8.4:1 CR vs 9.2:1 CR

[A. Jay]

I need a rebuild and since I'll have it all apart I was thinking about n/a pistons. I've been reading up a lot on raising compression but I can't find anything on such low power goals as mine or for the way I'll use it.

The question is which compression ratio is more fun for strictly DD, 8.4 under fuel cut or 9.2 under...detonation? How much hp can I get before detonation?

I probably won't ever see more than 95F ambient, and I don't want to consume anything more/else than 91 gas. I'm also not interested in ethonal due to the cost of converting and because it's not very available in my area.

 

[hvyman]

Iirc n/a pistons are a bit weaker. Id just keep the turbo pistons and run more boost. Could also run a slightly thinner hg and raise the comp to like 8.7:1 or so.

 

[Van]

I need a rebuild and since I'll have it all apart I was thinking about n/a pistons. I've been reading up a lot on raising compression but I can't find anything on such low power goals as mine or for the way I'll use it.

The question is which compression ratio is more fun for strictly DD, 8.4 under fuel cut or 9.2 under...detonation? How much hp can I get before detonation?

I probably won't ever see more than 95F ambient, and I don't want to consume anything more/else than 91 gas. I'm also not interested in ethonal due to the cost of converting and because it's not very available in my area.

My 7MGTE is at 9.4:1 compression, and the motor pulls smoothly from 1500 up to 4800RPMs, on the CT26. Although, the head has extensive reworking of the intake and exhaust ports, mated to a three inch exhaust, the CT26 is the restriction. The motor is intended for the track, but is fun to drive on the streets. I'm still getting good fuel mileage. Van

 

[IJ.]

Low boost high static CR has a LOT of benefits for a DD car, as long as you can keep it out of detonation they're a joy to drive.

 

[Nick M]

9.2 isn't high for pump gas, unless you are running high boost with an agressive tune.

 

[mecevans]

Im at around 9.0 to 1. The turbo spools pretty quick and has a lot of power down low. I start building boost around 2200 rpm. At 7 psi I have to use mid or premium grade gas.

Na cams
3in dm dp
Cone filter

 

[radiod]

I'm running 9.1:1. 57-trim CT spools significantly faster than my buddy who's running 8.4:1. I've got 9-10psi @ 2600rpm, I start seeing boost well before 2,000rpm. Stock fuel system. I've never tried running less than 94 Octane from Chevron.

 

[RazoE]

NA pistons here in a 7MGTE, BPU mods, I hit boost at 2000rpm...

but I don't plan on going any higher power than that, atleast not for a long time...

 

[A. Jay]

The na-t sticky mentions more than once that 300+whp is achievable on n/a pistons, no mention on how (I can safely assume 91 didn't suffice), but it shows that the pistons are capable of withstanding the power.

So yea, Ima do it It's just that when I was setting my AVC-R, the minimum duty cycle was giving me a peak of 8.5psi. I wonder if it'll be higher/too much for me with high compression. It would suck to have to run just the wastegate (which cracks open gradually as you approach its max pressure) and maybe have a net loss in spool.

 

[Nghty89]

9.0 cr and higher turbo motors are great! My 7m last summer was the most fun I have ever had at only 11psi and 93 octane. 250whp on a hot summer day and ran like a top.

Droid X via Gummyjar 2.5

 

[Blackdawg]

Im at around 9.0 to 1. The turbo spools pretty quick and has a lot of power down low. I start building boost around 2200 rpm. At 7 psi I have to use mid or premium grade gas.

Na cams
3in dm dp
Cone filter

id get rid of those cams man.. http://www.supraforums.com/forum/showthread.php?572162-DUDE-Should-I-get-a-GE-CAM-For-MY-GTE-!-!

interesting info tho! i bet its a hoot to drive when you have boost at 2000 or less...wish id know that. Otherwise i wouldve gotten a smaller HG in my build

 

[Devin LeBlanc]

I really like my NA-T, I have slightly higher CR than stock NA as well due to the head being decked and using stock size HG.. It is a lot of fun to street drive because of how fast it gets in boost due to the higher compression ratio.. The off boost power it brings makes the car feel sooooo much faster than a GTE.. However I was having pretty severe detonation at 12+ lbs on a STOCK CT with a BIG front mount with 91 octane..

I am now using E85 and happily boosting with timing advanced even more Its a real pleasure to drive Now if I could just get the trans to hold together.. Damn auto lol