4A-GE engine mix - question

[Uzelac]

I'll give it a try, measure all and see if i have to add anything.
Since i'm plannig to go to 282-300 duration cams maybe i will even give it a try with 11,5-12:1 CR. If that shows to high, i will have no other option but to try and enlarge volume of chambers.

Thanks once again.

[Project D]

with cam around 300°, 12:1 is pretty fine actually :wink:

[Uzelac]

Project D Wrote:with cam around 300°, 12:1 is pretty fine actually :wink:

Will see, would be nice
We have problem with gasoline quality here, and i'm still not brave enough to fill it with E85. Not sure how 4AGE would handle it

[oldeskewltoy]

Project D Wrote:with cam around 300°, 12:1 is pretty fine actually :wink:

actually might not be enough compression!!


Uzelac - BEFORE you do ANYTHING, I strongly recommend you research "dynamic compression ratio". Learn how camshaft duration can affect cylinder pressures.

Concerning E85... as long as you have enough volume in the injector... the 4AG can easily run on E85

[Uzelac]

Hi, I've been reading about dynamic CR and how cams affect it, overlap and stuff but haven't found any in detail articles. Found that topic on many places but nobody really got into it. at least what i've seen.
Do you know some good place to learn about it, share some links?

Thanks

[oldeskewltoy]

I did a search on Google after I got an email from Web camshafts. Most of what is on Google is people asking similar questions... you have to sift through...but there are some good explanations.

The following in no particular order

http://www.empirenet.com/pkelley2/DynamicCR.html

http://www.popularhotrodding.com/tech/03...index.html

http://kb-silvolite.com/article.php?action=read&A_id=36

[Bean]

The popularhotroding is a good one.
To sum it up: the earlier your inlet cam closes (smaler no after BDC) the higher is the DCR and hence a lower static CR is needed and viceversa.

From top of my head my cams close about 62 ABDC so I'm aiming for ~11.5 scr to have ~9 dcr along with good grade fuel and cooling.

[Project D]

oldeskewltoy Wrote:

Project D Wrote:with cam around 300°, 12:1 is pretty fine actually :wink:

actually might not be enough compression!!

Actually you are right, 12:1 for 300 camshaft is a little bit low to get the maximum efficiency, but it also more reliable for a "street car".
(For real 300° @ 100° ATDC you are supposed to get something around 13.5 / 14:1)

But it depend of the "real" duration of the camshaft
304° is the duration @ 0mm but most manufacturer also give the duration @ X lift (0.1mm for most japanese brand) and this duration is more accurate to calculate the DCR.

Quote:Uzelac - BEFORE you do ANYTHING, I strongly recommend you research "dynamic compression ratio". Learn how camshaft duration can affect cylinder pressures.

I have made a little program on excel for that

[Uzelac]

Thanks for links, will read ASAP.

This should be fun car, both for street and occasionally track.

I'm not looking for perfection, my crank and rods are stock, and i'm using 3rib block.
It should be enough for what i hope, that's 8000rpm and 165+ hp.
If i achive that, i will be happy

Quote:

Quote:Uzelac - BEFORE you do ANYTHING, I strongly recommend you research "dynamic compression ratio". Learn how camshaft duration can affect cylinder pressures.

I have made a little program on excel for that

Link ?

[Nomuken]

300° cams; street; 8000rpm red line.
These things won't go together.

300° cams will make their power beyond 8000rpm

300° cams are pretty bitchy to drive at low rpm and will need quite some rpm to idle right

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