stockhatch

iTrader: (12)

Howdy. I have read tons of threads regarding GTE internals in the stock vvti GE block, and I don't like the huge CR drop. If one were to swap in non VVTI GE pistons and rods and run a TT head gasket, do you know what final CR you would end up with? People seem to make 600whp with the non vvti GE parts, so if the CR is closer to 10:1, it seems like that would be a great, affordable route.

TIA

exist3nce

Thats a good question regarding what the resulting CR would be.... however I don't think anyone would swap GE pistons for some more GE pistons, considering they are one of the weak points. However I was looking at aftermarket pistons and there are ones that you can drop in that give a 10.0 CR (I'm assuming using the TT headgasket).

stockhatch

iTrader: (12)

Yeah aftermarket is an option as well. I know most people wouldn't think of going to another set of GE pistons, but I'm not sure why. They are very proven in the SC NA-T world to support well over 600hp without being time bombs.

mitsuguy

iTrader: (2)

I think what he is talking about is GE non-vvti pistons into a vvti GE motor...

definitely doable, keeps 10ish to 1 compression ratio... (vvti motors with stock pistons are 10.5:1)

Is there a reason you don't want to lower compression? I just did GTE pistons, GTE head gasket, skim cut the block and head, and compression ratio should be somewhere around 8.5:1... GTE pistons and head gasket with a GE head should give about 8.3:1 compression, it loses 2 points due to the size of the combustion chamber in the head... cleaning up my block and head should have given me those 2 points back, which is where I get 8.5:1

Another option for you is to run GTE pistons for the strength with a thinner, GE style head gasket... Ge headgasket .2 mm, GTE headgasket, 1.3mm... With the thinner head gasket, I would expect around 9.0 or 9.5:1 compression ratio...

I am loving mine... just got her running yesterday and very responsive... not quite as responsive as when it was turbo'd on 10.5:1, but will handle the power...

Back to the beginning... GE non-vvti pistons and rods are definitely tougher than GE VVTI pistons and rods, GE pistons and rods are similar to the GTE stuff, the rods appear identical...

stockhatch

iTrader: (12)

Yeah, thats what I was saying. Non- vvt-i GE pistons and rods into a vvti GE block. I want the higher compression because it will spool faster and be snappier out of boost. Also, if I ever wanted to revert back to NA to sell the car, get an inspection etc, the car would behave better and not be even slower than it was stock.

mitsuguy

iTrader: (2)

I think you are overplaying how much spool difference there will be, in fact, on my car, the difference was almost unnoticeable going from 10.5:1 to 8.5:1... The bigger difference will be determined by overall turbo size and picking an exhaust housing that is sized properly for the power you wish to make...

its tough tuning a high compression ratio car, especially if you want to stay on normal gas... run e85 all the time and put in a fuel system that can handle it, and you're better off, but regardless of the tune, 12ish psi is the most I would ever run on stock compression and regular gas, and only then with a full standalone computer that allows enough timing pull to prevent detonation...

stockhatch

iTrader: (12)

I am just basing my opinion on my gte SC. Off boost, the thing is a slug. I would run an aem and tune for knock. At any rate, I'm just thinking aloud. Who knows if I will ever even end up with an IS. Lol

mitsuguy

iTrader: (2)

What size turbo? mine starts to spool at 1500 rpm and is into boost even at modest throttle levels... I haven't run it hard enough to know what full spool is since I built it lower compression, but it really doesn't feel any different than when it was high compression...

stockhatch

iTrader: (12)

Interesting. I am running GT28 hybrid twins in TTC right now. I have also run the GTE with no turbos at all and it was probably the slowest car I have ever driven. That is another one of my concerns. If I decide to take the turbo off the car, I want it to drive like a stock IS without having to go back into the bottom end.

mitsuguy

iTrader: (2)

I understand the second concern, but, if your GT28's are ~that~ laggy, then perhaps the hotsides are too big, or something is wrong - you should see full spool on those between 3000 and 3500 rpm... the 1jz guys are getting full spool on pairs of those around 3500-3700 rpm... that's not bad, unless you are in an auto car without a stall converter...

Rising_Sun

iTrader: (2)

I also came from a GTE car to a NA-T build. Over time I've tried 6 turbos from 60-1 to a 67 mm turbo and with 8.5 compression and off boost response is pretty sluggish. My current setup is NA-T with a GTE headgasket and my head shaved .5mm (Approx 9.5:1) with a 67mm turbo boosting 18lbs. IMHO the drive-ability is insane! I can reach full boost in 1st gear before 3000rpm with almost no lag at all. Low compression is a thing of the past maximizing HP through the RPM band makes the car more enjoyable rather than peak HP.

stockhatch

iTrader: (12)

The second concern is more the primary concern, though seeing what the high compression guys are making even on pump gas is impressive. The beauty is that they don't sacrifice anything down low. I am for sure going to try a NA-T with decent compression if i do build another car.

exist3nce

I am also of the mindset to try to keep high compression as long as possible for that nice NA-like feeling and response. Higher CR does in fact spool the turbo quicker all other things being equal. How much quicker? Depends on the rest of the setup and tuning. I plan to keep mine at 10+ CR until I absolutely have to lower it, and even then I don't want to go below 9 - 9.5.

psyxho

Im looking to boost my is should I use the gte in my vvti bloxk or do ge piston with gte rod

psyxho

How much power u making