1g Auto Slingshot Build

[1SIC1Gb]

Going to see if we can blow it up on the dyno Monday.

 

[1SIC1Gb]

Headlights and front end buffed. If you can't tell, the paint totally sucks on the car. The p.o sprayed it with single stage black and it started raining once done is my guess. So about every 6 months I have to buff it and it still looks terrible. Cage and paint are on the list .

 

[1SIC1Gb]

Dyno went well. Absolutely great power band, car is very solid.
Maxed out the 12cm housing at 40psi which I expected. the great thing about it is i can build 20-22 psi on the footbrake with a 35 shot within less than 3 seconds.

 

[1SIC1Gb]

 

[bastarddsm]

Just about 700whp? I'm very suprised it made that much through that housing, but congrats.

 

[b00stedtalon2]

Good stuff. When are you planning on going to the track?

 

[1SIC1Gb]

Not sure yet, but this copper headgasket is a real pain. Keep having to retorque it . But it should be easily enough to go 9s. Welded center diff, and it spins all 4 from a 55 roll on my street wheels.

 

[CrackedDSM]

Good stuff, man! Gee, I guess twin-scroll does work...

 

[bastarddsm]

Dude, get your BS out of here. It makes good power, but a real 67mm in an open .82 housing makes a lot more.

 

[b00stedtalon2]

Not sure yet, but this copper headgasket is a real pain. Keep having to retorque it . But it should be easily enough to go 9s. Welded center diff, and it spins all 4 from a 55 roll on my street wheels.

Typically with a copper gasket, you need to re torque it 3 times before first start. We usually do it every hour after the head as been installed. The first 3-5 heat cycles it will be needed as well. After that you should be good.

 

[1SIC1Gb]

Typically with a copper gasket, you need to re torque it 3 times before first start. We usually do it every hour after the head as been installed. The first 3-5 heat cycles it will be needed as well. After that you should be good.

When you retorque it , you break each one individually, starting with the center and torque it back to final torque? Or how do yall do it?

 

[b00stedtalon2]

When you retorque it , you break each one individually, starting with the center and torque it back to final torque? Or how do yall do it?

For retorque, you'll want to loosen the nut and retorque back to your spec, one stud at a time. I also re-lube the nut each time. Start in the middle and follow the factory torque sequence.

 

[1SIC1Gb]

An open t3 design would absolutely flow more than this, but I know for a fact it wouldn't be able to do this. Yes it would get on the converter but it would take 75-125 shot to get it there which would be a ticking time bomb on the transfer gears splitting the trans.

 

[bastarddsm]

Hey sorry I didn't mean to clutter your thread, I just really do not like Cracked, and his comment was a stab at me.

Anyway, I'm very surprised to see how it's working. I'd be more convinced if it was a 5 speed because I don't have anything to reference it toward. Any plans in looking at exhaust pressure?

What's the ETA on a track visit?

 

[1SIC1Gb]

I don't plan on checking the back pressure, I'm sure it's pretty high, but i should be going to the track as soon as possible.

 

[1SIC1Gb]

To test the back pressure I'd need to weld on a fitting to my manifold pre turbo correct?

 

[bastarddsm]

Yeah I'm on a cast manifold, and I just drilled and tapped a runner for 1/8 pipe and then used a swagelock fitting and 18" of 1/4" stainless line, connected to a 100psi sensor with some hose. Seems to work good.

I did one at the turbo outlet to measure the exhaust system backpressure, and was really surprised at that. Mine has about 8psi at full tilt trapping 130. It's a full 3" with a 3.5" straight through muffler.

 

[1SIC1Gb]

Ahh... More machine shop issues. Retorqued the headstuds today and one of them wouldn't tighten up. It was starting to get water in the oil and here's why. The inserts for the 1/2" headstuds were very close to coming through into the coolant passage on the very far #4 cyl studs, well they cracked into the coolant passage today. Not in not sure what they are going to do, I may need to get a new block. What

 

[Brandon Mau]

Nice build, unfortunate about that coolant jacket mishap though.

 

[1SIC1Gb]

So I took it in to the machine shop, going to have to get a new block. Just going to move everything over to this one . Crappy but they are taking care of it for me . Nice to have a machine shop with good service.

 

[bastarddsm]

Ditch the 1/2" studs.

 

[donniekak]

Ditch the 1/2" studs.

Agreed. 12mm l19 or 625 studs are plenty. With the 12mm tool steel studs the issues aren't clamping force and bolt stretch. It's the span of aluminum between studs flexing.

The 3000gt guys mill out the area under the fire ring, weld it solid and deck the head. There is still plenty of water running through the heads, but the head deck is much less likely to flex.

 

[Critic4Du3ce]

Holy shit you really been going through stuff. Hope after this new block everything goes smooth man

 

[1SIC1Gb]

It sure would make things less complicated .. But I can torque the 1/2" studs to 115ft/lbs which also helps with lifting and flex.

One of the big things too is the steel head inserts which I already have . I'm going to talk it over with my machinist . He has some new inserts for the studs that are much smaller (leaving more meat around the block to prevent this)

 

[b00stedtalon2]

It sure would make things less complicated .. But I can torque the 1/2" studs to 115ft/lbs which also helps with lifting and flex.

One of the big things too is the steel head inserts which I already have . I'm going to talk it over with my machinist . He has some new inserts for the studs that are much smaller (leaving more meat around the block to prevent this)

That much torque distorts the head. I've never gone past 95ft lbs on any 4g63 build.