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Guest Enzo

Tuning the naturaly aspirated starlet

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Guest Enzo

Tuning the Naturally Aspirated Starlet


Where to startâ?¦..

As Toyota operates component sharing ethics to the way with which they design there cars this means you have a lot of options when deciding what you want to do to your na. this also means that all the parts listed below are interchangeable between any e series engine. with a naturally aspirated engine the general idea with tuning is to get the air in and burnt gasses out as quickly and smoothly as possible.

the 4efe is by no means a powerhouse but produces a modest output of power for its size. while you will never get big numbers from doing light tuning to the engine it is possible to make the unit much more responsive. if you have the money its possible to make any e series engine a Dohc 16 valve a manic hi revving unit.

inlet manifold

first off you are best hunting out a corolla inlet manifold, while not increasing the actual output of the engine it will iron out any flatspots and change the power characteristics making the tiny 1.3 rev cleanly to the 6200 rpm redline.

this four branch manifold is less restrictive in design compared to the normal log type manifold. worth noting that this manifold also changes the induction roar going from a deep course induction roar changing to a more tiny v-tech howl. after fitting this you will find yourself bouncing off the rev limiter alot more.


* note four branch corolla inlet manifold mated to standard inlet box with k&n

filter + cold air feed

if you are after a decent induction noise then by all means change the filter but if you would like to keep the little usable torque lower down the rev range its recommended to stick with your airbox but upgrade the oem filter to something from k and n. that would remove the major restriction.

Cold air is the key here. A drop in induction air temperature of 7 degrees c, gives a 1% horse power gain. Engine bay temperatures can easily be about 50 degrees c, and outside temperatures about 15. Thats 35 degrees or 5% of a power increase if your car is sucking in outside temperature air. the best thing about it is its free.

Fast flowing air is colder again, so if your air filter, induction filter or whatever is being bombarded with air being forced down a tube from the front of your car, you are going to get more power, it might not be much but every little helps.

Aftermarket/Custom Exhaust System

New section for you mate :lol:

4-1/4-2-1 Exhaust Manifold

the cast unit isnt the best in design. you should bin it in favour of a four branch manifold. it naturally has better flow properties adding power all the way through the rev range.

A 4-1 manifold promotes top end, and a 4-2-1 manifold promotes mid range power.

Shown is the 4-2-1 manifold made by OBX.


A Brief Review of the 4-2-1 OBX Manifold

A handful of ep n/a tuners are running this manifold along with the 5efe which is the engine that this particular manifold was intended for. This setup along with other breathing mods such as cold air induction and high flow exhaust are producing very satisfactory results. The whole car will feel so much more drivable especially at higher revs with sufficient power and torque being provided from the 5efe and the high flow characteristics of the 4-2-1 OBX manifold producing modest performance gains at the mid/higher end of the rev range.

The n/a E series engines are low powered but they are very efficient, the 5efe/5efhe being the much better base to work from than the 4efe. Various modification on the manifold itself and a custom exhaust will be involved for this particular manifold to fit as it was intended for the Paseo underbody.

Increasing fuel pressure

A slight increase in injector sizes with the use of a rising rate fuel pressure regulator like fse's power boost valve and setting up with a fuel computer like an SAFC will also help generate more power.

other e series engine options

Gi spec 4efe(100bhp)

first off sticking with the 4e-fe.

the most powerful version of this was found in the latter ep82 soleil and 82 gi...

the latter was produced as a homologation for the N1 production race series.

basically this engine was almost identical to the 4e-fte minus the turbo and used slightly smaller injectors ..

but shared the same inlet manifold and larger 76 mm throttle body

the final output figure is 100ps. thats just under 100bhp

the engine limiter would stop the fun at 7200rpm..... this would be a great engine to find but it would be very uneconeomical to do this conversion unless you found one in a scrapyard somewhere local going ridiculously cheep.

it would not be as straight forward to fit either because of the older generation loom.

Most Japanese racers junked the standard intake to fit quad throttlebodies..these can be sourced second hand on the japanese yahoo auction site. 140-160 is achievable with this setup but its not a realistic proposition in realworld terms

pros..cheap to insure(if you want to tell them).. very economical peaky high revving natured engine

cons...these things are rarer then rocking horse shit so finding a scraped one would be almost impossible

Uk spec Toyota Paseo 5efe engine 89bhp

The ep91 starlet shared its platform with the Toyota Paseo. This includes suspension, engines and many other components.

because of this the 90bhp 5e-fe engine is a straight swap from the Paseo.

