[suprathepeg]

Hey all I need some advice. I just bought an 86 4runner and 5spd and 22re. being as sickas I am I have already baugh the first lift kit and am planning an engine swap. I'l like to swap in either a 5mge or a 7mge I want to increase the power but want to keep it at or just under 200hp. Being that I don't need to max out the power of these engines I want to know how best to maximize their fuel economy?

I am more interested in the amount of torque that these engines make from the factory and their long power bands. I am looking for solutions byond intake and exhaust. Can any of you pros out there help?

 

[SupraFiend]

well I'm guessing a 7mge would be little more fuel effiecient, not just because its newer technology, but because it makes more torque too. Torque is the key to fuel economy. Do what you can to boost your torque levels and get some nice low rear end gears and you'll get excellent milage on the highway. In that line of thought, keep the exhaust at 2.25 inch and do what you can to open up the intake. Ditch the clutch fan too. If your really serious about getting wicked milage, go standalone. Actually, if you go 7mge, you can use the Techtom system (fairly cheap, Reg Reimer sells it. Sub $500) to change the oem fuel maps. A wideband would be advisable.

 

[suprathepeg]

what is the techtom?

 

[DriftMe]

I have a question... the 7M-GE, that is 24-valve correct. Can the head off of that be used on the 5M-GE, or will the combustion chamber be too large and severly drop the compression because the 7M-GE has as larger displacement?

 

[suprathepeg]

Swapping the heads is fine however you will need to swap over all of the electronics from the 7m to make it work. At that point you may as well have just bought a 7mgte and swapped that in.

 

[DriftMe]

what do you mean by, "all of the electronics"?

 

[suprathepeg]

Basicly everything you would have to do to swap in a 7mgte. Harness, ecu, everything. Essentially the head is the only real differance between a 7m and a 5m. If you are considering doing this I would suggest you spend the extra $500 and do a 7mgte.

I am planning a 7mge swap into my 86 4runner rather then a 7mgte only cause I don't need the extra 50+hp and I don't want the turbo to break when I am 2 feet deep in the mud.

 

[zank]

Swapping the heads is fine however you will need to swap over all of the electronics from the 7m to make it work. At that point you may as well have just bought a 7mgte and swapped that in.

dont you also have to change the pistons on the 5M if you were to put in the head of the 7M? Just something I read a while back :wink:

 

[suprathepeg]

I'm not sure about that but it sounds like it could be true. Come to think of it I think I heard that before too.

 

[zank]

I'm not sure about that but it sounds like it could be true. Come to think of it I think I heard that before too.

the 7M head has 4valves per cyl and the 5M has only two valves per cyl. I think the grooves in the Pisotns would not match? :? someone correct me on this if im wrong, please. BTW this topic has been discussed many many many times, I just never looked into it

 

[SupraFiend]

techtom is a rom burning or flashing, not sure which, system for 7m and 2j computers. It allows you to program your own fuel and timing maps into the stock ecu. And yes Zank, you are right. You might actually be able to make the engine run with 5m pistons and 7m head, but if the timing belt broke or you played with your timing too much, you would have a nasty mess on your hands. No real advatange to 7m head on a 5m block, but the other way around is another matter....

 

[DriftMe]

I think you got that wrong, 4-valves on any motor is better than two large valves. I won't get into the details, but I think I'll stick to the 5M-GE for my purposes. How many MPG should a fairly new 5M-GE get according to specs.

 

[suprathepeg]

Some have said 20 - 25 mpg depending on gearing. I have heard that the 7mge is better.

 

[RWDCelicadude]

You also have to remember that in a truck you'll get much worse mileage than in a supra, even if you have the same motor. The truck weighs more and on the freeway pushes a lot more air, causing the motor to work harder, not to mention turning taller tires with more rolling resistance, etc, etc. If you wanted a good mileage car find the 22RTE out of the same year 4runner and swap that in, you can easily get 200hp out of it. I guy I saw had a mildly boosted 22rte with 204hp and 235lbft at the rear wheels in his 4runner. The 7MGE is a nice motor but don't be to hasty to drop the 22RE.

 

[suprathepeg]

I thought about that but the cost of a solid 22rte is probably about $2000+ CDN more then a 7mge and I want something that I won't have to worry too much about out in the bush otherwise I would just add a turbo to the current 22r.

 

[SupraFiend]

I think you got that wrong, 4-valves on any motor is better than two large valves. I won't get into the details, but I think I'll stick to the 5M-GE for my purposes. How many MPG should a fairly new 5M-GE get according to specs.

No I didn't, you are partially wrong and you misinterpreted what I said. When I said theres no advantage I was refereing to a 7m head on a 5m bottom. Its the same amount of work to get a 7m head working on a 5m block as it is to just swap in the whole 7mge, less actually. Then you get the dissplacement bump, the right pistons for the head and a newer bottom end. As for the 2 valve bit, your also wrong. 2 bigger, beefier valves are stronger and allow more flow then 4 little valves, not to mention it makes a cheaper and easier head rebuild. Now the benefits of a 4 valve head on an NA engine probably overweigh those strengths, but its a whole other matter on a heavily boosted engine. A 7mgte bottom with 5m or 6m head would be a wonderful combination.

As for the worse gas milage in the truck, its hard to say. Definatly worse wind resistence, but those old toy trucks aren't that heavy, and our cars aren't exactly paperweights. Keep in mind gas milage is directly proportionant to RPM and load. The more torque you have to play with, the lower final drive ratio you can run with a lower rpm at the same speed. Bigger tires will travel a longer distance at the same rpm. 5mge swaps are pretty common on old toyota pickups, and when the 4bangers are swapped out for them they usually get better gas milage as the motor doesn't have to work so hard to move the truck. A gutless 4 cylinder will be working under max load to keep a vehicle like that going, while a torquey 6 cylinder will be just cruising at low rpm.

Supra motors are pretty common swaps in toyota pickups, check around for some forums on those trucks and there should be plenty of info out there on this. The diff I'm putting in my supra came off a supra that was having its 5m swapped to a pickup.

 

[DriftMe]

As the 5M-GE comes in the Celica Supra in a normally aspirated form, that is why I don't like two valves per cylinder. Want a better explanation, I wouldn't mind. Simply though, until I know of what material the valves are I'll assume that they're forged a decent quality aluminum alloy.

My main problem with having two large valves of most any material is that the greater surface area of the valve face is going to absorb a lot of energy, heat, from the combustion. Having a very large intake valve will pose a greater problem because this also offers a large surface area in contact with the air/fuel mixture prior to ignition. This can lead to a transferrance of energy from a combustion to the valve and then into the intake charge prior to the next combustion. In any motor's form this is detrimental because the heated intake charge will now be more prone to pre-ignition. It is also possible for the air density to change within the head's ports prior to it's passing into the combustion chamber. If this occurs it is theorhetically possible that the high pressure air within the ports to be acting against the low pressure air traveling through the runners and into the head ports, this can create further turbulence and a loss of air stream velocity.

 

[Dave A.]

You could supercharge the 22R and get loads of bottom end torque and pulling power and still get decent MPG. The cost to add the blower would probably not be cheap though! The 22R is a lighter weight engine and a pretty stout engine as well.