Οδηγός προετοιμασίας αγωνιστικού 4AGE by Technosquare (με φωτογραφίες)

[Erebos]

Βρήκα στο MotoIQ ένα αφιέρωμα/οδηγό για την προετοιμασία ενός αγωνιστικού 4AGE από την Technosquare και θεώρησα ότι περιέχει κάποιες χρήσιμες τεχνικές πληροφορίες για όσους έχουν οποιοδήποτε ατμοσφαιρικό 4AG.

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For serious motors Technosquare starts with a later model second generation, post 1988 4AG(ΖΕ) block as found in the supercharged AW11 MR2 or the AE92 Corolla. This block is important for a all out effort 4AG because the older AE86, NA AW11 and AE82 4AG block is much weaker and block integrity is an issue for high powered 4AGs. The late block has beefier construction and deeper external ribbing for strength as well as piston cooler oil squirters. Milder motors under 180 hp can use any 4AG block. As the first stage of block prep, the interior of the block is polished to remove any stress risers where a crack could start, speed oil return and to remove embedded casting sand. This is a big issue with iron blocks and an amazing amount of sand is removed while polishing. The sand can break off and end up in the oil, not good. The block is checked to see if align honing and is needed. The interior of the block is shot-peened to stress relieve it and to help improve fatigue strength.





This piston cooler nozzle squirts oil on the underside of the piston crown, helping to keep it cool. This greatly reduces the chances of detonation and piston failure. The notch cut right below the cooler body and the other notch in the blocks internal reinforcing rib to the far left care cut by Technosquare to clear the rod bolts due to the 83mm stroker crank that will be installed in this engine.





The pebbly texture of the main bearing saddle shows the surface finish that shot-peening leaves. A critical area to watch on a 4AG is the area where the main cap meets the block. The 4AG block is prone to flex in high power applications causing bearing and crank problems. When the block starts to flex, this surface starts to get a polished look and the main cap gets loose. In this case the block must be align bored to save it although some engine builders will probably feel that the block must be discarded.





The block deck is fine milled for flatness and then lapped on a surface plate for absolute flatness. This is important for seal when using MLS (Multi Layer Steel) performance head gaskets. The block is bored 2mm from 81mm to 83mm for this monster 1800cc stroker engine and honed with a fine 600 grit stone. The bore is then plateau honed for good ring seal with modern low tension rings. You can't see it but before machining the block's water jackets were filled 1/2 of the way to the deck of the block with Hard Blok, a cement based block filler. This material helps support the cylinder walls while still retaining heat conductivity. With a big bore, this is an important step to assure longevity and good ring seal in the thin wall somewhat weak 4AG block.





The 4AG's oil pump gears become unreliable at around 8000 rpm. TRD used to have special stronger gears but these have not been available for a long time. The alternative is to dry sump the engine. For a max effort 4AG, a dry sump is worth the expense in increasing reliability. Here the main passage from the removed stock oil pump is blocked off.





This restrictor is placed in the block deck to limit the amount of oil pumped to the top end. This reduces windage for increased power and lower oil temps and sends more oil to the main and rod bearings. This mod can be done for engines running the stock oil pump as well and it is probably needed more in that case!





This beefy cast Formula Atlantic dry sump oil pan was important in a Formula Atlantic car because the engine was a stressed member and the 4AG is a wimpy flexy engine that would self destruct with chassis loads being fed through it. The thick pan reinforces the block. For sedans the heavy duty pan helps strengthen the block for durability reducing main cap walk and flex for longer bearing and crank life. A Barnes 3 stage drysump pump is used with 2 scavenge and one pressure stage. The dry sump ensures that the engine will always get a good supply of oil not matter what the G load or how high the rpm.





