ECUtune forged pistons for NA SVXii

longassname · #1 08-08-2007, 12:48 PM

I thought I'd start a new thread dedicated to the upcoming batch of forged pistons for naturally aspirated SVXii. There has been interest in and requests for forged pistons for naturally aspirated SVXii and we've got almost enough people who say they are ready to order to be able to get a batch made at an affordable price, $800 per set including rings and pins.

These pistons are geared for and will be optimized for naturally aspirated SVX's so there are some notable differences in the piston design from the ones we got made for forced induction. Most notably they will not have lateral gas porting so the rings will last longer and they will have a compression ratio in the range of 9.3 to 9.5. This compression ratio will work better with the poorer quality fuel they are selling these days and let us run mid grade and probably even regular unleaded.

They will have deep valve recesses to maintain zero interference with the ECUtune camshafts. They will use japanese rings and be designed the correct size to allow a good hone of the cyllinders.

I'll go collect up the names I have thus far for the head count on this batch and make another post to start the head count. I haven't done a good job of keeping track of people yet so if I forget you or count you and you weren't 100% ready and in please correct and repost the list.

thanks

longassname · #2 08-08-2007, 12:58 PM

Ok, I know there are more but I couldn't find them so guys that I missed please add yourself and repost.

Headcount to date:
Nickfu S.
EarthWorm

NikFu S. · #3 08-08-2007, 11:41 PM

/subscribe

Is the lower compression ratio going to have any other noticeable effects or advantages?
Disadvantages?

Dessertrunner · #4 08-11-2007, 02:14 AM

Mike why not up the compression ratio above standard then I would be interested. Matt had to shave the heads to increase his and that resulted in big problems for him. It would be better to do it with pistons.
Tony

longassname · #5 08-11-2007, 06:00 AM

It must be nice to live somewhere where the gasoline is good enough to consider increasing the compression ratio. The petroleum refiners and the environmental protection agency have been on a spree of reformulating the gasoline over here in the states. Each new formulation seems worse than the last. For street use we'll make more power with lower compression.
To run higher compression here you'd have to run race gas.

If we can get together half a dozen people who want high compression pistons we can get a batch of those made too.

Quote:

Originally Posted by Dessertrunner

Mike why not up the compression ratio above standard then I would be interested. Matt had to shave the heads to increase his and that resulted in big problems for him. It would be better to do it with pistons.
Tony

NikFu S. · #6 08-11-2007, 02:30 PM

Yeah, they don't offer premium fuel in Alaska so I won't be in for higher compression.
Octane booster are rising in price here too so lower comp would be paying for itself in the long run. (Very long run.. )

LAN, nobody is willing to install pistons (nobody I can trust), and it was difficult enough to even find someone to do the seals on my engine so I won't be installing these any time soon. I'll probably do it next year along with cams so time is no longer an issue.

XT6Wagon · #7 08-18-2007, 02:10 AM

Lower compression does cost some power, but honestly too many people raise the compression and end up with nothing better than stock.

9.5:1 is a good ratio for this as you lose little compared to the higher CR, yet it doesn't require the exacting tuning and ultra complex engine management that running 10:1 or higher on 87 octane takes.

I doubt that there is anyone here not willing to give up a couple peak HP for easier tuning, and extra reliablity in the real world where gas pumps can spit out stuff way off the pump label at times.

sicksubie · #8 08-18-2007, 12:03 PM

we have stations around here that we can get 94, 97, 104, and 110 octane gas at. 110 is around 7.65 a gallon i believe

longassname · #9 09-04-2007, 09:43 AM

Well this thread isn't getting the attenion I would have hoped. The couple of people who said they were definitely in on forged pistons that I lost contact with are still lost. Come on now...who wants to build an SVX engine? I want to build a new engine for my pearlie soon. I'd like to get these pistons ordered asap.

SVXRide · #10 09-04-2007, 01:07 PM

Michael,
Can you be a little more specific regarding what $800 buys? Tool steel wrist pins? How much lighter than stock? Good up to 20-30 psi (okay, so some of us might just stray into the pressurized arena in the future

)? Type of compression and oil control rings?
Thanks.
-Bill

TomsSVX · #11 09-04-2007, 02:11 PM

Quote:

Originally Posted by SVXRide

Michael,
Can you be a little more specific regarding what $800 buys? Tool steel wrist pins? How much lighter than stock? Good up to 20-30 psi (okay, so some of us might just stray into the pressurized arena in the future

)? Type of compression and oil control rings?
Thanks.
-Bill

Bill, if you want to be forced... get the 8.5cr pistons we already have made...

Tom

SVXRide · #12 09-04-2007, 02:36 PM

Quote:

Originally Posted by TomsSVX

Bill, if you want to be forced... get the 8.5cr pistons we already have made...

Tom

Think I'd rather have the higher compression now and just have to "live" with only 5-6 psi in the future

-Bill

TomsSVX · #13 09-04-2007, 05:35 PM

Quote:

Originally Posted by SVXRide

Think I'd rather have the higher compression now and just have to "live" with only 5-6 psi in the future

-Bill

Then keep the stock bottom end and just do the heads... These pistons are meant for an N/A build and will only be a restriction on boost if placed into a FI motor. I meant we are flowing ssssooooo many more CFM's with the lower compression pistons... with the 9psi pulley sicksubie is seeing 6.5-7psi at WOT. It could be an air leak but his AFR's are telling me otherwise

Tom

SVXRide · #14 09-04-2007, 06:38 PM

Quote:

Originally Posted by TomsSVX

Then keep the stock bottom end and just do the heads... These pistons are meant for an N/A build and will only be a restriction on boost if placed into a FI motor. I meant we are flowing ssssooooo many more CFM's with the lower compression pistons... with the 9psi pulley sicksubie is seeing 6.5-7psi at WOT. It could be an air leak but his AFR's are telling me otherwise

Tom

I hear you...I'm just worried about the ring lands that several folks (you included) have found a way to break off under only slightly severe use. I don't want to rebuild the engine with stock pistons only to have the pistons go south after a single 100 shot of NO2

-Bill

TomsSVX · #15 09-04-2007, 06:40 PM

Quote:

Originally Posted by SVXRide

I hear you...I'm just worried about the ring lands that several folks (you included) have found a way to break off under only slightly severe use. I don't want to rebuild the engine with stock pistons only to have the pistons go south after a single 100 shot of NO2

-Bill

My lands gave way under heavy doses of detonation on 12psi... none of us have had issues with the 9psi setup. If you are gonna run big N20 meaning 100 shot or more I would say go with the better pistons but 10psi max is good for the stock pistons... the rods may be another story but don't you have Sti rods you are installing?

Tom