*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*= Subject: Re: 4AGE performance From: Geoff@ihug.co.nz (Geoff) Article: 4526 of rec.autos.sport.tech Date: Mon, 16 Oct 1995 08:23:41 +1300 In article <45hbcs$3q1@cantua.canterbury.ac.nz>, Neil Briggs wrote: > Does anyone have any thoughts or information to improve the performance > of Toyotas 4AGE engine. I was thinking maybe sports exhaust to start with > (but not excessively loud) and maybe new air filter. These are supposed > to work alongside handling improvements like good tyres etc. > Any advice would be appreciated. I KNOW there is someone reading this who > has WAY more experience with this than I do. > Thanks I have been involved with a friend's GTi Corolla over the last 3 years or so. A Uniflow or K&N filter and 21/2" exhaust (Coby resonator adn Dynomax muffler) was the first step. The exhaust made a real racket in the car so we replaced the Coby straight through resonator with one with a cone in the middle designed for RX7's and this made it bearable for daily use. The Coby extracors we fitted were a 4-1 design with very short primaries and IMO a wast of money. They also cracked from vibration every 3 months and we got sick of welding them up. The air temp at the throttle body was 55 degrees C at fast highway speeds and 31 degrees just behind the headlight. Chris made a cold air box with the filter behind the left front headlight. The battery had to be replaced with a smaller one and new mounting brackets made. This made a difference of 1kW on the dyno. The result of all this was the mixture was very lean, and a few hours on the dyno at Steward Automotive helped to fix this. Next step was to get Lyn Rodgers here in Auckland to flow the head and take 30 thou off it to boost the compression. The standard Yamaha designed head flows very well, it was mainly a tidy up and recut the valve seats with a 3 angle valve job. Make sure you get someone who knows what they are doing nad has a flowbench, otherwise they can make things worse, Teh area around the back of the valve is very important to good flow on this head. This was around 10hp. As mentioned earlier, the Coby extractors are crap. The standard 4-2 manifold section actually works quite well as I believe that this cannot be replaced for racing in Japan, so one alternative is to make a good 2-1 section and replace the bit where they have squashed 2 pipes into one. Lyn had the design of a 4-2-1 system for these motors, and I don't have the lengths here, but it first joins under the block and the 2-1 part happens after the front axle. We made this system, and it is a prick to fit without it hitting something under hard accelleration. The power was much the same a stock up to 6000 RPM, but then it keeps climbing up until redline. Kelford Cams in Christchurch do a set of cams for these engines, but they have no dyno figures and cost $800 or so. They have a higher lift and longer duration and this will make an already peaky engine unusable for the street. The new extractors have now made the engine so lean, it is at the limits of what the stock engine computer can be adjusted to (running 1.5% CO at idle and geting slightly richer further up the range). Idealy, the EMU should be replaced with an aftermarket one like Motec or Stewart, but this is $2000+ and while there is more power and drivcablity there with better carburetion, it will have to wait until later next year. One other thing to do is to make some slotted cam wheels so we can degree the cams, as planing the head has retarded the cam timing by a few degrees. All my notes are at Chris's place, so I am going from memory here, but I think power went from 78Kw to 109Kw. Even 78Kw is healthy for one of these motors - they seem to vary a lot depending on how they are looked after and driven. It now has 100,000km on it (around 50,000 since we started the mods) and the rings are getting a little worn, although within limits, and the motor will be coming out shortly to be freshened up and perhaps a few mor mods done to it. It gets used every day and has been run on Castrol or Motul synthetic for the last 60,000 km. What car are you going to do these mods on? An MR2 may be a little crowded for the extractors without some tricky pipe bending. The other alternative is 1/ a 4AGZE supercharged motor and black box or 2/ the 2L motor. I have heard or seen both of these fitted to Corollas before. Geoff