4A-FE Engine Tuning

	Engine Tuning

When my car first failed its MoT i took the oppurtunity to: A) get my hands dirty B) upgrade rather than replace	Now this was previously thought to be a rather difficult task, most beleive that 4A-FE upgrades (bar the usual filter and exhaust) are custom jobbies and very expensive. This is not entirely true.
Now for a Naturally Aspirated engine one of the easiest ways to increase power is to up the compression ratio. Normally done through High Compression piston (often forged) for those of you with the later 4A-FE as found in the AE111 your pistons are already higher compression than earlier models.	Earlier 4A-FE Compression Ratio: 9.5 : 1 AE111 4A-FE Compression Ratio: 9.8 : 1
Whilst this may not seam like a significant change, it really is noticeable so for those of you with older 4A-FE's get yourself some AE111 pistons. There is an alternative route to upping the Compression Ratio, which is the route i have taken as i already have an AE111. This is the use of a thinner Head Gasket, standard composite gasket is 1mm thick. Now would also be a good time to upgrade to the reliability of a full metal Head Gasket, these can be obtained from head speacialist who will measure your heads dimensions and make one in any material you like, e.g copper. This is slightly more costly than i would like, it just so happens that the bigger brother of the 4A-FE, the 7A-FE uses a 0.5mm two ply full metal Head Gasket (its almost as if Toyota wanted you to use it!) this will be an exact fit as seen below.

When my car first failed its MoT i took the oppurtunity to:

A) get my hands dirty

B) upgrade rather than replace

Now this was previously thought to be a rather difficult task, most beleive that 4A-FE upgrades (bar the usual filter and exhaust) are custom jobbies and very expensive.

This is not entirely true.

Now for a Naturally Aspirated engine one of the easiest ways to increase power is to up the compression ratio. Normally done through High Compression piston (often forged) for those of you with the later 4A-FE as found in the AE111 your pistons are already higher compression than earlier models.

Earlier 4A-FE Compression Ratio: 9.5 : 1

AE111 4A-FE Compression Ratio: 9.8 : 1

Whilst this may not seam like a significant change, it really is noticeable so for those of you with older 4A-FE's get yourself some AE111 pistons. There is an alternative route to upping the Compression Ratio, which is the route i have taken as i already have an AE111. This is the use of a thinner Head Gasket, standard composite gasket is 1mm thick. Now would also be a good time to upgrade to the reliability of a full metal Head Gasket, these can be obtained from head speacialist who will measure your heads dimensions and make one in any material you like, e.g copper. This is slightly more costly than i would like, it just so happens that the bigger brother of the 4A-FE, the 7A-FE uses a 0.5mm two ply full metal Head Gasket (its almost as if Toyota wanted you to use it!) this will be an exact fit as seen below.

Metal Head Gasket from a 7A-FE fitted

I estimate that this should raise the compression ratio from 9.8:1 to around 10.3:1 this will certainly make things more fun! Now don't consider the above project lightly it is several hours of hard work it should not be attempted 'overnight' give it a more time like a weekend or so. Warning to anyone who attempts this, the camshaft nuts are a pig! and don't over tighten anything in the head it is made of alloy and you will have to re-tap it, then find new bolts to fit that tap. Not fun. My biggest handy hint is to remove the radiator it makes life so much easier. Also have some boiled water handy for the Coolant pipes as they really do stick. Probably the most important one Label everything! i purchased a Bic marker pen that writes on almost any surface, just for this project! moving on...
Now i also took the oppurtunity to replace the camshafts, which will need running in, they are around the 270 degree duration mark and 8.7mm of lift. they were custom one offs and not cheap so i wouldn't reccomend them to anyone who is looking for a low budget project. The cams also require speciallly made shims, care of Arrow Precision, once the differences between the two cams were measured I sent away a sample shim and they have created 16 new shims for these high lift cams. Combined with the thinner head gasket this engine may become an interference enigine (this is only really a concern if my timming belt snaps). Below is the my 4A-FE with head re-fitted and uprated cams in place.

I estimate that this should raise the compression ratio from 9.8:1 to around 10.3:1 this will certainly make things more fun!

Now don't consider the above project lightly it is several hours of hard work it should not be attempted 'overnight' give it a more time like a weekend or so. Warning to anyone who attempts this, the camshaft nuts are a pig! and don't over tighten anything in the head it is made of alloy and you will have to re-tap it, then find new bolts to fit that tap. Not fun. My biggest handy hint is to remove the radiator it makes life so much easier. Also have some boiled water handy for the Coolant pipes as they really do stick. Probably the most important one Label everything! i purchased a Bic marker pen that writes on almost any surface, just for this project!

moving on...

Now i also took the oppurtunity to replace the camshafts, which will need running in, they are around the 270 degree duration mark and 8.7mm of lift. they were custom one offs and not cheap so i wouldn't reccomend them to anyone who is looking for a low budget project. The cams also require speciallly made shims, care of Arrow Precision, once the differences between the two cams were measured I sent away a sample shim and they have created 16 new shims for these high lift cams. Combined with the thinner head gasket this engine may become an interference enigine (this is only really a concern if my timming belt snaps). Below is the my 4A-FE with head re-fitted and uprated cams in place.

The AE111 was indeed the pinnacle of the 4A-FE, as seen above even the exhaust manifold is standard
When increasing compression ratio, it is important to note that with increased compression there is an increase in the chance of pre-detenation. This, unsurprisingly, is an undesirable occurance. In order to minimise this it is time to turn to TRD, this is one of the few instances where you will have to fork out some cash for a brand name product, around £50 for the 71 degree thermostat. This is a whole 11 degrees coller than the original which ic 82 degrees. Unfortunately only TRD do a reduced temperature thermostat for the 4A-FE but hey at least there is one. With this thermostat in place you have now give you engine's cooling system the best possible chance the prevent 'pinking' (pre-detenation).

The AE111 was indeed the pinnacle of the 4A-FE, as seen above even the exhaust manifold is standard

When increasing compression ratio, it is important to note that with increased compression there is an increase in the chance of pre-detenation. This, unsurprisingly, is an undesirable occurance. In order to minimise this it is time to turn to TRD, this is one of the few instances where you will have to fork out some cash for a brand name product, around £50 for the 71 degree thermostat. This is a whole 11 degrees coller than the original which ic 82 degrees. Unfortunately only TRD do a reduced temperature thermostat for the 4A-FE but hey at least there is one. With this thermostat in place you have now give you engine's cooling system the best possible chance the prevent 'pinking' (pre-detenation).

4A-FE Power!