E16T

velardejose · Post by **velardejose** » Sat Sep 23, 2006 7:02 am

I assembled it with a 2mm thick copper decompression plate to see if it worked
Its been 4 months and no problems

sentra_t · Post by **sentra_t** » Sat Sep 23, 2006 7:12 am

2mm copper gasket + 1 mm extra head gasket = 3mm, isnt it too much?
How does it run before reaching boost?
Does it run harder than it did when you has 9:1 CR?

SammyET · Post by **SammyET** » Sun Sep 24, 2006 9:39 am

well you can never have too little compression with a turbo... you just have to pump boost through it!!! look at cons ET.. 6:1 comp + 40psi... mad!

Sam

exanator · Post by **exanator** » Sun Sep 24, 2006 11:18 am

but does that really work out right???? lowering comp and adding boost does it add up???

sentra_t · Post by **sentra_t** » Sun Sep 24, 2006 11:53 am

wassup393 wrote:well you can never have too little compression with a turbo... you just have to pump boost through it!!! look at cons ET.. 6:1 comp + 40psi... mad!

Sam

Im sure that car should fly... but i dont think a 6:1 CR engine would make a good daily driver.
My intention is to give it 14 psi of boost, max...maybe even 20 some day, but i think that 8:1 is enough for me.
What do you think about lowering compression thue lowering the pistons?

Post by **tassuperkart** » Sun Sep 24, 2006 12:03 pm

Weeeeellll yes and no.

Look at the really mad RB26's over 9:1 CR stock and they get some pretty good numbers from them in stock build.

Theyre only 2 and a half litres so many hundreds of KW with over 9:1 CR is not to be sneezed at.

Very large numbers can be gained from really careful attention to the little things that contribute towards the dreaded detonation ( a thread on its own) and some really close attention to tuning.

having to lower CR's by a huge margin is usually a compromise for a poor combustion chamber design and also results in an extremely "doughy" engine altho with something running at 40psi boost i suspect that this is the very least of their concerns!

However, as an aside, a really low CR with virtually no "squish" area (which is arrived at when simply spacing up the head a-la- e15et), altho not the most efficient setup in terms of flame front control, results in a very complete fuel charge "burn" and often very good emissions numbers!!!!!! (as if that matters LOL)

L8tr
E

velardejose · Post by **velardejose** » Tue Sep 26, 2006 12:53 am

Hmm
Sentra t and I share a common problem
Carburetion will never be as exact as an electronic fi system
You can walk the razor's edge with a computer managed counter weight system
Or you can do it using a pole and your bare hands...
Using high cr + boost needs gas and exact timing management
Better stay in the safe side of the curve by lowering cr and running 'conservative' psi figures (14 - 16)
I've been there...
Comments?
Peace

Ben Hewitson · Post by **Ben Hewitson** » Tue Sep 26, 2006 12:27 pm

where abouts in Aus do you get copper gaskets.? i've had 1 made and it was crap. didn't line up for shit so i built one myself.. but its difficult. is it wise to put a 1mm copperie AND a normal graphite gasket. what about stainless. i can have that laser cut no worries.? or is copper ok.. considering it needs to be re-anealed every 10,000km's or so....?

sentra_t · Post by **sentra_t** » Tue Sep 26, 2006 12:45 pm

Ben Hewitson wrote:where abouts in Aus do you get copper gaskets.? i've had 1 made and it was crap. didn't line up for shit so i built one myself.. but its difficult. is it wise to put a 1mm copperie AND a normal graphite gasket. what about stainless. i can have that laser cut no worries.? or is copper ok.. considering it needs to be re-anealed every 10,000km's or so....?

I think the best way to lower compression is to lower the piston height about 1mm, that will have the same effect the gasket has but without the risk of blowing head gaskets.

Ben Hewitson · Post by **Ben Hewitson** » Tue Sep 26, 2006 1:54 pm

sentra_t wrote:I think the best way to lower compression is to lower the piston height about 1mm, that will have the same effect the gasket has but without the risk of blowing head gaskets.

as opposed to the rist of shattering a stock piston because you shaved 1mm off it. do you think thats a safe option.? i guess it comes down to timing again. a thinner crowned piston is not really going to get damaged if you can keep it to reasonable temperatures and supress detonation as much as possible with carefull timing.

as it stands an E15ET engine has 3mm shorter rods to lower compression over the standard E15 engines. meaning the pistons dont come close to the deck anyway.

sentra_t · Post by **sentra_t** » Tue Sep 26, 2006 2:44 pm

Im really not sure what option is safer.
But i guess that if the pistons have enough material it could work.
Ive seen some engines run that way, and other with higher gaskets.
Any other opinion?

Paul Smith · Post by **Paul Smith** » Tue Sep 26, 2006 4:14 pm

Here you go Ben. Check out the link.

http://www.ridgecrest.com.au/

BennyET · Post by **BennyET** » Tue Sep 26, 2006 4:21 pm

sentra_t wrote:Im really not sure what option is safer.
But i guess that if the pistons have enough material it could work.
Ive seen some engines run that way, and other with higher gaskets.
Any other opinion?

i'm using a shim plate, but only cause my head has a been shaved too many times which left me with too much compression. no probs in 20K, oh i think it was about 3mm

angel · Post by **angel** » Tue Sep 26, 2006 6:56 pm

nismo85et wrote:
sentra_t wrote:Im really not sure what option is safer.
But i guess that if the pistons have enough material it could work.
Ive seen some engines run that way, and other with higher gaskets.
Any other opinion?
i'm using a shim plate, but only cause my head has a been shaved too many times which left me with too much compression. no probs in 20K, oh i think it was about 3mm

how does one test the compression ratio, my head has be shaved heaps of times, and im worried that my compression is to high as well.

cheers

Post by **tassuperkart** » Tue Sep 26, 2006 7:09 pm

Angel
Dont get too bernt outof shape about CR.

if you can run the same boost numbers and engine goodies that the next bloke has with slightly higher CR then you will produc more grunt and a livlier engine than the stock CR guy.

if you engine runs happily with the tuning numbers you are using then leave it alone.

Head shims and so-on are a very "how-ya-goin" low-tel method of lowering CR and an infinitely more desireable solution is to choose a piston with a similar compression height but a bigger bowl cc than what you have right now.

The thinner shims available for many OHC engine are mostly for restoring cam/crank dimension to bring cam timing back to stock as the head is lowered after machining.