03 cobra engine build questions

[diehl.21]

hey guys I am having an engine built at the machine shop using the stock Kellog crank, Stock Manley rods, I need to order pistons suggestions on make and what compression?


2.8 kenne bell mammoth lc
3.5" Blower Pulley
Lower pulley Metco 4#
ARP Head studs
Still has t56 manual transmission
Exedy Stage 2 Clutch
Resurfaced Flywheel
Busa Pumps
Full bassani exhaust with long tubes
Irs with 4.10 gears
Dual 044 fuel pumps
80lB injectors

 

[01yellercobra]

What fuel are you planning to run?

 

[jrgoffin]

The finest mod motor pistons out there now are from Gibtec.

Build thread with everything you want to know:

http://www.modularfords.com/threads/236857-Aluminator-Gibtec-Build

 

[Nightmare302]

Any company can make a custom piston. Gibtecs are no better than anyone elses custom piston the only advantage is they already have a base design due to Ed. If you go gibtec (which is a great company to deal with) do not let them lower the piston in the whole as many tend to do.

9.5:1 is a good compression for a street car with a big twin screw. Get intake reliefs in case you add cams later down the line, you do not need exhaust reliefs. If you want out of the box setup go wiseco.

My custom came from CP.

 

[Soap]

Ditch the 4.10 gears and get a set of 3.55's (or even lower).

--Joe

 

[Roots-type]

I've got the stock 3.55's from my old 04 IRS. Id sell them cheap if you're interested..

 

[99 KOBRA]

I have Manley pistons. About 9.5

 

[IllCobra]

http://www.lethalperformance.com/manley-4-6l-5-4l-11cc-dish-pistons-0-020-over.html

Could anyone give me their thoughts on these pistons.... I dropped a valve seat and it did some damage and the shop that has my motor is replacing the stock pistons with these.

 

[99 KOBRA]

http://www.lethalperformance.com/manley-4-6l-5-4l-11cc-dish-pistons-0-020-over.html

Could anyone give me their thoughts on these pistons.... I dropped a valve seat and it did some damage and the shop that has my motor is replacing the stock pistons with these.

I think those are the Manley pistons my engine builder (JBA) used.

 

[IllCobra]

I think those are the Manley pistons my engine builder (JBA) used.

How do you like them? Anyone have an idea how much hp they can handle?

 

[Nightmare302]

The week spot on those manleys is the wrist pin. -11cc dish will also put compression are 9.1-9.2:1.

 

[99 KOBRA]

I'm not really qualified to comment on the pistons. JBA tuned the rebuilt engine on a Mustang dyno. It's a ported (stage 8) Eaton that did 412 rwhp. By way of comparison, 412 rwhp on a Mustang dyno equates to approximately 460 rwhp (SAE) on a Dynojet.

 

[IllCobra]

I'm not really qualified to comment on the pistons. JBA tuned the rebuilt engine on a Mustang dyno. It's a ported (stage 8) Eaton that did 412 rwhp. By way of comparison, 412 rwhp on a Mustang dyno equates to approximately 460 rwhp (SAE) on a Dynojet.

Well how is your car holding up? How long and how many miles does it have with the rebuild?

 

[IllCobra]

The week spot on those manleys is the wrist pin. -11cc dish will also put compression are 9.1-9.2:1.

Is that a common issue?

 

[99 KOBRA]

Well how is your car holding up? How long and how many miles does it have with the rebuild?

After 9 months and 2,000 miles, so far, so good!

 

[IllCobra]

After 9 months and 2,000 miles, so far, so good!

what was your break-in period like? I assume you gotta take it easy for a few hundred miles at least...

 

[99 KOBRA]

what was your break-in period like? I assume you gotta take it easy for a few hundred miles at least...

They had me vary the RPM for the first 500 miles (i.e., don't put it in 6th and cruise at 2,000 rpm for 500 miles)

 

[Nightmare302]

Is that a common issue?

Yes many of the off the shelf kits come with very thin wrist pins made out weak material. I think people have actually found that the standard manley is thinner than the factory cobra wrist pin.