Our Performance Engine Rebuilds
Here at MR2 Tuners, we know what it takes to build high performance Engines. We know the strengths and weeknesses of each 1st & 2nd generation MR2 Engines (4AGE, 4AGZE, 5SFE, 3SGTE). That combined with experience and gathered knowledge from race engine shops, we confidently build up strong engines capable of high HP.
How will we do YOUR engine?
In most cases, based on your horsepower output desires, we will tell you your options of what needs to be done to accomplish those goals. Utilizing proven engine rebuilding techniques, parts, and assembly methods (more information on these below).
Engine Rebuild Techniques - A Step by Step Look
1)Stock Engine Disassembly & Inspection -
In many cases, MR2s come to us with engines damaged already, thus prompting the owner to go ahead and strengthen the "bottom end". So the first step is to diagnose the failure and problems occured with the stock engine. We completely disassemble the complete engine. We look over and inspect ALL engine components. In many cases parts are measured to ensure within TOYOTA specifications. This not only done to analyze the original problem, but ensure out of spec or damaged parts are disgarded. This also helps the owner decide what they would like to do. For instance if I found a cracked piston ring land, requiring a new piston, which requires overboring, you'd probably decide to replace them all with superior parts. While on the other hand, if the piston/rings were fine and the head was the problem you might not do a full bottom end rebuild.
2)Inspect components for microfractures -
There are many stories of engine catastrophies caused by unseen fractures/cracks. The eye cannot be trusted in many cases and it's simply the best bet to have all materials checked. The stock 3sGTE pistons for instance tend to break ring lands. While visible once completely broken, small fractures may be present and unseen by the human eye. Using special dies and magnaflux techniques we can spot and inspect for these weeknesses before they cause anymore pain.
3)Engine Block Cleaning -
All blocks are hot tanked to remove all contaminants (oil, carbon, etc). (NOTE: Blocks are Magnafluxed after cleaning). All passes, oil squirters, water jackets are all cleaned out.
4)Block Machineing / Balancing & Blueprinting -
For High Output engines, this is one of the critical areas to do right, and can seperate the good builders from the bad. All parts have tolerances, and a well built engine will take all the actual part tolerances in account. These include size, clearances, and even weight.
The whole process of matching up each piston to a rod to create equal weight from one cylinder to the next even including the crank is called balancing. A uniformly balanced engine will run smoother and can be capable of higher than stock RPMS (still limited by other factors though). There are various levels of balancing also, some merely balance the parts available to the closest they can without removing material. A full balance will include removing material to ensure all parts are practically identical in weight. Which method you choose really depends on the HP & RPM range you require. Once all the weights are matched up you must record what the parts match with and what cylinder they go to. This is in essense part of the blueprinting process. The other portion of blueprinting is measuring the actual clearances of the parts. These clearances tell what EACH CYLINDER needs to be Bored and Honed to, in order to ensure the best seal.
For example, a race engine builder will insist on having the Pistons, rings,...basically the whole bottom end such that he can ensure the Cylinder is made exactly to what is necessary. A normal machinest will merely require the overbore size. While using a standard overbore size may do for a simple rebuild on a stock engine, it won't account for differences in each piston and thus won't be optimized for the most power.
Once all the information is taken, the machinest will prepare the block to be overbored and honed to the exact specifications written on the blueprint. Before they begin a TORQUE PLATE is installed on the block. The Torque Plate is a thick piece of metal that placed on the deck of the block and TORQUED down in place of the head. This is required as when a head is torqued down it distorts the block to a certain degree. If you bore out a block without this, you aren't taking this distortion into account and thus the cylinders will not be as TRUE as they can be. Again this is another distinction between a good engine builder and a bad one. If your looking at high HP numbers and they don't use a torque plate, go somewhere else. After the plate is fixed and then attached to the machine, they will overbore the cylinder to about 75-85% of whats required. THEN they will hone it out the remainder of the way to ensure they do not go beyound the bore size required.
5)Engine Block Deck & Head Surfaces -
In many cases, as is one of the weeker points of the 3sGTE engine, the head gasket blows or the head warps. These issues must be resolved, before proceeding. In many cases this includes milling down the head/block (Note: Very rarely are the blocks warped). Doing so causes two problems: 1-It raises engine compression, 2-It removes the smooth finish that TOYOTA creates on the head and block mating surfaces. On a turbo car, these are not desireable. Many times they are compensated by going to a thicker head gasket (normally a metal one). This brings the compression back, however the mating metal surfaces must be brought back to adequate smoothness. Special machines are used to practically polish the deck of the block and bottom of the head. This is critical to help ensure a metal head gasket (far better than stock composet) will seal correctly. In cases were the block & head are fine, the stock smoothness is usually adequate. If they are fine, we still recommend using a good metal head gasket like from HKS or TTE(Team Toyota Europe).
6)Head Rebuilding -
Heads, like anything else, build up carbon & oil deposits. Heads are also carefully cleaned (NOT HOT TANKED, as they could warp) and checked for fractures. The valves are removed and residue removed. Seat surfaces are lightly re-done, with 3-or-5 angle valve jobs available. Valve oil seals are also replaced. If the customer is going with bigger lift cams, then the springs are replaced with higher performance ones at this time.
7)Engine Assembly -
Once all parts are ready, blue-printed, etc. we begin to put the engine together slowly. From the crank all bearings are installed with special lube to ensure damage doesn't occur before oil pressure is built. Each main bearing is measured for proper oil clearance. It is absolutely necessary to ensure proper clearances in the main and rod bearings. Too little and it robs power, and oil can't do it's job, which can lead to seizure or spun bearing. Too much and the components could move/vibrate, and well...you can imagine the rest. I've encountered a couple people who merely went by the numbers written on the block for bearing size. While you might get lucky with that, wouldn't you rather know for SURE! Thrust clearance is also checked...basically if there's a spec, we'll check it. The pistons are installed to the rods to ensure proper play in the dowel. Previously, as verified by the machinest, the rings are checked for gap clearance in their specific cylinder. Then rings are installed on the pistons and each is put in, in accordance with the blueprint.
PARTS