My Starlet page
The plans for the three engines to go into the Starlet
There are a few other engines I'm going to be fitting to the car, as time goes by.
The first engine to go into the Starlet was to be the 4AGE as has been described on the previous page, however that plan has changed and now the engine to stay in the car long-term in a 4AFE, but it'll come out for the 7AGTE 20v engine described below for a while while I run that engine. More on that next section.
The head that I'm going to use is from the largely despised 7AFE. It's a long story but it turns out that there's three basic head types that the 4AFE & 7AFE in combination have. There's a very poor one that's by far the most common and they have rather small inlet ports that come out low on the inlet side and so the angles the air has to go through to get to the combustion chamber is extremely poor indeed. Those heads are boat anchors.
The first head of interest is quite common on the Aussie & other market 7AFE's, and they have two small inlet ports for each cylinder. They use the Toyota TVIS device to try to improve the low-end torque without sacrificing the top-end power. They have a lot more potential as the ports go into the head at a steep angle and so have the opportunity to flow a lot more air. The port angle into the head is similar to the 20 valve 4AGE, but of course they only have the two inlet valves. Both this head and the type above have the fuel injectors either in the head or remotely out in the inlet manifold. This head is the one I was going to use for the 4AFE project, but I found a much better 'F' head a few months later ....
The head in question is pictured below, and as you can see it only has a single inlet port per cylinder, but they also go into the head at a rather steep angle. This makes for a damn good inlet port for not a lot of work. Again there are two types for this head, but the variations are only relatively minor changes in the port bifurcation divider and bolt hole bumps in the port.
However, the combustion
chamber will need a lot of work to make it produce a lot of power. I've
looked at a lot of different types of engines and found certain
consistancies with squish areas that I will be using when finishing the
chamber. I'll also be trying some Formula One style tricks with the
chamber. This means a complicated piston top shape, and hopefully I can
get exactly what I want made. The exhaust ports will also need a lot of
work, but fortunately the work that needs to be done makes them end up
all the same gives them a very efficient shape. The other reason I want
to use this head is because they use 31mm diameter cam buckets, rather
than the smaller 28mm ones that the 16 valve 4AGE's use, and somewhat
larger than the 23mm ones the 20v heads use, so I can run a cam with
quite a lot of duration & lift without having the lobes run off the
sides of the buckets. I have found a standard 31mm Toyota bucket that
no shims at all (it has a small 'stem' underneath that is trimmed to
the right length to get the right valve clearance) and so is very light
|Speaking of the camshaft, this is
the profile I've decided to try first. It's around the 280° mark
and has 0.445" or 11.3 mm lift. Only the large 31mm diameter bucket
will allow a cam this big to be run with success.
Other things I'll be doing with the engine are - 7AFE block but still use a 4AGE crankshaft because that lets me run longer con-rods, (The 7AFE block is taller than the 4AGE) which reduces frictional losses and increase piston dwell time at TDC. Yes, they will weigh more than a shorter rod but I'll be getting the new ones made up at PAR Engineering in Sydney, though the weight will be largely offset as they're titanium.
The engine will also be
completed in three stages -
1. Wet-sumped with a Motec M4 Pro running four injectors that sit in the inlet manifold. This is mainly to set-up the engine and run it in carefully, as I have less things to go wrong as it will in the final configuration.
2. Dry-sumped, to improve power a little but also to make the engine more reliable in competition as the oil flow will not suffer under heavy braking and/or cornering. After a decade+ of fiddling with the dry-sump systems used on my racing car, we have a pretty good idea of how to build a good one. I have some plans for the system on this engine that make it very simple and far fewer parts than they usually have. This makes it lighter and hopefully more reliable. (and less oil leaks!!)
3. The second set of four injectors to be fitted. The engine will end up with eight injectors, four in the inlet manifold behind the throttle butterflys and another four out in the end of the inlet trumpets. There is a little more power to be gained by doing this, but it's complicated and will take some time to get right with the sequencing of primary and secondary injectors. This is why I don't want to run the engine in with it in this configuration as there is a greater chance of getting it wrong and causing damage. It was also get a Motec M48 to run it at this point.
|I have recieved the throttle bodies for the engine, and they are in the photo on the right. They are paired, like Weber carburetors, and are of very high quality. They are 45mm diameter and were made at Alloy Race Components. The reason why I picked those is because they are very short indeed and I need as much space as possible to fit everything between the inlet trumpets and inlet manifold flange. It's going to be tight ....|
|In July 2006 the
custom-made forged pistons from Wiseco finally arrived, and they look
great. They're 82mm slipper type and weigh only 256 grams, and that's
before some hand-lightening. The gudgeon pin hole, as you can see, is
very high and that's so the con-rods can be made as long as possible,
to reduce rod angularity.
No photos of the tops sorry, as that's a bit of a secret for now.
On the right is a photo of the exhaust ports. It's hard to see but a heap of metal has been added to the ports in various places to allow them to be reshaped from round to oval. The ports are only roughed out in that photo, the final finish is to come.
|Some minor progress
- The block has been aged and in the photo on the left I am about to
take it to the local shop to get dipped for cleaning, to get most of
the rust off. The aging process is simply leaving the block out in the
weather, as BMW did with their turbo F1 engines of the mid-80's. A
light coating of grease over the areas you don't want to rust, then
leave it for a few months ...
