High or low Compression 5e-fte

[karl.]

Im currently thinking about building a high compression 5efte engine It will be running a td04 or maybe even a td05 if it comes to it.

My question is, Do I build a high compression or low compression engine?

Low compression will mean:

more boost, therefore I will have to buy arp head bolts.
less chance of det, so I can run standard petrol.
Slower spool time so I would have to buy a hybrid/billet turbo.
I will be running more boost so I will have to buy bigger injectors.

High Compression will mean,

I can get away with standard head bolts since i will only be running around 1.4/5 bar.
I will have a quicker spooling engine so I could go for a td05 instead of a billet td04 etc
I can run a standard toyota mls 0.5mm gasket so I will save money there aswell.
I will have to run super instead of standard fuel.
I can keep my current injectors that have just been rebuilt.


What do you think or will a high compression engine wont perform as good as I think?

 

[weeJohn]

I built mine with just over standard compression, but its not running yet so cant really answer whats better. Momentum Motorsport build Evo engines this way, end up running less timing advance and get a better power graph though the rev range according to them.

I did go with ARP head bolts, as they are reusable I see them better value for money in the long run. Jury is out on the Toyota 0.5 gasket still I think and I wouldnt run anything less than super in a turbo engine no matter what way its built.

 

[goldenvtr]

depends what you call as "high"

i went from 7.5 to 8.1 and still with i could go higher but my pistons are 10cc dished so i cant go much higher now. i still run 2bar boost ona td05 20g and it spool ok for a track car ( thats what i use it for) but on the road it needs more compression or smaller turbo in my case, but i wanted all out power lol

 

[ramses974]

Hi, i tried a lot of turbos and set up with my Seo... finaly, i am with high compression(9.5) and a vf35 billet..the spool is the same as a standard td04 on a 4e... i do not speening the wheels it is just like driving a big engine . Tuning is the key too i am not going over 1.2bar. Soon i will install my aem methanol kit for the 1.4 1.5b ...

 

[gorganl2000]

i know some of the US guys tended to run stock compression 5e turbo engines
and depending on what you want from your engine it maybe ok to do that-------but as ramses974 said, having it properly tuned is very important

imo, with major improvements in ecus, knowledge, gas, etc over the years, tuning a HC turbo car can be done....the 5e engine highest stock compression is 9.6-9.8 if i remember correctly........but guys out there are turbo charging even higher compression hondas....so what is deemed high compression is really relative now

if you put stock 4efte pistons in the 5e, the compression is around 9.0-9.1...so lots of options

 

[Skalabala]

depends what you call as "high"

i went from 7.5 to 8.1 and still with i could go higher but my pistons are 10cc dished so i cant go much higher now. i still run 2bar boost ona td05 20g and it spool ok for a track car ( thats what i use it for) but on the road it needs more compression or smaller turbo in my case, but i wanted all out power lol

Hi bud
How did you get your 8.1?

The problem of running high compression is that the physical design of the engine was not mend for it.
New fuel and management helps but you will also need to do work on the combustion chamber of the engine.
Make sure the piston is smooth. And a lot of work needs to be done to the head.

The combustion chamber of new cars allows for high combustion characteristics

So in your case I would go for 9:1 with the needed work done

 

[ramses974]

In addition, methanol water kit will help a lot for reliability

 

[gorganl2000]

In addition, methanol water kit will help a lot for reliability

i believe meth/water has great benefits for tuning....however, i'd add that its best to get a proper kit with some kind of fail safe mechanism
if you tune your engine to rely on the meth kit, then if it stops working your engine is likely to have some kind of damage, that's why i insist on a fail safe option, which is usually associated with the more reputable brands

i think 9.0-1 is a good ratio for the 5e turbo engine...i've seen people run the 5e with 4efte pistons to very good effect for a LONG time

 

[ramses974]

i believe meth/water has great benefits for tuning....however, i'd add that its best to get a proper kit with some kind of fail safe mechanism
if you tune your engine to rely on the meth kit, then if it stops working your engine is likely to have some kind of damage, that's why i insist on a fail safe option, which is usually associated with the more reputable brands

i think 9.0-1 is a good ratio for the 5e turbo engine...i've seen people run the 5e with 4efte pistons to very good effect for a LONG time

Methanol kit is very good and you are right...it is dangerous to tune with it if the system can stop working.this is why my car is only at 1.2b without methanol and with methanol i can add a fuel cut if the water tank is low or if it stops working... for me maximum boost on a high compression is 1.2b well tunned cause there is a time any value we can done to retard timing will result a loss power or a heat (timing thresold)... in my experience 1.2b is the limit and 0.8b is very very good for spooling and power...
Remember if you’re running a 9.0:1 compression ratio @ 1 bar you’ll achieve an effective compression ratio of 18:1
If you’re running a 7.5:1 static compression ratio and 1 bar of boost you achieve an effective compression ratio of 15:1.

 

[sx_turbo]

8.5:1

is the best reliable all rounder, its also the stock compression of a 4efte

 

[gorganl2000]

8.5:1

is the best reliable all rounder, its also the stock compression of a 4efte

ain't the stock CR 8.2 for the 4efte???---that's what people have been saying for year on the forums

i dont know if there is a best CR....i'd more say it depends on what the build is for
personally, i prefer a higher CR with less boost for an everyday car
a real dragger may want low/7.5 CR with a ton of boost
rally, hillclimb, etc may prefer some other CR to suit their needs

 

[gorganl2000]

Methanol kit is very good and you are right...it is dangerous to tune with it if the system can stop working.this is why my car is only at 1.2b without methanol and with methanol i can add a fuel cut if the water tank is low or if it stops working... for me maximum boost on a high compression is 1.2b well tunned cause there is a time any value we can done to retard timing will result a loss power or a heat (timing thresold)... in my experience 1.2b is the limit and 0.8b is very very good for spooling and power...
Remember if you’re running a 9.0:1 compression ratio @ 1 bar you’ll achieve an effective compression ratio of 18:1
If you’re running a 7.5:1 static compression ratio and 1 bar of boost you achieve an effective compression ratio of 15:1.

the extra joy of the kit is that the water/meth helps with cooling...so cylinder temperatures are dropped, hence less chance of detonation
plus your cylinder and combustion chamber is pretty clean as well...lol

i've seen slightly higher boost ran on the CR you mentioned, but some timing retard had to be used on those cars, as you said as well

 

[ramses974]

ain't the stock CR 8.2 for the 4efte???---that's what people have been saying for year on the forums

i dont know if there is a best CR....i'd more say it depends on what the build is for
personally, i prefer a higher CR with less boost for an everyday car
a real dragger may want low/7.5 CR with a ton of boost
rally, hillclimb, etc may prefer some other CR to suit their needs

i am totaly agree with gorganl2000,a high CR with less boost is very very good for response and dayly driving . i have owned a 7.5CR on a 4e with 1.8b of boost for everyday to go to work...believe me or not , but i prefer my 5e high CR at 0.8b ,it is very very incredible in term of response and torque is very usefull