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My Twin-Turbo SBC 240Z Build


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Any progress?

 

 

Sorry for the lack of updates... I was out of town for 16 days, then I was helping my son work on his Datsun 510. Anyway enough of the excuses :-)

 

I got it on the road for the 1st time last week. A few nagging annoying problems, but nothing major so far. I have an oil leak that appears to be coming out of the back of the intake manifold. I’m guessing the seal between the manifold and the lifter valley (I did use a generous bead of RTV, not the stock gasket). Not sure if its boost related or not, but it wasn’t leaking before the turbos went on. I tried disconnecting the PCV, thinking I was boosting into the crankcase thru it, but it only got worse! I also have an intermittent electric problem that I need to track down that kills the engine. I might be the supply for the MSD module, but it doesn’t happen long enough to trouble shoot. Just a PITA when it decides to quit... especially in traffic :-(

 

OK, so impressions? I have to say WOW! The boost comes on pretty quick and you can definitely feel it. The 1st day I took it out, the roads were wet (this is near Seattle!) and no matter what speed I was going, the rear end would break loose when boost started kicking in… not a very friendly car to drive in the rain. We just had a couple of dry days, so I got to “feel†the acceleration… pretty cool! Remember, I’ve got the wastegates set to only 5psi, so I not adding a ton of power, but its definitely working for me.

 

I want to add some insulation to the hood above the turbos (gets pretty hot to the touch, but no paint discoloration) and fix some of the other minor issues, but so far I’m happy with the results.

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At 5 psi you should not have a problem. You'll have to reseal the intake of course with some RTV. The biggest problem I've seen is around 10 psi. Thats when it starts pushing oil out the breathers. I've ran as high as 17 and it is more of a flow of oil out the breathers. A surge tank will fix this. On two forced induction motors we haven't had a problem with the intake sealing using rtv at the front and rear. If you don't have oil out the breathers it's most likely a bad seal. Also if you have your jetting spaced out like I had mine 81 primary 94 secondary you'll have to be carefull with that due to uneven distibution of fuel. I saw some heat on my #1 and #2 pistons when I changed my heads. BRPV's will take care of that problem. At low boost (>10psi) though you should'nt have a problem. Good luck and don't get frustated with it because it's a blast with a good tune!

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At 5 psi you should not have a problem. You'll have to reseal the intake of course with some RTV. The biggest problem I've seen is around 10 psi. Thats when it starts pushing oil out the breathers. I've ran as high as 17 and it is more of a flow of oil out the breathers. A surge tank will fix this. On two forced induction motors we haven't had a problem with the intake sealing using rtv at the front and rear. If you don't have oil out the breathers it's most likely a bad seal. Also if you have your jetting spaced out like I had mine 81 primary 94 secondary you'll have to be carefull with that due to uneven distibution of fuel. I saw some heat on my #1 and #2 pistons when I changed my heads. BRPV's will take care of that problem. At low boost (>10psi) though you should'nt have a problem. Good luck and don't get frustated with it because it's a blast with a good tune!

 

I think the seal was bad all along and the added blow-by is now pushing oil out the seal. It may be hard to inspect because it's so tight to the firewall (set back even further than JTR by 3/4 inch). Maybe if I pull the distributor I can get a better look. At worst, I'll pull the intake and re-seal. I didn't expect much blow-by since I did a leak-down check before I added the turbos and the worst cylinder was 97% The thing I don't understand is why it got worse when I disconnected the PCV. I unhooked the line that goes to the base of the Throttle Body and plugged it and just left the PCV in the valve cover open and I got lots of oil running down the bell housing. I hooked it back up and its leaking just a little.

 

Thanks for the reply... I'm now hooked on boost :-)

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  • 1 month later...

Looks awesome! Have you ironed out any of the little problems? Yes boost is addicting, Im figuring that out as well.

 

I actually met if I remember correct your brother in law... hes going to school at SFCC over here in Spokane. He heard me talking to a friend about my Z and showed me your build. If Im not remembering correctly that hes your brother in law, hes into VWs... maybe that narrows it down. :)

 

Keep up the good work!

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Looks awesome! Have you ironed out any of the little problems? Yes boost is addicting, Im figuring that out as well.

 

Still working on some of the issues... seems that with the nicer weather, I've been catching up on more of the work around the house that piled up over the winter.

 

I actually met if I remember correct your brother in law... hes going to school at SFCC over here in Spokane. He heard me talking to a friend about my Z and showed me your build. If Im not remembering correctly that hes your brother in law, hes into VWs... maybe that narrows it down. :)

 

Close, that would be Ken, my daughter's SO and dad to my beautiful 7 month old grand-son. In fact he was here, in western WA last weekend and I gave him a ride in the Z. I think he was impressed!

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