Is there some kind of chart somewhere? I'd like to know a safe limit for turning the boost up.

My blower is a v-1 and is rated at 680hp, so I may max it out at 750 anyway with my planned 10lbs.

No intercooler, maybe in the future. Have a meth inj kit and boost timing controller. Iron heads and forged srp pistons.

 

with a meth kit and good gas, i'd say quite a bit, get a knock sensor and guage if you're really worried about it.

 

I have one but it never seemed to work. Couldve been a bad knock sensor. It was a cheap led gauge off ebay. That could be at fault too.......

 

IIRC summit had a few, I thought autometer made one as well.

 

yeah it probly depends on the gas you use and the tune. 9:1 seems pretty good for boost, but with iron heads 9:1 aint bad for n/a motors either. if it was aluminum i'd say 9:1 is a good ratio to shoot for. it still should be good with 10 psi tho. i've seen alot of ppl running 7-10psi on stock motors like LT1's with 10.5 to 1 compression

my buddy ran 12 on his L98 before the bottom end blew L98's are 9.3 to 1

 

Wow, thats a lot of stress on a stock crank. I'm surprised the pistons didnt shatter first.
I know that boost raises your compression, and there must be a known limit of some sort on forged parts, compression wise.
I think I'll max out this blower though, either cfm or rpms, before I max out the boost potential of my engine.
With the smallest pulley I have, I'm taking this blower to its rpm limit at around 6k rpms. That was about 15 psi on the 305. My 383 breathes much better, so the psi will be lower. Its also recommended with the carb that I have that I dont take it above 10 psi. Maybe the shaft seals wont hold up?

 

if the rest of the motor is build right, 7-10psi will be awesome for power on a 383.

 

www.turboforums.com

batass read on there different buildups. Also people have taken stock bottom end 350s to the low 9s with boost. It helps that you don't spin a boosted motor to the moon in most cases.

 

RPM is what hurts parts more so than pressure from forced induction. Forced induction just adds more heat which can seize rings and melt pistons (if it goes lean). Pistons and rods and crankshafts can stand LOADS of cylinder pressure at lower RPMs if the temps aren't too high. info care of Corky Bell. Very good chart about how crankshaft stress is related to RPM and boost - boost had a minimal effect.

 

indeed, corky bell is a great turbo author.. maximum boost is a good source for the beginner and advanced ppl as well.

 

So you are liking that forum now, eh?

 

^ Heh, pretty cool forum....

 

it's alright, although that forum much like this forum, when I have a question it often goes unanswered because no one knows

Luckily I'm pretty good at wasting hours that should be doing work on doing google searches for what I need to learn. That and my AEM wideband will help in tuning this spring

 

You haven't shared any pics yet. If you are tuning in Spring, I'm guessing you are close?

I think I remember you picked up of GN turbos and I/C's, right?

 

still don't have the fmic, piping, or the bov. The fmic and bov I'm assuming will be shipped to me shortly, I already paid for them. The piping I'm up in the air about making my own out of exhaust piping or buying those ebay one size fits all kits and piecing it together that way with some fab time. Pics will be sometime before spring lol.

 

If you do with the universal IC mount kit post the wall thickness on the pipe. You get a lot of alum. for the price. I am wondering how thick it is.

I read the ebay single turbo headers had 1/8" wall pipe........I measured one a week ago and the wall was .050" (18 gauge) S/S.

 

Must be lonely at the top eh? J/K, I know that feeling. I always ask the really hard questions too.

 

I have the same problem. Why won't anyone answer my "how much HP will my 350 make with twin turbos at 12 PSI?".......or "will the bottom end handle boost?"

 

I'll post the thickness if I decide to buy one of those kits, I know a few other people who have bought the kits, maybe I'll ask them to bust out the caliper and get a measurement. He got all his piping, t-bolt clamps and silicone ends and elbows that he needed for under 260 to his door. Extremely cheap IMO.

nah it's not lonely at the top the air is cleaner and the competition sees my taillights.

hehehe. I just can't wait to make my thread, 2 turbos + custom ground roller cam + 350....will I run 12.99 yet?

