NA builds. How far to go?

[oldeskewltoy]

kazi Wrote:Hi all.

So in a few months ill be taking my engine out as it needs a refresh and I'm after some more power. I'm looking to stay 16v and go ITBs. I've had a read over Bill Sherwoods page about power build but wanting to get some feed back from people that have gone for power and more up-to-date info.

I'll be forging the bottom end and putting the compression ratio up but not sure what to do with the head work and getting mixed feedback, The head i'll be using will be a blue top and most likely be going for a Link ECU. I'm wanting to aim for a min of 160hp.

Cams are a sure thing but no idea on what size to go for. Would you uprate the valves springs and over size the valves or just replace with OEM parts. Some people say that OEM valves and springs will be good for 180-190 others say that they need changed at 160hp.

Also, Has anyone done a power build on a 3 rib block and 40mm crank? A lot of people say go 7 Rib and 42mm but I'm not seeing any bad evidence against the 3 Rib.

Car is a road legal car that only gets use at the weekend and a few trackways a month.

What have you done and how have you found it? I don't want to find that i've replace/uprated and to find that its having negative effects more than positive.

Thats my ramble for now. Any help would be great!

Hmmmm, saw(read) you put a "high torque" engine in.... before we make a whole bunch of recommendations, do you have a dyno print out, and a current list of modifications for the current engine?

160hp, or 160whp??? The former isn't all that hard, or expensive, the later is significantly more money, and requires some careful building.


What is your budget??


You can make power on a 40mm rod journal crankshaft, you want to do it before 8500 rpm (sustained rpm - before 8000) Easiest way to retain 40mm rod journal crank and keep piston option high would be to use Molnar 40/20 H-beam rods ($450 ish per set)

Without going into a long winded description, the earlier crankshaft's counter weights are not all "equal". This inequality can lend itself to a torsional difference that becomes evident @ , or around 8500. Careful balancing can protect the crankshaft, but if your goal is a 9000 rpm engine you want to begin with a large (42mm) rod journal crankshaft. Or better yet a $3500+ Formula Atlantic crank

Now, this inequality has an advantage... less mass. The 40mm rod journal crank is over a kilo lighter. Add in the rods I mentioned, and a quality light weight flywheel, and the engine response will put a smile on your face.

ALWAYS new valve springs (with a few exceptions). The stock valve are plenty for 160crank hp, and are acceptable for 160whp (REQUIRES proper headwork).

Cams would be required for either 160 crank hp, or 160whp.