The Difference Between Big Port Small Port?

[turbo_maniac_wayeda]

What are the differences between the Big port and small port engines?

T-vis and non T-vis?

The differences on high torque?

I really want to know the differences as im really into these cars alot

[jay13]

glad to hear you like them, after restoring mine people love it, even parking in it town i get people coming up to me and asking all questions about it as they don't really see them any more, anyway back to your question, hope this helps:

The second-generation 4A-GE produced from 1987 to 1989 featured larger diameter bearings for the con-rod big ends (42mm) and added four additional reinforcement ribs on the back of the engine block, for a total of seven. The TVIS feature is maintained. It is visually similar to the first-generation engine and the power output is unchanged, but the upper cam cover now featured red and black lettering. The first- and second-generation engines are very popular with racers and tuners because of the ease of modification, simple design, and lightness. The TVIS equipped model is an ideal candidate for a turbocharging overhaul because it contains the so-called "big-port head", meaning the head had the large cross sectional area intlet ports.

The third-generation appeared in 1989 and was in production until 1991. This engine has the silver cam covers with the words only written in red, hence the nickname "red top". Toyota increased the compression ratios from 9.4:1 to 10.3:1. To correct the air-speed problems of the earlier genrations of engine the heads inlet ports were redesigned to have smaller cross section inlet ports, and hence has been nickanmed as the "smallport head". This change in the intlet ports negated the need to have the need for the earlier twin runner manifold and was replaced with a single runner manifold. Additional engine modifications to extend life and the reliability included under piston cooling oil squirters, thicker connecting rods and other components. Also of note the pistons were changed to accept a 20mm fully floating gudgen pin unlike the 18mm pressed in pins of the earlier versions. All non-US market 4A-GEs continued to use a MAP sensor, while all of the US-market Toyota 4A-GE came with a MAF sensor. The only exception was the US-market 1990-91 Geo Prizm GSi, which was equipped with the MAP. This engine revision upped the power to 138 hp (103 kW) at 7200 rpm with a torque of 110 ft·lbf (149 N·m) at 4800 RPM..

[turbo_maniac_wayeda]

Brilliant thats some useful info bro, also my brother has mk2 corolla gti with the mk1 engine T-vis model, now i think the guy who had it before didnt know thats was a mk1 engine and bought it and installed it but couldnt get the car to crank up and was very sluggish, now my brother took it to a tuner and got it sorted as the engine mangement light kept coming on making the car sluggish....

Now the tuning place told us that it was a knock sensor....

One of my question is did the mk1 Engine t-vis model have a knock sensor???

and aslo because thats sorted now the tuner told us that it has big injectors on it and thats whats holding back a bit of the power and making it not idle/rev the way it should.... and we need to get it remapped?

is this true? please help because he really wants to keep the corolla gti and show people out there what a beauty these cars can be...

[turbo_maniac_wayeda]

anyone?

[citycash]

Just came across this thread from 2008 - It's now 2019 but I can answer this.

The earlier 4age did not have a knock sensor but the third generation 4AGE Came fitted with a Knock sensor.
So if you install an earlier 4AGE engine into the AE92 corolla that came with 3rd Gen 4AGE it will not run due to the lack of nock sensor.
Perhaps if you could fit a bracket to the side of the head so that the Knock sensor could pick up signal from the engine then it you may get away with iy.
I only found this when I bought a replacement 4AGE for my 1989 Corolla Gti, I was told that the engine was from a 1990 model but only when it was too late I found that it came from a 1988,
the garage called me and said we have fitted you engine but there is no where to fit the knock sensor,
I part exchanged it to get rid of it.