if he drops an engine in qualifying, can have a spare in the car by race time. (happened with a tranny @ Jetfest, right?)

I dunno... what does the compression come out to if you lower to 9.0:1 pistons and shave the head .040? What 9.9:1? Make that the theoretical max?

[lapp]

Originally Posted by brads03zx3

Maybe +-.2 compression (or a similar small range)

11.7 Compression
The mechanical compression ratio may not be altered directly. However, tolerance of up to 0.50 points over the factory published
number is allowed to account for such things as shaving the head in order to true it.

[BUR_ZX3]

heh... so my 9.9 number would be within that spec.

[airforcefocus]

Honestly, I had over 95,000 miles on the flea, and when I sold her, the compression was perfect across the board, and you know what she went through. I believe the ZETEC is an extremely robust block, especially with the minor modifications allowed in SF. I ran the RBR car for over 10K miles and a LOT of that was track miles with the PW kit on there. If I can get 10K track miles out of the Focus before I had to freshen her up, I would be happy.

Bottom line is that shortblocks are fairly cheap, heck, I traded a whole ZETEC engine for pizza! The longer we can keep bottom end modifications at bay, the more comfortable I am in knowing the car is indeed spec. If we get 50+ cars on a national level, then I think this topic may be prudent, but I don't believe the current numbers warrant a change at this point.

[Yel900rr]

I can have stock compression pistons made and not be a custom price. Our pistons have bigger valve reliefs for the FR head. Better pistons and rings can make a little more power with a better seal in the bore especially under heavier loads.

[BigSandwich]

Airforcefocus is on the right track here. I thought economical piston rod combinations already existed. But most people refer to them as stock short blocks.

With the scope and intent of spec focus I don't see the need or reason to poor a bunch of money into the bottom end. Since I have not heard of one report where a Spec Focus has blown out the bottom end or hand any bottom end issues even with the increased RPM ranges.

And if Ted implements a reasonable RPM limit for a stock bottom end then you don't have to worry about it.

[BUR_ZX3]

Originally Posted by Yel900rr

I can have stock compression pistons made and not be a custom price. Our pistons have bigger valve reliefs for the FR head. Better pistons and rings can make a little more power with a better seal in the bore especially under heavier loads.

Curious. I was looking at the Diamond Pistons... how much for stock CR?

[Ted7rns]

Originally Posted by BUR_ZX3

Granted, nobody has let go, but has anyone run a full season racing yet? (Does Leo even?) And even as such, Leo has far more resources available to him than the common racer, and if he drops an engine in qualifying, can have a spare in the car by race time. (happened with a tranny @ Jetfest, right?)

We have more then full session then average race season.....I can tell you this the original Zetec motor that I have used and that Bob Evans has now, has 9 races, 10 qualifying sessions, 15 practice sessions, 24 Time Trial Session and 6 hours in an Enduro race with a total of about 28 track hours. The motor is still running strong.

Also Leo has ran his motors like crazy including the testing. There was some weekends when they would go out 10-12 sessions a day.

I don't think with the amount of HP and the Rev limits we have in the Zetec will cause any problems at the bottom end.

[Ted7rns]

Originally Posted by Yel900rr

I can have stock compression pistons made and not be a custom price. Our pistons have bigger valve reliefs for the FR head. Better pistons and rings can make a little more power with a better seal in the bore especially under heavier loads.

If thet have bigger (or different) valve reliefs then OEM pistons, then it can't be used.

The rule states Exact equivalent shall be defined as the same dome/dish/valve relief configuration, weight, ring thickness and location, and pin location as the OEM replacement piston.

But, if you can get me some hard numbers we could change that rule.

[BUR_ZX3]

Alright, fair enough. Then its off to see if this shortblock is gonna work for me.

[recar]

So I can have a .020 overbore piston as long as its the same shape, weight, and pin configuration as well as have a non OE rod correct?

And this combination can have a slight bump in compression from stock?

[brads03zx3]

As the rules are currently written, no change in compression is legal. The threads debating the rules are confusing. Reference the spec focus rules for clearification.

EDIT: My mistake...up to .5 points up due to truing.

[Yel900rr]

I can get the pistons made to exact stock specs if that is what you need. I should be able to do these for 495 a set.

