Anyone with flattop/turbo/p90

[Doug71zt]

I'm considering putting flattop forged pistons in my Turbo F54/P90 combo. I'm going to unshroud the valves so that will increase the head volume. I did a search but didn't find anyone that said they were running this combo. Math works out to 8.5-8.8 to 1 CR. Any comments before I spend the money and get the die grinder out?

 

Thanks - Doug

[Lockjaw]

I have flat tops in my engine. Ordered them from Ross Racing. Since I did not measure the deck height before I tore the engine down they ended up sitting a MM down in the bore. I had the block decked 30 thou, and they work well.

 

I have a stock cam and 150 to 160 psi cranking compression. I can run 18 psi on pump gas with a hybrid.

 

I do run a set of 240 rods though. I wanted to improve the rod to stroke ratio, plus if I ever get a diesel crank, I am pretty much ready to go.

[Doug71zt]

Were they off the shelf or a custom job? How much did you pay for the set?

[Lockjaw]

Yeah all L series pistons are essentially custom since there were so many rod and piston combo's with those engines. The pistons were 68 bucks a piece. I bought the good tapered chromoly piston pins, and they were 110 bucks.

 

Here is the deal with piston work. Flat tops are cheaper than a dish since the dish requires extra work on the lathe/cnc machine.

 

As I have said in the past, Ross should still have my info, we would just have to adjust the pin height for your application. I would have to hunt for the invoice, but I still have it somewhere. You have to give them a job number or something like that so they can pull the spec sheet.

 

One other thing to consider, and why I did not take advantage of this is beyond me, diameter does not affect price, so you can go out to 89 mm and the price is the same. I only went to 87, so I could have picked up another 8 cubic inches had I gone with the 89 mm bore, which is what I will do next time.

[Lockjaw]

Yeah the guys name was Rick I think. All I know is one guy was an ******* and the other wasn't.

 

Yeah it will take me a little bit to find it. I have to think about things for a minute. You will have to lower the pin height 1 mm for the below deck height of my piston, then drop it 3mm for the 240 rods, and then raise it however many mm extra stroke the LD engine has.

 

I am supposed to have around 8.5 to 1 compression. That is figuring in a 0 deck, which I don't have. I am probably a little lower, maybe 8.2 or so. The engine is pretty responsive off boost though, but I have a stout timing curve in the ecu according to Clark at JWT.

 

I will hunt around and see if I can find the invoice.

[Lockjaw]

My job number at Ross is 48067.

 

Just remember that my pistons were for stock 280 stroke, 240 rods, and the pin was to high by 1 mm, if you want a zero deck height.

 

The pistons with pins weighed 504 grams each

 

and they are 87mm bore with 1.5mm first and second ring grooves, and a 4mm oil, which is pretty standard.

 

They looked good when they arrived to, I hated to take them out of the plastic and put them in my engine.

[Doug71zt]

Thanks for the info. I'm going to have to scare up some L24 rods when I get home. Thinking about this last night - If I'm going to do a new bottom end - why don't I get the LD crank and I'm sure you know the rest of this story. Anyway - what CR do you figure that you are running now? If you wouldn't mind could get the job # for your pistons.That would give me a starting point. Is there a specific person that you deal with at Ross?

 

Thanks - Doug