 

How about my seat cutter question?

https://www.thirdgen.org/forums/tech...dius-seat.html

Only 14 views even.

 

I was surprised when I looked at the ebay single header. I was like that could be 16 gauge. I put the calipers on it and saw it was 18 gauge. You can see why the headers crack near the welds. The thin S/S and brittle welds (blackish color) are a weak point. They run a quick TIG over the center of the weld to give it a small gold (good weld) appearance.

If you do measure the pipe, do the couplers too. I wonder if they are 3-ply. The T-bolt clamps look a little strange. Not like a truck or normal S/S strong T-bolt clamp. They look like they would get the job done though. If the pipe is thin then that is a good thing or the pipe would oval/crush.
----------
I never visit the tech/general board..........make that 15 views and still no answer.

 

Probably have to put some good gas in it and sticky tires. I wouldn't go under a 14 flat. They make you put a helmet on and the booming bass out of the radio doesn't sound as good at the tree.

 

got you covered

 

Yes, the walls are extremely thin on the AL tubing from ebay. I used some on the turbo Corssie I just finished because that's what the customer brought me. On the good side, it is extremely light and came with a black annodized finish (appeared to be 18ga).

I wouldn't trust the welds on there. Especially if it's 18ga. The headers on the Corssie were built with 14ga mandrels and welded along anywhere the primaries were remotely close. The y was made with 16ga and when installed we jumped up and down on it to make sure the turbo didn't need another support bracket (maybe wasn't the best test, *but*).

the only thing I really didn't like that I went with anyways was the fact that he brought some 18ga 2.5" mandrel u-bends that was intended for the I/C piping, but he didn't bring anything for the downpipe and it was made with it. Good thing he brought the AL tubing or the job wouldn't have gotten done in time for him to go home on Sat (started 12pm Th). The 2" pipe from the turbo to I/C was also made with the same material as the y, let's see how long it will last.

His tranny blew out on Sun while "playing with it a little" and the pipes are now getting coated, so we will see.

LOL junk.

Can't wait to get the meter for the flow bench. $500 is a lot of cash right now with the shape of the economy, but saving for it now. I'm building a FlowQuik setup on th loft at the shop, the rest of the materials is cheap or is already in the garage.

 

I don't know anything about valve cutting. I know more angles are better but that is about it. I have read Vizard's valvetrain book probably 10 times. My last valve job cost $45 for a pair of V8 heads. It wasn't the prettiest job but it seems to work fine.

 

It's not that difficult with todays tooling. There is no more machinery and you just have a handful of carbide cutters with various angles on them and a t-handle. Then there is a pilot you stick in the valve guide to keep everything concentric and straight. Neway is the brand I'm looking at. Found a nice 4 angle set with pilots for just under $400 new (they go for that used on ebay). Comes with 15*, 31*, 45*, and 60* cutters. Then all I need to buy is the 70* cutter (another $150 IIRC) and I can make 5 angle valve jobs in about an hour or less. The AL 60* heads come with a 5 angle job, and I would like to expand the head rebuilding/porting to other platforms.

Here is some cross sections of a 3400 head (the one I had a question about)...

http://60degreev6.com/gallery/browse...es&c=11&page=5

 

18 gauge isn't bad for the IC pipes. Did you get lucky with the bends or did you have to cut the stuff? You would get a laugh watching me cut alum. pipes with the sawzall. I run tape around the cut line so I can keep it straight.

I am ordering some 309 rod this week so that I can modify it to fit properly and may add some braces directly to the manifold itself. I need to finish off some of the welds to (pin-holes).
Was that both of you jumping on the header together? Trying to picture the balance/jumping coordination. On the count of 3....wait on 3 or after 3?

Wow, you two had your hands full. Nice job. The 2" pipe to the IC should be fine.

That is the fun part of boost. It shows you where all the driveline weak links are.

I once had the great idea of using a TPI V8 analog MAF to make a bench. Another project that was never done.

 

LOL

Ther was actually three of us, and it's funny - I thought for sure they were at least my age. Both are 19!!!.