It has yet to be polished internally, and the oil passages worked on to improve the flow.
On the right is the scavenge pump assembly for the dry sump system. It's made from two sets of 4AGE oil pumps and will be bolted directly to the front of the oil pump cover, driven off the front of the crank pulley. I'm going to use a conventional 4AGE harmonic balancer-type pulley (albeit with one row cut off) as I'm concerned about the crank vibes at high revs. It's in the photo on the left, and it's from a 20 valve Blacktop engine, so one of the younger ones.
The con-rods, as I type this, are nearly done and are being made by a company down south. A friend of mine is getting an identical set of rods from them as well, and we've been waiting for well over a year for them now. Neither of us in very happy about this at all and while I'm not in any particular hurry for them, he has missed several important dates for the car as he can't put the engine together. We're getting them through a dealer closer to home and he's been fine, but I will not be doing business with that company down south ever again. The only reason we're sticking with them as the price is very good - especially for titanium rods - and as I type this, they're nearly finished. (I hope!)
This engine will be ready when it's ready. I plan to run it to 9,500rpm and although I'm expecting about 240hp from it, it should still drive as well as a standard engine does around town.
7AGTE 20 valve
The next engine I'm going to build for the Starlet is a 1.8 litre 7AGTE 20 valve one. That's a 7AFE bottom end, a 20 valve 4AGE head, and a 1998 Subaru WRX turbo. This engine is just for fun, and although I do not favour the 20v head for naturally aspirated engines I think they're a very good thing for forced induction as the variable inlet cam timing should let the turbo spool-up faster at low revs than what it otherwise would. They also have more valve area than the 16v does standard, so that allows for more air to be pushed into the chamber by the turbo. I have a set of stock 4AGZE 8:1 compression pistons for it, but otherwise the bottom end will be fairly standard. I only plan to run about 7,000rpm, so the not-so-strong 7AFE rods should hold together well enough.
I have some sneaky plans for the intercooler (A water-to-air, but not conventional) and the way the turbo is mounted.
In the interests of keeping the rest of the mechanicals together, I have bought a bell housing that lets a 4A or 7A block bolt up to the very strong W series Toyota gearbox, and I also have a W-57 sitting at home waiting for it. I'm expecting up around 300 ft-lbs of torque and about 350hp from the engine, so there is no way a typical T-50 would take that and live. Same goes for the diff, I am currently hunting for a narrow Hilux 7.5" diff to put under the back of the car as they're very hard to break.
This engine is a low-budget one, and it's really just for a bit of fun. So it won't stay in the car, but will be sold at some point after it's been run for a while.
Another engine that I came across that should be a lot of fun to have in the small car is the 2.5 litre Suzuki V-6. They're 85mm x 75mm bore & stroke and I'm pretty sure that I can go out to an 88mm bore and so end up with a 2.74 litre engine. They're all alloy and have a 60° bank and so are quite light & compact. Good for the tight Starlet engine bay.
On the left
is a cut-away diagram from the factory manual. In the middle is is a
friend's two litre version and you can see that the sleeves that the
pistons run in are very thick indeed, thus there's good hope that a 3mm
over-bore can be done. On the right is one of the heads from that
engine and the very good inlet ports can be seen clearly here.
|Finally some pics of the engine!
It's fairly tall as it comes stock, but with a shallow sump and individual throttle bodies on a curved inlet manifold it'll end up fitting under the bonnet of the Starlet no problem. It also has a coil-on-plug system so that'll come in handy.
the right is the engine with one of the cam covers removed. I was going
to pop one of the heads off, but I ran out of time while I was on
holidays. To get the heads off, all the front of the engine also has to
come off and that takes some time.
The ports look extremely good, however getting the engine into the Starlet will be a touch more difficult than I thought as you can see the water return from each head going into a single outlet down the valley. This can't be changed, so we'll have to move the engine a little further forward than what I wanted to originally.
Estimated Power Runs
Some estimated power runs, using my trusty Engine Analyser Pro 2.1D & 3.3 'software dyno' program. These are runs based on older information I have, the latest ones show a bit more power from the two planned engines.
On the left is the 'plain'1587cc 16v 4AGE, the second is the 7AFE headed 4AGE (bored out to 1626cc), the third is the turbo 1762cc 7AGE with the 20v head, and on the right is the Suzuki 2737cc V-6.
|To back up the
estimated power figures of the 4AFE, here's an example. As fate would
have it, a friend of mine overseas has built an engine almost identical
to what I will be building. It's in an off-road buggy and on an engine
dyno it has made 248hp at 9,000rpm.
It's almost identical in every way, except the advantages mine has is that I'm using the better head, bigger valves, 1mm bigger bore (~40cc's worth), a better ignition system, and a more efficient oiling system. The advantage the buggy engine has is that it uses bigger cams.
So all in all I think it's not unreasonable to expect a similar power from my engine.
Back to the Starlet page
For more motorsport links, try the motorsport section on my links page.
site owned by
Back to the Index pagePage & contents where applicable © Bill Sherwood