Done a quick search and couldn't find any definitive answers.

Now, I'm rebuilding my motor and fully building it this time. Running my existing JE 9.0:1 Pistons, Eagle H Beam rods, Darton MID sleeves, full Supertech valvetrain, custom ramhorn manifold, Garrett GT3076r .63 etc.

I'm going to purchase a new block for the sleeves to ensure the engine builder has a fresh block to start with and knows everything is spec'd properly.
I've got two options, JDM Blacktop B18c (GSR) longblock or a JDM ITR longblock. The JDM B18c longblock will cost me nothing after parting it and the ITR longblock will cost me ~$250 after parting it.

Now my question is, I know the ITR head is mildly ported and polished from factory so this should flow better than the GSR head. Is it worth me going down the ITR route for this extra flow or will the gains be absolutely minimal on a boosted setup. Power goals are 450whp on pump gas with a nice responsive setup. Car is a weekend driver with the occasional outing on the circuit and drag strip.

If the ITR head means I can make the same power with 1-2psi less boost over the GSR head, I'd consider this worth the extra cost.
Also, is the ITR crank stronger than the GSR?

Cheers,
Cam

 

No. and the ITR does NOT mean it makes the same power with 1-2psi less boost pressure. Its not worth the extra cost. The difference in risk is the static compression, which means more attention should be paid to TUNING more than airflow from the head.

You'll need to put your attention towards the turbo kit , tuning and other supplemental components, not just the longblock.. Don't over think this. Which ever works best for your budget is the one longblock you should choose.

good luck.

 

i'd start with the itr longblock if that's all it's gonna cost you. itr cams will cost you about that price anyway.

 

Thanks for the info.

ITR longblock is complete minus cams whereas the GSR block is fully complete. I've got CTR cams going in it. If there's zero benefit running an ITR head over a GSR head and they can both flow the same then GSR it is.

I previously made 415whp on the stock sleeved set up before busting the oil pump (alloy crank pully, no harmonic damper =( ). Plenty happy with that power for the street, nice and responsive so if I'm able to pickup any gains with one block over the other I may as well do it now. I'm not going for all out power, just a responsive reliable set up with a nice fat power band.

 

if it's without the cams, i'd just go for the gsr block.

 

GS-R block, the quench pads in the head will work better with your low compression. If you were going with a flat top piston I would say a Type R would be alright.

 

IF you already have CTR cams just do the GSR long block. you can do some hand polish and port match work to the GSR head but not needed. You are going to run JE pistons so having the ITR for higher compression is pointless. The GSR and ITR bottom ends are both built pretty much the same, well balanced, crank griddle, piston oil squirters and the same oil pump.