That's what it was IJ, the bottom of the bores had to be clearenced for the extra stroke, there was also a rod that was hitting the area were the oil pump mounts that had to have a little taken off. Thanks for jogging my memoryIJ.;1226666 said:
Discussion on the potential of the 7MGE
- Thread starter dexterrogers
- Start date
Potential of the 7MGE IMO:
It doesn't have much potential in stock form because it's already well made. The intake is pretty good, the exhaust manifold is pretty good, it's got ACIS, etc. All the changes you make won't make that much of a difference until you change the internals and other major parts around. Even changing around the most restrictive part of the car won't do much (Exhaust). You'd have to raise the compression, etc.
The biggest weakness of the 7MGE is the car that it came in. The MKIII is too heavy to move that fast with just the 7MGE so putting it into an MKII would be great. That's easily around a 500-600 lb difference in the car. If you gut the MKII or do mods that make it even lighter (Fiberglass/Carbon Fiber stuff) then it'll be great.
It doesn't have much potential in stock form because it's already well made. The intake is pretty good, the exhaust manifold is pretty good, it's got ACIS, etc. All the changes you make won't make that much of a difference until you change the internals and other major parts around. Even changing around the most restrictive part of the car won't do much (Exhaust). You'd have to raise the compression, etc.
The biggest weakness of the 7MGE is the car that it came in. The MKIII is too heavy to move that fast with just the 7MGE so putting it into an MKII would be great. That's easily around a 500-600 lb difference in the car. If you gut the MKII or do mods that make it even lighter (Fiberglass/Carbon Fiber stuff) then it'll be great.
IMHO
The downfalls in the 7M design are.
1. Due to the undersquare design (small bore long stroke) the engine output at high rpm is limited. This is due mostly to small valves relative to the cylinder capacity and the high average piston speed at high rpm.
2. Other factors are the inlet ports are more side draft in design than down draft. The best 4V heads have inlet ports that are designed with a large downdraft angle.
Other than that the remaining issues are just to do with reliablility.
Such as headgaskets, rod knock, and cam bearings.
The downfalls in the 7M design are.
1. Due to the undersquare design (small bore long stroke) the engine output at high rpm is limited. This is due mostly to small valves relative to the cylinder capacity and the high average piston speed at high rpm.
2. Other factors are the inlet ports are more side draft in design than down draft. The best 4V heads have inlet ports that are designed with a large downdraft angle.
Other than that the remaining issues are just to do with reliablility.
Such as headgaskets, rod knock, and cam bearings.
What chokes? I get 35-36mm on the 45s to fit a 7M to stock redline fairly well. How is the tuning going? I bet it runs quite well
MrWOT;1246704 said:What chokes? I get 35-36mm on the 45s to fit a 7M to stock redline fairly well. How is the tuning going? I bet it runs quite well
?? Huh?
Hey sorry, I fell off the side of the planet, took me a while to find my way back. The chokes are 36mm, it revs up very nicely but is slower on the return, I'm wating to get a wideband to do some more tuning, in the meantime I've been tucking the wires and cleaning up the engine bay. I'm feeling it's running rich, judging by the plugs and jet engine-esk exhaust haha
hey just wanted to say thanks to everyone for the input, as she progresses I'll be sure to give updates.
Not to get out of topic but why not completely rebuild that 7M and drop that baby in 1985-1994 Toyota Pickup! It's WAY less weight than our Supra's and if I'm not mistaken, you could order a set of motor mount brackets from BIC Performance and you can surely see some serious horsepower free'd-up from our heavy-ass MK3's!!! Just 2 sense!
quick question what about a 87mm bore and an 11.5:1 comp ratio? strictly theoretically, assuming decent internals and whatnot, what kind of power? what would be the max bore for a 7m? just curious.
This looks promising........if you have mass quantities of money laying around.........
http://www.importperformanceparts.net/imports/strokerkits_toyota2.html
http://www.importperformanceparts.net/imports/strokerkits_toyota2.html
Seriously doubt even the heavy block would go 87mm and not have issues.
