80 Cutlass SBC multiport turbo street/strip

64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
891
93
Upstate NY
My son bought this just before a year ago as a rolling chassis that was in the process of being turned into a dirt street stock car. No engine, trans or interior, other than a misfit seat with a set of vice grips on the steering shaft. He had the motor from a previous car with a set of stock heads. He bought a set Profiler 185's and bought a turbo manifold kit, that we wouldn't recommend to anyone, and put a used core T3 turbo on it that he aquired for free. The engine build is as follows :
Large journal 327 .030 over" with 6.25" Crower rods, Probe forged pistons, stock crank cut ,020". Compression is 9.9:1, give or take .1 The rotating assembly is balanced. A Comp boat (marine) cam with .500 lift with the 1.6 Comp roller rockers. It has a TPI from an 85 Vette intake and fuel system with 27lb injectors being run with an MS2. Due to the turbo build, he attempted to swap the injectors to a set of 60lb South Bay Deka injectors, but they sent us 80lb by mistake and told us to keep them rather than send them back. The turbo has since been upgraded T4 76 mm On3 due to the T3 was choked out before 4000 rpms. The T3 had amazing throttle repsonse from from 1500 -2500 and could easily be at full boost, 7 psi, within 2 seconds, but the WOT performance was pathetic. It made less than 290ish HP and 340ish torque, but before 3500rpms. At that point we put on the T4. It's been to the dyno only once since then and it ran out of fuel at 4800, single Walbro 255, through the stock fuel lines size of 5/16", but made 348 HP and 410 torque.

The trans is a CK Performance Stage 2 with all of the billet goodies. It is rated to handle 650 ft/lbs. We sued the stock 7.5 with 3.73 gears and Torsen diff that we already had and a set of S10 28 spline axles.

The car gets between 20-21mpg on the highway with a set of 275/60 15 drag radials. The goal with this thing is for it to be a 500WHP with fuel economy over 20mpg.

Winter upgrades consist of another Walbro 255 supplying the driver side fuel rail. An 8.5 rear from a Buick GN that were are putting a Quick's Performance posi in with 30 spline Moser axles. A Straub Technologies custom ground cam that seems mild as heck to me, but Chris Straub says we should be making 500 at the crank with on pump gas with no loss or better fuel economy. A home fab rebuild of the headers, so that the turbo will fit under a stock hood and flow somewhat better.

There is a bunch of custom built stuff and bought upgrades that we've put on the car. UMI torque arms, vacuum pump that is triggered by the ECM to run in boost, refabbed rear crossmember, Ebay 31" CAC, electric fans and shroud from an LT1 Camaro, Speedway universal radiator, CS 130 alternator, HVAC delete panel - homemade, B&M ratchet shifter, complete dash with Autometer gauges. I'll attach more pics and progress as it goes.

Forgot the complete interior is from an 82 Grand Prix bought at the local JY for $100. The driver seat needs a refurb or replacememtn, but the rest is in better than good condition.
 

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64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
891
93
Upstate NY
Forgot to add, that both frame rails were in poor condition behind the rear supsension when he bought it, but we welded in new tail sections and installed a new body mount kit at the same time a year ago.
 
drogg1

drogg1

G-Body Guru
Jan 25, 2009
894
28
Cool different build.

Are you using a boost referenced fuel pressure regulator?

I would expect one 255 lph Walbro to be plenty:

255 lph = ~67.36 gph

With a turbo engine you are running at a Brake Specific Fuel Consumption (BSFC) of >0.6 lbs of fuel per hr for each HP it produces. Lets take at 0.7 on the safe side. Gas weighs around 6 lbs/gal.

6 lbs/gal * 67.36 gph = 404.16 lbs/hr

(404.16 lbs/hr) / (0.7 lbs/hr*HP) = ~577.3 HP.

You are using the 80 lbs injectors then?

They should be good for (80 lbs/hr * 8 * 0.8 Max duty cycle) / (0.7 lbs/hr*HP) = ~734.1 HP

https://www.rceng.com/technical.aspx?UserID=30541400&SessionID=QnmyggRI5dOGw2atlegu

How do you like tuning MS2?
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
891
93
Upstate NY
Cool different build.

Are you using a boost referenced fuel pressure regulator?

I would expect one 255 lph Walbro to be plenty:

255 lph = ~67.36 gph

With a turbo engine you are running at a Brake Specific Fuel Consumption (BSFC) of >0.6 lbs of fuel per hr for each HP it produces. Lets take at 0.7 on the safe side. Gas weighs around 6 lbs/gal.

6 lbs/gal * 67.36 gph = 404.16 lbs/hr

(404.16 lbs/hr) / (0.7 lbs/hr*HP) = ~577.3 HP.

You are using the 80 lbs injectors then?

