Originally Posted by DOHCEJ22E1
The 96 25D heads are better suited for TQ due to the wider intake ports & the VERY small exhaust ports. The quench chambers are suited prefectly for the 2.5 bore. These heads would be perfectly for a smoothly running engine. Smoothness contributes heavily to reliability & response.
Yes, the design from the factory is better suited to lower end torque on a stock motor. I'm not disagreeing. Especially since I am ALL about low end torque, to the point of obsession almost. But, there really is just not enough of a difference to warrant getting a set of HLA heads and putting them atop a lower end that already has the cloverleaf heads that are already ported and matched to the ported intake manifold. Yes, the chambers obviously fit a 2.5 bore, but they chamber has a different design. The cloverleaf design is just better, and creates less volume in the chamber when compressed. Thus, compression is increased (especially with a Cometic 0.027" head gasket) and not only low end torque in increased, but the whole power band raises.
I've pondered over which head would be best for a boosted or NA build. I used to be all for the HLA since they used a hydraulic lifter. But, you can't rev them as high as the solid lifer heads. Currently, his motor is designed to have a bit a peaky power band. But that's nothing that some cams can't fix. Since we're not talking about that much of a difference in power and not even that much of a difference in the low end, I see no point to spending money on another set of heads. The cost to benefit ratio is just not worth it to me. If his heads weren't already ported, and we weren't talking about high compression and cams and such, I would be all for the HLA's.
Just what I would do, is all.