(that and 250cc ISN'T going to make an NA a firebreather)
(that and 250cc ISN'T going to make an NA a firebreather)
Tire Shredder;1224921 said:
True.
The restriction is displacement and fixed cam timing. That is why it is popular to use a turbo. You are making the engine bigger.
The best inline six I can think of off the top of my head is the last BMW with 335 flywheel horsepower. That was with a lot of rpm. And variable cam timing and lift, so that low end power was not lost with the high rpm head and cam profiles.
If someobdy does it, like defiant, ported the head to be more like a group a head, custom cams with more lift and duration, more compression, you can get over 300 hp. But you are limited by the displacement. As poodles mentioned already, torque x rpm. Torque is a function of displacement. I would also use a custom made long tube 6 into 1 header, and an extrude hone manifold. I am not sure about the ACIS after porting the manifold. Maybe custom, getting rid of the valve, but keeping the y pipe for more volume to the plenum.
Jervis Mcstabby;1221045 said:
The head isnt perfect, the intake angle of attack is less than desirable, but can be compared to the bigport 4age head. And from the factory there is massive valve shrouding and lots of excess material to be removed. However it is very workable and you can find some serious gains.
I think you are gonna find alot of gains right in the head. All of the toyota designs I have worked with have major casting flash, and protrusions that need to be addressed. The seats need to be honed cut, and blended into the combustion chamber and port.- There are major gains to be had focusing on the areas around the seats. You will gain lots of torque focusing around the seat/combustion chamber. This will improve low lift flow.
All of the flash should be removed.
The exhaust ports are only flowing about 66 percent of the intake which means they should be opened up about 10-12 percent larger, for a good breathing NA 75-78 percent of the intake side. Take off minimal amounts of aluminum on the combustion chamber side, because these areas are going to keep your compression high. Just do a blend from the seats to the head on the combustion chamber side. But go wild on the exhaust ports (leave some material on the head to prevent reversion). Intake side, just clean the flash. OS exhaust valves are a must for NA power, as the stock ones are too small. The stock cams are tiny compared to whats out there 7.6 lift and 199 duration is pretty small. The headwork combined with serious cams will net you serious power.
256 + cams and high lift will give you what you want, 272s might lope, and may be as large as you can go with the stock AFM. (it might be different than a 4age)
I would go shimless which will be good for valvetrain weight loss, and massive cams without flicking a shim.
Do all this and smooth out the runners and of course the other boltons mentioned (Adjustable pulleys), and you will see some serious gains.
I personally wouldnt worry about the bottom end until you get the head flowing up to what you want.
I think you are gonna find alot of gains right in the head. All of the toyota designs I have worked with have major casting flash, and protrusions that need to be addressed. The seats need to be honed cut, and blended into the combustion chamber and port.- There are major gains to be had focusing on the areas around the seats. You will gain lots of torque focusing around the seat/combustion chamber. This will improve low lift flow.
All of the flash should be removed.
The exhaust ports are only flowing about 66 percent of the intake which means they should be opened up about 10-12 percent larger, for a good breathing NA 75-78 percent of the intake side. Take off minimal amounts of aluminum on the combustion chamber side, because these areas are going to keep your compression high. Just do a blend from the seats to the head on the combustion chamber side. But go wild on the exhaust ports (leave some material on the head to prevent reversion). Intake side, just clean the flash. OS exhaust valves are a must for NA power, as the stock ones are too small. The stock cams are tiny compared to whats out there 7.6 lift and 199 duration is pretty small. The headwork combined with serious cams will net you serious power.
256 + cams and high lift will give you what you want, 272s might lope, and may be as large as you can go with the stock AFM. (it might be different than a 4age)
I would go shimless which will be good for valvetrain weight loss, and massive cams without flicking a shim.
Do all this and smooth out the runners and of course the other boltons mentioned (Adjustable pulleys), and you will see some serious gains.
I personally wouldnt worry about the bottom end until you get the head flowing up to what you want.