FP crank and Mazdaspeed 10.7:1 Compression ratio pistons

[f1yen]

Hey guys,
Do you know where I would be able to find a FP crankshaft and the Mazdaspeed 10.7:1 CR pistons? (piston stock diameter would be FSY4-11-SA0, and .025over -SB0)

from reading, it looks like corksport may have sold the pistons before... I did not see them now.

I am trying to get prices; and see if a build is feasible.... (cheers2)

 

[tweety2300]

You do NOT want high compression with boost

 

[BRIAN_MP5T]

That plus Turbo will require so much ignition retard that you will make very little power and or restrict the level of boost to low like 5 or 6 PSI Maximum

 

[f1yen]

LOL yeah, I know I don't want the High compression with boost!! Thanks for the concern tho! I know we don't want to add more people to the boom list. I have a little project up my sleeves, or, at least I want to price it out...

It would be a custom build, I did not read anyone else doing this....but (from what I read) the FP is the other mazda crank that is forged, and it swings for 1.8L And I *think* it will just bolt in and have same outputs.
That FP crank coupled with our FS rod length and pistons (and FS block) will put me at a low 6.7 compression ratio, which is too low for street driving.
Getting the highest compression (10.7CR (least dished out)) pistons will bring the compression ratio up to 7.55, which could be driveable on the street. With this, boosting until the same mean cylinder pressures are the same means 12.5 psi. and would have plenty of potential for upping the boost without detonation. What do you guys think?

All this is assuming the crank is directly below the pistons, (non-offset crank slider), which probably a good assumption.
This is also assuming the stock FS rod length, I will be contacting some more suppliers today to see what I can change on the rod length for aftermarket rods. This could get my CR up to a more street friendly 8's

So while I may be reducing to 1.8L I may be able to bore out the block and gain back some of that volume. I feel that this will set the car up for some great boost and alot of reliability with less detonation.

So yes, I am still trying to source and find prices for the FP crank and the high compression pistons (10.7) for the FS. (alright)
Can anyone help?

 

[tweety2300]

I will tell you even with a turbo that starts spooling up around 2000 rpms and peaks at 3200 with 7.9:1 compression sucks. And by sucks I can't pull a hill at 45 without downshifting, and to keep up with traffic I'm am almost always in boost up to the speed limit. There is no low end power. Dsm guys are at 7.8:1 stock why do you think they usually bump it to 8.5:1 when they build their cars?

But obviously with this amount of work its not a daily. If you got the money go for it, it may be the beginning to a whole new breed of Mazdas. Last I checked speed circuit and cr3 have the fsze pistons. And junkyard crank would be the best bet. If it doesn't work out donate the pistons to me

 

[f1yen]

Problem 1: It would be a daily, thanks for the info tweety. What kind of boost are you running with 7.9?

I have a setup that might be able to do 8.63 CR (FPcrank, K1_5.400" rod, and 10.4CR pistons) I guess I was trying to stay at a lower CR and use more boost to my advantage, I will have to read up on what CR's more people are doing with boosted engines.

*edit FPcrank!!!

 

[tweety2300]

It's what my 323 is stock, I'm running 18psi on a turbo a bit smaller than the t25. There's one person I know of running a t28 on 25psi with no issues. But the b6t is way stronger than the fsde.

Why not just do what everyone else does forged rods and 8.5:1 weisco pistons and run a t28 on 14psi. Supposedly more than 14 psi the maf will read weird and you have to upgrade to a map

 

[f1yen]

Hmm I was unaware that the weisco pistons lowered your CR (drunk)
That does sound optimal to me now, since I would also not have to give up the 0.2 liters of power.
I'll have to definitely check it out! Would the MAF read funny at both relocated and pre-turbo?

 

[tweety2300]

You can get them to make whatever compression ratio you want

And I'm not sure on the specifics of it the maf I just know that most people stop at 14 psi because the maf won't read right or something

 

[TURBOJ1]

You do NOT want high compression with boost

NOT entirely true....you can with E85,also spoke to the owner at K1 rods and he said the speed 3/6 guys are running high compression with e85 with GREAT success (700hp)......YA,those were HIS words

 

[tweety2300]

Ya the fsde is made of glass though

 

[TURBOJ1]

Ya the fsde is made of glass though

Agreed.....but it still is possible

 

[shane02pro5]

Most afcs I believe only go up to 1bar of boost that might be the limitation. I had to add a Joe P FCD past 18psi for the maf problem with my old IHI turbo which is a bit smaller than a disco potato...

 

[tweety2300]

Maybe it is in the ssafc then, makes more since considering the maf reads airflow not pressure, I've always been confused by that