One of the weakest parts of the 4AG is the crank support system. The main caps flex and distort under heavy loads causing the main bearings and even the crank to fail. This happens above 9000 rpm and 220 hp. Tomei makes these main cap reinforcements out of high strength steel. The tops of the cast factory main caps are machined flat and the main bolts replaced with ARP studs. The reinforcements are then bolted on top of the main caps. This greatly reduces flex improving bottom end life, especially when combined with the Formula Atlantic oil pan. This mod is also useful with turbo cars.





The bearings are ACL tri metal heavy duty Formula Atlantic bearings. The Tri Metal construction give superior load bearing capacity. The bearings look ugly as the latest trend in racing bearings is to forgo the traditional zinc plating top overlay. On a stock engine this zinc gives a bit of embedabilty making the bearing less sensitive to dirt. The thinking is that this zinc layer reduces heat transfer and does nothing in a racing engines that is cleaned carefully during assembly.





High strength ARP studs allow a higher torque and more clamping load for the cylinder head and main caps. Studs are also inherently stronger than bolts and unlike the stock torque to yield bolts, they can be reused. Special hardened washers and high strength nuts are used as well but are not shown.





CBY, a Japanese 4AG tuner supplied this billet stroker crank. At 83mm of stroke, up 6mm from the stock 77mm, this crank punches out the 4AG to 1800cc when paired with 83mm big bore pistons. The stroker motor is good for 30 more hp over the standard 1600cc engine. The stock 4AG crank is also a weak point on the engine. The early AE86/AE82/AW11 version of the 4AG had smaller rod journals at 40mm and were very weak. The stock crank fails at the #3 rod journal when the revs are pushed beyond 8000 rpm and the power above 180 hp. The CBY crank is made of high strength 4340 high nickle alloy and uses the larger diameter 42mm late rod journal size. The CBY crank has generous fillets and chamfered oil passages and is post machining heat treated and shotpeened for extra durability. If you are building your own low buck 4AG, it is advisable to run the later 1988 and up supercharged MR2/AE92 crank, rods and bearings. This crank is much stronger.





CBY rods are H beam and feature super strong rod bolts and floating pin bushings. They are machined from 4340 alloy billets. The piston pin uses the larger late post 1988 4AG 20mm diameter as the smaller 18mm early pins were prone to distort and wear the rod bushing at high RPM. The CBY rods are shotpeened for greater fatigue strength.





Greddy cam drive belt is heavy duty and Kevlar reinforced for extra strength and durability at high rpm.





HKS supplied this MLS (Multi Layer Steel) head gasket, important to ensure sealing at high compression ratios. MLS gaskets require good block and cylinder deck preparation to obtain a good reliable seal.



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[metritis_ae86]

πολυ καλο..

[TOLIS EE80]

Συνοπτικα αναφερονται καποια πραγματα και εδω.
http://www.billzilla.org/4agmods.htm#220hp

[KOSTAS_KE35]

ενδιαφερων!

[Erebos]

Technosquare's Monster Naturally Aspirated Toyota 4AG part 2


The 83mm x 83 mm stroker motor gives 1800cc. The 200 extra cc's makes a huge difference, fortifying the 4AG's notoriously narrow power band. The engine cranks out over 250 crank hp, more than the most highly developed Formula Atlantic engines of yore and 30 more hp than the previous 1600 cc version of this motor. On a Dynopack chassis dyno the 4AG ripped out 216 whp, a hell of a lot for a naturally aspirated 4AG. You have to remember that a RWD set up typically robs 20% from the crank power levels vs the 15% more efficient FWD transaxles typically steal.




Wiseco forged pistons are used. To maintain the best possible stroke to rod length ratio, the pin is moved as high in the rod as possible. It even intrudes into the oil ring groove slightly. Strut type construction is used for light weight. The skirts are moly coated for less friction and better wear of the skirts and cylinder walls. The dome volume is set to give a 13:1 compression ratio. Technosquare deburrs and cleans the dome of all sharp edges which could create a hot spot causing detonation. The piston feature double pin oilers and use a tapered wall lightweight 20mm tool steel piston pin for minimal weight. This is the post 1988 4AG pin diameter, up 2mm from the older, weaker, flexy 18mm pins. The pin is retained with Cosworth style round wire retainers.