Undoubtedly the cheapest and easiest conversion for the starlet. this engine produced close to the same power as as the gi at 100ps but a healthy dose more torque of 96lbft due to the bigger displacement.

The 5efe engine revs to 5800rpm compared to 6200rpm of the uk spec 4efe...interestingly enough both engines are close to identical bar the head which is 10mm taller and the rods which are different to accommodate this. everything else is the same bar a few sensors that are interchangeable.

Plug in the 5efe and your good to go. saxo beating power for not much cash

you would also need the 5efe exhaust manifold to fit your stock exhaust or an aftermarket four branch manifold.

the only way telling the 4e-fe and 5e-fe is the engine code which is underneath the exhaust manifold.

note - you would have to take the exhaust manifold off to read it.

pros....... cheap to insure (again if you want to tell them) better fual economy than before.....easy usable power.

cons.... limited na tuning potential compared to the turbo

hi revving 5e-fhe 108/110bhp

The next engine after the normal 5efe is the more advanced 5e-fhe(h denotes a higher compression)

on top of that this engine had thicker rods, larger injectors(225cc)and higher lift cams. the redline is 7200 rpm.

some versions also came with an adjustable acoustic intake system pushing the peak torque father down the rev range to make the engine more tractable at lower revs..sort of like the tvis or beams systems found on other toyotas.

the engine produced only ten bhp more then than the normal 5efe but the real difference is in the way this engine delivered that power.

The 5e-fhe came in the jdm Cynos and gulwing Sera. To find one of these engines is not too hard but because of its age the loom is different to the one in your na ep. you will need an electrician to get everything running right.

Pros..... peaky engine that loves to rev, low to midrange torque on ACIS equiped cars, fuel economy.

Cons...fitting this engine is more hastle then the normal 5efe. but still fairly straight forward compared to other engine conversions out there..

Chasing big manic power from your e series engine

Because of the similarities between all e sereis engines these same principals will work on all. this route can get expensive as you will need to take the engine out and open it up. to get decent figures you will need to

  • increase the compression ratio by skimming the head
  • have the head thoroughly ported and polished
  • install hi lift cams + uprated valve springs
  • port and polish the head
  • blue print the engine
  • fit aftermarket quad throttlebodies

Increasing the compression ratio.

Compression is free power to n/a cars. Get a mm or so milled off your head. This will reduce the squish area of your combustion chamber and with basically the same amount of air and fuel mixed and then burnt in a smaller space naturally you will get a bigger bang. Make sure to consult an expert who knows all about head skimming before you set out to do this. You can also upgrade to a thinner head gasket which will again raise your compression ratio. TRD produce 0.5mm and 0.6mm items.

Increasing the duration of the cams

To get the most out of the engine you would need to increase the duration of the cams. this will in tern alter your power band pushing it higher up the revrange.

Porting & Polishing

porting and polishing the head or gas glowing this involves matching the exhaust and inlet ports to the size of the inlet manifold and exhaust manifold. at the same time you would be trying to reduce the resistance of any obstacles mainly around the valve stems. doing this means that air will enter and exit the engine faster. note. it is a good idea to keep the surfaces rough on the inlet side to disturb air going into the engine.

porting and polishing is a bit of a fine art.

Blueprinting an engine

this involves lighting and balancing the engine. the purpose of this is so you can safely and reliably run the engine at higher rpm

still to finish this write up and talk about throttlebodies+ ad pictures



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Looking sweet boss man.

Im off to college now bro but Ive quickly added in red, some figures that shud be changed next to the old ones.

Peace bro


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Guest Enzo

thanx mate for your input, your a superstar jozman :lol:

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Guest Enzo

do you have any pics of your four branch manifold man??

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I'll throw them up in here later mate.

Bit busy at college here, under pressure haha.

Talk soon


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Pics added bro :lol:

I've added a little snippet in there too on the 4 branch mani.

All good boss. I done a little spell checking and tidying up, only briefly tho.

Bet it looks tidier eh...



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