need opinions if this would work ok....

[Blazer406]

Ok.... tell me if this is a good idea / or if it might work.

Take a 8.5:1 350 or 383... put a holley commander 950 MPI complete system..........list any potential problems I might run into bringing two pressureized pipes into the throttlebody..... maybe vortec heads if you want to stay fairly low buck...a cam cut for turbo setup (could even be hyd. cam to keep costs down)..... not too hot.... power range to 6000 would suffice....2 stock GN turbos...(should be able to find these used and relatively inexpensive.... they also have integral wastegate)....2 stock GN intercoolers.....(also easy to find and relatively inexpensive)...... I was thinking about 800 hp @ rear wheels would not be too much to ask out of this combo on pump gas.

 

[TurboTR]

I'm not sure the stock GN turbos will get you the ~ 450 hp ea to give you the 800 rwhp. If you're really going to do it, might as well just do it right to begin with

TurboTR

 

[Blazer406]

What is a realistic goal then if 800 RWHP is not attainable? I gotta start somewhere. I just would like to build a super low buck setup for starters, and eventually work up to bigger (read much much more expensive) equipment and eventually make 1000 RWHP on pump gas in a street car. John Meany's TT vettte is 1300 HP on pump gas off of 400 ci. He does have 18 deg splayed valve heads. I just thought I would slowly work toward maybe 1000 HP from a more reasonable (affordable) combination. I think heads are available for under 2000 (per pair complete) that flow over 300 cfm on the intake and would make excellent choice to achieve the 1000 hp goal......... eventually.

 

[JDEstill]

Here's a stab at what I think you'd get out of that setup:

Engine Data
engine rpm 5500 revs/min
displacement 350.0 cu inch
volumetric efficiency 85%
number of turbos 2
compressor efficiency 65%

Ambient Conditions
local baro pressure 29.92 in Hg
ambient temp 80 deg F

Conditions at Compressor Outlet
outlet pres 18.0 psig
outlet temp 316.0 deg F
P2/P1 2.38

Conditions at Intercooler Outlet
manifold pres 16.0 psig
manifold temp 120.0 deg F
IC pressure drop 2.0 psi

Results, mass and volume flows
compressor air flow 33.9 lb/min, actual
compressor air flow 256.2 gm/sec, actual
total engine air flow 512.3 gm/sec, actual
compressor air flow 493.3 ACFM, actual inlet
compressor air flow 297.4 ACFM, actual outlet

A/F ratio 11.5:1
fuel specific gravity 0.735
fuel required 5.89 lb/min
fuel required 57.7 gal/hr

engine hp potential 505.1 hp @ BSFC=0.7
engine hp potential 589.3 hp @ BSFC=0.6
engine hp potential 707.1 hp @ BSFC=0.5

Net result:
I think 2 stock GN turbos would be the right size for this type of engine. I think you'd most likely see about 550-600 flywheel hp out of it once it was tuned well, 700 hp would be pushing it, 800 hp pretty darn unlikely. Of course, that is all based on the assumptions made in the calcs above, and as always garbage in = garbage out. I'm assuming you could only run about 16 psi on pump gas for example. If you could run more (which you could with race gas), then you'd get more air flow and more power.

John

 

[Craig Smith]

Unfortunately, I really don't believe that there is a low-dollar route to the hp levels you are hoping to attain. If nothing else, you will have to spend a lot of money on bottom end parts that will survive under such conditions. The heads that John has on his car are WAY over $2000 for a set, and that's where you need to spend money to make power. All said and done, I don't think you can reliably make that kind of hp for any dollar amount under 5 digits, and that's just the engine. Turbos, etc. are in addition to that estimate. I could be wrong, but I would plan on some overtime if I were you.

 

[Blazer406]

Guess I was just daydreaming......

Well,

I still think I might try and build a twin turbo system using some better heads and cam than I originally posted. I just wanted to see what type of responses I would get from a relatively low buck attempt. I couldn't bring myself to spending $400 for a set of vortec heads that have a NA hp potential of about 400 streetable hp (pump gas compression ratios) when I could spend around 1000 dollars for much more hp potential. I am sure the two stock GN turbos won't be ideal, but hey.... they are cheap, and I can always get the kinks worked out and upgrade to larger turbos and to a larger more efficient intercooler in the future...... meanwhile I am having lots of fun even if it is ony 500-600 hp......

 

[Blazer406]

after further research.....need some opinions

Hey guys,

After some more thought and a lot of reading, I have a new (similar) senario I need some input on. I saw a post on another forum on a guy "Grapeape" that has a twin turbo 385 cu in SBC with trickflow twisted wedge heads. I have attached an image of a dyno pull he did last year non-intercooled at 12 psi boost on pump gas. I really like this setup b/c it is the same cylinder heads I already have. Take a lookat it:

http://home.jam.rr.com/bdykes/dynoscan.jpg


The turbos he uses are a little bigger than stock Buick GN turbos. From what I have read, a stock Buick turbo flows about 35 lb/min of air. His turbos flow about 45 lb/min air. After putting his combo in JDEstill's excel sheet (excellent by the way) I started to play with the VE until I achieved GrapeApe's HP. I then modified the boost setting down to about 8 psi (still non intercooled) and the flow decreased from 45 lb/min to about 35 lb/min.....in line with what a stock Buick GN turbo can put out happily...... the hp level possible is still real good....533hp at .7 bsfc up to 747hp at .5 bsfc. I have also looked at the new Holley StealthRam and using the FAST ecu with wideband O2. I think this is a very do-able combo that would run impressively fast for a street driven car. As money was accumulated, you could upgrade turbos and then on to an intercooler for similar numbers and even besting what he had (with some more boost).


What do you think?

 

[Blazer406]

Bump for another look at the combination......... Need input.........

 

[NOSjohnWE4]

TT setup

There are more than a handful of people out there who are already doing and have done this type of setup...myself included.
There are many opinions out there you just have to go with the one that you feel most comfortable with. I personally don't have more than 4 or 5,000 into my motor and it's survived many runs with a 200+ shot of Nitrous (over 600hp total). It's all in HOW you build it AND the combination of parts! This motor is getting 2 stock GN turbos a fresh set of lifter, maybe a new cam and 2 intercoolers from a GN. I feel 550-600 is EASILY attainable on average boost (14-16lbs.)as I look at others who have done it.
I plan to make some patterns and then if anyone wants to do a TT 350 (any size Chevy small block), I will have a kit, hopefully cheap so that others can benefit from my experience. I'm so tired of looking for ways to get some HP and every supercharger and turbocharger kit is a huge sum of money. I'm here to help out everyone! HTH...


John C.
LedSLED Motorsports