Hi guys, A friend asked me for suggestions on his project car -- he owns a 2002 Lexus IS300, naturally aspirated and 4-speed automatic. The engine is a late model 2JZ-GE VVT-i, mated with A340E gearbox and open differential. It was supposed to be A650E 5-speed automatic but the gearbox died and the previous owned fitted the stronger old 4 speed instead. This car was his daily driver -- but suffered from gearbox issues and the timing belt broke and therefore the engine is not running. He always wants a manual sleeper and he decided to build his IS. We've decided to go a budget 1.5JZ build -- and here's our situation: We've found a 1JZ-GTE VVT-i off from a 2002 Verossa VR25 JZX110 for cheap -- done 105,200km and works fine but the block have some minor damage around the engine mounts and therefore the parts dealer offered us a discount for that. The engine was mated with a R154 5-speed manual, and we thought that this gearbox suits us -- moderate handling, more robust than W55 and cheaper than Getrag 233 (V160 / V161). In fact the parts dealer offered us to get the differential for an additional 300 bucks if we buy the engine and the gearbox and he'll offer the brakes of the Verossa for cheap. My friend decided to go for 1.5JZ as he is paying the tax for a 3000cc car and it's simply impossible for him to change the engine model and displacement listed on this car's registration -- as this would be illegal in China. However the old 2JZ block carried the engine number and the car can pass inspection with a proper 1.5JZ build. The manual labour is relatively cheaper here than western countries and he can get a discount for that as he'll be building this car at his mate's workshop. The plan is to build a 1.5JZ utilizing current resources: Get the holes drilled for the oil squirters on the 2JZ-GE block and install the oil squirters and oil supply from the 1JZ. Swap over the 1JZ-GTE forged pistons and head, keeping the 2JZ-GE rods and crankshaft. Use the stock 1JZ-GTE intake manifold and exhaust manifold, keep the stock CT15B turbocharger but rebuild with steel shaft and HKS actuator to run at 1bar (14.5psi). Keep the stock 1JZ-GTE engine management but go for a slight chip-tuning (fuel economy oriented) with speed governor (180km/h) removed. Maybe go for the HKS cold air intake and HKS Silent Hi-Power exhaust. Use the 440cc injectors and stock intercooler from JDM 2JZ-GTE VVT-i -- got for free from a friend as surplus of upgrading his GS300 JZS160 (with Aristo V300 2JZ-GTE swapped). Keep the stock 1JZ flywheel and clutch to mate with the R154. An estimate of the overall power will be around 350hp / 260kw and 500Nm. We'd like to know if this plan is practical, and / or if we need any improvements on that plan? Many thanks in advance
Don't bother with the 1JZ pistons and oil squirters, the 2JZGE setup is fine at that level. They're only needed if you were going to run 20psi+ Don't bother with the diff either, nothing really to be gained unless it's the same sized crown wheel (7.5 or 8) and it's a LSD and the IS300 is an open. Don't bother with the Verossa brakes either Grab the driveshaft from the Verossa too I'd be surprised if the 1JZ computer will run 440cc injectors on a 1.5JZ and be driveable, but budget for a piggy back fuel controller like an Apexi SAFC and a good road tune at the least
Much appereciated. I'm pretty much sure that the differential is a TORSEN LSD. The driveshaft is longer than the IS300 driveshaft and we'll have to cut and weld it. We're already working on the oil squirters because reliability is our first priority -- that's why we ordered a steel shaft for the stock CT15B turbocharger as we are going 0.9~1bar (13~14.5psi). We're also worried that if we need a bigger intercooler cause the Aristo intercooler is quite tiny -- but not too large to be visible as that would cause trouble. If the 1JZ computer won't run 440cc injectors we would have to find a cheap computer that would allow us to use the 440cc injectors. Also we planned to get some structual reinforcement, including a strut bar and a custom made X-shaped crossbar at the trunk -- as the rear seats are not foldable. Now we're worried if the stock IS300 brakes are strong enough and do we need a brake upgrade. Anyway, the progress is good up to this stage.
Driveshaft front halves should be able to be swapped over but do some checking on this. You could just get a FMIC kit and paint everything black if you want it not to stand out. Otherwise the factory Aristo intercooler is sufficient at those boost levels. Did you read what i said about the SAFC? That should allow you to run the 440 injectors on the stock ECU as cheaply as possible, otherwise you're looking at an aftermarket ECU with full wire in or adapter harness (ie Haltech) but that is overkill at 350hp / 1bar Your obsession with reliability at those power levels is a bit strange tbh. There are examples out there of stock bottom end N/A 2JZ engines pushing 450hp / 20 psi reliably so 350hp / 1 bar is an absolute doddle. Don't bother with the trunk reinforcement, you haven't mentioned it will do anything other than road driving so the factory chassis will be fine for that. If you were running 800nm+ of torque and 265 semi slicks in competition drifting then yes, otherwise it's utterly pointless in a road car. Fresh, high temp brake fluid and uprated brake pads on the factory gear will be more than sufficient if (by the sounds of it) cost is an issue. Otherwise consider using LS400 front calipers and discs, but will require an adapter kit to fit (plenty on the market)
Thanks a lot. The SAFC is a good idea so maybe we won't need a new computer but we're already going to drill the holes and install the oil supply for the oil squirters. However we're not sure about the difference of brakes between the JCE10 and the JZX110. My friend loves touge driving (not necessrily drifting) and this car is more likely to be built for that purpose -- kinda casual way, not really a serious drifter. Anyway the cost won't be too high and we are just building this car for fun.