This close up shot shows the radical pin placement, intruding into the oil ring groove. This sort of design usually has higher oil consumption but allows the longest possible connecting rod for an improved rod ratio and lower piston speed. The piston has anti detonation grooves between the top of the piston and the top ring. These grooves buffer the detonation shock waves and protect the top ring. The also reduce the contact area high on the piston for less friction. The grooves also reduce expansion at the top of the piston to reduce the likelihood of scuffing under extreme heat. A pressure equalization groove between the compression rings improve ring seal at high rpm by acting like a reservoir for leaking combustion gasses, improving the seal of the second ring.




The rings are fairly conventional. The upper compression ring is a narrow 1mm chrome face design. The second compression ring is a 1.2 mm iron ring. Both rings are low tension for reduced friction and less likelihood of flutter at high rpm. The oil ring is a conventional 2 rail design.




The stock 4AG valvetrain uses shim on bucket valve adjustment. This system has trouble at over 8000 rpm and 8.5mm of lift. The cam lobes tend to flip the valve shim off of the top of the cam follower. When this happens the cam lobe beats on the retainer and causes the keepers to fall out and the valve to drop, destroying the engine. To prevent this from happening the valve train is converted to TRD Formula Atlantic stuff. Double valve springs are used with titanium retainers that are designed to accept a small adjusting shim. The cam follower goes over the shim preventing it from getting flicked out by the cam lobe. You can see one of the small adjusting shims next to the cam followers. This is called a shim under bucket system and is used in motorcycle and other high RPM engines. TRD big valves are used, they are 2mm bigger than stock. TRD Formula Atlantic cams are also used, 320 degrees intake duration and 304 degrees exhaust duration. Both cams have 11mm of valve lift. The cams are set on a 102 degree lobe center.




The cylinder head is rough ported by Hasselgren and finished by Technosquare. A late post 1988 4AG head is used as it has a smaller but better flowing intake port. The intake and exhaust ports have smoothed short side radius, moved back port splitters and raised flattened roofs. The combustion chamber is unshrouded by the valves and the deck surface is fine milled and lapped on a surface plate for better sealing.




The combustion chamber valve unshrouding is shown here, you can see how the edge of the combustion chamber is moved back from the valve and valve seat. This really helps flow as the valve starts to open and close. A 3 angle valve job is used with the top 30 degree cut blended into the combustion chamber and the 70 degree throat cut blended into the seat and port wall. The 45 seat is kept to around 1 mm in width on the intake side and 1.2 mm on the exhaust side.




The intake port starts with the valve bowl. The valve seats are opened up for the bigger valves and opened though to the valve bowl. The valves are supported by bronze TRD valve guides. The entrance to the bowl is opened up and material is mostly removed at the port roof. The short side radius is rounded.




You can see the extent of roof flattening in the intake port here. This gives the best flow with the least volume for good port flow velocity. This gives the best throttle response and widest power band. The port splitter is moved back to give more flow area without increasing volume much. The EGR bosses in the roof of the intake ports are plugged.




The exhaust ports have the same sort of treatment as the intake ports. The valve seating surface width is slightly wider at 1.2 mm to improve valve cooling.




Like the intake the exhaust has more material removed at the roof and has the port splitter moved back. You can clearly see how the bowl area is opened up leading into the port.




The sides of the valve bucket hole have to be milled out to clear the high lift TRD cam lobes.




You can see how the cut outs work to clear the cam lobes here.




The assembled head with the TRD big valves.

[Erebos]

Technosquare's Monster Naturally Aspirated Toyota 4AG - Part 3



The first issue to address was the lubrication system. As the 4AG has an iffy lubrication system, mostly due to very fragile oil pump gear rotors that become marginal above 8000 rpm, a dry sump system is essential for engine longevity. The 4AG also pushes the demand on the oil system to high levels. It has a marginal amount of bearing area for high rpm operation and any air entrapment in the system or fluctuation of oil pressure can cause failure at high RPM.