They should be good for (80 lbs/hr * 8 * 0.8 Max duty cycle) / (0.7 lbs/hr*HP) = ~734.1 HP

https://www.rceng.com/technical.aspx?UserID=30541400&SessionID=QnmyggRI5dOGw2atlegu

How do you like tuning MS2?
You're correct about the Walbro 255, but you neglected to take into consideration the line size. I'm only using factory 8mm lines from an early 90's pickup. Maybe it should've made more before running out fof fuel. I was watching the laptop and the fuel pressure gauge during the dyno runs and the fuel pressure waivered and it knocked, so whether it's the pump, lines or perhaps needs a filter change, I'm positive the pressure waivered. In terms of the dyno numbers, keep in mind that those numbers are from a chassis dyno. I always question the accuarcy of all chassis dynos. The proof should be in a weight and time slip which will occur come spring/summer.

Yes it is boost referenced through the stock regulator.

Regarding the injectors, it worked out OK that we got the 80's in error, because were going to put E85 to it next year as well. I'm hoping the E85 will put us over the 500whp goal. But I'm sure that it'll hammer the fuel economy though. But it's not that difficult to swap between the two and just change the tune or add a flex fuel sensor if I feel the need.

I like the MS alot. I bought it assembled with the relay board. It was very easy to hookup and use. For a GM with a 7 or 8 pin HEI module and multiport it is as close to plug and play as you can get. We built our own engine harness due to the harness that came with TPI setup we bought had more shorted circuits than good ones. I'm presently using it to control the vacuum pump and a knock sensor. I'm going to have it running the TCC before summer.

Jim
 
drogg1

drogg1

G-Body Guru
Jan 25, 2009
894
28
You're correct about the Walbro 255, but you neglected to take into consideration the line size. I'm only using factory 8mm lines from an early 90's pickup. Maybe it should've made more before running out fof fuel. I was watching the laptop and the fuel pressure gauge during the dyno runs and the fuel pressure waivered and it knocked, so whether it's the pump, lines or perhaps needs a filter change, I'm positive the pressure waivered. In terms of the dyno numbers, keep in mind that those numbers are from a chassis dyno. I always question the accuarcy of all chassis dynos. The proof should be in a weight and time slip which will occur come spring/summer.

Yes it is boost referenced through the stock regulator.

Regarding the injectors, it worked out OK that we got the 80's in error, because were going to put E85 to it next year as well. I'm hoping the E85 will put us over the 500whp goal. But I'm sure that it'll hammer the fuel economy though. But it's not that difficult to swap between the two and just change the tune or add a flex fuel sensor if I feel the need.

I like the MS alot. I bought it assembled with the relay board. It was very easy to hookup and use. For a GM with a 7 or 8 pin HEI module and multiport it is as close to plug and play as you can get. We built our own engine harness due to the harness that came with TPI setup we bought had more shorted circuits than good ones. I'm presently using it to control the vacuum pump and a knock sensor. I'm going to have it running the TCC before summer.

Jim
Ya 8 mm / 25.4 mm/in = ~.31 in lines might be the restriction.

It's nice you got those 80 lbs/hr injectors though if you're going to run E85. I have also been reading up about modifying carbs and running FI with E85 and it definitely requires a beefy fuel system. So, I guess you will want that second Walbro anyway. I kinda like the idea of running two instead of one larger pump. You will definitely want to step up to a -6 or -8 line or equivalent soon if so though.

I have also though about using MS2 or MS3 and probably will replace a lot of wires in the harness if I do. Glad to here it is fairly plug and play.

Cool car Jim. I will definitely be watching this thread for updates.
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
891
93
Upstate NY
Ya 8 mm / 25.4 mm/in = ~.31 in lines might be the restriction.

It's nice you got those 80 lbs/hr injectors though if you're going to run E85. I have also been reading up about modifying carbs and running FI with E85 and it definitely requires a beefy fuel system. So, I guess you will want that second Walbro anyway. I kinda like the idea of running two instead of one larger pump. You will definitely want to step up to a -6 or -8 line or equivalent soon if so though.

I have also though about using MS2 or MS3 and probably will replace a lot of wires in the harness if I do. Glad to here it is fairly plug and play.

Cool car Jim. I will definitely be watching this thread for updates.
FWIW, I spent too much time researching the fuel system, filters, lines, line size while we were building this because I didn't want my son to spend the money to build a system only to find out that it woerks, but needs to be added to in the future, which equates into good money on top of bad. So at the end of the day, we bought a $100 pump kit and $60 primary filter and used stock and JY parts for the rest. With the idea that we'll see how ot works and change from there. After running it on the dyno we found 340HP and 400+ torque on the cheap system. So adding a second pump means that the fuel system is going to be capable of 700ish HP and 800+ ft/lbs (at the wheels). That was the thought process I employed.

We are using #6 line for the second pump and are not planning on upgrading the first line unless my son has some money burning a hole iin his pocket.
 
online170

online170

G-Body Guru
Oct 28, 2010
728
63
Thats one badass build!

Are you the guy with the single turbo nailhead?
 

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