[Ted7rns]

11 Engine

11.1 Engine assembly

11.2 Balanced and Blueprinted Engines
Engines may be balanced and/or blueprinted. Lightning of parts beyond what is necessary to balance is prohibited.

11.3 Bored Engines
Engines may be bored to a maximum of .020 inch over standard bore size. Factory replacement pistons or the exact equivalent
shall be used. Exact equivalent shall be defined as the same dome/dish/valve relief configuration, weight, ring thickness and
location, and pin location as the OEM replacement piston. Wrist pins must also conform to OEM specifications. In the event that a
.020 factory replacement piston/wrist pin is not available, the .020 pistons/wrist pins shall not weigh any less than then a standard
size OEM piston.

11.4 Piston rings
Piston rings are unrestricted.

11.5 Head Intake and Exhaust Ports
Cylinder head intake and exhaust ports may cannot be machined. Non SVT-Zetec motors may use CNC Ported heads from Ford
Racing (#M-6049-ZX3P) 2.0 Duratec may use CNC ported head #M-6049-D23P. No other non factory porting can be done and no
other aftermarket heads may be used.

11.6 Valves
Valves and valve seats may be machined and may only be replaced with the exact factory equivalent. Valve guide material is
unrestricted. Non-SVT Zetec may use exhaust valve M-6507-ZX3 and intake valve M-6505-ZX3.

11.7 Compression
The mechanical compression ratio may not be altered directly. However, tolerance of up to 0.50 points over the factory published
number is allowed to account for such things as shaving the head in order to true it.

[recar]

Ted with all due respect please stop quoting the rules, I'm seeking your guidance as series director. I have already have made a significant investment in my car, my motor has very high mileage. My motor is going to the machinist Mon., as soon as he measures the bores I would like to order parts an get this car done. I would like to complete HPDE 3 & 4 this year. I do not have the luxury of a long race season due to the fact that I live in the northeast.

[Ted7rns]

Originally Posted by recar

Ted with all due respect please stop quoting the rules, I'm seeking your guidance as series director. I have already have made a significant investment in my car, my motor has very high mileage. My motor is going to the machinist Mon., as soon as he measures the bores I would like to order parts an get this car done. I would like to complete HPDE 3 & 4 this year. I do not have the luxury of a long race season due to the fact that I live in the northeast.

WITH ALL DUE RESPECT I was responding to brads03zx3 post. Also the only guidance I'm going to give you is throught the rules. YOU MUST FOLLOW THE RULES!!! It's that simple.

If you would like a rule change then fill out the request waiver and formal announcement for your request will be given within 30 days. http://specfocus.drivenasa.com/partswaiver.htm

My suggestion to you is to follow the rules I have quoted. Also please don't tell me what I can post on the Official Spec Focus forum section.

So for the heck of it here's some more rules i'm going to qoute.

2 Intent
The intent of these rules is to provide mandates to ensure that all vehicles are constructed and modified within clearly established limits, so as to ensure an even platform, in which a contest of driving skill may provide the most talented drivers with great rewards.

3 Purpose
The purpose of this series is to provide an avenue to promote sponsor brand awareness on a national scale. Additionally, this series should provide a stage to showcase driving talent, in hopes that the most talented drivers will advance to even higher-level professional series.

4 Format
Modifications, addition or removal of parts are not allowed, unless specified or approved in these rules. Additional modifications are not permitted. These rules are not intended as guidelines; rather they shall serve as the national set of rules, and must be strictly followed.

27 Non-conforming Equipment/Equipment Certification
Series Officials must approve any equipment that does not conform to the Series Rules in advance. For consideration, approval must be made in writing sixty days prior to the date of competition. After receiving the petition, the Series Officials will make a formal announcement of the petition and must rule on the petition within 30 days. The remaining 30 days after ruling will allow other competitors to evaluate newly approved.

[recar]

Ted I apologize, I think you may have taken my comment out of context. I was hoping for a answer/suggestion or a little direction in conforming to the rules.

[Ted7rns]

Originally Posted by recar

Ted I apologize, I think you may have taken my comment out of context. I was hoping for a answer/suggestion or a little direction in conforming to the rules.

No Problem. Right now I'm working on something that might help, and it will be a little change of the rules.