The Barnes dry sump pump has two scavenge and one pressure stage. The pump is belt driven from the crank. The TRD oil pan is very thick and greatly strengthens the block.




The low profile of the dry sump pan is shown here. The braided black hose is the external coolant bypass hose that max effort 4AG's need to prevent overheating.

To assure a steady supply of air free oil, Technosquare relied on a Barnes 3 stage dry sump system with a modular pump with two scavenge and one pressure stages. The two scavenge stages suck windage from a TRD Formula Atlantic pan. The pan is an important element in improving the engines structure. Since the 4AG's lightweight block is not well suited for stressful high RPM and high power use, it is reinforced by the beefy pan. The pan was designed to be a structural part as the engine is a stressed member when it is installed into a Formula Atlantic race car chassis.




The bypass hose takes hot coolant from the back of the head to improve coolant flow in the head. This helps keep #4 cylinder from running too hot.


The pan was built to greatly reinforce the wimpy 4AG block for this use and Technosquare used it to help keep the 4AG block from flexing. A TRD thick and strong Formula Atlantic valve cover was also used for this reason as the valve cover is also designed to strengthen the engine assembly in a Formula car chassis. These reinforcing parts should greatly increase the bearing and crank life as these were always marginal in the racing versions of the 4AG due to block flex at high rpm.
Oil pumped from the pan is cooled by a large Greddy oil cooler and de-aerated in a large Peterson tank. Peterson tanks are great because they are two- piece so they can easily be disassembled and thoroughly cleaned in case of an engine failure.




The coolant bypass hose goes to the discharge of the water pump then to the radiator. You can also see the beefy strong casting of the TRD Formula Atlantic oil pan.






The induction is handled using a TWM intake manifold with huge 50mm TWM individual throttle bodies sporting short 40mm velocity stacks. A TWM fuel rail feeds 285cc Denso injectors. A vintage TRD FIA N-1 4-1 header handles exhaust duties. We feel that there is a lot more power to be found in a modern header design with larger stepped primaries and a merged collector.




The TRD Formula Atlantic valve cover is very thick and strong which helps reinforce the weak 4AG block. This helps improve bearing and crank life.




The Autronic ECU, CDI box and Wide band controller mount on the firewall inside the car.




The CDI runs in individual coil mode and fires these coils from a Honda CBR Motorcycle one per cylinder.
Engine control is managed by an Autronic stand alone ECU and CDI system. The CDI fires Denso Iridium sparkplugs with an individual coil ignition system using Honda CBR coils acting directly on the plugs. Power transfer is handled by a twin disc OS GIkken clutch and lightweight flywheel.




An OS Gikken twin disc clutch and steel flywheel couple the engine to the transmission.




The TRD FIA N1 4-1 header is more of a vintage racing piece. A modern header would probably be good for more power.




The lower line is the old 1600cc engine. The upper is the result of adding the stroker crank.
In initial dyno testing the monster 4AG belted out 183 whp @ 8750 RPM with 122 lb/ft of torque at 6250 rpm on Technosquare's notoriously conservative Superflow dyno. This would probably equate to around 200 whp on a Dynojet or 230+ at the crank. This is in line with the most developed 4AG's ever built during the engines racing heyday in the Formula Atlantic era but with a wider powerband and more torque that the increased stroke gives.

YouTube Video

We feel that there is potentially a lot more power to be found with development of this engine if Technosquare's customer wants to find some budget to do so. A custom modern designed header should help considerably. Also the cylinder head was put together using well worn vintage TRD parts, especially the valves which were worn thin with a narrow margin and sunk deep into the valve seats. Newer modern valves and a correct valve job should free more power as well. WPC treatment could also help. We think that there is another 10-20 hp to be found here.

We will continue to follow Technosquare's development of this engine in the future.