So im rebuilding the f24c. I did in fact find very small nicks on the cylinder walls.(Maybe 3 all together) I did some research and talked to a few people. Im going to have the cylinder walls honed out .25 mm which will take the nicks out clean the walls up, and drop some mahle low compression pistons in. Im not sure what head gasket to run yet. The turbo im running (gt28rs) is not nearly the size i would like for this set up. The question i have is, will 15-18psi on this turbo and new compression set up be ok or is the boost going to have to be turned way up to the point it start blowing hot? Im not looking for crazy HP #'s. I just want TQ mainly, anything around 325-350 is sufficient. Thanks in advance

 

Run a stock head gasket with 9.1 or 9.5 pistons. Its pretty much a simple build.

 

This is pretty much what I will be running (9.6:1) stock HG. The main reason people run the 3mm HG is to lower compression on the stock engine. Since you are getting lower compression pistons, this will not be necessary. I can't help you out on the turbo question as I am trying to figure that part out myself now.

Good luck

Josh

 

I believe that the gt28 is too small to run on that setup no? you wanna raise the boost but having such a high flowing motor/head, i believe it would just start blowing hot hair and increase your chances for detonation.

I haven't studied up on my turbo's lately but it just seems small...quick spooling for sure though.

 

The turbo spools very quickly...I believe anything above 18psi on the gt28rs is out of its effeciency rating. I know when the turbo was turned up to 22psi on the dyno, thats when the problems reared their ugly head. I do want the gt3076r, which will give me the quciker spools but not to the point of blowing massive amounts of hot air. Im still new to this so im still baffled by the current turbo setup with the mahle pistons im getting off of a guy on here.Will i have to up the boost too much with the compression being brought down? Will leaving the current compression ratio (10:5 i think) cause the same problems i had? They are mahle pistons that will run about 10:5 and with a 2mm headgasket should drop it to around 10:1.

Another question i have is, to what point can you hone these frm sleeved engines?

 

If you are using the low compression mahle h22 pistons you should have much less than 10:1.. remember those pistons sit about 0.040 below the deck, stock pistons sit 1mm above the deck.

They have low compression pistons for ap1 and ap2 motors that will give you 8.9:1 or 9.5:1 in an ap1 engine or 9.5:1 in an ap2 engine.

 

I forgot to add, the guy im getting the pistons from is going to see if theres sufficient material to machine the dome off them, to drop the compression down..Thanks for the help wadzii

 

The pistons I have offered Redline are the +1cc pistons which work out around 10.7 compression in a F24 stroker. I was going to measure them up to see if I can machine them back similar to the -7cc depressed domes on the H22 turbo pistons.

The F24 strokers using H22 rods use a 22mm rather than a 23mm pin of the F20.

BTW, the GT28 is going to be flow limited. I've used them on 4age 1600cc motors and it topped out around 320 hp (crank). As the revs went up the boost tapered off. We made a huge bellmouth intake leading into a 6" duct which helped a little. The other problem with a small turbo that spools up at really low revs is the risk of detonation, the engine is moving so slowly at the point you need very little advance. Especially if this is below thevtec switch over point as there will be very little spill on the cam overlap, increasing the dynamic compression. This could be a contributing factor to this engines demise.

 

First you should look up the concept of quench, which you will loose with a thicker head gasket.
Second, don't even think of boring the block and if you are going to hone you better hope that the shop you take it to really knows what they are doing. The hypereutectic silicone impregnated cylinder walls require an ENTIRLY different honing process with different tools than ductile iron sleeves.

 

The GT2860RS is going to be very flow limited. I've only seen it do about 320whp on various engine setups. That equates to only about 7psi on 2.0L F20c. To take max advantage of your lowered compression, I personally think you should go bigger. A GT3076R will make 500whp on pump gas with low compression. The downside is that it will be quite laggy compared to the GT28.

Maybe a bit of a compromise would be a GT3071. If you get the one that is internally wastegated, it should be an almost direct replacement for the GT28, with I think the compressor housings being a little different.

The wheel sizing goes:
GT28: 60mm compressor, 53.8mm turbine
GT3071, internally wastegated: 71mm compressor, 56.5mm turbine
GT3076: 76mm compressor, 60mm turbine