How to build an NA engine...

[GA61XX]

Good thread.. I found the same thing with my 21R-C.. in short you can't make power, but you can free up power.. eg. port matching the inlet manifould to the head, this will reduce Eddy currents, & free up the air flow into the head..

[Nim]

good post mate, should get some of those honda boys to read it....some of them seem to think they can rev their VTEC's to 12,000 rpm just by pulling it apart and balancing it....they also think this will give them most awesome powah!

Already started directing them here.

[rms]

General extreme comments can be a bit tricky to defend. Also things like 5000 ft/min and 300 ft/sec are guides, albeit good guides.

Other things to consider are frictional losses ( a 5 litre V16 just can't quite make the same power as a 5 litre V8)

A 5 litre V16 will have more frictional losses but will have more valve area to capacity and has the potential for more power.

300 ft/sec has been used as an optimum figure in pure race engines for many years. Production based race engines have compromised port designs and a theoretical 300 ft/sec may not be optimum due to other factors.

Keith Duckworth, founder of Cosworth, once stated "turbo's are for people that can't build engines"

When you start looking for maximum power a turbo engine will cost as much or more than an n/a engine.

[Fish]

maybe that should read co-founder of cosworth rms

[roadsailing]

good thread here,

When you start looking for maximum power a turbo engine will cost as much or more than an n/a engine.

unless you mean something other than what im thinking, nonsense!

EDIT:

as per what Ed says below, i agree, but how do you define what an engine's potential power is?

[ed]

he means to fully optimise and capitalise on a turbo configuration for absolute maximum output (not just 'more than') is harder and more expensive than an NA engine

[ed]

but how do you define what an engine's potential power is?

you establish the maximum operating tolerances for all your components. ie rpm and piston speed, combustion chamber size and possible valve and port size. port potential and orientation. turbo turbine/compressor map details... blend it all together, and stretch every component to its sustainable limit

[RyleyMA61]

sweet ed, thanks!!!!

+rep

[Wedged'86]

That's gotta be the longest guid i've ever seen on the net.
And considering how difficult a subject it was covering it was pretty complete.
The man knows his shit!

kudos.

[The Real Roadrunner]

no, i just want the more customised map

generalisation = appreciation by a wider audience

+rep for the post

but you should be neg repped for forgeting that the sm4 has an injector calc that will allow you to change injectors mithout the need for a full tune (more of a tidy up).

and without your comp ratio and cams mos' maps will need alot of retuning anyway .

cheers
linden

[ed]

just want to try and not bed-in the engine on a virgin tune... a good base map will get it out of the woods for the first 10mins will the rings bed

[The Real Roadrunner]

very true, but with a competent tuner and your knowledge of the engine build and an sm4 he should be able to rough up a map to suit without even starting the engine.

please tell me your not planning on trying to run this thing in with no load on it?

cheers
linden

oh forgot you went gapless, honestly never had experience with them so i cant really comment.

[Mos]

Lets for a moment forget that the IS has a returnless fuel system....
The SM4 doesn't have a setting for the type of return system (afaik), so while tuning it on the IS fuel system will give you the VE table, it won't be very useful.
To get the closest tune on my engine with your manifold we'd need to rig a return type system in the bay using a 5L jerry can - don't worry, I've done it before, will be fine

Mandatory on topic content - what would one expect in terms of power increase changing *only* the manifold/throttle bodies?

Mos.

[gianttomato]

Big budget build....might want to "invest" in $1K engine dyno tune?

Just putting it out there.....

[gianttomato]

Mandatory on topic content - what would one expect in terms of power increase changing *only* the manifold/throttle bodies?

2JZ went from 115 to 148 rwkW.