JoeNova

Stock bottom end street car. 6900 is slightly north of where I plan to rev, even with the 92mm. Although, after seeing that someone recently broke into the 4s on a stock bottom L33 with rod bolts, I might pick up some rod bolts and try my luck up around 7000 (I also have an L33).

hellbents10

iTrader: (10)

I think RPM is a key component on making the most power possible with stock stuff. I like to see good power from 5500-6800, if you want more power real early it is trouble.

JoeNova

I just don't want to have to rev to 4500 on the street to make decent boost. If I can have at least 12 PSI on the street by 4200 RPM that would be perfect.

At the track I'll have to rev to 6400 on a 28" slick and a 3.54 rear to hit 150 mph in the 1/4th. On my 275 radials (26.66" tall) it'll take me 6700 to hit the same 150. So that RPM/Gearing is ideal for me.

3pedals

iTrader: (3)

Dont even bother with rod bolts. I turn my 6.0l 72-7300 on every shift. 160km stock bottom end

stock48

iTrader: (17)

Yes I ran 8.9@158mph with my car at 3350 lbs with a box stock cast S475/83/T4 in hot summer DA on a botched run. I really think I could go mid 8's with that turbo on a good pass. This is on a lq4, I belive a 5.3L would be more efficient with that turbo and could run a little better. Im however running a Glide which is much more efficient than a 4L80E.

JoeNova

And if I come across a rediculous amount of money, I'll probably switch to a built glide with a gear vendors overdrive unit, or maybe back to a TH400 with a lower gear.

RonSSNova

iTrader: (3)

A TH400 with a 2.20 low gear would be interesting. Not cheap though.

So, sounds like you get to choose the ext turbine your own bad self as it seems there are a few opinions on what to use. Although the 92 sounds promising.

Although I'm ready to try mine with the slicks etc, nothing but rain here for the next ten days. I've seen our early season rained out clean through May before.......it sucks.

JoeNova

I'm still stuck between the 87 and 92, although it looks like I can get the spool I want with the 92 so I'll probably go that direction. It will also get me the extra kick I need with the 4L80e and multi-leafs in the rear.

JoeNova

I know I'm bringing this back from the dead, but things change.

The car is no longer being built to be competitive in X235. I'm going to buy a roller later on down the road and convert it to drag-only duty. For now, this car is primarily street duty.

So I was wondering, would it still be possible to crack an 8 second quarter mile pass with an S476R and a 83mm/1.10 T6 turbine. Cam is still going to be the 218/218 on a 5.3 L33. I just want it to be primarily a street car. Going to try to keep weight around 3300 lbs, and the 92mm wheel isn't needed for the extra power. I know I'll be giving up a bit on the top end, but I should gain that much back in spool with the 83mm wheel, and I'll still be going with a divided T6 housing.

Sarg

iTrader: (6)

Well this right here shows that it should be possible. Even larger motor and was still able to deal with it and go 8s.

3pedals

iTrader: (3)

What makes you beleive the 83 will spool faster than the 92? You do realize that the larger 92 has extra leverage over the compressor wheel compared to the 83.
Have yiu ever spun a fan using an air hose? Try it. Aim the hose at the tip of the fan and note how fast it spins up, then try aim it close to the hub and note the difference. .........

NSSANE02

iTrader: (14)

That's a terrible example. The smaller opening would create a higher velocity in most cases, which would spool faster/sooner.

3pedals

iTrader: (3)

this is plain wrong.
its the a/r of the housing that necks down the incoming exhaust gasses to create velocity inside the turbine, the diameter of the turbine wheel gives the gasses leverage on the shaft and compressor wheel, and also determines the overall flow of the hotside of the turbo.
smaller turbine diameter does not necessarily mean faster spool

69-chvl

iTrader: (11)

This is interesting b/c I too was seeking boost to come it pretty fast for a nice street-driving experience. Here's what I have:

5.3 stock w/LS6 cam
s475 t4 1.10 83mm
ls3 mani's
2.125 hot side, fully divided w/2 38mm's
th400, 10" TSI low-stall conv., 3.27 rear, 28" tires
A2A I/C

In 3rd gear, I get about:

rpms/psi
3970 = 5psi
4355 = 10psi
4539 = 11psi (wastegate spring)
4825 = 12psi

The boost gauge zero's out at about 3400 rpm in all gears.

Looks like my boost comes it slower than most folk's combo's here. I do run a lot of timing, AFR is 11.5. For the extra 250.00 for the t4 housing, extra w/g and the trouble of going with a divided hotside, I would of expected the spool to be about 1000 rpms quicker. Should of just went with the 650.00 s475 and been done.

But, it does feel very responsive driving around. Need to stop looking at the tach/boost gauge and just enjoy the drive !!!!!

3pedals

iTrader: (3)

^ you should measure back pressure pre turbo, and see whats going on.
If pressures are high then is probable that a larger exhaust wheel, but yet the same 1.1 a/r housing could help you

Sarg

iTrader: (6)

Checked for intake or exhaust leaks? That spool sounds aweful slow.

JoeNova

I'm kinda going for budget here. A 92mm exhaust wheel would cost about the same as sticking with the 83 and getting a billet compressor.

The 92 spooling faster is a bit situational. Its heavier as causes the exhaust gases to be more spread out and less concentrated, reducing impact velocity. The reason spraying onto a larger fan causes it to spin helps is the extra leverage. You're concentrating the force on the part of the blade that is best leveraged. This isn't a real world situation.

69-chvl

iTrader: (11)

Nothing major that I can see....I guess I can disconnect the BOV reference line just in case its opening. I dont have a boost controller hooked-up at the moment so I guess the gates might be cracking open a bit...need to do that first.

3pedals

iTrader: (3)

Have you looked at the inside of a turbo?
The first place on the turbine that the exhaust touches after squeezing through the housing, is the tips or the turbine wheel.

Extra leverage is your freind, but of course sizing is important. You dont want to go too big either.

LILHEMI

your converters too tight. get that **** loosened up like a $2 ***** and then post back.