What kinda boost can I pull off premium?

[WiseAssJester]

If a car detinates hardcore you'll fry a set of pistons lickitysplit.

I'm thinking of pulling about 8.2 to 8.4:1 compression and bouncing off of about 25 psi of boost. Maybe 30 if I buy a two stage electronic boost controller.

Buuut.. that depends on when I have to hit race(104 octane) gas.. Does anyone have any ideas?

[suprra_girl]

lower the compression, mhg, arp head studs and correct machining to head and block

you will blow the livin shiteeeee out of it if you run 30psi on a stock engine

if you haven't done the hg yet do that first!!!

let us know what mods you have done to the engine and it's history

[WiseAssJester]

Completely forged rotating assembly, studded top and bottom ends. Aftermarket hg.


Basically, I've got the build written down and its... extensive. Nothing I build is low grade or cheap. But the motor will be able to withstand 8k RMP, but will stop creating power at 7 to 7.5.


I'll probably keep it to around 20-25 psi of boost. I'd like to keep the static compression ratio at about 8.2-8.4, but I'm considering staying cool 7.8 or 8:1.


My other car is all motor. NA 79 Z28 330 RWHP and 360 rear wheel torque. Not bad for an NA build at my altitude, but the Supra is going to bypass 400 rear wheel horses.



EDITED: Also, what kind of boost does the stock turbo pull? Is it a garret and hits 30? Or will I need to go out and pick up a t3/t4?

[suprra_girl]

ahhhh okie dokie... that makes me feel a bit better lol

i'm only gonna run bout 15psi and my compression is 8.0:1

well... in theory... with correct machining and forged bits and metal hg it should be able to take a hammering
i think a t3/t4 will be a bit small to be honest... look at going bigger t04 or even with an SP series turbo

the stock turbo is a Toyota CT26 (i believe the only car manufacturer that has brought out it's own turbo)

the stock turbo can pull about 250whp in good condition but once upgraded it can pull 3-400whp depending on the compressor size... once you start going 60 - 62 trim they do start becoming unreliable

good luck on the monster and be sure to keep updating

[WiseAssJester]

Thanks a lot homeslice.


I have a work provided vehicle for going to work and back.. and groceries and what not. Its a lot easier to say "I'm sorry" then ask for permission.

So the car is only gonna run about 50k miles before I pull it apart and freshen it.

That and I always baby my babies.


So about when do I have to hit up 104 race gas?

[rnoswal]

I think that at about 10 to 1 compression you are pushing the 93 octane pretty good. My Celica had 14 to one compression and had to use 110 octane. It would be nice if there was a chart that listed what compression you get with different boosts. There is probably a formula to figure it out. There are other sites that have monster outputs from the 7m engine, maybe some of them would have a formula for what you are looking for.


Russ

[WiseAssJester]

14 to 1 off of a Celica? I didn't realize they made dome pistons that big.. or a head chamber that small. Damn.


And 12:1 compression will push a muscle car(350) on 93 octane, altitude dependant.

Actually, I'm pushing about 10:1 right now, maybe a bit higher, off of my other car and haven't had much detination. Actually, because of the incredibly oversized camshaft, I had to bump up the timing a touch. Err.... more then double stock.. Heh. SHould be between 4 and 8 degrees stock. I'm running at 15.

[rnoswal]

Well I had a set of Wiseco domed pistons that had 25 cc domes. The head was milled so that the chambers were around 65 cc's. Giving a couple of cc's for the head gasket. I had close to 42 cc chambers. That put the compression right at 14 to one. I also had the timing set to 35 degrees total advance at 4000 rpm. I usually ran it to 7500 rpms before letting off. I had dual Dellorto carbs and that was a fun dirt track car to run. I wish I had the carb set for the Supra, 3 side draft carbs!!! Oh yeah. I had to sell the Celica though, they dropped the class at the end of last year. I sure do miss it.

Russ

[intense 7MGTE]

In order to run 30psi of boost you will need a bigger turbo first of all. The stock CT26 can only push out 15psi and at that point it is just blowing hot air. Secondly you will need a stronge top and bottom end wjich you have. Then you will need a tuning computer like a VPC2, a SAFC or better yet a EMS from AEM. Then you will need to run at least 100 octane to keep the motor from blowing sky high. 91-93 pump gas just will not cut it.

[WiseAssJester]

At what altitude? Tempuratures?


I appreciate the input, but lack only forced induction experience. I've built other beasts a'fore.


Thanks matey.


20 or 25 considered safe?