best cr for 1.6 bar td05

AdamB

Member +
Well using the cylinder diameter 74.5mm and chamber size 39cc makes the same compression ratio.

Note that the calculator doesnt use head gasket diameter,most of them are 75mm [ Aftermarket ones i mean.]

It does make a lazy engine offboost.

So what do we do with such an engine to make response better?

Port and polish the head
Some advocate a port only as polish doesnt help much.

And what else?

Port the intake side, never polish! Port and polish the exhaust side.
Cams and a custom intake manifold. The shortest route possible for the fmic.
It's also down to the map, its possible to run a lean burn mixture to help start spooling the turbo sooner :)
 

buckets

Member +
Port the intake side, never polish! Port and polish the exhaust side.
Cams and a custom intake manifold. The shortest route possible for the fmic.
It's also down to the map, its possible to run a lean burn mixture to help start spooling the turbo sooner :)
does bigger cams help spool up or create more lag
 

AdamB

Member +
Cams shift the powerband of the engine. You can use them to your advantage, depending on turbo application. For stock turbo setup and quite a few others like td04, vf series the stock cams are more than capable of giving a half decent turbo spool, plus they aren't exactly cheap off the shelf items. For example if your turbo doesn't make full boost till 4500rpm, you could get cams with a duration that will help bring the turbo upto full boost earlier. Although most cams will be more beneficial if you raise the rev limit, which is what you do if you have a larger turbo that takes longer to spool.
 

Chris@CCM

Member +
U can't say that 8.2-1 will run 2 bar boost on every type of engine dude every one is different loads and loads of factors to take on board some engines take loads of timing some don't some take very little
 

bongskag

Member +
port your throttle body! thats what everyone forgets to do when building their engines, I went as far as slimming the buttefly down. and port matching beyond the standard gasket sizes helps too,

Are you sure you want to run 1.6bar with such a high compression ratio ?

if your running 23.6 PSI (1.6bar) of boost (at an altitude of 0 feet). and Your motor's static compression is 8.3 :1. at this boost level and altitude your effective compression ratio is 21.63 :1 ??!! seems a little high but when you compare it to a a static ratio of 7.3:1 there does not seem to be that much difference in there 19.02 :1 for a stock ratio of 7.3:1

although I would be able to run 1.9 bar (28psi) and still have the same effective compression on boost as you if you was running 1.6bar

around 21:1!!?? So I guess its down to how much stress you want to put on the engine.


both figures seem really high ! as petrol N/A cars run anywhere from 10:1 - 14:1 . I guess this is why so many lads break rods, melt pistons or fry the rings pushing silly boost on stock internals. NOTE: a stock C/R of 8.3:1 with standard boost comes out at around 14.5:1
If your running 1bar this jumps up to around 16:1

Hope this helps you work out what gasket to get, I went for the TRD just to be safe and give options for the future.

@david "that doesnt seem right to me weisco say compression ratio with their 10cc dished pistons is 7.8:1 with a standard gasket so a .6 one would bump it up a bit "
weisco would have to know your CC volume , pistons to deck height ETC. im sure there information all comes from OEM numbers and figures just with the -10cc added for the pistons. as soon as you deck the block and skim the head youve lost around .5mm from both surfaces !

Hope this helps you work out what gasket to get, I went for the TRD just to be safe and give options for the future. :) and remember, have fun..
 

AdamB

Member +
U can't say that 8.2-1 will run 2 bar boost on every type of engine dude every one is different loads and loads of factors to take on board some engines take loads of timing some don't some take very little

Would it not depend on the map Chris? Surely though running that sort of boost on a stock compression ratio will lead very little timing to keep the det away?
 

Skalabala

Member +
4EFTE cylinder head is a YAMAHA product so I am sure it flows good.
You can retard timing on low rpms to speed up turbo spool and run lean CO.
Nothing wrong with polishing a injection turbocharged engine intake ports :)
Perfect boost pipe size also helps.
And some good detail to port matching.
Bigger throttle body :)
And most important a good stand alone with a good tuner.

You could see a typical 400rpm quicker spool up time when doing things right.
 

AdamB

Member +
Why would you polish the intake side of a cylinder head? You would get no swirl effect before the air hits the valve. That's fine if running direct injection, but for manifold injection the fuel won't be atomized in the air charge. It will just flood the inlet manifold.
 

sx_turbo

Lifer
Why would you polish the intake side of a cylinder head? You would get no swirl effect before the air hits the valve. That's fine if running direct injection, but for manifold injection the fuel won't be atomized in the air charge. It will just flood the inlet manifold.

x2
 

sx_turbo

Lifer
U can't say that 8.2-1 will run 2 bar boost on every type of engine dude every one is different loads and loads of factors to take on board some engines take loads of timing some don't some take very little

on most modern engines i'm certain it is possible,

an old a-series engine is of poor design and dett occurs rather easy, although the design of the chambers themselves creat good swirl and you get a nice burn out of them, the whole desin of the 5 port and siamese bores proves very problematic when performance tuning, the design of the engine creates hot spots, and although an excellent design for its small package and efficiency in standard trim, the 3 main cap design is also very limited because of crank whip, but not so much a probolem when built properly.

the efficiency of the 4e engine along with its smoothness and when good qaulity strong internal parts are used and a good engine build i'm pretty certain that these engines can take it.

its alwways a possibility until someone proves me wrong
 

AdamB

Member +
Yeah in affect, when you port you use carbides or stones, use stones for alloy heads because its a softer material. Polish to me means making the material smooth, making it shine like chrome is just what happens when you make material smooth.
When you see pictures of cylinder heads that have had port and polish, the pictures may look like its a smooth finish, but infact it shouldn't be, you should be able to run your finger through the port and feel it to be rough. Cylinder head work is an art, and takes practice to perfect it.

If you want to know more about cylinder head work I would recommend this book, it is fantastic and I loved reading it!
How to build, Modify and power tune cylinder heads by Peter Burgess and David Gollan
http://www.amazon.co.uk/Build-Modif...6769/ref=sr_1_1?ie=UTF8&qid=1324034153&sr=8-1
 
Last edited:

jayc-glanza17

Fresh Recruit
only use shell v-power bud..
and the mapper has tuned few starlets, sure he stop advancing ignition if get det..
oh and be mapped on EMU
 

Skalabala

Member +
Also remember that a dished piston will give you a more stable quench.
So running a 8.5:1 will be fine.
Starletgt bud, a lot of people will say you are wrong about polishing the intake side :(
To me, injection + boost + polished head = WIN
 
Also remember that a dished piston will give you a more stable quench.
So running a 8.5:1 will be fine.
Starletgt bud, a lot of people will say you are wrong about polishing the intake side :(
To me, injection + boost + polished head = WIN

well am with you skalabala, ive used numerous raceheads over the years and had good gains from them. that ruff bumps on the head will do sweet f all realy, air will be spiraling through the maniflow to the head anyway. Do u realy think that tiny rough patch makes a difference? the king of all custom head makers doesnt either.
 

AdamB

Member +
It's not the air! It's the fuel, trying to atomize fuel on a smooth surface isn't going to happen. The fuel will stick to the sides of the port and won't be suspended in the air.

Who's the king of custom heads then?
 

Chris@CCM

Member +
8.5 to one is too high for big boost on pump fuel for me ,if I was getting a head done I would not be getting a mirror finish on the inlet side
 
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