Yes we worked from 12pm TH until 2am Fri, came to my house to sleep a bit and my kids start getting up at 6-6:30. We left here to stop at the parts stor and was working again by 10am. I stayed at it the couple of times they had to run and get something (I'm the only welder) and we started the car about 8am. He ended up spending 1/2 the origional quote he got - through me

It was actually really fun, just tiring. THEY are still quite a bit younger and had more energy. We hardly stopped to eat or drink, lol.

 

I remember those days. Start taping a car off in the morning and spend the day, night, day, and night taping off stripes and spraying color. I don't miss them.

 

depends on alot of things...CR, fuel grade, fuel management, turbo sizing, rpms, tuning, heads and cam combo etc. too many factors

 

wheelsup....i think he was being sarcastic. hehe.

 

Hey Steve, I hope you are prepared for the full effects of boost!

 

..................cause you know once you get that first full blast of full boost, you will be walking around with a big silly a$$ grin on your face all of the time

 

nah, I've had 2 stages of nitrous....I know all about the grin.

 

But nitrous is like a quickie..............boost is like a raw, satisfying, full out, no holds barred, all-nighter .....ahhhhh...... errr.... ehhh.......cruise that is

 

well when i pop this motor quick....i'll make sure to yell. This twin turbo thing isn't cheap at all. money pit....money pit.

 

BUT you will never have to fill a bottle again, lol.

the last build FELT like a No2 shot, that's for sure. You knew when you got over 1psi. Nothing like doing a 30mph burnout in a Corssica,

 

Ha hA....I just got done spending close to 600 on pistons plus 280 for rings, plus 3000 for a blower, plus whatever it'll cost for a fuel system to feed this thing...plus a rotating assy balance - and a distributor....join the club!!

 

Don't feel bad. V6 pistons START at $600 :P

 

I'm thinking of the commercial - where the guy gets slapped in the head - "You coulda had a V-8"....lol

 

I was about to say it Confuzed, but you beat me to it.
Makes you wonder why people will spend more to get 3/4 of the power

Ahh, don't get me wrong, i'd like nothing more than another Royal Blue 1993 Pontiac Sunbird with the 3.1L, except with a turbo charger. But in a muscle car? Nah, needs 8 spark plugs

 

EH? Let's see you keep up with this...



You have to remember I have done all the V8 stuff. Best car my friends and I built was a 355/th400 in a 1986 Mustang notchback. It ran 11.8x on the motor and a best of 10.33 on the juice. This was >10yrs ago, though.

I build these V6's for fun, nothing more. I have vehicles from 6 to 10 cyls in my driveway.

Maybe to you thing there is nothing like having 8 sprak plugs, but it's even better when you toast a BBC with a 200 something ci engine in a car that weighs the about the same :P

 

I've got a 9.1:1 iron headed 350 scb and have been running a P1sc procharger blow-thru for a while @ 10 lbs with no issues. Still on cast pistons and nodular crank. It runs real strong-

http://www.youtube.com/watch?v=zuaVGZfjkcM

 

Holy hell, you guys grabbed this thread and ran off to turbo land with it.

Just kidding, xpdbl13, I have the utmost respect for your car. Just your car.
I didn't know that about boost and the bottom end.

I just got my sumped tank in and will be bolting up the supercharger this week. Should only take a day, its been on and off many times with the old engine, so I know my way around it. Got my LM-1 in hand. Need to get my new rear tires and wheels put together and on this week too. Should a be a fun week!!!!

Still stock rear though................

 

So you are still rocking the 3.08 open diff? I am guessing since it is a 91 rs. in the same boat but torque over cam the gearing with low thirteen second blasts. lol

 

I thought they were 2.73s....? Yep open diff. But with the new motor it lays both tires down. I bought some 4.10 gears and a locker but dont really know how to put them in myself and dont want to pay to have it done, when ill be buying a whole new 12 bolt soon.....

Yea those gears are worthless, but with stock tires, they just smoke anyway until I hit third.

 

Depends on what engine and tranny it came with. I know tbi 5 spd came with 3.08's

 

... heh, tell that to these guys, Click Here.


-Rob

 

Auto 305. On that list in the tech section, it says stock were 2.73. Ouch.

 

yeah the auto's were worse off lol.