Isayimandrew's Twin Turbo Build

Elmo370z · 04-20-2022, 11:15 AM

What did you have done to the heads again?

isayimandrew · 04-20-2022, 11:35 AM

Quote:

Originally Posted by Elmo370z

What did you have done to the heads again?

Most of the work was done on the block. The only thing they did on the heads was machine them to accept the larger studs and clean and inspect them.

Elmo370z · 04-20-2022, 08:37 PM

Quote:

Originally Posted by isayimandrew

Most of the work was done on the block. The only thing they did on the heads was machine them to accept the larger studs and clean and inspect them.

Be interesting to see your journey, as this method has everything negative going against you. Good luck, I hope this hold up.

redondoaveb · 04-20-2022, 08:56 PM

Quote:

Originally Posted by Elmo370z

Be interesting to see your journey, as this method has everything negative going against you. Good luck, I hope this hold up.

What psi does the stock block start lifting heads?

Hotrodz · 04-20-2022, 10:46 PM

Quote:

Originally Posted by redondoaveb

What psi does the stock block start lifting heads?

Stock block 750 plus and built motor 800 plus. There is a reason Seb only tunes to 700whp regardless of stock or built. The key is torque. Now you can dial the tq down to around around 500 tq at 700whp. When I was on a stock block w/stage 1 turbos I was at 600whp and 559tq. That said the smaller turbos spool much faster and the tq comes on fast.

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redondoaveb · 04-21-2022, 12:04 AM

Quote:

Originally Posted by Hotrodz

Stock block 750 plus and built motor 800 plus. There is a reason Seb only tunes to 700whp regardless of stock or built. The key is torque. Now you can dial the tq down to around around 500 tq at 700whp. When I was on a stock block w/stage 1 turbos I was at 600whp and 559tq. That said the smaller turbos spool much faster and the tq comes on fast.

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Hey Bob, I was talking about boost and head lift. Mine's making over 700 and probably around 530ft.lbs. but as you know, we went with the larger turbos so they spool slower and the torque doesn't hit so hard. That's at 15psi. 15 psi shouldn't have headlift issues and the OP wants to stay in the 600-650 range.

My point being. My car made 745 at a little less than 16 psi before we backed it off because stock block. The OP is using the Stage 1 turbos and won't be seeing 16 psi so I don't see him having any concern with headlift as Elmo was pointing out. He needs a stronger bottom end with those smaller turbos which he has.

My car could easily hit 800whp at less than 17 psi. If 17 psi isn't in headlift territory then I'd just build the bottom end too.

That's the reason I was asking what the threshold psi number is for headlift on the stock top end

Hotrodz · 04-21-2022, 09:37 AM

Quote:

Originally Posted by redondoaveb

Hey Bob, I was talking about boost and head lift. Mine's making over 700 and probably around 530ft.lbs. but as you know, we went with the larger turbos so they spool slower and the torque doesn't hit so hard. That's at 15psi. 15 psi shouldn't have headlift issues and the OP wants to stay in the 600-650 range.

My point being. My car made 745 at a little less than 16 psi before we backed it off because stock block. The OP is using the Stage 1 turbos and won't be seeing 16 psi so I don't see him having any concern with headlift as Elmo was pointing out. He needs a stronger bottom end with those smaller turbos which he has.

My car could easily hit 800whp at less than 17 psi. If 17 psi isn't in headlift territory then I'd just build the bottom end too.

That's the reason I was asking what the threshold psi number is for headlift on the stock top end

Copy that! PSI and compression ratio work together. If you are running stock block 11:1 you well need to achieve the same results as lower ratios such as 9:1. I am at 11:1 and 20.5 psi for 700whp and 607tq. Many start see head lift at 23psi and above. For a stock block with stage 1 turbos 14psi will get you just over 600whp and 500tq. Things will start to fail at 700whp on stage 1 turbos. It may not be head lift but the rods may decide to put windows in the motor.

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Elmo370z · 04-21-2022, 08:02 AM

Quote:

Originally Posted by redondoaveb

What psi does the stock block start lifting heads?

You and bob are correct. It’s about torque. Cjm car never lifted head even over 50 plus passes and the drag strip. He ran 700-800+whp.

redondoaveb · 04-21-2022, 09:30 AM

Quote:

Originally Posted by Elmo370z

You and bob are correct. It’s about torque. Cjm car never lifted head even over 50 plus passes and the drag strip. He ran 700-800+whp.

At what psi does headlift become a concern?

Hotrodz · 04-21-2022, 09:41 AM

Quote:

Originally Posted by redondoaveb

At what psi does headlift become a concern?

So about 17psi **** starts to go south on stock block with stage 1 turbos. You may not get head lift but you may!

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isayimandrew · 04-20-2022, 10:49 PM

Quote:

Originally Posted by Elmo370z

Be interesting to see your journey, as this method has everything negative going against you. Good luck, I hope this hold up.

I hope it does. I'm pretty much just going with Jotech's recommendations and they have some solid builds. I'm also not chasing a specific number and they know that so I don't think we will be pushing anything to the limits.

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04-20-2022, 11:15 AM	#1 (permalink)
Elmo370z A True Z Fanatic Join Date: Apr 2013 Location: st. petersburg Posts: 5,730 Drives: 09 nissan 370z Sp M6 Rep Power: 295380	What did you have done to the heads again?